The Strange case of Epsilon Aurigae July 12, 2009
Posted by jcconwell in Astronomy, IYA 2009, Observatory, stars.Tags: EIU, Epsilon Aurigae, International Year of Astronomy, IYA 2009, Observatory, stars
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When I was a freshman in high school and first developed my interest in Astronomy, two of the more fascinating sources of knowledge I had were the books, “The Universe” by Issac Asimov and the “Guinness book of World Records”.
I still remember running across, in Guinness, the record “the largest star” ….which refers to the diameter of the star, not the mass of the star. Back then the record holder, according to Guinness, was Epsilon Aurigae B, the second member of the binary system (hence the B). The brighter member of the system, Epsilon Aurigae A , is a FO supergiant star visible to the naked eye as a 3.0 magnitude star. Given the temperature from its spectra, and at a distance of about 700 parsecs or 2300 light years, that means its about 100 times the diameter of the Sun and about 50,000 time more luminous.
Epsilon Aurigae in mid July before dawn
You can find the star in the East before dawn, just to the right and slightly above the bright star Capella.
The real interesting object , is not the FO star, but its companion. The system is what astronomers call an eclipsing binary. The system first caught the eye of astronomers when it was noticed that it was a variable star. A star that varied in brightness. In this case, it change between 3.0, and dims to 3.8 magnitude and back again to 3.0, over a cycle of 27.1 years. Now some star are what are called intrinsic variables, meaning the stars pulsate and actually change in brightness, not so here.
Light Curve from the last eclipse
The companion of the FO star happens have its orbit alligned to our eye so it passes in front of the primary star, blocking some of the light … hence eclipsing binary. Now eclipsing binary stars not uncommon, but in this case, the eclipse last for over 2 years! Meaning, whatever the companion is, it’s VERY big.
Notice I’ve stopped calling the companion a star, since it’s also very dark. Much darker than any star it’s size has a right to be. So dark, that astronomers don’t know for sure what it is. The best theory is it’s a large disk of gas and dust surrounding a hidden star that orbits Epsilon Aurigae. If you look at the light curve, above, you’ll notice it brightens in mid-eclipse. Some speculate there might be a double star rotating in the center of the disk that clears out a hole for the light of the main star to shine through.
Much of this is speculations, since 27 years ago astronomers weren’t able to get a good spectra of the object. So one of the projects, at the EIU observatory, are students trying to get spectra before and going into the eclipse. We hope the edges of the disk will be thin enough that we can see a change in the spectra as light starts to dim. You don’t need a big telescope since at 3rd magnitude the object is quite bright. So wish us luck, and if we see something we’ll let you know.
Listen to the PODCAST about Epsilon Aurigae at 365 days of astronomy
For More information on how you can contribute go to web site: citizensky.org
Measuring the Black Hole July 9, 2009
Posted by jcconwell in Black Holes, General Relativity, IYA 2009, Podcast.Tags: blackholes, EIU, IYA 2009, Podcast
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Today’s podcast at 365 days of Astronomy is about measuring those mysterious objects, Black Holes. Usually you think about the tidal forces of a Black Hole ripping and compressing anything falling in until it’s so hot, about 10 million K, that it emits x-rays.
credit: NASA Chandra Space telescope
In today’s pod-cast sponsored by the EIU Physics Department learn how radio telescope aid our knowledge of these dark objects. Go to:
http://365daysofastronomy.org/2009/07/09/july-9th-measuring-the-black-hole/
A Paradise of Astronomical Proportions July 2, 2009
Posted by kanewbyscience in Astronomy, Observatory.Tags: Astronomy, Observatory
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EIU Astro welcomes Kristen Harvey who has her blog at: http://kanewbyscience.wordpress.com/
Try to dream of a tropical paradise. What do you see? Palm trees? Frozen drinks with umbrellas? Crashing waves? That is what I had in mind; at least, until I discovered the paradise of astronomical proportions that sits at the top of Mauna Kea on the Big Island of Hawaii. When I planned my last two trips to the Big Island of Hawaii, I booked my time with palm trees, black sand beaches, and hikes deep within extinct lava tunnels. I now realize that by doing this, I managed to overlook the obvious.
A state with an intense lighting ordinance to ensure for the darkest skies possible, Hawaii provides one of the clearest, most unique places to get a view of our expanding universe. The nature of the island itself is what leads to the astronomical possibilities of this location. Almost 14,000 feet above sea level and surrounded by ocean, the average cloud height is approximately 9000 feet, placing an observer high above the distortion of the clouds while at the summit. The cloud layer also keeps observers free from atmospheric pollutants and excessive moisture. This particular aspect puts Hawaii on the top ten list of clear sky proportions; producing close to 300 clear nights a year.
