COMING EVENTS Webelo Astronomy Night

7:00 PM Friday, Oct. 28 3139 Wescoe Hall

Public Observing

Sunday October 30 Prairie Park Nature Center

8:00 PM

Wings in Orbit: Legacy of the Space Shuttle

Dr. Steve Hawley Saturday, Nov. 5, 3:30 PM Spencer Museum of Art

President

Rick Heschmeyer rcjbm@sbcglobal.net

University Advisor Dr. Bruce Twarog btwarog@ku.edu

Webmaster

Gary Webber gwebber@ku.edu

Observing Clubs

Doug Fay dfay@ku.edu

Report from the Officers: A Hearty Welcome to new club member CHRIS STUMP Congrats also to club member Howard Edin who created an Iphone app for Meteor Show-ers. He submitted it In July and it has been in the app store ever since. You can see what it’s about on the web at: http://itunes.apple.com/us/app/meteor-shower-guide/id451911714?mt=8&ign-mpt=uo%3D4 Our first meeting of the semester went well with a fine turnout and a talk on the exponentially growing results from the Kepler Mission. For

those interested in perusing the world of Kepler on their own, check out their web site at http://kepler.nasa.gov/.

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Volume 37 Number 10 October 2011

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INSIDE THIS ISSUE

Nebulae (continued) 2

Nebulae (continued) 3

NGC 3393 (continued) 3

NASA Space Place 4

Wings in Orbit Poster 5

NGC 3393: Black Hole Pair 6

The Lagoon Nebula 7

Living the High Life 8

Dinosaur-Killing Asteroid? 9

Asteroid (continued) 10

Nebulae – Clouds in Space By Bill Pellerin, Houston Astronomical Society, GuideStar Editor

When you look at the sky, what do you see? On a clear night, you’ll see stars, perhaps the moon, perhaps one or more planets. Do you ever see

clouds in space? They’re a bit harder to see than many of the bright objects, but they are often the most interesting objects in the sky. These objects are generally called nebulae (the plural of nebula) and the word ‘nebula’ is from a Latin word meaning ‘cloud’. They don’t look like small points of light; they look hazy and, well, cloudy. For a long time, we didn’t know what these ob-jects were, but now we do. If you listen, you’ll often hear observers say that an object is ‘non-stellar’ – meaning that it is not a star – meaning that it is

nebulous. Let’s begin with a bit of history.

One of the kinds of nebulae seen by early observers was a spiral nebula. One of the first observers to see these spiral nebulae was a British fellow

named William Parsons, the 3rd Earl of Rosse. In 1845, he built a very large telescope – called the Leviathian. With this telescope, he saw the spiral

structure of M51, the object we now know as the Whirlpool Galaxy. In 1889, Vincent Van Gogh painted the famous ‘Starry Night’ which includes a spiral

shape in the sky thought to be inspired by the drawing of Lord Rosse. Lord Rosse didn’t know what he was seeing, though and neither did anyone else. The mystery continued until the early 20th century – some astronomers holding to the notion that everything that exists is within the Milky Way and

some astronomers convinced that there were other galaxies outside the Milky Way. In April of 1920 a debate was held between Harlow Shapley (who had already determined the center of the Milky Way by mapping out the po-sitions of globular clusters), and Heber Curtis. Shapley supported the Milky Way is everything position, and Curtis supported the idea that galaxies ex-

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About the Astronomy Associates of Lawrence

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The club is open to all people interested in sharing their love for astronomy. Monthly meetings are typically on the second Fri-day of each month and often feature guest speakers, presentations by club members, and a chance to exchange amateur as-tronomy tips. Approximately the last Sunday of each month we have an open house at the Prairie Park Nature Center. Periodic

star parties are scheduled as well. For more information, please contact the club officers:our president, Rick Heschmeyer at rcjbm@sbcglobal.net, our webmaster, Gary Webber, at gwebber@ku.edu, or our faculty advisor, Prof. Bruce Twarog at

btwarog@ku.edu. Because of the flexibility of the schedule due to holidays and alternate events, it is always best to check the Web site for the exact Fridays and Sundays when events are scheduled. The information about AAL can be found at

http://www.ku.edu/~aal. Copies of the Celestial Mechanic can also be found on the web at

http://www.ku.edu/~aal/celestialmechanic

This month is a busy period, with most of the events loaded near the end.

