Next Meeting: Friday, February 3, 2017
Open to the Public: TAAA encourages the public to join our general meetings held on the first Friday of the month in the Steward Observatory Lecture Hall (Room N210) on the U of A Campus.
Location: USGS Building, Room 253 (520 North Park Ave)
Contact: Dennis McMacken
OPEN TO THE PUBLIC.
Come and learn your way around the night sky to add to your observing enjoyment. Meetings are on the second Thursday of each month.
In the classical Niels Bohr model of the atom, the one that we were taught in first-year chemistry, electrons whorl around the nucleus in what appears to be an analog of a miniature model of our solar system. In the four dimensional atom (I have included the time dimension) electrons occupy a fuzzy area— the electron cloud— of a specific orbital. These orbitals are not arranged in a “plane of the ecliptic” flat fashion like the planets in our solar system (please note that many minor planets of the Kuiper Belt do not occupy the plane of the ecliptic) but within clouds that appear balloon-like and spreading in all directions from the nucleus. To make it clear, the electron cloud is not a physical bellowing, misty mass of suspended particles or smoke but the area of uncertainty occupied by the electron. The true whereabouts of the electron is unknown; defined by the Heisenberg uncertainty principle which states that we can measure one of a subatomic particle’s properties — location, speed or direction — but not all three. Measuring one will change the others.
Each orbital of the atom has a specific maximum number of electrons that can occupy it. Within the atom electrons jump from one orbital level up to another and then return back again, analogous to children bobbing around on a trampoline. As electrons return to their original ground state (the children descending to the head of the trampoline) they release a packet of energy known as a photon—light. The activities and numbers of electrons of each chemical element or compounds release a specific light signature that helps us to identify that chemical or compound and the nature of its behavior. These light signatures encompass a broad gamut of energies known collectively as the electromagnetic spectrum.
Over millions of years, humans and other animals have evolved to develop specialized photon receptors: eyes. Although they are an ingenious invention, eyes are limited to a very narrow range of the electromagnetic spectrum that we call the visible spectrum. This is the bright, white light that is emitted by our sun and glows in the 5000°K temperature region. It is needless to say how invaluable this adaptation has been for us. Moving about on the surface of the Earth, this visible light range has helped us to perceive and adapt to our world, and manipulate our surroundings to our desires. For the majority of human existence, our eyesight provided us with evidence of reality and “proof” of matters that required validation.
Light has been so essential to our reality that over the millennia humans have coined a number of phrases to express just how important it is. Everyone knows “seeing is believing” and that light is truth. “I am the light…” Christ is quoted as saying in the Bible. “Children go into the light” is expressed by the psychic in the in Steven Spielberg’s Poltergeist. Light is both truth and good. When we want to be deceptive or keep something from someone else we keep them in the dark. Monsters lurk in the dark and hide under our beds when we are children. Scary movies play upon this to take advantage of our strongest primal fears. But we live in an age where we know “seeing” is not always believing and sometimes when we see something it is merely a ruse to keep us in the dark.
The curiosity and ingenuity of humans has led us to the discovery of the electromagnetic spectrum and the pursuit to identify exactly what light is and to understanding its behavior. But more importantly it has also led us to the awareness that seeing something with our eyes alone is not always the whole story. Nature does, in fact, keep most of her secrets hidden in a realm way beyond the limitations of our eyesight.
Located 1500 light years away in the constellation Orion is IC 434 and the associated Horsehead Nebula. The Horsehead Nebula itself is a dark absorption nebula that is very difficult to spot. Large aperture, an H-beta filter and careful hunting will help you to find it nested inside of its companion emission nebula, IC 434. IC 434 is believed to be excited by the star Sigma Orionis, the star at the eastern end of Orion’s belt. IC 434 appears as a cloud with streamers, of gas rising from it. In images the cloud glows pink because of ionized hydrogen gas. The streamers are believed to be the result of magnetic fields produced within the nebula. The Horsehead itself is a projection of the cloud and is a protostellar factory similar to the Pillars of Creation in the Eagle nebula.
In my research I have discovered that the expression “a horse of a different color” has been attributed to at least three different sources: Shakespeare and medieval knights. One source claims that Shakespeare was the first to use the reference of “a horse of that colour” to refer to the same matter, in his play Twelfh Night.
My purpose is, indeed, a horse of that colour.
And your horse now would make him an ass.
Ass, I doubt not.
O, ’twill be admirable!
Twelfh Night, Act2, Scene 3
According to that source, Shakespeare used this phrase several times in his writing, which the source believes indicates that the phrase “A horse of a different color” originated before Shakespeare’s time.
In today’s parlance the phrase refers to something of a different matter altogether. Since it’s unlikely that the true historical origins of the phrase will ever be known, I will lay claim to it in this article. I am employing the expression “a horse of a different color” to briefly describe the electromagnetic spectrum and its relationship to astronomical objects. In this example I employ the great stallion in IC 434.
Radio waves reside at the low-end of the electromagnetic spectrum and range in size from one millimeter to over 96 kilometers in length. They are the longest wavelengths of the electromagnetic spectrum and the lowest detectable energy. Because of their size, radio waves are unaltered by other types of light. They are also able to pass through most materials uninhibited and unaffected by the molecules of the substances through which they pass.
We are familiar with radio waves and their applications to communications, which includes radio, television and cellular telephones. Radio sources are naturally occurring too. On earth, lightning produces radio waves and in space all celestial objects emit them as products of atomic interactions. Nebulas, such as the Horsehead Nebula, appear as clouds of gas and dust in optical instruments. These clouds visually occlude stars and protostellar matter and prevent observations of objects within them.
Because of their long wavelengths, radio waves require large metal receiving dishes to focus them and achieve resolution. Today’s radio telescopes are combined into arrays of multiple large dishes — such as the Very Large Array (VLA) in New Mexico and the Atacama Large Millimeter \ Submillimeter Array (ALMA) in Chile. Radio telescopes can push back the veil of secrecy in celestial objects and reveal information about the location, density and motion of the gases — including hydrogen, which constitutes three quarters of all matter in the universe — in addition to studying Astrochemistry, the chemistry of astronomical objects. It reveals nascent stars forming within the hydrogen columns of gas and dust that create the fingerlike extensions seen in close-ups of nebulae.
Of course, radio astronomy is applicable to all celestial objects and in my example I use IC 434 to demonstrate how these invisible wavelengths of light can help us to examine the structures of the universe. IC 434 is an emission nebula over which a dark absorption nebulosity is laid. The structures of celestial objects beyond the visible spectrum of light are color-coded in Representative Colors (sometimes referred to as false color) by scientists to help them understand the processes and composition of them.
Using the 30m radio telescope near the Pico del Veleta in the Spanish Sierra Nevada, astronomers have discovered hydrocarbon molecules within the Horsehead Nebula. Here on earth, these molecules provide humans with their primary source of energy (in addition to their primary problems of global climate change). Examinations have revealed 30 different hydrocarbon molecules — more than 200 times the total hydrocarbons available on earth! These molecules, like much of the nebula itself are eroded away by the ultraviolet light from the star that powers of nebula.
Microwaves are wavelengths of electromagnetic radiation that range from 1 millimeter to 1 meter in length. Some sources include them within the radio wavelengths of the spectrum, however their name indicates that they are smaller, more compact waves than those of typical radio broadcasts. While microwaves do have applications in communications, such as cellular and satellite, in addition to microwave cooking and radar, microwaves are also emitted by cosmological sources. Radio telescopes, such as the Atacama Large Millimeter \ Submillimeter Array in Chile are able to tune to the smaller wavelengths and study everything from the cosmic microwave background, to galaxy formation, stellar and planetary formation and the composition of planetary atmospheres within solar systems.
In nebulae, such as IC 434, microwave analysis can be used to study protoplanetary systems and their formation and to discover and analyze organic compounds. Combining the light of x-ray and visual astronomy to microwave imaging provides a more complete picture of how galaxies, nebulae, supermassive black holes and all other cosmological objects work. Microwaves can reveal invisible extensions in cosmological objects, such as the outpouring gases from supermassive black holes, in greater detail than other wavelengths of light.
Just below the visible red portion of the spectrum, between wavelenghts of 30 centimeters and 740 nanometers (a nanometer is 1 billionth of a meter), resides infrared light. This bandwidth covers more than 1000 times the range of the visible spectrum of light! We are familiar with infrared light as heat that warms our skin on a sunny day or rises up from our cooking devices. Some sources divide the infrared portion of the spectrum into several divisions but astronomers generally speak of infrared as near and far.
At the near end of the infrared spectrum lies light of low intensity. We generally use this light for broadcasting through fiber optics and controlling channels from a remote, such as your TV remote. Everything operating at a temperature of about 268°C (514°F) and above emits infrared radiation. More than half of the energy coming from our sun is in the infrared wavelengths. Even the light bulbs in your home emit most of their energy as infrared light.
Infrared light is easily absorbed by water vapor, therefore astronomers have to place telescopes in very high and dry locations in order to be able to detect and analyze the near infrared portion of the spectrum. The far infrared portion of the spectrum never passes through our atmosphere. Therefore, the best location for analyzing the infrared spectrum is from space-based telescopes. Over the past few decades advances in CCD imaging has allowed for detailed observations of celestial infrared sources.
Due to its longer wavelengths, infrared light is subject to less scattering through the gases and dust of interstellar space. This allows astronomers to make discoveries inside of structures such as galaxies and nebulae which would otherwise be obscured by the clouds. Infrared light can also be emitted by objects that are otherwise too cool to radiate in visible light. Because of this property astronomers have discovered objects such as the streamers of dust in IC 434 and other nebulae, in addition to asteroids, comets and other objects too cool to be picked up by visible light astronomy. Infrared detection has allowed astronomers to cut through the dust lanes of the Milky Way and reveal structures on the opposite side of our galaxy. Infrared astronomy is also applicable to the study of planets and Astrochemistry.
In the visible light spectrum, our eyes see IC 434 as a grayscale image. Our eyelids are designed to flicker several times per minute, like the shutter on a video camera, to help us see moving objects; to avoid becoming prey or to capture prey. This adaptation to survival on planet Earth has rendered us virtually colorblind to deep space objects. Unlike the shutters on our cameras, our eyelids do not remain open long enough to saturate our retinas with the light coming from nebulae such as IC 434.
Our cameras, however, are capable of leaving their shutters open for lengthy periods of time, in addition to being sensitive to fainter emissions, and saturating the photoreceptors of our digital chips with the low intensity light of deep space objects until we can render an image of intense color. This compensation for nature’s adaptation to survive on our planet has allowed us to study and appreciate these cosmological horses of a different color. Where a nebula such as IC 434 is spread out over such a broad swath of space, reducing our eye’s perception of it, our time exposures compensate and gift us with an awesome image that we only wish we were capable of seeing in the full colors of the cosmological palette. Moreover, these colors reveal a great deal about the mechanisms of nebulae and the stars that created them.
Undoubtedly, the discovery of the spectrum and the invention of photography which followed (the discovery of the Camera Obscura not withstanding) led to a craving among scientists to find out whether more secrets of the cosmos lay hidden deep within the invisible parts of the spectrum. Even the early black and white plate photographs revealed previously hidden characteristics of cosmological objects. In addition, the beginning amateur astronomer must realize, at least to some degree, the impact that photography has had upon astronomy. One can only imagine the amazement that astronomers themselves felt when they looked upon those early photographic plates.