The summit has been an astronomical beacon since the early Polynesians who used the stars at their vantage point for navigation, astrology, agriculture, and astronomy. Researchers have not been able to prove if the ancient Hawaiians themselves were making observations from Mauna Kea, but it is known that “kilo hoku”, or star watchers, were among the most respected of society members. As the islands were later discovered by Captain James Cook in 1778, astronomy further developed its importance on the region. Cook’s ships brought with them telescopes; over 100 years before the first permanent telescope was brought to the island in 1883 (West, Michael). It was the University of Hawaii, during the 1960’s, however, that really pursued the possibility of astronomical observatories at the summit. Mauna Kea now has thirteen functioning telescopes ranging in size and function. This impressive list includes, arguably the most important, and notably the largest optical/infrared telescopes in the world; the Keck telescopes.
A view from Mauna Kea showing the observatories that outline the summit.The summit provides opportunities for even the most amateur of astronomers. A Visitor Information Station courtesy of the Onizuka Center for International Astronomy is a start. With computers showing active feeds from Mauna Kea telescopes, videos, handouts, smaller telescopes for use by the public, tours, and stargazing programs this is an initial stop to get prepared for the actual summit. Commercial tours are available to take you up and down the summit, although visitors and tours alike do not seem to be allowed at the summit after dark. Several galleries along the summit are open during the day for viewing, but do not think you are going to walk up to the Keck and get your hands on a telescope. Although galleries may be open, the telescopes themselves are off limits to the public and generally close by late afternoon as the professionals prepare for research and viewing after dusk.
Once the amateurs and tourists have left for the night, the research begins. Exploration into the fields of astronomy being done through the use of the telescopes on Mauna Kea ranges far and wide. From images and research on the sun and solar flares to planet formation and astrobiology, Mauna Kea is proving to be a center for education, research, and development when it comes to learning about our expanding universe.
Image of Titan, Saturn’s largest moon, taken February 15, 2005 before the Cassini spacecraft’s third flyby of the moon. This image was taken with the Keck II telescope on the summit of Mauna Kea. Photo courtesy W. M. Keck Observatory/SRI/New Mexico State University.Now, as you contemplate your exotic tropical paradise once more, does it look a bit different? I can tell you this; my next trip to the Big Island will include a visit up the Mauna Kea summit and a glance into a paradise of expanding magnitudes.
Links visited and helpful resources used while writing this post:
A Gentle Rain of Starlight: The Story of Astronomy on Mauna Kea; Text by Michael J. West
History: Deep Space 1 June 30, 2009
Posted by gnhsphysics in Astronomy, Space Craft.Tags: Astronomy, EIU, physics, satellite
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EIU Astro is happy to have our first guest contributor for the summer, Paul Holder, whose blog is at: http://gnhsphysics.wordpress.com/
Deep Space 1 was launched from Cape Canaveral on October 24, 1998. During a highly successful primary mission the team tested twelve advanced high-risk technologies in space. In an extremely successful extended mission it encountered Comet Borrelly and returned the best images and other science data ever obtained from a comet. During its successful hyperextended mission, it conducted further technology tests. The spacecraft was retired on December 18, 2001.
Deep Space 1 was the first spacecraft to utilize ion engines. Ion engines use ejected ionized xenon gas instead of chemical propellants. Only a very small amount of xenon is ejected at a time. It may take four days or more just to use one kilogram of xenon. Becasue of this small ejection mass, the reaction force experienced by the spacecraft is also small. If you rest a piece of paper on your hand, the paper pushes on your hand about as hard as the ion engine pushes on the spacecraft. The benifit of the xenon ion propulsion is that unlike chemical engines, which generally can only be operated for minutes, ion engines can be operated for years. Even though the force that acts on the craft is small, it is applied over a long period and produces a large impulse. The net effect of this is a large change in momentum (velocity), eventually attaining speeds far beyond the reach of chemical propellants.
Deep Space 1, using less than 74 kg (163 pounds) of xenon, accelerated by about 4.3 kilometers/second (9600 miles/hour) over a period of 678 days. This is greater than any spacecraft has ever been able to change its speed and a longer duration than any previous propulsion system. This was attained while operating conservatively. DS1 could have achieved still higher velocity, but mission controllers had to fulfill defined mission objectives.