The first big event is Webelo Scout Astronomy Night on FRIDAY, OCTOBER 28 at 7PM in 3139 Wescoe Hall. If the weather cooperates, we will have telescopes set up outside Wescoe for observing at 8PM after the interior presentation by Rick. With over 200 attendees, the more scopes we have set up, the better. So, think about coming down and showing off your exper-tise and your astronomical equipment. The same weekend is our public observing session on Sunday Oct. 30 at the Prairie Park Nature Center. With new moon, it should be a great night for dark sky objects. As always, if you can help, let Rick know.

One of the major events of the year will take place on Saturday, November 5, 2011 at 3:30 PM. Dr. Steve Hawley, retired astronaut and KU Professor of Physics and Astronomy, will give a public talk at the Spencer Museum of Art on the legacy of the Space Shuttle Program, which ended this year after 30 years of extraordinary history. The lecture is tied to the publication of the book “Wings in Orbit” and is free and open to the public. Following the lecture (4:30), there will be a reception and book-signing. Please help spread the word about this lecture and en-courage anyone and everyone to attend. A poster for the event is enclosed in page 5. The Space Program was featured in the latest issue of the KU Alumni magazine and the article can be accessed on-line at http://www.physics.ku.edu/momentum/pdfs/kansasalumni.pdf. Any suggestions for improving the club or newsletter are always welcome. Hope to see you all at the first meeting in 2 weeks.

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isted beyond the Milky Way. It was Edwin Hubble who settled the issue when he determined the distance to the Andromeda Galaxy using Cepheid variables. He announced his conclusion in early 1925, and from then on as-

tronomers knew that these spiral nebulae were, in fact, separate galaxies. They only look nebulous because they are so far away that we cannot easily resolve individual stars.

So, galaxies are not nebulae. What’s left?

Nebulae are usually identified as emission, reflection, or dark. An emission nebula is one which glows (red) be-cause material in the nebulous cloud of interstellar dust is ‘excited’ by radiation from an imbedded star or an

imbedded white dwarf. For a planetary nebula, an imbedded white dwarf radiates a lot of UV (ultraviolet) radia-tion. This radiation strikes the molecules of the gas which absorb this energy and re-radiate the energy as light. A reflection nebula is one which simply reflects light from a star or a set of stars. This reflected light looks blue to us, for the same reason that the sky looks blue. The blue light is reflected by the cloud and some of that reflected

light reaches us. The Trifid Nebula has both an emission component and a reflection component.

A dark nebula looks like a dark spot in the sky because the dark nebula hides any stars or glowing nebulae that may be behind the dark nebula. A common example is the Horsehead Nebula in Orion. Another favorite is Bar-

nard 68 in Ophiuchus.

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and becomes hotter. The obscured regions around both black holes block the copious amounts of optical and ultravio-let light produced by infalling material.

At a distance of 160 million light years, NGC 3393 contains the nearest known pair of supermassive black holes. It is also the first time a pair of black holes has been found in a spiral galaxy like our Milky Way. Separated by only 490 light years, the black holes in NGC 3393 are likely the remnant of a merger of two galaxies of unequal mass a billion or

more years ago.

Dubbed "minor mergers" by scientists, such collisions of one larger and another smaller galaxy may, in fact, be the most common way for black hole pairs to form. Until the latest Chandra observations of NGC 3393, however, it has has been difficult to find good candidates for minor mergers because the merged galaxy is expected to look like an ordinary spiral galaxy.

If this was a minor merger, the black hole in the smaller gal-axy should have had a smaller mass than the other black hole before their host galaxies started to collide. Good estimates of the masses of both black holes are not yet available to test this idea, although the observations do show that both black holes are more massive than about a million Suns.

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So, this is how the nebulae look, but knowing this does not answer the question: What are these things? So, let’s look at nebula in a different light (so to speak). If we think of nebulae as pre-stellar or post-stellar, we end up with a much better understanding of the nature of these objects and their place in the universe.

