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Sunday, July 27, 2014

Wide-Field Galaxy Imaging

The night sky in the spring is packed with a plethora of galaxies just waiting to be observed and imaged. Recently I was browsing through my copy of Sky and Telescope's "Pocket Sky Atlas" by Roger W. Sinnott. I came across the pages that cover the constellations Virgo and Coma Berenices. After noticing how many "red" symbols were on the page representing galaxies in the area of these constellations, I had the idea of remotely imaging a particular area that would be condensed with some of these galaxies with a wide-field telescope.

Galaxy Group in the Virgo Cluster with NGC 4461 in the Center - Image by Michael Petrasko and Muir Evenden
Galaxy Group in the Virgo Cluster with NGC 4461 in the Center Image by Michael Petrasko and Muir Evenden

I then accessed the planetarium software on my computer, "Stellarium", to determine the best time to image a cluster of galaxies. After surveying the night sky in New Mexico in the software, setting the time of night roughly an hour and a half after sunset there, I found a grouping of island universes in Virgo that would be worth giving a shot at. I found a galaxy in the grouping that would be the "targeted center galaxy" for the image frame. This galaxy would be NGC 4461, a spiral galaxy in Virgo. I ended up taking a series of ten luminance images over a period of two nights on T14, a Takahashi FSQ Fluorite 160mm telescope with an SBIG STL-11000M CCD camera via the itelescope.net remote robotic telescope network. My associate, Muir Evenden, then processed the raw image files using the CCD image processing software PixInsight. What I found interesting with the results was all of the different types of spiral galaxies that were caught in the image.

This type of data gathering could be a fun and interesting exercise for students participating in astronomy education projects. Students could be tasked with identifying the designations and galaxy types in the image field utilizing astronomy software and/or star atlases as I did.

The galaxies caught in my image are located in the Virgo Cluster. This cluster of galaxies whose center are about 53.8 light-years away in the constellation Virgo. Comprising approximately 1300 (and possibly up to 2000) member galaxies, the cluster forms the heart of the larger Virgo Supercluster, of which the Local Group is an outlying member.

Many of the brighter galaxies in this cluster, including the giant elliptical galaxy Messier 87, were discovered in the late 1770s and early 1780s and subsequently included in Charles Messier's catalog of non-cometary fuzzy objects. Described by Messier as a nebula without stars, their true nature was not recognized until the 1920s.

The cluster subtends a maximum arc of approximately 8 degrees centered in the constellation Virgo. Many of the member galaxies of the cluster are visible with a small telescope. Its brightest member is the elliptical galaxy Messier 49; however, its most famous member is the also elliptical galaxy Messier 87, which unlike the former is located in the center of the cluster.
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Monday, July 7, 2014

The Great Fireball of 1966

At around 7:15pm on Sunday, April 24, 1966 - forty-eight years ago tonight - I was 8 years old and just passing by the open front door to our house, which faced due west, at 55 Haddon Ave., Falmouth, Mass. I remember that the sky was still light and absolutely cloudless (about 30 minutes after sunset) when I noticed a ball of light about the size and brightness of the full moon approaching from just slightly to the left, or, south. I remember feeling frozen in place as I watched this thing – I thought it was maybe a burning aircraft – moving parallel with the rooftop of the Hall School which was about 200 ft. away, directly across the street from the house. My brother, Barry, and cousin, “Binky”, yelled over to us as they crossed the front yard later that night, that they had seen a “flying saucer” earlier, just above the Falmouth Public Library, which was just across the street to the south. Something was mentioned about the Lawrence High School just across Shiverick’s pond to the west, and the Falmouth Fire Department were mentioned also. Funny that I did not connect these two events! (This is the night I had run out the front door into the street and stubbed my big toe!)

Sky and Telescope Magazine Cover - June 1966
Sky and Telescope Magazine Cover - June 1966

The object was very bright and seemed to have what I thought of as “sparks” coming from the trailing end, which was teardrop-shaped. It had a long, even, a white train of smoke trailing behind it, much like a thick contrail, which crossed the entire length of the sky. At times, the object's trailing edge became greenish in color, the leading edge yellow-orange, while the main body remained white. It seemed to pulse slowly several times, brightening with each pulse and I wondered if something else was going to happen to it. During these moments of brightening, the “sparks” separated from the main body and trailed it by at least two or three diameters. I remember thinking how strange it was that these sparks, or fragments, were detaching from the object and that they became visible only after they were some distance behind it. The fragments themselves alternated green and orange and left short trails of their own. I distinctly remember thinking that I couldn’t account for what it was I was seeing and I was especially boggled by the fragments trailing behind the object, seems to ignite only after they were some distance away. I wished that I could predict what was going to happen to the object next but I had had no similar prior experience with anything like this. I felt quite at a loss for an explanation for what I saw. Later that night, I had heard my mother on the phone, tell someone that there had been an announcement about the object on TV, about halfway through The Andy Griffith Show. I don’t know what channel it was or what the station call letters were.

