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Monthly Target List For Explorations With MicroObservatory Each month the sky presents us with a dazzling assortment of spectacular objects on which to train our telescopes: variable stars, nebulae, galaxies, and clusters of galaxies, to name a few. As the Earth makes its yearly trip aroundthe Sun, different objects slide into view in the nighttime sky. Any given object (the Andromeda Galaxy, for example) is likely to be visible for several months; however, each potential target has an associated "peak viewing time". This is the time of year when that object will be at its highest point above the horizon at the darkest hour, namely midnight. So while it's possible to take good images of the Andromeda galaxy for much of the fall and winter, you're likely to get the best images of it in mid-October. This packet consists of a month-by-month list of some of the most interesting targets for the MicroObservatory telescopes. The objects are listed according to the month of their peak viewing opportunities as described above; in most cases you will be able to get good images even a couple of months before or after the peak viewing month. We've also provided some practical information (each object's coordinates on the sky), as well as some of the most exciting current and historical research tidbits about each target. "Cool Facts" consist of descriptions of each object, as well as some fascinating properties of the object. "Connections" are questions which are meant to get you thinking about conceptual ties to other areas of astronomy, the physical sciences, and sometimes other disciplines. "What's Hot" lists some of the most exciting cutting-edge research being done with NASA spaceborne instruments and other telescopes. "Web Resources" points you to some potentially useful websites for more information. "People" lists scientists who are doing state-of-the-art work on the target in question, and who also have an interest in contributing images and data for the FGU curriculum. "Activities/Challenges" are suggested ideas for investigations that can be carried out with the MicroObservatory telescopes, sometimes supplemented with images and data from the scientific community. Month Name of Target RA Dec Cool Facts Connections January Galaxy Group NGC2300 (Agglomeration of galaxies, gas, and possibly unseen matter) 07:32.0 +85:43 In visible light, this is a beautiful group of galaxies. But there is also an abundance of invisible searing-hot gas. What's keeping it from boiling away? There's got to be a huge mass of additional What keeps the Earth's atmosphere in place? Why doesn't the Moon have an atmosphere? Where does one find other examples of dark matter in the Universe? Why is ultra- dark matter exerting a gravitational pull on the visible gas and galaxies to hold the whole cluster together. The only way to "see" the million-degree gas is in X-rays! hot gas only detectable in X-ray light? February (visible + X-ray image) Bode's Galaxy M81 (Spiral Galaxy) 09:55.6 +69:04 This beautiful grand-design spiral is in close interaction with its nearby companion, M82 (see below). The two galaxies had a close encounter a few tens of millions of years ago, leaving some scars on M81's spiral pattern. In a billion years or so, the two galaxies will collide and will probably merge to form a single, larger galaxy. February Cigar Galaxy M82 (Irregular Galaxy) 09:55.8 +69:41 This somewhat disk-shaped irregular galaxy recently had a near-collision with its neighbor M81 (see above). The encounter left M82's core disrupted, and triggered a heavy bout of star formation. In addition, M82 is the brightest galaxy in the sky in infrared light. March Galaxy M106 (Spiral Galaxy) 12:19.0 +47:18 Like many galaxies, M106 has a huge black hole at its center, tens of millions of times more massive than our Sun. The black hole in the nucleus of M106 was found in 1995 by astronomers who noticed the great speeds with which the gas in the galaxy's center was swirling around. This was the very first supermassive black hole to be definitively discovered. Think of what you may know about Kepler's laws as they work in our own Solar System. How can we use information about the orbits of the planets to figure out the mass of the Sun? Could you use a similar technique to figure out the mass of the black hole at the center of M106? March The Virgo Cluster (Cluster of Galaxies) 12:30 +12:30 (approximate center) The nearest large galaxy cluster to our own Local Group, the Virgo Cluster is a spectacular sight, containing over 2000 galaxies, and like NGC2300 (see above), it also harbors a large amount of hot, invisible gas, detectable only in X-rays. The gravitational pull of this huge cluster is large enough that our own Milky Way and other nearby galaxies are being noticeably pulled toward Virgo. The Virgo Cluster is huge many millions of light years across! Is there anything in the Universe that's bigger than a cluster of galaxies? What about superclusters? (Perhaps we ourselves live in one - how would we know?) What exactly are the biggest objects in the Universe? What's Hot Web Resources People Activities/Challenges Most of the huge hot gas clouds out there are found in big galaxy clusters like the Virgo cluster (see below). The gas cloud in NGC2300, discovered by NASA's ROSAT satellite, was the first such beast to be seen chandra.harvard.edu/photo/0087 gcn.gsfc.nasa.gov/~horner/cluster/ Laura Grego at the Center for Astrophysics in Cambridge has made observations of the hot gas in galaxy clusters with the CHANDRA X-ray telescope. With the help of information provided