But this does not devalue visual observation! In the centuries preceding photography — including the centuries preceding the development of the telescope — careful observation honed the analytical skills of astronomers and opened up a whole new universe to humankind. There is a special visceral experience that only visual observation can offer a type of “seeing is believing”. If you are a casual observer — that is if you are not an astroimager — then you have to tease out details in celestial objects with patience and persistence. IC 434 and the Horsehead Nebula will challenge your patience and persistence.
Another source says that the phrase “A horse of a different color” originated from jousting medieval knights who rode horses of different colors to identify themselves to their supporters — much in same way as modern sports teams wear different uniforms to identify themselves to their fans. The third reference says that the phrase derives from the gambling habits of medieval knights. “A horse of a different color” implied that the opposite gambler or team had won a bet.
Spanning a range of 380 nanometers to 10 nanometers is the ultraviolet portion of the spectrum. Ultraviolet light falls into a frequency range between visible and x-rays. We are familiar with some of this spectrum because of the warnings issued about damage to our skin and cancer. However, the majority of ultraviolet light does not reach Earth’s surface. Ultraviolet light is divided into three sub-bands: UVA, UVB and UVC (far ultraviolet). The wavelengths from 10-180nm range propagate only in a vacuum and are referred to as extreme wavelengths. UV radiation possesses enough energy to cause atoms and molecules to ionize by stripping off electrons that would otherwise keep them bound to each other. It results in the breakdown of chemicals that would otherwise remain stable. This makes UV light harmful to life but renders the colorful gases we see in images of nebulas, such as IC 434.
Since most of the UV frequencies are absorbed by the upper atmosphere, ultraviolet astronomy is performed by satellites, either in Earth orbit or in space. In addition to the sun, numerous celestial objects emit ultraviolet light. Large young stars are a significant source of these wavelengths. Ultraviolet light helps to reveal details in planetary atmospheres and highlight filaments of gas that can be found in nebulas. Ultraviolet measurements of inter-stellar gas clouds is used to understand densities, temperatures and chemical compositions of stars and galaxies. If the Milky Way galaxy was viewed in ultraviolet light most of the stars would disappear.
My first recollection of the expression “A horse of a different color” is from the 1939 movie the Wizard of Oz, starring Judy Garland as Dorothy. When Dorothy and her dog Toto, along with the Straw Man, the Cowardly Lion and the Tin Man arrive at the gates of the Emerald City they have trouble convincing the guardian of the gates to let them in. They finally convince him that they just have to see the wizard, to which he replies:
“Well, bust my buttons! Why didn’t you say that in the first place? That’s a horse of a different color! Come on in!”
Once inside the Emerald City, they find themselves riding on a horse drawn carriage. The horse changes colors as it pulls them around the city. Dorothy remarks that she has never seen such a horse before and asks the driver what kind of horse it is, to which the driver responds:
“No, and never will again, I fancy. There’s only one of him, and he’s it. He’s the Horse of a Different Color you’ve heard tell about.”
Ranging above the ultraviolet spectrum between wavelengths of 10 nm and one pico meter (a pico meter is one-trillionth of a meter) are the x-ray bands of the spectrum. X-rays are divided into two categories: soft and hard x-rays. Soft x-rays range in wavelengths of 10 nm to 100 pm and hard x-rays range in wavelengths of 100pm to 1 pm. Hard x-rays reside in the same wavelength of the spectrum as gamma rays. Gamma rays, however, are produced by atomic nuclei while x-rays are produced by the acceleration of electrons.
We are familiar with x-rays in their applications to medical diagnostics. X-rays are also used in the industry. As an astronomical tool, x-rays are used to examine neutron stars, pulsars, black holes or galaxy clusters. Massive, compact stellar remnants such as these strip material from companion stars and create discs of extremely hot gases emitting x-rays, as the gases spiral inward toward the cannibalizing star.
Our sun also produces x-rays within the chromosphere but it is not as strong as source as these other stellar objects. O and Wolf-Rayet type stars create strong solar winds, much stronger than those of the sun. These winds create shockwaves that heat their plasmas, which in turn emits x-rays. Long-term observations of these stars have revealed that the solar winds are confined by magnetic fields.
X-rays are damaging to living tissue. So while they are used in medical diagnostics and applications to the treatment and cure of cancer, they also pose a harmful threat and must be used judiciously. Fortunately for us, our atmosphere absorbs the x-rays from the sun and other celestial sources. The water vapor within our atmosphere is opaque to x-ray photons. As a result, it is necessary for us to build satellites and detect x-rays from orbit or deep space.
Occupying a frequency of less than 100 pico meters, in the hard x-ray range of the spectrum, are the gamma rays. Gamma rays are usually produced through the nuclear reactions of fusion, fission, alpha decay or gamma decay. Astronomers generally define gamma rays by their energies without specifying the processes that created them. Extremely powerful outbursts of gamma rays, known as Gamma Ray Bursts (GRBs) are energies exceeding those of radioactive decay. Astronomers believe that these GRBs are produced by the collapse of stars into explosions known as hyper-novas.
Because gamma rays are unable to penetrate Earth’s atmosphere — an advantage to life on our planet — it wasn’t until 60 years after their discovery that theory of gamma ray production by cosmological objects was confirmed. In 1963 the United States Air Force launched the Vela satellites with the mission of monitoring nuclear tests by the Soviet Union during the height of the Cold War. The satellites flew at altitudes of up to 65,000 miles above the earth. The Vela satellites carried detectors not only capable of finding gamma rays but determining the direction they were coming from. Much to the scientists’ surprise, they were finding gamma rays from outside of our solar system. They had discovered the first Gamma Ray Bursts (GRBs).
In addition to space-based probes, gamma rays are detected by measuring the interactions of cascades of particles as they pass through the upper atmosphere. Through this analysis, astronomers are able to trace the gamma rays back to their source of origin. Astronomers also use gamma ray detection for determining elements on other planets in our solar system. Gamma rays are also produced within the sun when high-energy particles collide with material in the sun’s atmosphere. When cosmic rays strike the surface of the moon they blast apart atoms and molecules within the lunar surface. This also produces gamma rays.
Highly magnetized, spinning neutron stars — pulsars — produce powerful electrical fields, millions of times more powerful than lightning on earth. These fields create showers of high-energy particles that result in beams of radiation of wavelengths from radio waves through gamma rays. Some of these pulsars are found powering nebulas. M1, the Crab nebula, is powered by a fast rotating pulsar that sends out beacons of electromagnetic energy.
As amateur astronomers, we have few means at our disposal for examining the entire electromagnetic spectrum. We do, however, have at our disposal numerous references for studying the universe that is invisible to us. It is our curiosity and passion for astronomy that drives us toward a deeper understanding and appreciation of the celestial objects we view through our telescopes. By combining what we learn about the cosmos with what we see through our telescopes we can employ both our eyesight and the minds’ eye to really see the vast and incredible universe that unfolds before us every awakening day.
It is my hope that I have instilled in you a desire to eagerly venture into the cosmos with an insight that will permit you, from this day forward, to see the unseen, to see, as it were, the light. I am willing to wager that during your next stargazing session your combination of passion, curiosity and love for astronomy will have you seeing all of your subjects as you have never seen them before. That’s a horse I’m willing to bet on.
This time of year always seems to carry with it a certain atmosphere. The holidays bring a dramatic change in people — both good and bad — along with the change in the weather. As a child, I remember this time of the year for all the holiday festivities and the specials that ran on television. One of my first experiences with a holiday story was the black and white movie version of Charles Dickens’, A Christmas Carol, starring Alastair Sim. This reverse version of Dr. Jekyll and Mr. Hyde, where Mr. Hyde turns back into Dr. Jekyll, was a stirring demonstration of two of the greatest human emotions: love and compassion! In the story a bitter old miser named Ebenezer Scrooge is transformed into a kindly and gentle soul after the visitation of the ghost of his former business partner, Jacob Marley, and three spirits who represent the ghosts of Christmas past, present and future.
As I sit here writing and listening to the music of Bob Marley (I don’t have any works by Jacob) I am reminded that I have to complete an article for December. Bob Marley may not be appropriate Christmas music but he does remind me of Jacob and that moving story by Charles Dickens. So here I am to haunt you with the forecast that this Christmas you will be visited by three spirits: the ghost of Stellar Past, Stellar Present and Stellar Future—all in one night. In their presence and enlightened by the knowledge of their workings I hope that you will be transformed into a new man. May the spirits move you and forever transform the way you see the universe.
Now that you have made it through the Thanksgiving holiday and are hoping that Santa is going to bring you a workout video, let’s start with a workout warm-up by lifting and toting that telescope. 1 and 2 and lift and carry and set up the tripod; 3 and 4; and collimate and…
There’s really nothing like a good workout to get the heart pumping and keep the joints flexible. But we are also going to workout our eyes and brains as we ponder the celestial objects overhead.
Wintertime brings on a great deal more than an opportunity to test your mettle against the frigid cold of the season. Darkness falls early this time of the year, so it’s easy to get outside and see many of the spectacular objects of December. In a single night, my neighborhood becomes haunted by the ghosts of stellar past, stellar present and stellar future. I’m no Scrooge! Every December, around Christmas, I pull my telescope out of the closet and set it up in front of my house to present the entire neighborhood with a Cosmos Carol. What could be a better and bigger gift than offering everyone the entire universe?
But I have a real star Party! I purchase bulk cookies, hot chocolate and coffee and have a microwave handy to warm the milk for the chocolate and a coffee marker for fresh coffee.What could possibly complement a good workout better than hot chocolate and cookies? I have a portable radio handy and put on some music to create ambiance for the evening. You can start the evening with appropriate stargazing music, such as the Planets by Holst or you may choose to create a compilation of astronomy related music. For me, music and stargazing goes hand-in-hand.
Ebenezer’s transformation from Mr. Hyde into Dr. Jekyll centers on a couple of supporting characters that include his clerk, Bob Cratchit and his entire family, and Ebenezer’s nephew and his family. Scrooge is visited by the spirit of Marley who informs him that he will be visited by the ghost of Christmas past, present and future to be shown the error of his ways and given another chance to make things right. As a reformed man, he wakes up to a new day — Christmas Day — with a brand-new heart.
Ebenezer had to wait until the clock struck 1 AM before he was able to start his journey to becoming a transformed man. You will be able to start your journey as soon as the sun goes down and your telescope is set up. Ebenezer’s journey to New Manville begins with a visit by the ghost of Christmas past, who shows him the pain and tragedy of all the things that Ebenezer missed — including lost love — during his youth. The universe is far kinder to us because light travels at a fixed rate of speed and we are able to journey into the past by simply pointing our telescopes anywhere. In essence, we haven’t missed anything from the stellar past. Nature offers up her secrets if we look far enough across the cosmic ocean. But the ghost of stellar past does reveal to us that there is pain and tragedy in the death throes of stars!
The Ghosts Of Stellar Past
Located 1500 light years from Earth in the sword of Orion’s belt is M42, the Great Orion Nebula. This combination reflection and emission nebula is the product of an enormous explosion of an old red giant millennia ago. When the fuel of that star was exhausted, its outer layers succumbed to gravity and collapsed into its core within a few seconds, until the atoms could no longer crowd together. With the explosive force of thousands of hydrogen bombs they were shot away at supersonic speeds into interstellar space.
The result is an expanding cloud of dust and gas that today occupies an area of 24 light years across by 50 light years high. As the cloud continued to expand outward at supersonic velocities the gases and dust crashed into one another further compressing them to form more complex molecules, including the organic molecules of living things. The death of the red giant mother that led to the creation of M42 also gave birth to new stars and nascent solar systems. Within M42 there are 700 known stars, 150 of which possess protoplanetary disks. These stars are at various ages of formation with the youngest and brightest members believed to be only 10,000 years old and the oldest no older than 300,000 years. Within dense cocoons of gas new protostars are
At the center of the nebula is a collection of four stars that form a trapezoidal shape known as the Trapezium. These four stars emit light in the ultraviolet region, exciting the surrounding gas and causing them to glow in the brilliant colors we see in images of the nebula. At the same time, the energy of the stars is carving a cavity within the nebula and causing many of the young stars to erode away. The nebula is both mother and cannibal!