Pre-stellar nebulae A pre-stellar nebula is one comprised mostly of the elements that will condense, under the pull of gravity, to

form new stars. The visible ones are those that are lit up by the new stars that have already begun to shine. The recipe for star formation is actually rather simple. Get a large cloud of about 75% hydrogen and about 25% helium, often with a little bit of heavier elements, and wait for gravity to do its job. As the mate-rial falls together to form a star, it begins to heat up. After some time the heat is high enough to initiate nu-clear fusion (hydrogen to helium) and the star begins to shine. It ultimately settles into mid-life on the main sequence and becomes an ordinary star. Its characteristics (color, size, lifetime) depend completely on the

mass of the material that formed the star. There are many examples of star forming nebulae – the best known of these is the Orion Nebula, M42. There are many others, including the Eagle Nebula, M16. The dark nebulae can be star forming regions as well, but the nascent stars cannot be seen visually but they

can be detected by infrared telescopes. Post-stellar nebulae

Stars eventually run out of fuel. Low mass stars fuse hydrogen to helium, then helium to carbon and oxy-gen. At that point the star is not, and will not become, hot enough to fuse carbon. The result of this failure is

a star that simply runs out of energy, but in its last burst of glory it becomes visible to us as a planetary nebula. The outer layers of the star are pushed away from the star late in the star’s life, and then are lit up by the ultra-violet radiation from the white dwarf star in the middle. (Calling what is left a ‘star’ is, in fact, a

misnomer. The white dwarf is glowing from the residual heat of the star’s glory days, but nuclear fusion has ended. In the end, it cools off and disappears.) Well known planetary nebula include the Ring Nebula (M57) in Lyra and the Dumbbell Nebula (M27) in Vulpecula. These planetary nebulae are only visible for 50,000

years or so, so look quickly. High mass stars (usually defined as being larger than 8 times the mass of the sun), often end their lives as

a supernova. A titanic implosion of material from the star produces the most energetic event in the uni-verse, the supernova. After some time, we’re left with a shell of the material that was blown away, and this eventually dissipates. We have two very good examples of supernova remnants to see. The Crab Nebula (M1) in Taurus is a compact supernova remnant, and the Veil Nebula (NGC6960 is a piece of the Veil) in

Cygnus is a very large remnant, about 3 degrees on the sky – so large that you may not be able to see the entire nebula in one telescopic view. Please go out and look at these, and other, nebulae. You will need dark skies for most of these. Having an understanding of the nebula’s place in the universe (pre-stellar or

post-stellar) makes the viewing all the more enjoyable.

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Dark Clues to the Universe

By Dr. Marc Rayman

Urban astronomers are always wishing for darker skies. But that complaint is due to light from Earth. What about the light coming from the night sky itself? When you think about it, why is the sky dark at all? Of course, space appears dark at

night because that is when our side of Earth faces away from the Sun. But what about all those other suns? Our own Milky Way galaxy contains over 200 billion stars, and the entire universe probably con-tains over 100 billion galaxies. You might suppose that that many stars would light up the night like daytime! Until the 20th century, astrono-mers didn't think it was even possible to count all the stars in the universe. They thought the universe was infinite and unchanging. Besides being very hard to imagine, the trouble with an infinite universe is that no mat-ter where you look in the night sky, you should see a star. Stars should overlap each other in the sky like tree trunks in the middle of a very thick forest. But, if this were the case, the sky would be blazing with light. This problem greatly troubled astronomers and be-came known as “Olbers’ Para-dox” after the 19th century as-tronomer Heinrich Olbers who wrote about it, although he was not the first to raise this astronomical mystery.

To try to explain the paradox, some 19th century scientists thought that dust clouds between the stars must be absorbing a lot of the starlight so it wouldn’t shine through to us. But later scientists realized that the dust itself would absorb so much energy from the starlight that eventually it would glow as hot and bright as the stars themselves. Astronomers now realize that the universe is not infinite. A finite universe—that is, a universe of limited size—even one with trillions of stars, just wouldn't have enough stars to light up all of space.