The team that developed and flew NASA’s Deep Space 1 spacecraft received the American Institute of Aeronautics and Astronautics’ prestigious Space Systems Award “For the outstanding performance of the team during design, implementation, test, operations, and extended mission including space flight test of 12 important, high-risk technologies.” The award was presented on April 2, 2003, during the Responsive Space Conference in Redondo Beach, Calif.
Observatory Open House Tonight! June 26, 2009
Posted by jcconwell in Astronomy, IYA 2009, Observatory.Tags: Astronomy, EIU, International Year of Astronomy, IYA 2009, Observatory
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The “Last Friday of the Month” open houses resume tonight at 9:00 PM, rain or shine! This month, if the cloud stay away we will try to see some of the wonders of our own galaxy the Milky Way, through the 16″ telescope. If it’s cloudy, come take a tour, rotate the dome, and ask Dr Conwell some questions.
Observatory Welcomes Moraine Valley Upward Bound June 25, 2009
Posted by jcconwell in Astronomy, Observatory.Tags: EIU, International Year of Astronomy, Observatory
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Click on picture for full size
EIU Observatory welcomes Moraine Valley Upward Bound Program. These brave souls walked a half mile from the road this afternoon in 97 degree weather! Just to see us in the daytime! It’s a good thing I didn’t tell them it was 108 under the dome, and 124 before the dome was opened. All turned out well. Everyone got CDs of astrophotos and they didn’t even mind my bad jokes, and I didn’t mind the good questions. I hope to Eastern sees some of them in the future as potential physics and astronomy students.
New Podcast at 365 days of Astronomy June 18, 2009
Posted by jcconwell in Astronomy, Podcast, Solar and Space weather.Tags: EIU, International Year of Astronomy, Podcast, Solar
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Today’s podcast sponsered by the EIU physics department is at :
http://365daysofastronomy.org/2009/06/18/june-18th-themisartemis/
THEMIS which stands for “Time History of Events and Macroscale Interactions during Substorms” is a constellation of 5 satellites and 30 ground-based observatories studying Earth’s magnetosphere and aurora. The main aim of these satellites was to answer fundamental questions concerning nature of an abrupt and explosive release of solar wind energy stored within the Earth’s magnetotail, known as a substorm. Having achieved most of its primary objectives of establishing when and where the substorms begin, the satellite mission will split up in July to become two missions. The first, THEMIS-Low, consisting of the three inner probes will continue to study the Earth’s space environment. The outer probes will explore the space environment of the Moon and renamed ARTEMIS: “Acceleration Reconnection Turbulence, and Electrodynamics of Moon Interaction with the Sun.” NASA has extended the THEMIS/ARTEMIS mission to the year 2012.
In this podcast we talk to Dr. Vassilis Angelopoulos, UC Berkeley, the PI of the mission, Dr. Manfred Bester, the THEMIS Mission Operations Manager and Dr. Laura Peticolas, the lead Education and Public Outreach scientist for this mission. We learn about the discoveries and insights learned from THEMIS, what we hope to learn from ARTEMIS and how these discoveries can be shared with the public.
Five New Supernovae Before Breakfast June 15, 2009
Posted by jcconwell in Astronomy, telescopes.Tags: telescope
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In a preview if the new superautomated survey telescopes that are appearing in the next few years…this from Palomar observatory. The venerable 48″ Schmidt telescope, the largest in the world, that was responsible for the grandfather of all surveys , the original Palomar sky survey has been automatated and given a new life as the 48-inch Samuel Oschin Telescope.
Edwin Hubble using the 48" Schmidt Telescope
An innovative sky survey has begun returning images that will be used to detect unprecedented numbers of powerful cosmic explosions-called supernovae-in distant galaxies, and variable brightness stars in our own Milky Way. The survey also may soon reveal new classes of astronomical objects.
All of these discoveries will stem from the Palomar Transient Factory (PTF) survey, which combines, in a new way, the power of a wide-field telescope, a high-resolution camera, and high-performance networking and computing, with rapid follow-up by telescopes around the globe, to open windows of discovery for astronomers. The survey has already found 40 supernovae and is gearing up to switch to a robotic mode of operation that will allow objects to be discovered nightly without the need for human intervention.
The Palomar Transient Factory is a collaboration of scientists and engineers from institutions around the world, including the California Institute of Technology (Caltech); the University of California, Berkeley, and the Lawrence Berkeley National Laboratory (LBNL); Columbia University; Las Cumbres Observatory; the Weizmann Institute of Science in Israel; and Oxford University.
During the PTF process, the automated wide-angle 48-inch Samuel Oschin Telescope at Caltech’s Palomar Observatory scans the skies using a 100-megapixel camera.