The object seemed to move perfectly parallel to the school rooftop, which was just a degree or two below the object, as it moved in a South to North direction. I was struck by the objects slow speed – about the speed of any plane I might have seen at the horizon at any other time. It seemed to take a long time to move across my entire field of view, which was clear all the way from the south to the north, except for the low school rooftop. The rooftop spanned almost the entire length of the western horizon but was itself only about five degrees in height and perfectly flat. I don’t remember hearing any sound at all. I remember thinking that the thing was going to explode at any time after it had swelled again and again. I remained quiet the whole time, not wanting to call out or call attention to the thing, but just watch and wait to see what was going to happen next. I don’t remember anyone else being around, anyway. Again, it seemed as if the event was endless and it struck me how the object seemed to go through many changes during its flight. I estimate the duration of the flight at about 30 seconds. Finally, it seemed to break apart completely and fade out just before disappearing below the tree line in the NNW.

A similar, nearly identical incident occurred in the summer of 1979 or 1980, during the late afternoon (I don't remember the date), which I also witnessed while at work at Quickset Harbor. A similarly sized object had entered the atmosphere - I estimated somewhere over Maine or Nova Scotia - at the NNE tree line and disappeared over the Atlantic Ocean, at roughly the SE tree line. I was able to time the duration of this object's flight - or as much of it as I had witnessed - at 45 seconds. The object's train, speed, and its color approximated that of the 1966 incident. My sister, Linda, claimed to have seen the object while in a friend's boat on Vineyard Sound, just outside of Falmouth Harbor.

I feel very lucky to have seen such rare and wonderful things.

Almost three months after the 1966 incident, on Friday, July 1st, Barry and Binky’s band, “The Beau Brines” opened for “The Animals” at the Cape Cod a-Go-Go, in Yarmouth, MA. On Christmas of that same year, I received my second telescope, a 3-inch Newtonian reflector. It had a white cardboard tube with a screw-clamp ball-and-socket tripod mount. I saw the moon for the first time with this instrument. I also had a black-tubed 3-inch alt-azimuth reflector a year or two earlier, but other than burning my retina with it trying to locate the sun, I only remember using it to try to locate the moon. I didn't find the moon but I did find the sun! This was also the year that I got to sit in the pilot’s seat of John Glenn's Mercury space capsule, “Friendship 7”.

Dale Alan Bryant
Senior Contributing Science Writer
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Saturday, July 5, 2014

The Supernova Next Door

The fierce and brilliant blast of a supernova heralds the explosive, violent death of a star, and these stellar conflagrations can glare so brightly that they may even outshine their entire host galaxy--at least for a time. On January 21, 2014, an exceptionally close stellar explosion became the brilliant object of pursuit for astronomers all over the world--as well as for several NASA spacecraft. The blast, dubbed SN 2014J dazzled the galaxy M82, situated a "mere" 12 million light-years away from our planet. SN 2014J is the closest optical supernova to light up the sky in twenty years--and it is potentially the closest Type Ia supernova to flare-up during the life of today's missions, astronomers said--providing a rare chance to study such Cosmic occurrences.

Image by John Strong of Galaxy M82 with SN2104J.
Image by John Strong of Galaxy M82 with SN2104J.

SN 2014J is the most brilliant supernova to be spotted from our planet since the gigantic stellar blast that popped off back in 1987--just 168,000 light-years away. In fact, the January 2014 supernova was so dazzling that it was brilliant enough to be discovered with a small 'scope peering up at the murky cloud-shrouded sky hovering above north London. On January 21, 2014, Dr. Steve Fossey, an astronomer at University College London, was taking a group of 21 students through a routine lesson with a 35-centimeter 'scope at the urban University of London Observatory. As he showed his students images of the galaxy M82, also known as the Cigar Galaxy because of its shape, they spotted something odd--a brilliant star nestled at the very edge of the galaxy's disk. M82 hangs just above the bowl of the Ursa Major (Big Dipper) constellation, and it has long been a favorite deep-sky target for astronomers.