Dark, cavernous areas within the nebula contain BOK globules. This is protostellar matter that will collapse under the forces of gravity to ignite as stars. In addition to the young, hot stars, the Hubble space telescope has spotted numerous black dwarfs within the nebula. These objects are too small to become stars and remain cold because they cannot sustain their cores way stars like our sun do. The Great Orion Nebula emits light predominately in the ionized oxygen region. You will find that an OIII filter will help you to pull out details of this stellar ghost.
M43 is a smaller nebula associated with the Great Orion Nebula and part of the entire structure known as the Orion complex. In images and shorter focal length eyepieces of our telescopes M43 seems to be attached to the Great Orion Nebula. It is also located 1500 light years from Earth in her prolific stellar nursery. Recent Hubble Space Telescope images have shown a lobe attached to M43 that is pushing back against the erosion caused by the ultraviolet radiation of the stars of M42.
Like a ghostly eye 2200 light-years away in the constellation Cygnus NGC 6826, the Blinking Planetary Nebula stares back at you through the telescope. This is a remnant of the star similar to our sun that grew to the red giant phase and then shed off its outer layers leaving a star of carbon and oxygen — a white dwarf — as a corpse. The gas layers expand into interstellar space and form a large bubble that emits light because it is excited by the ultraviolet radiation of the white dwarf at its center. Planetary nebulae result when low mass stars like our sun swell into a red giant phase at the end of their life. Instead of erupting in violent explosions, they shed their outer layers to create ghostly and beautiful clouds. Unfortunately, the white dwarf star that is left behind generates enough energy to quickly erode the nebula, and these types of nebulae have short periods of only about 10,000 years, as opposed to the billions of years of their parent stars.
Located 6500 light years away in the constellation Taurus is M1, the Crab Nebula. Like the Great Orion nebula, M1 is a supernova remnant, that has expanded to currently occupy a radius of 10 light years and is still expanding at a velocity of 1500 kilometers per second. Through the telescope M1 appears as an oval shaped mass of filaments. These filaments are the remains of the layers of the parent star’s atmosphere.
The beating heart of the Crab Nebula is a pulsar — a neutron star rotating at approximately 30 times per second. The pulsar is approximately 30 km across and emits radiation in x-ray wavelengths. This ionizes and excites the cloud of gas which is predominantly hydrogen and helium. The nebula is visible to telescopes with apertures as small as 4 inches but it glows at a magnitude of 9.0 and details of it can only best be experienced through a large aperture telescope. The pulsar beating at its heart is only visible through apertures of 20 inches or larger.
The supernova explosion that created M1 was witnessed by Chinese astronomers in 1054 A.D. It glowed so bright that it could be seen in the daytime and people could read by it at night for two months after the initial explosion. According to Chinese records M1 was the brightest object in the sky, next to the moon, and reached the magnitude of -7.0. It remained visible in the night sky for 653 days after its initial discovery.
The clock struck 2:00 and Ebenezer was awaken by the spirit of Christmas Present. Ebenezer was taken along the streets of the city and shown the tragedy of those who were less fortunate. He had walked among those streets every day and seen the suffering of the masses but he chose to remain blind to them and ignorant of the fact that if all men truly loved each other they could solve all human suffering. The second ghosts to visit us, the Ghosts of Stellar Present, will take us through the streets of our “star city,” the Milky Way, and show us some souls that burn brightly — in some cases upon other worlds. However, I caution you to not be complacent because even our star, the sun, could rear up an ugly head and deliver a storm that could one day leave us hoping for mercy. Humans may be cruel but nature has no concept of good and evil. Its cycle of destruction and creation are simply defined as “existence”.
Ghosts of Stellar Present
If you need to show a ghost of stellar present, you wouldn’t have to go any farther than your backyard. Our sun is an excellent example of a medium yellow star that burns brightly enough and long enough to sustain planets that harbor life. If you own a solar telescope or solar filter and you prefer to set up in the daytime, than the sun would be both an easy target and a well-known celestial object for presenting as a ghost of stellar present. But if you’re looking for a nighttime analog there are billions of type G stars in the Milky Way galaxy. First, we will start by talking about our sun. Regardless of any nighttime analog you may choose, the knowledge that you will glean about our sun will be applicable to understanding the stellar object.
Located approximately 93 million miles away is our star, the sun. The sun is the beating heart of our solar system and is in essence a hot, glowing ball of plasma with an influence that extends well beyond the orbit of Pluto. Without our sun there would be no heat or life here on earth. The gravity of the sun holds the entire solar system together. The sun generates an electrically charged magnetic field that is conducted throughout the solar system creating a stream of electrically charged gas — the solar wind — which travels through the solar system in all directions.
The sun’s interaction with our planets drive the ocean currents, weather, climate, our seasons, the radiation belt and the auroras. Although it is the only one we have, our sun is one of billions of yellow stars throughout the Milky Way. The sun and our entire solar system formed within a giant rotating cloud of gas and dust — a solar nebula — approximately 4.5 billion years ago. As gravity caused the nebula to collapse, it began to spin faster creating a flattened disk. Our sun was created when the bulk of the material, 99.8% of the mass of the solar system, was drawn to the center, and under the influence of gravity ignited to create our star.
Our sun is 1.3 million times the size of the earth! With a radius of 695,508 km and as much as 332,946 times the mass of the earth, our sun may seem like a very large star, but it is in fact an average star and there are many more that are several times larger. Different parts of the sun rotate at different velocities but at the equator the sun spins around approximately once every 25 days. At its poles, the sun spins around once every 36 days.
The sun’s mass, like all other celestial objects, is held together by gravity. The sun itself consists of six different regions: the core, the radiative zone, the convective zone, the photosphere (which is the visible region), the chromosphere and the corona. The temperature of the sun’s core is 27,000,000°F, a temperature that is hot enough to sustain thermonuclear fusion. At the core, atoms of hydrogen are fused (cemented together) to create helium and more complex elements.
The core creates energy to produce all the heat and light of the sun. The energy is radiated outward from the core into the radiative zone where it bounces around for 170,000 years until it can reach the top of the convective zone. In the convective zone the temperature drops to 3,500,000°F and large bubbles of hot plasma begin to migrate outward. Although the temperature of the surface of the sun is only 10,000°F it is still hot enough to create and boil carbon!
The photosphere is a 300 mile thick region from which most of the sun’s radiation escapes into space. In our eyes this radiation appears as sunlight and takes eight minutes to reach the earth. Above the photosphere is the chromosphere and the Corona, a tenuous, thin atmosphere. When we hear of or see solar flares and sunspots for ourselves, this is the area in which they occur. The light of this region is far dimmer than that of the photosphere and the only time that we are able to ever see it is during a solar eclipse. Ironically, the temperature in the sun’s atmosphere increases as the altitude increases — reaching as high as 3,500,000°F. The source of this heating is a scientific mystery.
The sun is a giant dynamo that generates a complex magnetic field that extends outward into interplanetary space. This region of influence is known as the heliosphere. A stream of electrically charged gas flowing from the sun carries the magnetic field into interstellar space. As the sun rotates, its magnetic field is churned outward in a giant rotating spiral.
The sun is not always a quiescent star friendly to life on earth. It goes through periods known as solar cycles, which occur approximately every 11 years. At that time the geographic poles of the sun change their polarity and the photosphere, chromosphere and corona transform from quiet and calm into violent. The height of this activity is known as the solar maximum. It is a time of sunspots, flares, solar storms and coronal mass ejections. They are the results of irregularities in the sun’s magnetic field and can release enormous amounts of energy and particles into space, some of which reach Earth. This space weather can damage satellites and affect the power grid, threatening the whole of civilization.
Forty light years away in the constellation Auriga is the giant double binary type G star, Capella (Alpha Aurigae). The two brightest stars of the system are type G, similar to our sun but about 10 times its diameter. The stars are orbited by smaller red binary companions. The two main stars are separated by only about 60 million miles, two-thirds the Sun-Earth distance and orbit each other every 100 days. Both the A and B stars are about 80 times as bright as our sun. Because of this, the system would be too hot to harbor complex life like that of Earth. Nevertheless, Capella is a good nighttime analog to our sun and a good choice for your nighttime viewing.
Capella A and B are both yellow-orange giant stars in a post-main-sequence phase. Both are older and many times larger than our sun. In this stage they have exhausted most of the hydrogen fuel at their cores and have expanded to five times their original size. Over the next few million years both stars will become red giants — a fate that will be shared by our sun in 5 billion years — and expand to hundreds of times their original size.
Capella A is the larger of the two stars with a radius 12 times that of our sun. Capella B as a radius of about nine times that of our sun. Both stars have masses and surface temperatures similar to Sol. Both stars are aged at around 500 million years old. Visually, Capella appears as a single star. A telescope resolves it into a type G binary, but the additional red dwarf binary companions will not resolve in amateur equipment.
Over the past few years red dwarf stars have come into light as astronomers have become more interested in them as possible targets for Earth-like planets. Red dwarf stars are much smaller than our sun and burn much cooler. But they also burn much longer and this combination opens the possibility to earth-like worlds occupying the Goldilocks zone in a proximity much closer to the star. Red dwarf stars also exist in a greater population than any other star type in the Milky Way galaxy.
Science fiction fans will remember that 40 Eridani A is the star of the fictional planet Vulcan, home to the first officer of the starship Enterprise, Mr. Spock. Unfortunately, no planet is known to exist around this star. Current technology is not up to the task of finding one. It has been calculated that a planet circling 40 Eridani A would be located at position of .68 AU away, 2/3 the sun-earth distance. The B and C stars would burn brightly in the Vulcan sky. Although both stars would be visible during the daytime their light would not be bright enough to completely negate the nighttime sky from the inhabitants of 40 Eridani A.
40 Eridanis C is a red dwarf star located 16.5 light years away in the constellation Eridanus. It is a member of a triple star system of Omicron Eridani composed of dwarf stars. The A star is a main sequence dwarf type G, similar to our sun but much smaller. 40 Eridani B is a white dwarf and 40 Eridani C is a red dwarf. The white dwarf B star would put out so much radiation that any planets circling it would be sterilized by its ultraviolet radiation. 40 Eridanis C flares with periodic increases in x-rays in addition to visible light. This, too, would prohibit the possibility of life developing on any planets orbiting this world. However, the star is an example of an M class dwarf and should be considered a good analog to Proxima Centauri B, our nearest neighbor which is now believed to harbor an Earth-like world.
Because of its close proximity to earth, 40 Eridani C is an easy telescopic target and another example of a Ghost of Stellar Present. Recently the news was buzzing with the announcement of the discovery of a small, possible earth-like planet circling our nearest neighbor, Proxima Centauri B. It appears that this planet resides in the Goldilocks zone of that red dwarf. When scientists talk about Earth-like worlds they are speaking of stars are in the right place – the right distance from their sun — to harbor liquid water. This doesn’t mean that the planet may contain complex life like our own. The search for life in the universe, at the present time, is a search for whatever life we may find. Most of this will probably be microbial similar to the single celled organisms we see on earth. Most of them will probably be extremophiles and thermophiles, organisms capable of existing in environments that would be hostile to us.