The flood of images, more than 100 gigabytes every night, is then beamed off of the mountain via the High Performance Wireless Research and Education Network¬-a high-speed microwave data connection to the Internet-and then to the LBNL’s National Energy Scientific Computing Center. There, computers analyze the data and compare it to images previously obtained at Palomar. More computers using a type of artificial intelligence software sift through the results to identify the most interesting “transient” sources-those that vary in brightness or position.
Within minutes of a candidate transient’s discovery, the system sends its coordinates and instructions for follow-up observations using the Palomar 60-inch telescope and other instruments.
Soon all of the steps in the process will be completely automated, including decisions about which transients merit a second look. When follow-up observations indicate that candidate transient detections show promise, a prioritized list of candidates is brought to the attention of astronomers from the PTF member institutions. Finally, an astronomer becomes personally involved, by performing detailed observations using telescopes such as Palomar’s 200-inch Hale Telescope, a Keck Telescope in Hawaii, or other partner telescopes around the world.
Upgraded 48" Oschin Telescope
The PTF is designed to search for a wide variety of transient sources with characteristic timescales ranging from minutes to months, giving astronomers one of their deepest and most comprehensive explorations of the universe in the time domain.
“By looking at the sky in a new way, we are ushering in a new era of astronomical discovery,” says PTF principal investigator Shrinivas Kulkarni, MacArthur Professor of Astronomy and Planetary Science at Caltech and director of the Caltech Optical Observatories. “Nimble automated telescopes and impressive computing power make this possible.”
“No one has looked on these timescales with this sensitivity before. It’s entirely possible that we will find new astronomical objects never before seen by humans,” says Nicholas Law of Caltech, the project scientist for PTF.
Because it looks for anything changing in the sky, the PTF survey covers a vast variety of different astronomical targets. The wide range of the survey extends across the entire universe. Astronomers expect to discover everything from stars exploding millions of light-years away to near-Earth asteroids that could someday impact our planet.
Much of the survey’s time is spent searching for so-called Type Ia supernovae. These supernovae, formed from the explosion of a class of dead star known as a white dwarf, are very useful to astronomers because they can help determine the distance to galaxies located across the universe. Those distances allow astronomers to probe the origin, structure, and even the ultimate fate of the universe.
By operating more rapidly than previous surveys, PTF will also detect objects of a completely different nature, such as pulsating stars, different types of stellar explosions, and possibly planets around other stars.
PTF’s innovative survey techniques also have raised astronomers’ expectations of finding new, unexpected, astronomical objects.
The PTF already has found many new cosmic explosions, including 32 Type Ia supernovae, eight Type II supernovae, and four cataclysmic variable stars. Intriguingly, PTF also has found several objects with characteristics that do not exactly match any other objects that have been seen before. PTF astronomers are eagerly watching these objects to see how they change, and to determine what they might be.
The quantity and quality of incoming data have astonished astronomers working in the field. On one recent night, PTF patrolled a section of the sky about five times the size of the Big Dipper-and found 11 new objects. “Today I found five new supernovae before breakfast,” says Caltech’s Robert Quimby, a postdoctoral scholar and leader of the PTF software team. “In the previous survey I worked on, I found 30 in two years.”
Source: California Institute of Technology
Herschel telescope wakes up! June 14, 2009
Posted by jcconwell in Astronomy, telescopes.Tags: telescope
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Hershel space telescope opened its hatch that has protected its sensitive instruments from contamination, allowing light collected by its 3.5m mirror to enter its supercold instrument chamber, or cryostat, for the first time The observatory’s quest is to study how stars and galaxies form, and how they evolve through cosmic time. The command sent on Sunday to fire two pyrotechnic bolts holding down the hatch was arguably the key moment in the European Space Agency (Esa) mission since the 14 May launch from Earth.
For more information go to the BBC NEWS. Also see an earlier article form May’s Blog here.
Oops! New podcast up at 365 Days of Astronomy! June 9, 2009
Posted by jcconwell in Astronomy, Podcast.Tags: Astronomy, EIU, International Year of Astronomy, Podcast
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Well, since I’ve been away visiting family and friends in Nebraska this last few weeks (twice!), I neglected to tell you about the new podcast that went up sponsored by the physics department.
While your there, check out the other wonderful podcasts, one a day. They are just perfect to listen to on a short commute, about 10 minutes. If you need a stronger longer dose, about 1/2 hour, you’ll not find any better than go to our friends at “Astronomy Cast”