The brilliant star, that Dr. Fossey and his students saw on an image snapped during a 10-minute viewing session, seemed to be a newcomer. Dr. Fossey could not remember ever seeing it before, and it was not present in images that he and his students looked up on the Internet. "It kind of looked odd," Dr. Fossey said on January 23, 2014, Scientific American.

According to the students who spotted SN 2014J, the exciting discovery was a stupendous surprise.

"One minute we're eating pizza, then five minutes later we've helped to discover a supernova. I couldn't believe it. It reminds me of why I got interested in astronomy in the first place," said student Tom Wright in a January 2014 statement to the press.

Another student, Ben Cooke, also commented in a January 2014 press statement that "The chances of finding anything new in the sky is astronomical, but this was particularly astounding as it was one of the first images we had taken on this telescope."

Something New In The Sky

All stars, large and small, "live" out their entire hydrogen-burning, main-sequence "lives" by maintaining a very critical and delicate balance between two constantly opposing forces--gravity and radiation pressure. The radiation pressure exerted by a star pushes everything outward and away from the star, and it keeps this huge, seething, glaring sphere of roiling gas bouncy against the squeezing crush of gravity, that mercilessly and relentlessly attempts to pull everything inward. The radiation pressure of a star on the main-sequence results from the process of nuclear fusion, which begins with the burning of hydrogen, the lightest and most abundant atomic element in the Universe, into helium--which is the second-lightest atomic element. This process, stellar nucleosynthesis, continually fuses heavier atomic elements out of lighter ones. In fact, all of the atomic elements heavier than helium (termed metals by astronomers), were created in the searing-hot nuclear-fusing hearts of the billions upon billions upon billions of stellar inhabitants of our vast Cosmic Wonderland--or else in the spectacular blasts of supernovae heralding the end of that long stellar road.

Most supernovae ignite when a solitary star runs out of its necessary supply of hydrogen fuel, and blasts itself to smithereens, thus meeting its fiery ultimate doom. Often, the supernova progenitor is a massive star, with an extremely heavy core that tips the scale at approximately 1.4 solar masses (the Chandrasekhar limit). Smaller, less richly-endowed members of the stellar community, such as our own Sun, normally do not die in the incredible brilliance and violence of a supernova conflagration, like their more massive starry kin. Small stars, like our own, perish with relative peace, and incredible beauty. Our Sun, at present, is a common garden-variety and a rather petite main-sequence Star. There are eight major planets, a multitude of lovely moons, and a large number of other, smaller objects, circling our Sun, which is happily situated in the distant suburbs of a majestic, large, barred-spiral Galaxy, our Milky Way--which is a beautiful, starlit pin-wheel twirling in Space. Our Sun, like all stars, will not live forever. Like all stars, it is doomed to, at some point, run out of its necessary amount of hydrogen fuel. Stars of our Sun's relatively petite mass can "live" out their main-sequence lives for about 10 billion years, happily and contentedly fusing their core's supply of hydrogen into heavier things.

However, our Sun is not exactly a spring chicken. In fact, it is a middle-aged star. It's not old, but it isn't young, either. However, it is experiencing a happy and productive mid-life, and is still sufficiently bouncy to go on merrily fusing hydrogen in its hot heart for another 5 billion years or so--alas, it has already lived for about 4.56 billion years!

When small stars like our own have finally succeeded in fusing most of their supply of nourishing hydrogen fuel, they swell into the glowering, bloated red giant stars. The elderly Sun-like star at this point carries a worn-out heart of helium, encircled by a shell in which there is still some lingering hydrogen that is being fused into helium. The shell swells outward, and the star's expiring heart grows progressively larger and larger, as the doomed star grows older and older. Next, the helium heart itself begins to shrivel up under its own weight--and as it does so, it grows hotter until, at last, it has grown so extremely hot at its center that the helium starts to fuse into the still-heavier atomic element--carbon. The Sun-like, petite star winds up with a tiny, searing-hot heart that manufactures more energy than it once did, long, long ago, when it was a vibrant young main-sequence star. The outer gaseous layers of the elderly, doomed star have become swollen and red. Tragically, in our own Solar System, when our Sun has finally become a bloated, old, red giant, it will furiously cannibalize some of its own planet-offspring--first Mercury, then Venus, and then (perhaps), our Earth. The temperature at the fiery surface of this hideous, hungry red giant will be considerably cooler than it was when our Sun was still a vibrant, young, life-sustaining Star!