The existence of life on other worlds will certainly be a transformative experience for the human race. Given the abundance of organic molecules in the interstellar medium it seems highly unlikely that life doesn’t occur in many places throughout the universe. Scientists are even turning to the moons of Jupiter and Saturn to find primordial life. Even extinct life, contained in fossils on Mars and possibly our moon, could teach us a great deal about the chemistry of life and may help to solve the debate over whether life originated here or was transported to earth via comets.
In A Christmas Carol, Ebenezer’s transformation is completed by a visitation from the ghost of Christmas future. After Ebenezer witnesses the loneliness and sadness that he could have prevented during his lifetime he repents as he kneels at his own grave. In the story, Christmas Day is tomorrow and we are led to believe a Christmas future, the day upon which Ebenezer is resting in a lonely grave, may be tomorrow. In fact, for all he knows Ebenezer may already be dead and the ghost of Christmas future may be simply showing him events that he cannot prevent. After all, he does ask a non-responsive ghost of Christmas future if the events he has witnessed are things that will be or things that must be.
As soon as Ebenezer awakens to realize that he is still alive and the ghosts have delivered upon their promise to reveal all to him in one night, he is an elated man (on Messier cloud nine) who immediately sets about to his business — mankind! Now I don’t know about you, but if I were kept up all night I would not be as cheerful as Ebenezer — at least not before I’ve had a few hours sleep and an IV bag full of coffee. That even includes awakening on Christmas Day with the knowledge that under the tree was that workout DVD I so coveted!
The Ghosts of Stellar Future
We do not have to fear the ghosts of stellar future because that takes place billions of years from now. Eventually our own star will bloat into a super red giant, then shed off its outer layers and become a planetary nebula similar to the Ring nebula in the constellation Lyra. The universe itself may have already seen its greatest star forming phase. As dark energy propels all the atoms of the universe apart into an eternally inflating universe, the stars we see today will eventually fade from view until they themselves are flung apart by the forces of that energy. While A Christmas Carol may have a happy ending, a Cosmic Carol will have a cold and tragic one.
The ghosts of stellar future that will visit upon us will be the ghosts of the astronomical near future — billions of years from now. We can see many of the spirits roaming our own Milky Way galaxy today, old stars that have grown into the monsters of the present. They are examples of stars of the future — stars like our sun and many of the others currently inhabiting our galaxy and the rest of the universe.
If there is an outstanding of the ghost of stellar future in December’s sky it would have to be Betelgeuse in the constellation Orion. Designated as Alpha Orionis, Betelgeuse is one of the brightest stars in the winter sky and part of the winter triangle. Betelgeuse is a super red giant near the end of its life cycle. If Betelgeuse was located at the center of our solar system its surface would extend beyond our asteroid belt, consuming all the inner planets out to Mars. It is located 640 light years away in the shoulder of the constellation Orion. When Betelgeuse dies it will produce an enormous supernova explosion, sometime within the next million years.
Like the star Mira in the Constellation Cetus, Betelgeuse is a runaway star plowing through interstellar space at 30 kilometers per second and leaving a bow shock in its wake. It is also classified as a semi-irregular variable star with periods of variability from 400 to 2100 days. Betelgeuse possesses at least 20-30 times the mass of our sun and 2 million times its volume. It shines 100,000 as brightly as our sun. High mass stars such as Betelgeuse exhaust their fuel very quickly, existing for only a few million years, as opposed to our sun which will live for billions of years. Betelgeuse is aged at 10 million years and is already nearing the end of its lifespan!
Stars at least five times the mass of our sun can grow into super red giants at the end of their life cycle and go out in a grand supernova explosion that results in either a nebula, similar to the Great Orion nebula, a neutron star or a black hole. The fate of Betelgeuse is likely to be another nebula similar to that of the Great Orion Nebula (M 42).
Stars 1.5 to 3 times the mass of our sun grow into red supergiants, die in a supernova explosion and leave a neutron star, while other, more massive stars can go on to produce a nebula or black hole. All of that depends upon their mass and how their atoms recombine in the final moments of their lives. Stars 15 times the mass of the sun may continue to contract to form a singularity—a black hole.Because of its mass Betelgeuse likely to become a neutron star. Neutron stars occur when the core of the star is compressed tightly and the electrons are stripped off from the atoms. The result is a large ball of nuclear material — matter of the atomic nucleus — the size of a city, such as New York or Paris. Consider an object twice the size of our sun compressed down into a city-sized object. The core is so dense and the gravity is so enormous that a single teaspoon of neutron star would weigh billions of tons!
Because of its density the gravity of a neutron star is so immense that to escape it you have to have a velocity of half the speed of light. A mountain on the surface of a the star would only be millimeters high. Light traveling around such a star would be gravitationally lensed, so astronomers would be able to see things behind a neutron star. A neutron star would compact 500,000 times the mass of the earth into a sphere of only 12.4 miles.
As the core of the star continues to collapse inward, its rotation increases in it can spin up to thousands of times per minute. These rapidly rotating stars are known as pulsars. They can emit beacons of light that can be picked up in the x-ray and radio spectrum. When viewed from Earth these pulsars resemble the beacon of a lighthouse. As material from the pulsar accelerates within its magnetosphere it produces gamma rays, which can slow the pulsar down. If the beam from a pulsar does not flash in the direction of earth, cannot be seen. All pulsars are neutron stars but not all neutron stars are pulsars.
Magnetars are neutron stars that have magnetic fields thousands of times stronger than the average neutron star. The drag of the magnetic field slows the star down so it takes much longer to rotate than a pulsar. Magnetic fields can be so strong that they will distort the shapes of atoms! A fracturing of the surface of a magnetar can release a large pulse of radiation that can be detected up to tens of thousands of light-years away. This release of radiation is known as a starquake. Magnetars can remain active for 10,000 years, after which the magnetic field is fully dissipated and the star cools down.
Sometimes neutron stars will collide and create a black hole. This process takes milliseconds to
occur. The rapidly rotating black hole created from the two neutron stars spins so fast that it emits jets of material that travel light years back into space. Images of these “quasars” have been seen at the centers of galaxies where supermassive black holes are rapidly spinning and digesting orbiting stars! In their gluttonous feeding, however, enormous amounts of material are ejected from the poles of the black hole into interstellar space. These are the jets that we see in images of quasars. Colliding neutron stars produce gravitational waves that can be detected with devices such as the LIGO detectors here in the United States.
What a piece of work is a man! How noble in reason, how infinite in faculty! In form and moving how express and admirable! In action how like an Angel! In apprehension how like a god!
Hamlet, Act 2, scene 2
Oh, if William Shakespeare had only been an astronomer! He might have written about what a piece of work the universe is. How elegant in its construction and workings, how infinite in breadth! How moving in mystery and intrigue! How secretive and yet willing to share her secrets! To look into her eyes is to look into a mirror and see yourself!
Call me Ishmael (my name is actually Paul). Whenever a balmy November wind blows across my bow and chills me to the bone, when the brisk November air suggests that autumn is turning to winter, when the skies of night become calm and tranquil and abound with good astronomical seeing, and whenever I find my heart longing for a dark observing site, I account it is high time to set sail into the infinite seas of the cosmos.
Pseudo Melville, The Great Whale
An AFSIG Article by: Paul Trittenbach
Moby Dick is probably the most infamous manuscript of Herman Melville. Scholars may disagree that it was his best work, but the novel does touch the soul of any reader. Moby Dick is fraught with emotional and philosophical undercurrents that leaves an indelible mark upon those who voyage through it pages. Melville inspired me when I found my thoughts turning to create a web article for November. Both Moby Dick and my composition have something in common—a great whale!
The Constellation Cetus, the whale, swims in the 13.8 billion light year ocean of our universe among other constellations associated with water: Eridanus, Aquarius and Pisces. In Greek mythology Cetus was known as “the sea monster” from the myth of the princess Andromeda. According to the myth, Andromeda’s boastful mother, Cassiopeia, angered Poseidon (the god of the sea) and the Nereids (nymphs of the sea), by claiming that she was more beautiful than they. Poseidon sent Cetus to punish King Cepheus and his wife Cassiopeia for the boast, requiring that they sacrifice their daughter to the sea monster or have it ravage their land.
King Cepheus and his wife chained their daughter to a rock so the sea monster could devour her. But just as the sea monster was about the partake of this delicacy, our hero Perseus entered the picture and killed Cetus, rescuing Andromeda from her fate. Later the two were married.
Cetus sits high in the southern sky and is prime for hunting by mid month. It possesses two red giants, one a pulsating variable—which is also a binary system— an orange giant and one G-type star smaller than our sun. It has 14 stars with planets and covers 1231 square degrees of space. There are three meteor showers associated with Cetus: the Omicron Cetids, October Cetids and Eta Cetids. The constellation is also home to nine galaxies available to amateur astronomers.
Unlike Capt. Ahab, I am unwilling to chase this whale around any maelstroms or round Perdition’s flames. I just sit patiently and wait until the earth transits around the sun and the overhead sky turns to the stars of autumn. Then Cetus presents itself overhead. There are plenty of other celestial objects to keep me occupied in the meantime. But when Cetus appears overhead it offers cosmic gems worth harpooning. In pursuit of our quarry, let’s first turn toward the stars of Cetus.
“…the great floodgates of the wonder-world swung open…”
Herman Melville, Moby Dick, or The Whale
Regardless of what aperture you choose you will never see Alpha Ceti V, the planet to which the genetically superior Kahn and his band of rebels was exiled by Capt. Kirk in Star Trek, the Original Series, after attempting to commandeer his ship. Made famous by the episode “Space Seed” and revisited in the motion picture Star Trek II, “The Wrath of Kahn”, Alpha Ceti (Menkar) has been deceptively hiding her planets. Of all the extrasolar planets discovered thus far none have ever been found around this star.
Designated as the alpha star, Alpha Ceti is actually the second brightest star in the constellation. Located 249 light years away, at magnitude 2.5 Menkar is a red giant with more than twice the mass and 89 times the radius of the sun. When it dies it will shed its outer layers and evolve into a planetary nebula, a fate that our sun will share in 5 billion years. Some people believe that Menkar is designated the Alpha Star because it sits close to the plane of the ecliptic and marks the path of the sun across the sky. In Arabic Menkar means nostril. The star sits at the head of Cetus.
Deneb Kaitos—Beta Ceti— is the brightest star in Cetus. It is located 96.3 light years away and shines at a magnitude of 2.04. Deneb Kaitos is an orange giant possessing 2.8 times the mass and 16.8 times radius of the sun. Deneb Kaitos has evolved from a main sequence star and is on its way toward becoming a red giant.
Plowing its way through interstellar space at 291,000 miles/sec the variable star Mira (Omicron Ceti) creates a bow shock and leaves a 13 light-year long tail of dust and gas in its wake. That light is visible only in the ultraviolet frequencies, and was detected only recently by NASA’s Galaxy Evolution Explorer telescope. Mira is a red giant star close to the end of its life. Mira has already ejected enough mass into surrounding space to create 3,000 planets the size of our home.
When it dies it will shed off its outer layers and become a planetary nebula. Mira is also a binary system. The B star (Mira B) is a white dwarf that is accreting mass from the primary. Images taken by the Chandra X-ray Observatory show that matter from the primary star is being consumed by the white dwarf. Both stars are separated by a distance of 70 astronomical units.
Mira is a pulsating variable star—the first of its kind to be observed—and is now part of a class of pulsating variables known as Mira variables (M Variables). All of the stars in this class, 6 – 7000 of them, are red giants that pulsate with varying periods of brightness of between 80 to 1000 days. Mira has a period of 332 days and can vary in brightness from magnitude 2.0-10. Mira is located 420 light years from Earth.