by a scientist, figure out the total mass needed to hold all of the galaxies in place. Now do a similar investigation for the Earth's in a small galaxy group. Recently, the Chandra X-ray telescope looked at another galaxy cluster, Hydra A, and found something extraordinary. Check it out on the web! The Hubble Space Telescope has captured M81 and its companion M82 in a beautiful image - check it out on the web! atmosphere, and for the Moon. (Time & Motion) www.seds.org/messier/m/m081.html antwrp.gsfc.nasa.gov/apod/ap000209.html www.seds.org/messier/m/m082.html antwrp.gsfc.nasa.gov/apod/ap000209.html In 1999 a group of radio astronomers used an ingenious technique to pin down the distance from Earth to M106. Using observations of the gas swirling around the central black hole, they found a distance of 23.5 million light years, give or take 1 million. Believe it or not, this makes M106 the object with the bestdetermined distance to date outside our own Galaxy! www.seds.org/messier/m/m106.html Lincoln Greenhill at the Center for Astrohysics has been involved for several years with the team that has been looking at M106 in radio waves. He was one of the people who discovered the central black hole, as well as figured out the distance to this galaxy. Month Name of Target RA Dec Coll Facts April Galaxy M87 (Giant Elliptical Galaxy in the Virgo Cluster) 12:30.8 +12:40 M87 is the biggest, brightest galaxy in the nearby Virgo Cluster. It is orbited by tens of thousands of globular star clusters (the Milky Way has only a couple hundred); it has a spectacular visible jet of gas ejected from the galaxy's core; and, like many galaxies, it most likely has a giant black hole at its center. April Galaxy NGC4565 (Edge-On Spiral Galaxy) 12:36.3 +25:59 This is a spectacular example of a spiral galaxy seen edge-on (see also NGC891 below). April Pinwheel Galaxy M101 (Face-On Spiral Galaxy) 14:03.2 +54:21 This is one of the most stunning face-on spiral galaxies in the sky. If current estimates of its distance are correct, it is also one of the largest disk galaxies, with a diameter of about 170,000 light years. M101 is probably the beststudied spiral galaxy outside our own Local Group. May Globular Cluster M80 16:17.0 -22:59 This globular cluster contains hundreds of thousands of stars. It's fairly low in the sky when observed from northerly latitudes, so it's best viewed around its optimal time of the year, which is the end of May. June Globular Cluster M13 16:41.7 +36:28 July Ring Nebula M57 (Planetary Nebula) 18:53.6 +33:02 Globular clusters are among the oldest objects in the universe some cosmologists' estimates of the age of the universe itself are known to be too short because globular clusters are older! M13 has at least one very young star in it, probably captured recently from elsewhere. The Ring Nebula is a planetary nebula, formed when a star much like our own Sun ended its life by swelling into a red giant and then shedding its outer layers. This nebula emits most its light at or near a single wavelength! Connections Why do some stars end their lives looking like the Ring Nebula, while other more massive stars die in violent explosions and leave corpses like the Crab Nebula (see below)? What's Hot Web Resources People Activities/Challenges www.seds.org/messier/m/m087.html A team of Japanese astronomers, using the ASCA satellite, have looked at NGC4565 in X-rays and have found two objects which are probably binary star systems containing black holes. Images taken with the ROSAT X-ray satellite have revealed the presence of two remnants of extremely violent explosions known as hypernovae. These explosions are much more powerful than supernovae, and may be connected to the mysterious gamma-ray bursts. www.seds.org/messier/m/m101.html www.astro.umass.edu/~wqd/hnr/hnr.htm Images taken of M80 with the Hubble Space Telescope reveal that there are lots of younglooking blue stars in this very old, mostly reddish cluster! It turns out that these stars only LOOK young - they're actually as old as the rest of the cluster, but probably had their outer layers stripped off during close encounters with other stars. www.seds.org/messier/m/m80.html Daniel Wang at the University of Massachusetts discovered the hypernova remnants in M101. He currently has high school interns working with him on his research. www.seds.org/messier/m/m013.html www.seds.org/messier/m/m057.html oposite.stsci.edu/pubinfo/pr/97/pn Take images of the Ring Nebula using various filters. In which one does it appear brightest? Why? (Light & Color) Can you find the faint star at the center? Month Name of Target RA Dec Coll Facts July Dumbbell Nebula M27 (Planetary Nebula) 19:59.6 +22:43 The Dumbbell is a planetary nebula like the Ring Nebula (see above). It's huge - the faint outer parts cover half as much sky as the full Moon! Like the Ring, it shines almost exclusively in light emitted by twice-ionized oxygen. August Star HD 209458 (Sun-like Star) 22:03.2 +18:53 This star has a giant, Jupiterlike planet orbiting it at a distance one-tenth the size of Mercury's orbit. The planet was discovered by observing the "wobble" it induces in the star's motion. Connections Is our own Solar System typical in its arrangement and spacing of planets, or is it unique? Could we "see" the Earth if we lived on a planet orbiting a distant star? Are planets the only places where life might develop? (This picture is an artist's rendering!) August Beta Lyrae (Eclipsing Binary Star) 18:50.1 +33:22 Beta Lyrae is a star with an invisible companion, another star, orbiting it. The primary star (the one we can see) is actually having some of its