The death of small stars like our Sun is relatively gentle, characterized by the "soft" puffing off of their outer gaseous layers of shining, multicolored gasses into the space between stars. These objects are so enchantingly beautiful that they are often referred to as the "butterflies of the Cosmos" by astronomers who are bewitched by the spectacle.

Our Sun will perish this way--with great beauty, and in relative peace. But this is because our Sun is a solitary star. It has no companion star around to disturb its hermetic bliss. The Sun's corpse will be a dense, small stellar relic called a white dwarf, and its shroud will be a glimmering, shimmering, "butterfly" with flying wings of many colors.

However, something very different occurs when a Sun-like star has another star for a companion--rudely disturbing its peaceful solitude. This can cause some very explosive things to happen. Small stars usually do not carry sufficient mass to go supernova. However, this kind of blast can happen if two stellar-relic white dwarfs collide and merge, or if a solitary white dwarf dwells in close contact with a companion sister-star--and victim. The unlucky companion star could be either a main-sequence star or a swollen red giant. In either case, the white dwarf, with a vampire-like hunger, sips up material from the companion star--and gulps down as much as it can until, at last, it can drink no more. The white dwarf "goes critical" just like the big guys, and blasts itself into oblivion in the supernova event called a Type Ia.

The Supernova Next Door

Astronomers think that SN 2014J is a member of the Type Ia class and that it can help explain how these supernovae develop. Type Ia supernovae are "standard candles"--that is, they are used as Cosmic measuring sticks by astronomers to help them determine the increasing expansion of the Universe.

Observations of SN 2014J's spectroscopy revealed its status as a Type Ia. This type of supernova brightens rapidly. Even though many such supernovae are spotted annually, they are usually much further away than the Cigar galaxy.

Astronomers around the world will now carefully observe the exact way in which SN 2014J brightens. They have used the consistency of the brightnesses of Type Ia supernovae in the past to make very precise distance measurements. In fact, these Cosmic "standard candles" were of critical importance in the discovery of the dark energy in the 1990s. Dark energy is a mysterious force, a property of Space itself, that is causing the Universe to accelerate in its expansion.

The Cigar galaxy's close proximity means that there are many existing images of it, dating from before SN 2014J exploded, including some that were derived from the Hubble Space Telescope. Astronomers will carefully study those images, searching for what existed in this region before the stellar blast. The Cigar Galaxy is heavily shrouded with dust--the light of the supernova shines on the dust in such a way that it may teach astronomers something about the galaxy, as well. One team of astronomers is currently searching for radioactive elements there, such as nickel, that some theories predict form in Type Ia supernovae.

One of the first telescopes to gaze at SN 2014J was NASA's orbiting Swift observatory, which captured an image of the supernova and its host galaxy, with its Ultraviolet/Optical Telescope.

"Finding and publicizing new supernova discoveries is often the weak link in obtaining rapid observations, but once we know about it, we can observe a new object within hours," Dr. Neil Gehrels told the press on January 27, 2014. Dr. Gehrels is the Swift observatory's principal investigator at NASA's Goddard Space Flight Center.

Judith E. Braffman-Miller is a writer and astronomer whose articles have been published since 1981 in various newspapers, magazines, and journals. Although she has written on a variety of topics, she particularly loves writing about astronomy because it gives her the opportunity to communicate to others the many wonders of her field. Her first book, "Wisps, Ashes, and Smoke," will be published soon.

By Judith E Braffman-Miller

Article Source: The Supernova Next Door
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Friday, July 4, 2014

Supernova SN1989B

On February 11th back in 1989, Mike Petrasko and I were doing research for the Harvard-Smithsonian Astrophysical Observatory's SUNSEARCH program, headed up by amateur astronomer and big-rig driver Steve Lucas, which allowed us to concentrate on monitoring a particular group of galaxies for the rare occurrence of a supernova event. Mike had recently acquired a copy of the Thompson-Bryan galaxy charts, which were then available as individual reinforced cards. These cards are used in comparing the appearance of a galaxy through a telescope to a known representation of the galaxy and its accompanying starfield. Any difference in telescopic appearance and chart appearance can be readily noted.