Of all the likely candidates, you would think the Star Trek writers would have chosen for a place to maroon Kahn and his band of genetic supermen, you would think it would have been Tau Ceti. Tau Ceti is a yellow dwarf star 11.9 light years distant that shines at magnitude 3.5. Is one of a few G-type stars that possesses less mass and brightness than our sun. In 1960 it was chosen by Frank Drake as one of the original Project SETI (Project Ozma ) candidates to search for intelligent life in the universe.
At millions of light years distant, galaxies are like great white whales swimming in our ocean universe. In binocular’s and small telescopes they shine as nothing more than milky clouds on the dark backdrop of space. It is difficult for us to wrap our minds around the great distances of the cosmos. Even members of our celestial neighborhood are trillions of miles away — far beyond our reach by any means of the rules of the Einsteinian universe.
Compared to the distances in our cosmic neighborhood, these great white whales are immense! But even the distances between them and the expanse of the universe itself makes them seem like amoebas in a drop of water! So here we are, Jonahs in the belly of a great white whale, staring out into the ocean with intense curiosity.
45 million light years away is Messier 77 (M 77, NGC 1068) a barred spiral galaxy at magnitude 9.6. It is one of the largest galaxies listed in the Messier catalog and the only Messier object in Cetus. It spans 170,000 light years in diameter and is the closest and brightest of the Seifert galaxies. These are galaxies that possess hot, highly ionized gases which emit intense radiation and glow very brightly. This radiation is caused by a very Active Galactic Nucleus (AGN) — a black hole — about 15 million times the mass of our sun! M77 also has very bright arms, the result of prolific star formation.
Located 250 million light years away is the spiral galaxy NGC 17. You will need a large aperture telescope to see this galaxy; it possesses a magnitude of 15.3. NGC 17 is believed to be a merger between two larger disk galaxies because it demonstrates prolific starburst activity and its core is still very rich in gases.
The barred spiral galaxy NGC 45 shines at approximately a magnitude of 10.4 and is located 32.6 million light years away. You will want to use a large aperture telescope to wrestle any details from this galaxy. Although it is very large, the surface details of NGC 45 are spread out and faint. This galaxy presents itself in a nearly face-on orientation to our plane of view.
At 236 million light years away the barred spiral galaxy NGC 47 shines at magnitude 13.5. Like NGC 17 and NGC 45 you will want to use a large aperture telescope to tease out any details from this galaxy. NGC 47 is a small galaxy with a very bright core.
Much closer to us, at 11.1 million light years is NGC 247, also known as Caldwell 62. NGC 247 is a small spiral galaxy— also classified as a dwarf spiral galaxy— and one of the closest to the Milky Way. It is a member of the Sculptor group of galaxies. NGC 247 possesses a bright nucleus surrounded by stars, gas and dust. The gas forms bright knots in the HII regions that are scattered throughout the galaxy’s outer arm.
Images taken by the Hubble space telescope show that NGC 247 has a large void in the HII regions, which spans nearly 1/3 of the length of the galaxy. Stars in this void are old, red and faint, and indicate that star formation has been halted in this region. It is believed the star formation in this region has not taken place in at least 1 billion years!
At 60 million light years distance the face-on spiral galaxy NGC 1042 shines at magnitude 11.0. It is typically associated with a nearby galaxy NGC 1035 and believed to be gravitationally bound to it because both demonstrate a similar red shift. NGC 1042 possesses a very bright Active Galactic Nucleus (AGN).
Located 60 million light years away, NGC 1055 is the dominant member of a group of small galaxies which are part of the NGC 77 galaxy group. Viewed from our position, NGC 1055 is an edge-on galaxy approximately 100,000 light years across. This galaxy possesses a large box-shaped halo that extends far above and below the galactic plane. In appearance, it bears some resemblance to the Sombrero Galaxy, NGC 104.
NASA images show faint structures within the galactic halo that are believed to be remnants of an interaction with a larger spiral that took place 10 billion years ago. Like NGC 77, NGC 1055 is a prolific star producer. NGC 1055 shines at magnitude 11.4 and will require a large aperture to be able to discern its structure.
NGC 1073 is a barred spiral galaxy similar to our own Milky Way that possesses a very active nucleus that glows in the HII region. It is 80,000 light years across and 55 million light years away. Hubble space telescope images show visible dark dust lanes, glowing in the HII region, young clusters of blue stars and an active nucleus which likely contains a black hole. NGC 1073 shines at a magnitude of 11.5 so you will want a large aperture to view this galaxy.
NGC 1087 is 80 million light years distant and 86,800 light years in diameter. You will want a large aperture to capture this galaxy. It shines at magnitude 12.2. It is classified as an intermediate spiral galaxy, possessing a small central bar of irregular features surrounding a disk. The overall surface brightness of the galaxy is very low.
Oh, Starbucks (Espresso, Frappuccino, iced coffee or dark roast)! Stand fast by my side. For I stand duty watch on the Forecastle and man the spyglass!
Pseudo Melville, The Great Whale
When the cold November wind blows across your bow and the nights become tranquil and accompanied by good astronomical seeing, I hope that your heart will yearn to shove off to a remote dark location and set sail into the infinite seas of the cosmos. There is a diamond mine out there, among the stars—filled with cosmic gems.
An AFSIG Article by: Paul Trittenbach
Under the darkness of a new moon sky on October 31 ghosts and demons will arise from the netherworld and walk upon the earth. This is the day of Samhain (pronounced “Sah-win”), summer’s end, a 2000-year-old Pre-Christian Celtic celebration held around November 1 for the ending of summer and the time of harvest. Some historical legends purport that the Celts lit bon fires and donned costumes to ward off the dead. In the eighth century Pope Gregory III declared November 1 All Saints Day and incorporated some of the Celtic celebration into the Christian.
Perhaps when humans invented religion we had a need to explain the good and evil we saw in each other, so we balanced the equation by creating the good gods above and the evil ones below. It is a theme that has permeated our literature and movies and has been handed down since the first spoken languages have appeared in our species. And throughout our history almost every culture has celebrated the dead in one way or another. All Hallows Eve was the evening before All Saints Day and later evolved into the modern day celebration of Halloween.
Modern-day Halloween is a playful way of dealing with death. It is a time when little goblins of the neighborhood come out to invade the night seeking treats and promising nasty little tricks to those who fail to deliver. To me, this night when the moon is dark is a great opportunity to dispel some of those demons with science. I propose that you offer them a treat they seldom if ever have experienced: a star party. It is an opportunity for fun suffused with education.
We begin our tour of celestial eye candy by introducing the pralines of the northern hemisphere: the double cluster of the constellation Perseus. NGC 869 and 884 lie 7,500 light years away. Star clusters are groups of stars that are gravitationally bound to each other and moving independently of the rest of the galaxy. The Perseus Double Cluster are the only two known clusters in the Milky Way that are gravitationally bound to each other and moving as a single component at 39 km/s (24mi/s) in our direction.
Each cluster consists of 300 known members of young blue-white stars 12.8 million years old. At the time when the light left these clusters to appear in the eyepiece of your telescope the first established human civilization was firmly planted between the Tigris and Euphrates rivers in the ancient land of Mesopotamia — it is today called Iraq. These were the Samarians, from which we have derived our modern-day word of summer. To them, as to us, the double cluster appears as a large, somewhat milky patch in the sky overhead and can easily be seen from a dark location.
This pair of open clusters is a stunning example of the treats available to amateur astronomers. I tell guests at public star parties that when they see these sparkling diamonds against the velvet black of space they will ask themselves why they never got involved in this hobby sooner. There are numerous other open clusters that you can compare against the Perseus Double Cluster; M38, 39, 34, 11 and the most infamous: M45, the Pleiades.
In contrast to the aforementioned open clusters are the globular clusters, such as M13. If the double cluster is the pralines of celestial eye candy then globular clusters must be the gumdrops.Turning to the globular’s immediately after showing the open clusters yields a stunning, “wow” moment for the audience. In addition to the visual impact of viewing the two types of clusters, both possess opposite historical and compositional backgrounds.
Globular clusters reside at the opposite end of the age spectrum. They are fossils of the cosmos nearly as old as the universe itself. M13 is 11.65 billion years old! Unlike open clusters which formed inside our Milky Way, globular clusters are nomads roaming the universe and temporarily taking up residence inside the halo of our galaxy. They are densely packed associations of stars — the proverbial Guinness book example of “how many people can you fit into a phone booth”.
On the evening of October 31 M13 will be in the western part of the sky, just above the horizon. This is the most densely packed globular cluster available to most of the northern hemisphere (Tucson, Arizona lies close enough to the southern hemisphere to catch a view of the Omega Centauri cluster). M13 consists of 300,000 known stars compacted into a spherical volume of 145 ly! In addition to explaining what a light year is in terms of distance, M13 is an exercise in warping the mind around celestial mechanics.
You can compare the distance between Earth and its nearest stellar neighbor, Proxima Centauri at 4.2 light years, away to the same spherical area at the center of M13. In the 4.2 light year distance between us and our nearest our neighbor M13 would have 100 stars! In the same spherical distance of 4.2 light years the core of M13 would be the residence of 1000 stars! You can point out that the known members of a star cluster are those that we are able to visually count and that the Milky Way is dominated by binary stars in addition to other star systems that consist of three or more members circling either one another or a common invisible axis.
At the time when the Kerbarian cave Culture of Haifa, modern day Israel, was being established the light from M13 was departing to arrive in your eyepiece. While those people were fabricating stone tools light from 300,000 stars shone brightly into the universe. M13 is located 22,200 miles away in the constellation of Hercules. It is a popular summertime object among amateur astronomers. From a dark site it appears as a small fuzzy patch and is easily viewed through a pair of binoculars or a small telescope. Telescopes, however, will resolve the patch into stars.
M2 and M15 both provide good examples of globular star clusters. M2 is probably easier to present from an urban area because of its magnitude of 6.4. At one time star clusters were grouped with the species of nebulae — murky patches of light scattered among the stars. The word nebula is ancient Greek for “cloud” and before the invention of telescope star clusters, galaxies and true nebulas were all cloud-like structures in appearance. Even into the early 20th century the Andromeda galaxy was known as the Andromeda nebula.
Now that you’ve demonstrated the magic of star clusters try pulling a binary star out of your hat. The constellation Cygnus, the Swan, hangs west of Zenith in October. Beta Cygni, otherwise known as Albireo appears as a single star to the unaided eye. However, it presents one of the most stunning binaries in the Milky Way galaxy. Albireo is also a test in color perception. One star is a cool orange while the other one is a hot blue. To my eyes, the primary appears as a golden yellow and the secondary is a hot blue. Together the two stars present a striking color contrast.
Alberio is located 380 ly (Light years) from Earth. Harvard University was being established when the light left Albireo to arrive In your eyepiece. The first and second component orbit each other with a period of 75,000 years. Two thirds of the stars in the Milky Way are binaries but few of them can boast the visual impact of Albireo. In addition to showing Albireo you may want to show the most common Milky Way binary, Polaris.
If you’re in the mood for telling ghost stories then nothing can be more appropriate than showing them a nebula. The best of the summer nebulae, the Trifid, Lagoon and Eagle lay low on the horizon. Those who have a good view of the southern sky may still be able to catch a fleeting glimpse of them. But there are other ghosts in the sky that we can turn our telescopes to.
