Alumni CLASnotes Spring 2006
In This Issue:

The Sky's the Limit

Robert H. Grubbs
Professor Jian Ge and the W.M. Keck Exoplanet Tracker
against the backdrop of an artist’s rendition of a very
young, active star orbited by a planet like the one
recently discovered. Named ET-1, the planet is one of
the first companions ever found with a star just 600
million years old.
UF’s astronomy department is well on its way to becoming one of the top departments in the nation. Partnering with Spain and Mexico to build the world’s largest optical telescope, Gran Telescopio Canarias, in the Canary Islands—set to open in 2008—is just one of the many projects causing the international reputation of the department to shine, according to Department Chair Stanley Dermott. “We have developed perhaps the best astronomical instrumentation group in the world,” he says. From discovering new planets to capturing images using the Hubble Space Telescope, the department continues to distinguish itself, as well as sharing its expertise with the public through outreach events. As Dermott fittingly puts it, “The future looks bright!”

Where No One Has Gone Before

If there is life on distant planets in our universe, Astronomy Professor Jian Ge may very well be involved in its discovery.

Ge and his team of planet trackers have just confirmed the existence of a new planet and finding life outside our solar system may not be so far behind.

On January 11, Ge and colleagues at UF, Pennsylvania State University, Tennessee State University, the University of Texas and the Institute of Astrophysics in Spain’s Canary Islands announced the discovery of a new planet orbiting a young star 100 light-years away, located in the direction of the constellation Virgo. The team used a single-object planet tracker located at Kitt Peak National Observatory in Arizona, but Ge’s new Keck Exoplanet Tracker, funded by a $875,000 grant from the W.M. Keck Foundation, will soon allow for the observation of 60 objects at one time and look roughly 1,000 light-years into space, versus the current technology of 200 light years.

“Planet detection is a very challenging job,” Ge says. “We need high precision, therefore you aren’t able to look at many objects. This new instrument will allow us to get a much bigger sample, and in 10 to 15 years, we hope to have looked at a million stars. This is the first time this has ever been done in human history.”

While planet ET-1—so named in part as an abbreviation for Exoplanet Tracker but also as a tribute to Steven Spielberg’s cinematic creature—is too close to its partner star to produce life, Ge is optimistic about finding life on at least one of the planets his team hopes to discover.

Also, edging closer to finding planets that harbor life, researchers, including a UF astronomer, have discovered the smallest planet yet identified outside our solar system. With a mass about five times that of Earth, the planet orbits a small star near the center of the galaxy in the constellation Sagittarius.

Located about three times as far away from its star as the distance from Earth to the sun, it is probably too cold to support life. But its presence suggests there are many other small planets orbiting the star, making it likely that at least a few are located in the “habitable zone”—the region around stars where temperatures are moderate enough for liquid water to appear on their surfaces.

“The good thing about this is it shows that planets this size might be quite common in habitable zones,” says Stephen Kane, a postdoctoral associate in UF’s astronomy department. Kane co-authored a paper about the discovery that appeared in the journal Nature in January.

Astronomers discovered the new, small planet by tapping a completely different stellar phenomenon: galactic microlensing. Most easily observed with small, older stars known as M dwarfs, microlensing occurs when light from a distant star encounters the gravitational field of a closer star as the closer star passes in front or just to the side of it. The gravitational field literally bends and magnifies the light.

The effect is a bit like the beam from a searchlight encountering a giant magnifying glass. But, for planet-finders, the key item of interest is that if a planet orbits the parent star, the planet’s gravitational field also acts as its own little lens—magnifying some of the distant star’s light in a brief but distinctive flicker.

“There’s a very subtle effect, a spike, and that’s what we’re looking for,” Kane says. “This has huge implications for finding life.”

Star Light, Star Bright

Vicki Sarajedini
Astronomer Vicki Sarajedini preps her STARLAB
portable planetarium for a public event at the Florida
Museum of Natural History in April.
When Halley’s Comet made its most recent trip through the night sky in 1986, Associate Professor of Astronomy Vicki Sarajedini, then just in high school, proudly set up her Sears, Roebuck & Co. telescope—paid for with money earned doing odd jobs around her parent’s dairy farm in rural Ohio—and invited the entire neighborhood to come out and take a look at the highly anticipated celestial object. As a winner of a National Science Foundation CAREER grant, Sarajedini has used $15,000 of her $480,000 award to purchase a portable planetarium to share with the Gainesville community.

Sarajedini has presented STARLAB planetarium shows at 12 local schools this year, as well to civic groups and at museum events. The lab can be set up in any room with a high ceiling and seats 20–35 people. “When children first see it they are just thrilled—they usually think it’s one of those bouncy things you see at fairs,” she laughs. “But once you crawl through the opening it’s really big, you can stand up, and when you turn out the light it feels like you are outside on a dark night, looking at the sky.”

Her own research focuses on galaxies billions of light years away, invisible to the naked eye and undetectable by most telescopes on Earth. Using images from NASA’s Hubble Space Telescope, Sarajedini is examining “active” galaxies, which have a super-massive black hole in their center millions of times larger than the sun.

She is married to fellow UF astronomer Ata Sarajedini, who has also received a CAREER award from the NSF. The Sarajedinis are among seven UF astronomy professors who have won the award in the past seven years. “No other astronomy department in the US has achieved this, as far as I have heard,” says Department Chair Stan Dermott. “Since only the top 10 percent of young tenure-track faculty in the United States get CAREER awards, we can safely say that we are hiring some of the best new faculty in the nation.”

Star Search

The Hubble Space Telescope, one of the most important pieces of technology in the history of astronomy, is expected to continue functioning for only a few more years. At that point, the scientific community’s ability to observe deep into space at visible wavelengths without the obstruction of the earth’s atmosphere will be history.

In anticipation of this loss, the Hubble Space Telescope (HST) Treasury Program was established to create an archive of digital images to be used by astronomers for decades to come. UF Associate Professor of Astronomy Ata Sarajedini is one of only a handful of researchers from around the globe selected to participate in the program, building the legacy of the groundbreaking telescope.

As principal investigator on a $550,000 grant from the HST, Sarajedini is leading a project to use the telescope to observe 66 of the closest globular star clusters within our galaxy. “These stars are thought to be the oldest in the Milky Way,” he says. “By studying them you learn not only their history but their current properties as well.” The HST has already sent back images of 20 globular clusters in its sample and is expected to complete the remainder by the end of the summer.

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