Supernova 1989B in M66 by J. Salmi of Finland
Image of Supernova 1989B in M66 by J. Salmi of Finland

We had set up in a secluded open field in N. Falmouth earlier in the night. It was early February and the temperature was, well, cold. Mike was using his mostly self-assembled 6-inch f/8 Newtonian, a scope he and I had put together in an afternoon, and myself an 8-inch f/6 Newtonian cross between a Meade and a Parks Optical, and both scopes equipped with a driven German equatorial mounting. Either scope has the capability of picking out galaxies in the depths of space to a distance of beyond 60 million light-years, which is the distance of the Leo-Virgo galaxy group containing the spiral galaxy M66 in the constellation Leo. That's roughly 6 trillion miles x 60 million, which is so far out into the Cosmos that I can’t even calculate the distance on a typical calculator – all the zeros won’t fit!

After we had set up, we took a break and drove down to Dunkin’ Donuts in Falmouth, which was open 24-hours back then, to get some coffee to bring back with us to the observing site. We set our still piping hot coffee down on a small, flat boulder nearby and resumed our observing session.

Through a telescope eyepiece, most spiral galaxies appear as a very dim, homogeneous, oval-shaped patch of light, spanning about a quarter of the field of view of the eyepiece, with little or no internal detail. It is the breaking of this homogeneity by a bright knot of light that we are looking for during these scans.

The method is simple enough; find the galaxy by slewing the telescope in right-ascension and center it in the eyepiece. Then slew the scope so that the galaxy is off to one edge of the field of view and slowly move the tube with your hand so that the galaxy moves across the field to the opposite edge. Moving the galaxy across the field in this way several times, while introducing an intentional tremor in the image by tapping lightly against the tube, allows the sensitive rods in your eye to pick up any breaks in the general homogeneous appearance of the galaxy. Normally, there are no breaks in continuity and we had been at this for years with nothing remarkable to note. By the way, after about an hour sitting on the boulder - our coffees were frozen solid blocks of ice which we never got to drink.

Mike Petrasko and his 6" f/8 Newtonian used to spot SN1989b on 02/11/1989
Mike Petrasko and his 6" f/8 Newtonian used 
to spot SN1989b on 02/11/1989

Then, around 2:00am, while observing galaxy M66, a spiral galaxy much like our own Milky Way galaxy by this method, something caught Mike's eye on the second slew across the otherwise black field of the eyepiece. He had noticed a tiny, bright dot of light near the outer edge of the galaxy. Asking me to take a look at it through my scope, I thought maybe this could be a foreground comet or asteroid or a foreground star in the field of view, the only other three things it could possibly be besides a supernova. We checked the Thompson-Bryan charts and there were no foreground stars noted in the area. Comets and asteroids are moving in orbit around the sun and the thing to do would be to watch for a period of a few hours to see if this new object was stationary or moved slightly from its current position.

We checked the position of the object again at about 5:00am and it hadn't moved. I was convinced that what I was observing was a star exploding in another galaxy. A thought crossed my mind… what if this star was the parent star of a planetary system in orbit around it, much like our solar system? What if one of the planets in orbit around this star harbored life of some kind, possibly intelligent life? A supernova explosion would almost instantly vaporize its planetary system far beyond the orbit of Pluto. Could I possibly be watching the extinction of an entire race of sentient beings in some far-off galaxy? With this thought, in the cold, frigid, lonely darkness, I began to tear up. It is akin to what Alyosha in “The Brothers Karamazov” might have felt in 1880 when, staggering out into the night from Father Zossima’s death-bed and “weeping even over those stars,” he perceived that “there seemed to be threaded from all those innumerable worlds of God, linking his soul to them, and it was trembling all over in contact with other worlds.” Mike and I packed up our equipment at dawn and went home, myself satisfied but slightly saddened, that we had actually watched a star explode in another galaxy.

The next day, Mike contacted me by phone and said he was able to confirm a supernova explosion in spiral galaxy M66, discovered several days previously by a Reverand Robert Evans of New South Wales. In astronomical discoveries, the first two discoverers share the credit if the reports are within several hours of each other. Alas, neither Mike nor myself fell into that category - this time. The object will forever be known as SN1989B. “SN” stands for supernova. “1989” is the year of discovery and “B” means the second supernova discovery of that year.

After years of searching, we had finally witnessed one of the many things in the night sky we had hoped to observe. I immensely enjoyed the time I spent at the telescope eyepiece, searching for supernovae and observing other objects such as Mars, Saturn, Jupiter, comets, asteroids and many other night sky wonders. Many, many more are to come. O-Team, over and out.

Dale Alan Bryant
Senior Contributing Science Writer
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