Aside from most of the planetary’s, reflection and emission nebulae appear as ghostly apparitions of black and white clouds hanging in space. M27, the Dumbbell nebula, is one exception. From our viewing angle the dumbbell not only appears dumbbell-shaped, because of the way that its lobes have expanded from the white dwarf driving it, but it also appears black-and-white to our eyes. Located 1200 away these expanding clouds of gas have been blown from a star similar to our sun 4000 years ago. At the time of this star’s death the Babylonians were developing mathematics.
The outburst of expanding gas lobes witnessed on M27 are one light year across and expanding outward at a velocity of 20 mi./s. The Dumbbell nebula was the first Planetary Nebula (PN) ever discovered. An Ultra High Contrast filter (UHC) will help you to pull out the details of the Dumbbell. An additional nebula to look for would be the North America nebula. For additional details on the North American nebula see my Cosmic Gems article from August.
For a nebula of a different color try M57, the Ring nebula. At the time when the light left this nebula 2300 years ago King Ptolemy II of Egypt was only a few years away from building the very first lighthouse at the mouth of the Nile. It would be 400 feet high and seen from 40 miles away. But the Ring nebula is a more substantial lighthouse, with the light being pumped out by a remnant of a star of similar mass to our sun, which upon exhausting its hydrogen fuel shed its outer layers in the last, great gasp of death. The remnant of the star is a white dwarf no larger than our earth.
Viewed from our position the outward expanding shell of gas and dust are excited by the ultraviolet radiation emitted by the white dwarf and radiating a rainbow of colors. Although M57 is also a planetary nebula it is a colorful contrast to that of M27. The nebula’s expanding shell of gas is 1.3 light years in diameter. Nebulae provide an opportunity to discuss how chemicals are formed within stars and the explosions that occur after their death. It is also an opportunity to explain how new stars are formed along with any planets or life that may occur on them.
You gotta have monsters! No Halloween story would be complete without them. So now we turn to the Alpha Star of the Constellation Taurus: Aldebaran. Aldebaran, the eye of the bull, is an orange giant star located 65 ly away. When the light left the star Ethel and Julius Rosenberg were being convicted of selling A-bomb secrets to the Soviet Union by the United States.
Aldebaran is a variable star but his variability is virtually unnoticeable to the human eye. It is also a binary star, possessing a secondary that is only three light seconds away (as opposed to our sun which is eight light minutes away).At 43 times the radius of our sun ( the radius of our sun is 432,000 miles) Aldebaran is a monster, although far from being the largest star known. The largest star on record is VY Canis Majoris, a red hyper giant and a eighth magnitude star 1420 times the radius of our sun!
Of course if you really want to talk about monsters point to the area of Cygnus X1. You will not be able to show them this black hole through your telescope but you can tell them that it was the first confirmed radio source verified as a black hole. Black holes like Cygnus X1 are the Frankenstein’s of nature. Cygnus X1 is considered to be a stellar mass black hole possessing 14.8 times the mass of our sun. It is located 6,070 ly from Earth.
Periodically stars many times the mass of our sun exhaust their fuel and the remaining material loses his outward push against the attraction of gravity. The mass of the star is so great that the gravitational attraction overwhelms all existing matter which collapses inward to an point known as a singularity — a word that means “mystery”. So powerful is the attraction of gravity that nothing can escape it, even light itself. As a result, black holes are mysterious in nature, having yielded up clues only from stars around them — some of them they are cannibalizing.
The nearby star orbiting Cygnus X1 is HDE226868 a ninth magnitude O-type supergiant star. You should be able to locate this star through your telescope. Here is an opportunity to explain the invisible electromagnetic spectrum and the x-ray radio source that makes detecting a black hole possible. It’s also a chance to discuss the radio spectrum and how humans use it in our modern world.
Physicists and mathematicians have determined that the space and time near black holes is radically changed from the Newtonian laws of the universe. As a result, black holes have become a favorite subject of science fiction — including Star Trek where the Enterprise frequently utilizes them to travel back in time. Studies indicate that black holes are quite abundant throughout the universe. In fact, it is an irony that black holes seem to be destructors of stars and also the creators of galaxies.
The last object that I want to cover in my Halloween star party is M31, the Andromeda galaxy (Andromeda nebula). The Andromeda galaxy is a large spiral galaxy, like our Milky Way, except possessing twice the mass. Andromeda has 1 trillion stars and is the largest galaxy in our local group, a group of 45 galaxies, which constitutes part of a super cluster of 2000 galaxies known as the Virgo Super Cluster. It is approximately 220,000 ly across (the Milky Way is 190 ly across) and 2.5 million ly from Earth. At the time when the light first left the Andromeda galaxy to appear in your eyepiece humans were fashioning their very first tools.
M31 is our nearest galactic neighbor. It is on a collision course with our galaxy, which will take place in 3.75 billion years. It is visible to the naked eye as a large fuzzy patch in the constellation of Andromeda. It is visible through pair binoculars and easily viewed through low power in a telescope. The nucleus of Andromeda is so bright that overwhelms the eye of the observer Tell your guests that to get a good view they should use adverted vision — turn their eyes slightly off center of the galaxy to see the details.
I think a themed star party like one for Halloween would be a great way to have fun while providing education and sharing a fascinating hobby. I can envision some of you dressed up as Darth Vader and turning the little goblins of your neighborhood toward dark side of day. A star party like this would be a great team builder for your organization — with opportunities for a variety of topics, from mythology to science, history and science fiction, art and culture. It’s an chance to demonstrate how we’ve come a long way from how the ancients thought about the universe to science casting light upon the truth.
Of course a Halloween star party is about serving celestial eye candy. But it would be a nasty trick to forget the confectionery treats. Halloween is a costume party, and not just one for the youngsters, with sugary rewards. Perhaps in 4 million years when Andromeda merges with our galaxy we will have a new name for candy bar. For now, we still have the old standbys that we grew up with: Three Musketeers, Snickers, Baby Ruth, Kit Kat… — to share with the younger generations. But for now and into the foreseeable future, remember, you can’t star gaze without the Milky Way!
On August 3, 1492 Columbus set sail into the Western Atlantic and the unknown. He was seeking a short trade route to the East Indies, the land of spices, the gold standard of the time. At 2 AM on the morning of October 12 a lookout on the Pinta sighted land. Columbus had not reached the Americas however, in fact he never made landfall on North America. Instead, on that first voyage his ships made landfall on an island that he named San Salvador, believed to be one of the Cays in the Bahamas.
During his voyages of 1499-1500 Amerigo Vespucci made landfall in the South American continent, in an area of French Guyana then the mouth of the Amazon River. Vespucci was credited with discovering the American continent and both North and South America became named in his honor. Neither he nor Columbus had actually discovered the New World. Many others had come before them, including the Vikings. But no one can discount the enormous contributions that their explorations have added to history and how they have changed the world.
You and I stand on the North American continent, gazing up, awestruck by the cosmos overhead. We may not be explorers and discoverers but we are in our own right as we stargaze with our unaided eyes, binoculars, telescopes and through the various sources of media that help us to make discoveries of our own. And unlike the world’s great discoverers, we can do it in relative comfort, even in the frigid temperatures of winter.
On August 3, 2016 the moon will be waking up from its new moon slumber and showing us a thin sliver of itself. This seems to be an appropriate time to set sail for the cosmic shores of the North America Nebula (NGC 7000). The discovery of this faint emission nebula is attributed to William Herschel on October 24, 1786. But like the rest of history, it to may have first been landed upon—for all we know—by the Vikings.
The North America Nebula is a great expanse of stellar remnant that covers an area of 50 light years high by 40 light years across — covering an area of sky four times the diameter of the full moons! The North America Nebula lies about 3° off the port bow of Deneb, the brightest star in the constellation Cygnus. It is a faint patch of light, although some sources indicate that it is easily visible to the unaided eye in a very dark location. The nebula lives up to its namesake forming the outline of North America, Mexico and Central America. It is closely associated with a second patch of nebulosity — the Pelican Nebula (IC 5070). The two are separated by a dark lane of dust. Both are located 1800 light years distant and considered to be part of the same supernova remnant.
A star at least 10 times the mass of our sun reaches the end of its lifecycle and grows into a super red giant. In matter of a few seconds it expends the full amount of hydrogen of our sun — 10 billion years worth! The remaining matter loses its tug-of-war with gravity and collapses inward, producing heavier elements along the way. Finally, a devastating explosion blows the matter into interstellar space at 20,000,000 miles per second, leaving a sphere of oxygen and carbon the size of our earth — a white dwarf. A supernova is born.
The matter from this conflagration becomes an enormous interstellar molecular cloud, covering a volume of space that spans light years. It consists of complex chemical elements and compounds — including the gold in your jewelry and the organic compounds of your body. But nature is a great recycling machine and this material will not go to waste. Supersonic shockwaves, gravity and pressure will fabricate new stars and possibly planets and life itself. These cosmic stellar remains are a nebula.
NGC 7000 glows red in images, due to the ionized hydrogen that composes the cloud. The white dwarf embedded somewhere within the nebula emits ultraviolet light — an energy source so powerful that it can eject electrons from the hydrogen atoms and recombine them with protons in other atoms to emit light in the Hydrogen-alpha wavelength. An H-alpha or UHC filter should help you to see the nebula in greater detail.
Edwin Hubble originally suggested that the power source for NGC 7000’s cloud was Alpha Cygni —Deneb. Spectral analysis, however, dethroned Deneb. Other astronomers inferred that the star HD 199579 was the culprit. However, some debate exists around that star possessing the right spectral emissions to excite the hydrogen cloud.
The nebula is also a star producing region whose residents include two open star clusters: Collinder 428 and NGC 6997. NGC 6997 is the most obvious of the two star clusters and is located along the East Coast of North America. Collinder 428 resides in the location of the state of Washington. Along the western edge of Mexico and Central America is a bright wall, a star forming region known as the Cygnus Wall. This region is both lit and simultaneously eroded by young stars that are partially concealed by the dark dust lanes they have created. The Cygnus Wall spans a distance of 15 light years!
The associated Pelican Nebula, IC 5070, is an amalgamation of three structures (IC 5067, IC 5068 and IC 5070) collectively classified as IC 5070. This too is a churning molecular cloud of gas and dust, as evidenced in Hubble images, constructing new stars within. Because it is part of the same structure as NGC 7000 it glows red in images too. The two structures — NGC 7000 and IC 5070 — are separated by a dark dust lane, perhaps our analog of the Atlantic Ocean.
Once you have sailed the coastline of the North America Nebula and explored its interior, hoist your mainsail to shove off for the right wing tip of Cygnus. 4° south of Epsilon Cygni we find ourselves adrift in the Sargasso Sea of the Veil Nebula. Early mariners were petrified at the thought of becoming entombed in this expanse of seaweed desert in the Atlantic but we will be pleased to be lost here for some time. This large, filamentous patch of nebulosity is a part of a larger structure known collectively as the Cygnus Loop. The Veil Nebula, Caldwell 34, is a complex of multiple structures — including NGC 6960, Caldwell 33 (the Eastern Veil), NGC 6992, NGC 6995, NGC 6974, NGC 6979 and IC 1340.
The Veil Nebula is the remnant of a supermassive star that exploded about 8000 years ago. It’s name is derived from the filamentous structures that compose it. It is located approximately 2100 light years away and spans an area of sky of 110 light years. Because the nebula is spread over a very large area it appears very dim, regardless of the fact that it has a relative magnitude of 7. its filamentous appearance is attributed to shockwaves that are so thin that the shell is only visible when viewed edge-on.
High velocity shockwaves from the ancient explosion are plowing into a wall of cool, dense interstellar gas, causing it to omit the light of the nebula. At one time the star that created this nebula was more than 20 times the mass of our sun! The Veil Nebula glows from doubly ionized oxygen. It can be best viewed using an 0 III filter.