Although the idea of a finite universe explains why Earth's sky is dark at night, other factors work to make it even darker. The universe is expanding. As a result, the light that leaves a distant galaxy today will have much farther to travel to our eyes than the light that left it a million years ago or even one year ago. That means the amount of light energy reaching us from distant stars dwindles all the time. And the farther away the star, the less bright it will look to us.

Also, because space is expanding, the wavelengths of the light passing through it are expanding. Thus, the farther the light has traveled, the more red-shifted (and lower in energy) it becomes, perhaps red-shifting right out of the visible range. So, even darker skies prevail. The universe, both finite in size and finite in age, is full of wonderful sights. See some bright, beautiful images of faraway galaxies against the blackness of space at the Space Place image galleries. Visit http://spaceplace.nasa.gov/search/?q=gallery.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

This Hubble Space Telescope image of Galaxy NGC 4414 was used to help calculate the expansion rate of the universe. The galaxy is about 60 million light-years away. Credit: NASA and The Hubble Heritage Team (STScI/AURA)

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NGC 3393: NASA's Chandra Finds Nearest Pair of Supermassive Black Holes Evidence for a pair of supermassive black holes in a spiral galaxy has been found in data from NASA's Chandra X-ray Observatory. This main image is a composite of X-rays from Chandra (blue) and optical data from the Hubble Space Telescope (gold) of the spiral galaxy NGC 3393. Meanwhile, the inset box shows the central region of NGC 3993 as observed just by Chandra. The diffuse blue emission in the large image is from hot gas near the center of NGC 3393 and shows low energy X-rays. The inset shows only high energy X-rays, including emission from iron. This type of emission is a characteristic feature of growing black holes that are heavily obscured by dust and gas. Two separate peaks of X-ray emission (roughly at 11 o'clock and 4 o'clock) can clearly be seen in the inset box. These two sources are black holes that are actively growing, generating X-ray emission as gas falls towards the black holes

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Into the Depths of the Lagoon Nebula Swirling dust clouds and bright newborn stars dominate the view in this image of the Lagoon nebula from NA-SAs Spitzer Space Telescope. Also known as Messier 8 and NGC 6523, astronomers estimate it to be between 4000 and 6000 light years away, lying in the general direction of the center of our galaxy in the constellation Sagittarius.

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Living the High Life This composite image of NGC 281 contains X-ray data from Chandra (purple) with infrared observations from Spitzer (red, green, blue). The high-mass stars in NGC 281 drive many aspects of their galactic environment through powerful winds flowing from their surfaces and intense radiation that heats surrounding gas, "boiling it away" into interstellar space. This process results in the formation of large columns of gas and dust, as seen on the left side of the image. These structures likely contain newly forming stars. The eventual deaths of massive stars as supernovas will also seed the galaxy with material and energy

The Lagoon nebula was first noted by the astronomer Guillaume Le Gentil in 1747, and a few decades later became the 8th entry in Charles Messiers famous catalog of nebulae. It is of particular interest to stargazers as it is only one of two star-forming nebulae that can be seen with the naked eye from north-ern latitudes, appearing as a fuzzy grey patch.

The glowing waters of the Lagoon, as seen in visible light, are really pools of hot gas surrounding the massive, young stars found here. Spitzer’s infrared vision looks past the gas to show the dusty basin that it fills. Here we see the central regions of the Lagoon with green showing the glow of carbon-based dust grains, and red highlighting the thermal glow of the hottest dust.

The various columns of dust all seem to point inwards towards the central depths of the Lagoon. These structures are being sculpted by the intense glow of giant, young stars found at the nebulas core. Within these clouds of dust and gas, a new generation of stars is forming.

This image was made using data from Spitzer’s Infrared Array Camera (IRAC). Blue shows infrared light with wavelengths of 3.6 microns, green represents 4.5-micron light and red, 8.0-micron light.