matter siphoned off into a swirling disk around the companion star by its gravity. When the companion with its disk passes in front of the primary star, it causes an eclipse and the primary star appears to get dimmer. October Andromeda Galaxy M31 (Spiral Galaxy) 00:42.7 +41:16 It's the closest spiral galaxy to the Milky Way, and by far the best-studied galaxy outside our own. It appears to have two nuclei at its center maybe it swallowed another galaxy whole at some point in the past! How can we learn more about our own Galaxy by studying our nearest spiral neighbor? Will we ever have a view like this of the Milky Way? October Galaxy NGC891 (Edge-On Spiral Galaxy) 02:22.6 +42:21 It's a spiral galaxy much like our own Milky Way, but you can't see the spiral arms because it's oriented edge-on. You can see a dramatic dark dust lane down the middle. A team of Dutch astronomers recently found huge amounts of molecular hydrogen in NGC891 looking in the infrared - could this be the "missing mass" in this galaxy? Why can't you see through the dust in this galaxy? Can you seethrough to the center of our own Milky Way? What makes something opaque instead of transparent? Why can you see through a thick pane of glass but not through a thin sheet of paper? What's Hot Web Resources People Activities/Challenges www.seds.org/messier/m/m027.html oposite.stsci.edu/pubinfo/pr/97/pn Astronomers recently saw the star get slightly dimmer at regular intervals - evidence that the planet is actually passing in front of the star! This means that we're seeing its orbit edge-on, and allowed astronomers to figure out the mass of the planet very accurately. astron.berkeley.edu/~gmarcy/transit.html David Charbonneau is a graduate student at Harvard University who was on the team that discovered that the planet passes directly in front of the star. Take several images of the star; can you tell if its brightness is changing? Is it doing so at regular intervals? With some additional info provided by a scientist, can you figure out how large the planet is? How large the star is? How large the planet's orbit is? The Chandra X-ray telescope has found strong evidence for a huge black hole in the center of M31. It seems likely that a similar, but much hotter, beast also lives at the center of our own galaxy. www.seds.org/messier/m/m031.html chandra.harvard.edu/press/00_releases/ press_011400m31.html ww.skypub.com/sights/northern users.erols.com/gmqm/arabastro.html www.auvel.org/zenithco.sufi.html www.seds.org/messier/xtra/similar/hodierna.html Michael Garcia is on the Chandra team which found the relatively lukewarm black hole at the center of M31. Take an image of M31; can you see the individual stars that make up this galaxy? Can you estimate how many stars there are in M31? How large should an individual star in M31 appear in your image? (Size & Scale) Astronomers at NASA's Goddard Spaceflight Center are mapping our own Milky Way galaxy all across the spectrum, from radio waves up through gamma rays. Might our own galaxy harbor large amounts of molecular hydrogen as well? Dave Leisawitz works with the COBE team at Goddard, and is involved in the Multi-Wavelength Milky Way project. Month Name of Target RA Dec Coll Facts Connections November Algol (Eclipsing Binary Star in the constellation Perseus) 03:08.2 +40:57 Algol is actually two atars in orbit around one another one is an ordinary main sequence star like the Sun, the other is a huge red giant. Algol's brightness changes when the red giant passes in front of the main sequence star and blocks its light from November The Pleiades, aka M45 (Young Star Cluster) 03:47.0 +24:07 It's a cluster of very young (only a few million years old) stars and their associated gas and dust. New stars are forming in our galaxy all the time, and some are much younger than our own planet! The Pleaides weren't even around when the dinosaurs walked the Earth. December Crab Nebula M1 (Supernova Remnant) 05:34.5 +22:01 It's spectacularly bright at all wavelengths of light, from radio waves up through gamma rays. No other source in the sky can boast the same! The Crab has a rich history starting with the supernova explosion which created it in 1054 AD. December Orion Nebula M42 (Star-Forming Region) 05:35.4 -05:27 The Orion nebula is a giant cloud of gas and dust. It's a fantastic laboratory for studying how stars like our Sun are born. It's visible to the naked eye, in the belt of the constellation Orion. Chemistry: How can we tell what anything is made of? Each chemical element and molecule has a distinct signature if you know how to look for it. Where does the water on Earth originally come from? What's Hot Web Resources People Activities/Challenges www.seds.org/messier/m/m045.html The Chandra X-ray telescope resolved the innermost regions of the nebula, and may provide clues as to the nature of the central generator (pulsar) that causes the nebula to shine so brightly. chandra.harvard.edu/photo/0052 www.seds.org/messier/m/m001.html super.colorado.edu/~astr1020/sung.html www.chaco.com/park/archaeology/nebula.html The SWAS infrared satellite is looking for signs of the presence of water and molecular oxygen in the Orion Nebula. Water helps gas clouds to cool and collapse to form stars, so it's important to know where water can be found in space. cfa-www.harvard.edu/cfa/oir/Research/swas.html www.seds.org/messier/m/m042.html Figure out how old the Crab nebula is by comparing images taken decades apart. (Time & Motion; Size & Scale) René Plume works on the SWAS satellite, and has been working closely with high school students in on Pittsburgh on some of the scientific analysis.