Hubble Space Telescope (HST) close-up images of the Veil Nebula reveals a bubble of gas that was blasted into interstellar space when its parent star detonated eight millennia ago. In the multi-spectral images it looks organic in appearance; an enormous transparent worm revealing its inner anatomical structures. Perhaps I am waxing romantic but it seems appropriate, with nebulas possessing organic compounds, to imagine it as more than a construct of pure physics. Images like this reveal so much more of the structure of these cosmic gems, enlightening us of the complexity and elegance of the cosmos.
To our eyes the gossamer structure of the Veil Nebula, matted against the jet black sky of interstellar space, is beautiful. It’s hard for us to imagine it as evidence of an immense nuclear bomb that detonated in our celestial neighborhood and was witnessed by ancient people. Perhaps in the cuneiform of the Sumerians or the oral stories of ancient American Indians there may be an eyewitness account of the event. Maybe one day we will uncover an edition of the Mesopotamian Daily Herald and read of one of the biggest news events of that time.
Having navigated the Veil Nebula we now set a compass heading 2.5° northeast of the double star Albiero and to the shores of Sharpless 2-91.To see this supernova remnant you will need a large aperture telescope.Use an OIII filter to view Sharpless 2 – 91. Sh 2 – 91 is a composite of tendril structures: Sh 2-91,Sh 2 – 94 and Sh 2 – 96. It is the shell of a star that exploded 20,000 years ago. This shell is 70 parsecs across and 2500 light years distant.
But Ahoy there, matey, we’re not through yet! After navigating the waters of Sh 2-91steer a compass heading 180° aft of Albiero and straight-on-through to the left wing of the Swan. The Swan swims along an enormous tear in the fabric of the Milky Way: the Great Rift. This is a lane of dark nebulosity that runs through the entire ribbon of the center of our galaxy. One point off our starboard bow we sight an orbicular dark cloud between Sadir and Deneb. This is a portion of the Great Rift known as the Northern Coalsack.
The Coalsack — that is to true Coalsack — is located in the southern constellation of Crux, 600 light years away from Earth. Whenever ancient mariners ventured into the southern seas and spied the Coalsack they shuddered in fear, for they believed it possessed properties of the occult. It is easy to understand how they must have felt; for it appears as a bottomless cavern amongst the stars. Our myths and religion are a bastion of hope pitted against our greatest fear of darkness and the unknown. Both the northern and southern coalsacks are icons of the primal impulses that can drive us mad with fear.
The Northern Coalsack spans an area of sky in northeastern Cygnus of 6° by 5°. It is the beginning of a long expanse of dark dust and gas that obscures and even conceals the stars behind it. This Great Rift slithers its way from Sagittarius to Cygnus. It gives the Milky Way its variegated appearance. Herein lies the irony of observing the Northern Coalsack: viewing it is like staring into the eye of some demonic spirit while simultaneously you are awestruck by a transcendent beauty. This dismal sea is flanked by two luminous bands of the Milky Way that make this piece of celestial eye candy worth relishing.
We may not have the navigational, morale and logistical concerns of Columbus and Vespucci. With a good star chart or a Go-To telescope we will not have weeks of endless cosmic ocean to cross to reach our destination. Secured in our holds will be our telescope, accessories and the all-important Oreo cookies. We may have to endure a long night away from our families but that’s the sacrifice of exploration. After all, it wasn’t easy for the ancient seafarers either. Bon voyage!
An AFSIG article by Paul Trittenbach
A long time ago there was a violent explosion and nearly nothing was left in its wake! A supersonic shockwave roared from the heart of the explosion and debris was hurled in every direction. There were no known witnesses to the great cataclysm. If anyone was around at the time, there would’ve been no survivors. All we have is the forensic evidence that tells us of a violent and horrible death.
When Shakespeare wrote of the struggles of humanity he could have just as easily been penning an exposition on the stars. Destruction and creation are part of the cycle of the universe. They are also the fabric of our literature and movies. There are those who burn out quickly but are remembered in legend because they shined so brightly. There are those who live long, moderate lives and die with little more than a stellar last gasp. And there are those that convulse before dying in powerful explosions, building monuments to their lives.
As our earth races around the sun and turns to face the summertime stars,
a dense murky patch of clouds and dust whorl overhead. We are facing in, through the Scutum-Centaur and Sagittarius arms of our galaxy, into the bowels of the Milky Way. Of the constellations that reside there, one of them, Sagittarius, is the focus of our attention this month. Here reside a couple of monuments to the lives of stars that once burned brightly. They are also popular summertime targets for amateur stargazers.
When Charles Messier cataloged M8 he was penning it into his list of celestial objects to avoid. It became one of 109 objects that were relegated to his “don’t see” file, but I recommend that you go there even if you have been there before. Messier 8, or M8, or the Lagoon nebula is an enormous interstellar cloud of gas and dust, the remains of the star that once burned brightly. It is classified as an emission nebula. Nebulae of this type are described as localized regions of ionized gas which emit light at various colored wavelengths, most of which are not visible to the human eye. M8 is located approximately 5200 Light years (ly) from our solar system and occupies a space of 140 ly high by 60 ly across.
M8 appears pinkish in color in time-exposure images, a flower in the celestial garden. This is due to ionized hydrogen (HII). But to our eyes M8 appears gray in color. This corresponds to the doubly ionized oxygen present and accounts for why the nebula is more vivid when viewed with an O III filter. The gases emit colors because they are ionized by the ultraviolet light emitted from an energetic white dwarf — the beating heart of the nebula. Hubble Space Telescope (HST) images show details of swirling twisters of gas and dust moving throughout the nebula. These twisters of dust and gas are the result of the difference between the hot and cold areas of the gases themselves.
Nature dictates that in order for a celestial mother to give birth it must die. In this case a violent explosion rips apart a star to create nebula which becomes a stellar nursery. M8 is also a complex of multiple structures — including a large open star cluster NGC 6530, Herschel 36 — the star that drives the nebula — and the Hourglass. NGC 6530 is a young, loose star cluster — most likely created within the nebula itself — composed of 50 – 100 young stars about 2 million years old. Off-center within the nebula is the Hourglass, a bright feature which appears to be a star forming region.The dark regions of the nebula are Bok globules, protostellar matter which under accretion forms the new stars in this nursery.
Our next flower in the celestial garden is Messier 20. M20, the Trifid nebula is next door to M8, astronomically speaking. Its name is derived from the three-lobed structure of the nebula. The Trifid nebula is a bonanza among nebulae — composed of three nebulas in one. The Trifid nebula is located at the same distance from us as M8 and astronomers believe that the two are closely associated, perhaps developed of the same origin. Like the Lagoon nebula M20 is a cocoon of interstellar gas and dust, and a stellar nursery.
This complex of emission, reflection and dark nebula is a combination of ionized gases of hydrogen, sulfur and oxygen. As with M8 this nebula appears gray to our eyes and images reveal a blue reflection nebula and red emission nebula nested together. Again, an O III filter will enhance the visual details in the telescope. The three lobes of M20 are separated by the lanes of a dark nebula, Bernard 85. Clouds of protosetllar Bok globules, through the influence of gravity, accrete to form new stars. But new stars currently being born within M20 are likely to never mature because the star that fuels the nebula is eroding away and will be unable to continue powering the nebula and its stellar hatchery.
Images by the HST reveal fingers of Bok globules amid dust and clouds within the nebula and the embryonic stars being created within. Detailed analysis in various wavelengths of light reveal that in these nearly opaque, cold clouds of protostellar matter material is metamorphosing into nascent stars; the term cocoon seems apropos. We will not be able to reveal these details with our telescopes but understanding the mechanics of the subjects in our eyepieces only adds one more piece to the vast cosmic puzzle. I also believe it makes our stargazing more interesting.
Binoculars and a telescope of any size will allow you to view M8 And M20. Take your time to look for the details in the wispy clouds of this nebula. Vary your magnification to tease out details and get a better look at features such as NGC 6530 in M8. Dark skies are always best for separating details so take advantage of our CAC or TIMPA facilities. And on all of those nights when the weather prohibits stargazing take the time to revisit these targets in your thoughts — stroll through the celestial garden and reminisce the remnants.
An AFSIG article by Paul Trittenbach
Located 1.4 billion kilometers (9.6AU) from the Sun is the second largest planet and sixth planet of the solar system: Saturn. Its beautiful ring structure makes it the most popular planet among amateur astronomers and the public alike. Like Jupiter, Saturn is a gas giant planet composed predominantly of Hydrogen and Helium.
Saturn was the most distant planet known to the people of the ancient world. It was not viewed through a telescope before 1610 when Galileo Galilei turned his 30-x refractor upon it. To his amazement, he saw a pair of objects on each side of the planet, and sketched Saturn as a three-bodied world. After numerous observations, he sketched these lobes as handles attached to either side of the planet.
In 1659 the Dutch astronomer Christian Huygens, using a more powerful telescope than Galileo’s, proposed that Galileo’s handles were in fact a thin flat ring that surrounded the planet. Later in that century, in 1675, the Italian born astronomer Jean-Dominique Cassini observed the division between what are called the A and B rings of Saturn. It is now known that the gravitational influence Saturn’s moon Mimas is responsible for this 4,800 mile-wide division, known as the Cassini division.
Saturn’s volume is 755 times greater than that of Earth. The winds of the planets’ upper atmosphere can reach up to 500 m/s, four and half times the speed of the fastest hurricane on Earth! Combined with heat rising up from the planet’s interior, these winds create the yellow and gold bands of the atmosphere. A day on Saturn lasts 10.7 hours and one year is equivalent to 29 Earth years.
Saturn’s rings are composed predominantly of water ice. The rings contain more than 23 times as much water as all the oceans of Earth. They consist of seven separate ring structures extending up to 282,000 km from the planet; about three quarters of the distance between Earth and the moon. The depth of the ring system is approximately 10 meters.
Saturn has 62 known moons. The largest moon, Titan, is bigger than the planet Mercury and the second largest moon in the solar system (only Jupiter’s Ganymede is bigger). Titan has a thick nitrogen atmosphere, similar to the early atmosphere of Earth. On Titan, the cold atmosphere causes methane — a normally gaseous compound on earth — to precipitate out of the atmosphere as rain. Titan has large lakes of methane and planetary scientists are interested in it because of its potential to harbor basic life. Further study of Titan may help scientists to better understand early Earth. Titan is the only other moon in the solar system where NASA has landed a probe.
Saturn’s moon Titan was discovered by Christian Huygens in the year 1655. Giovanni Cassini followed up with the discovery of the next four moons: Iapetus, Rhea, Dione and Tethys. In 1784 William Herschel discovered Mimas and didn’t sell at this. More than 50 years had passed before the discovery of Hyperion and Phoebe. As the size and resolving capacity of telescopes increased, so too did the number of discoveries of new moons around Saturn. Additional discoveries came via robotic probes, such as the Cassini mission earlier this century.
Iapetus is a two-faced world — having one side that is highly reflective and as white as snow and another side as dark as black velvet. Mimas has an enormous impact crater on one side that nearly split the moon and half. The moon Enceladus has a fractured surface where water can escape, through evaporation, into the atmosphere. This displays evidence of active volcanism on the planet. Phoebe and several other moons, orbits retrograde to the planet. Sixteen of Saturn’s moons orbit and a tidal lock with the world, always keeping one face toward the planet.