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Origin of Dinosaur-Killing Asteroid Remains a Mystery Observations from NASA's Wide-field Infrared Survey Explorer (WISE) mission indicate the family of asteroids some be-lieved was responsible for the demise of the dinosaurs is not likely the culprit, keeping open the case on one of Earth's greatest mysteries. While scientists are confident a large asteroid crashed into Earth approximately 65 million years ago, leading to the extinc-tion of dinosaurs and some other life forms on our planet, they do not know exactly where the asteroid came from or how it made its way to Earth. A 2007 study using visible-light data from ground-based telescopes first suggested the remnant of a huge asteroid, known as Baptistina, as a possible suspect. According to that theory, Baptistina crashed into another asteroid in the main belt between Mars and Jupiter about 160 mil-lion years ago. The collision sent shattered pieces as big as mountains flying. One of those pieces was believed to have impacted Earth, causing the dinosaurs' extinction. Since this scenario was first proposed, evidence developed that the so-called Baptistina family of asteroids was not the re-sponsible party. With the new infrared observations from WISE, astronomers say Baptistina may finally be ruled out. "As a result of the WISE science team's investigation, the demise of the dinosaurs remains in the cold case files," said Lind-ley Johnson, program executive for the Near Earth Object (NEO) Observation Program at NASA Headquarters in Washing-ton. "The original calculations with visible light estimated the size and reflectivity of the Baptistina family members, leading to estimates of their age, but we now know those estimates were off. With infrared light, WISE was able to get a more accurate estimate, which throws the timing of the Baptistina theory into question."

WISE surveyed the entire celes-tial sky twice in infrared light from January 2010 to February 2011. The aster-oid-hunting por-tion of the mis-sion, called NE-OWISE, used the data to cata-logue more than 157,000 aster-oids in the main belt and discov-ered more than 33,000 new ones. Visible light re-flects off an as-teroid. Without knowing how reflective the surface of the asteroid is, it's hard to accu-rately establish size. Infrared observations allow a more accurate size estimate. They detect infrared light coming from

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Scientists think that a giant asteroid, which broke up long ago in the main asteroid belt between Mars and Jupiter, eventually made its way to Earth and led to the extinction of the dinosaurs. This artist's concept shows a broken-up asteroid. Image credit: NASA/JPL-Caltech

AAL Astronomy Associates of Lawrence

University of Kansas Malott Hall 1251 Wescoe Hall Dr, Room 1082 Lawrence, KS 66045-7582

Celestial Mechanic October 2011

the asteroid itself, which is related to the body's temperature and size. Once the size is known, the object's reflectivity can be re-calculated by combining infrared with visible-light data. The NEOWISE team measured the reflectivity and the size of about 120,000 asteroids in the main belt, including 1,056 members of the Baptistina family. The scientists calculated the original parent Baptistina asteroid actually broke up closer to 80 million years ago, half as long as originally proposed. This calculation was possible because the size and reflectivity of the asteroid family members indicate how much time would have been required to reach their current locations -- larger asteroids would not disperse in their orbits as fast as smaller ones. The results revealed a chunk of the original Baptistina asteroid needed to hit Earth in less time than previ-ously believed, in just about 15 million years, to cause the extinction of the dinosaurs. "This doesn't give the remnants from the collision very much time to move into a resonance spot, and get flung down to Earth 65 million years ago," said Amy Mainzer, a co-author of a new study appearing in the Astrophysical Journal and the principal investigator of NEOWISE at NASA's Jet Propulsion Laboratory (JPL) in Pasadena. Calif. "This process is thought to normally take many tens of millions of years." Resonances are areas in the main belt where gravity nudges from Jupiter and Saturn can act like a pinball machine to fling asteroids out of the main belt and into the region near Earth. The asteroid family that produced the dinosaur-killing asteroid remains at large. Evidence that a 10-kilometer (about 6.2-mile) asteroid impacted Earth 65 million years ago includes a huge, crater-shaped structure in the Gulf of Mexico and rare minerals in the fossil record, which are common in meteorites but seldom found in Earth's crust. In addition to the Bap-tistina results, the NEOWISE study shows various main belt asteroid families have similar reflective properties. The team hopes to use NEOWISE data to disentangle families that overlap and trace their histories. "We are working on creating an asteroid family tree of sorts," said Joseph Masiero, the lead author of the study. "We are starting to refine our picture of how the asteroids in the main belt smashed together and mixed up."

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