Studies by NASA’s Cassini probe indicate that Saturn has a dense core of rock and ice, solidified by Saturn’s intense pressure. The core is surrounded by a metallic liquid hydrogen layer — similar to that of Jupiter, but considerably smaller. Saturn’s magnetic field is 578 times as powerful as that of Earth, but still smaller than Jupiter’s.
The rings, and most of the moons lie totally within the influence of the planet’s magnetosphere. The magnetosphere is a magnetic field surrounding a planet, where electrically charged particles of the solar wind interact with the magnetic fields of the planet. This is the area in which planetary auroras are created.
Saturn can be easily observed through a small telescope, making it accessible to anyone. The deadline for our observing season, however, may be closing within the next month as monsoons begin to dominate our southwestern sky. The planet reaches opposition on the morning of June 3 at 1:00 AM. But any time throughout the month of June and the entire summer will be good for seeing the planet, which is available to us until October.
TAAA Support of Public Mercury Transit Event At Brandi Fenton Memorial Park
By Jim O’Connor
Pictures by Jim Knoll
TAAA has a long history of supporting Pima County Natural Resources/Parks and Recreation and their active astronomical outreach programs. Usually these events are at either the Ironwood Picnic Area on the West Side, or Agua Caliente Park on the East side. For the Mercury transit, however, the venue would be Pima County’s Brandi Fenton Memorial Park. TAAA has performed public Astronomy Festivals at that location in the past, so it was a familiar location.
The event was scheduled from 8 AM through 10 AM, which was a segment in the middle of the transit. The transit itself was forecast to occur from 4:12 AM through 11:42 AM, with sunrise around 5:35 AM, so most of us planned on being there at our earliest convenience, and to stay through the end of the event.
I tried to arrive by 6:30 AM, but my guess on how long the drive would take was wrong, and I didn’t show up until around 6:40. Alan Klus had his dual mount already on the sun, while Jim and Sue Knoll were finishing their setup. As I was setting up, Ron Brewster and Bill Yohey arrived and began setting up, as well as a young lady with a 10” Dobsonian reflector who I did not recognize. We ended up with a mix of white light and H-Alpha scopes. I thought about both options, and while my white light choice would be 90mm, larger than my 60mm Lunt solar scope, I also wanted to take a chance on more solar artifacts being available in the Lunt. Jim Knoll also has Lunt 60mm, but while I have a B600 blocking filter, Jim has a B1200, resulting in a tighter frequency band and more detail in his images. This holds true in eyepiece views, but I push mine through a Mallincam Xterminator, and the resulting image in the attached 19” monitor does well at pulling out details. Unfortunately, I left my laptop and camera home, so I couldn’t capture transit images, nor any of the crowd we had attending the event. Jim Knoll provided some photos he took.
As soon as I got completely set up, the first solar image showed Mercury right where it should be. When Jim commented that he was getting prominences in his view, I altered my exposure time and, sure enough, in my view there were two fountains at the top of my screen, one at approximately 11:30 on the face, and the other at about 12:30. Each was three to four Earth diameters, and resembled spraying fans. Positions on the screen are kind of irrelevant, because not only does the telescope and blocking filter diagonal provide an image rotation, but the image orientation itself is dependent on the orientation of the camera in the eyepiece opening. I readjusted the shutter speed to lose the prominences but highlight the surface characteristics. The sun itself was very entertaining, with multiple wide, long, and arching filament groups and several dynamic, bright white active regions. During the morning, I had about 65 or more visitors. Everyone was amazed at the view, not only the crisp, black disk of Mercury, but all of the other artifacts that varied over time. I had two large poster sets at the table; one had solar characteristics, examples, and stellar evolution, the other had displays of the Mercury transit, an image of Mercury, and a fact sheet about Mercury. The visitors to my setup were all very excited to see not only the transit itself, but all of the solar action. I made sure to tell everyone about Saturday’s TAAA Astronomy Festival at the same location. I was also able to hand out about 10 solar tattoos to young children in the visitor groups. Some of the visitors were bicycle riders and people walking their pets who were pleasantly surprised to find us, and it was a great educational opportunity on the nature of the orbits in the Solar System, and also to discuss stellar evolution. There were even some folks, young and old, who wanted to discuss the varying forms in which stars end their existence. We were not terribly busy, and the chance to spread the information was great to have. Toward the end of the session, after about 10 AM, I enclosed the monitor in a box to cut down on reflections from people’s clothing onto the screen, but the matte surface of the monitor does well on its own to put out a good image, as long as the sun is behind or to the side of the observer. The visitors did seem more comfortable with the shadow box, though. And about a dozen people took smart phone pictures of the great solar images.
Many thanks to Bill Yohey and Jim Knoll for helping me get all my equipment over to the truck after it was all over. And thanks to PCNRP&R for having such a great educational event. We opened a lot of minds, and sparked a bit of curiosity in the crowd that showed up.
South Rim Coordinator
Grand Canyon Star Party
Only one transit observation has trickled in from John Kalas, but will include a surprise below. I’ll include a couple pictures too. Here is John’s:
Mercury Transit – 5/9/16
I awoke at about 7:00 am and took my 11×80 giant binoculars with solar filters out in the backyard to assess the transit and make the big decision of whether or not to lug out the telescope. I should have set up the telescope the night before and left it parked overnight, so it would be accurately aligned for the transit but I was lazy.
The transit was about mid-way, so I decided to get out the scope. By about 8:00 am, the Astro-Physics 130mm refractor with a Thousand Oaks white light solar filter on an A/P 600 mount was ready-to-go. On went the Canon 60Da DSLR camera at prime focus and I started experimenting with the manual settings of exposure time and ISO speeds. After several trips into the house with the camera’s memory card to review the images on the computer, I settled on 1/8000th of a second exposure time and an ISO of 1600. Being that I didn’t have a precise polar alignment, I had to slightly re-align the sun in the camera’s view finder for every shot. Shown here is the start image and the last image.
A Few Shots from the Mercury Transit
With the Mercury transit already underway at sunrise, I was visualizing a shot of “Mercury rise” as it cleared the Catalina Mountains, so on Saturday I scouted a few locations for a clear view – tough to find in the metropolitan area with trees, power lines and easy access. I finally found one near the east end of Roger where it meets the Rillito Wash near UA Farms.
Since I never use an alarm clock, I actually had to test it to see if it worked for my 4:50 wake-up call so I could drive the mile or two and set up. Conditions looked great – the picture at left shows my setup – the TEC 140 (plus 1.4X Canon extender) on my Alt-Az mount, with the location on the right slope of a hill. The shot, close to my visualization, except for perhaps a saguaro or two, is shown at right. Mercury had just cleared the slope at lower left.
What is interesting to me are some of the atmospheric effects of the low sun. We all know about the “green flash” as the atmospheric dispersion gives any setting object a green or blue upper edge and a red lower edge. You can see it on the above image. But if you examine the image of Mercury, or even the sunspot, you can see the inky spot has a reddish upper edge, and blue/green lower! Of course it is caused not by the black dot, but rather the illuminated upper edge of the lower edge of Mercury is green… An enlargement is shown at left.
At his point I retired to home, where I had setup and aligned the AP1200 the night before in the back yard. Spending about 30 minutes figuring why the scope wasn’t tracking (Duh – in my sleep-addled state I’d hooked it up wrong!). Eventually I got underway – fortunately the trees blocked the low sun, so I got going about mid-transit. So I’ve got hundreds of images thru the thing – perhaps they’ll get turned into a movie someday. Shown here is a 2-image stack very near 3rd contact showing a full-resolution shot of the TEC+1.4X extender+Canon XSi camera. I couldn’t be happier with the resolution, just my processing skills how to proceed with a few hundred images!
I hope all who had a chance to observe had a great Transit!
Oh Yea – the surprise!
Since Tom Polakis just spoke to the TAAA 5 weeks ago about time-lapse imaging, I’ve absolutely GOT to show you his treatment of today’s transit! Using a Lunt100, he took high-speed video of the last 10 minutes including egress, and used about half the frames to make 31 frames of fantastic! Gif is shown here, and the link to his pbase gallery is here. “Mike drop” here… Just amazing!
Most Tucson amateur astronomers know what happens on the first Friday of the month – the monthly meeting of the Tucson Amateur Astronomy Association (TAAA)! Arguably living in the astronomy capital of the world, we have some pretty good meetings. With the Kitt Peak National Observatory, the Planetary Sciences Institute, Steward Observatory and the Lunar and Planetary Lab all headquartered in central Tucson, we are rarely lacking for world-class lectures about the universe or latest data from spacecraft. We even get great lectures from TAAA members themselves, some of them working at the above institutions!
Last night was the first Friday, so of course, we got together, but our normal lecture hall at Steward Observatory was being used for final exams – it is that time of year! So we arranged to meet across the street at the auditorium of the Lunar and Planetary Laboratory. The location fell into the theme of the evening – celebrating the history of LPL. The traditional Beginner’s Lecture was a showing of the great documentary “Desert Moon”, a 2014 movie by Jason Davis. Using archival footage as well as interviews with early employees, it tells the story of how LPL played a central role in the space race and eventual landing on the Moon. Gerard Kuiper, who founded LPL in 1960 is at center in the right image, and Ewen Whitaker, one of the main interviewees, is at right.
The movie is a testament to Kuiper’s leadership and assembling this team around him, most just barely out of their teens! They played central roles as Kennedy surprised scientists by declaring the Moon as a goal for NASA. Starting with the lunar atlas Kuiper started at Yerkes Observatory, after founding LPL they supported virtually all the lunar missions leading up to the landing. Fortunately, the movie Desert Moon is free for viewing on-line, and at 35 minutes long, is a great watch, even on a computer screen. My favorite scene is the un-narrated final scene when some of the now “old-timers” who played such central roles, put their swagger on and strutted down the University Mall – shown at left!
The main meeting started promptly at 7:30, and after a few announcements and business (Springtime Board Elections!) the main lecture started – given by LPL director Timothy Swindle. He admitted that the first half dozen slides of his normal talk were well covered by “Desert Moon”, so modified his presentation somewhat. He also announced that much of what he presented was covered in a recent book, recently published by UA press – Under Desert Skies by Melissa Sevigny. Reading her book would likely be a great addition to the information gleaned from Dr. Swindle’s presentation.
Dr. Swindle points to the launch of Sputnik in the 50s, and the 6 week period in Spring of ’61 in forming the direction of LPL’s mission to the Moon and beyond. So the developing space race kept funding levels high and the department focused both on the Moon and a fledgling planetary space program. After the successes in the Moon landings, UA continued involvement in the Pioneer, Voyager, Cassini and Mars missions.
He told the story of Lujendra Ojha, an undergraduate from Nepal working on a student project with data from HiRISE, under the direction of principle investigator Alfred McEwen, and discovered “streaks” on the inner walls of craters and gorges that follow up spectroscopy showed was briny water – one of the first direct indicators of water on Mars.
He also told the story of Richard Kowalski. One of the primary research works of Steward and LPL consists of searching for Near-Earth Asteroids with the Spacewatch and Catalina Sky Surveys. Kowalski is the ONLY observer to discover objects BEFORE they struck the Earth, one exploding over Sudan, the other striking the Atlantic Ocean. He is shown at right holding a small piece of the asteroid/meteor that landed over Sudan.
He closed out his talk with the latest mission coming out of LPL – the OSIRIS-REx mapping and sample return mission to an asteroid. Facing a launch this September, it arrives at Bennu in 2018, and returning with its precious cargo in 2023. Answering questions for a good long time, it was a great talk and enjoyed by all.
After the meeting’s conclusion, most stayed to interact outside the auditorium over snacks. Another great meeting! The next one will be the day before the Grand Canyon Star Party starts the first weekend of June!