As the 2010 American Astronomical Society meetings wind-down, two items from the program caught my attention (in addition to Michael Crowe's Doggett Prize and invited presentation, mentioned last time). Both made news.
First, at a press conference held Tuesday, NASA Kepler team members announced the spacecraft's discovery of five new exoplanets beyond our solar system. These are the first exoplanets detected by Kepler since science operations began last May. Predictably, all five were given spectacularly memorable names: Kepler 4b, 5b, 6b, 7b, and 8b.
This is understandable: one day, Kepler-discovered exoplanets may number in the hundreds. Or more. No one will know how many until at least November 2012, when science operations are slated to end.
Relative sizes of Kepler 4b, 5b, 6b, 7b, and 8b. Credit: JPL/NASA
Kepler 4b through 8b are gas giants, also known as "hot Jupiters" because of their extreme temperatures (2,200 to 3,000 degrees Fahrenheit) and large sizes (about the mass of Neptune to about 1.5 times the mass of Jupiter). You can read the full NASA news release here.
The second item raised an eyebrow when I heard about it yesterday. Scott Gaudi, an astronomer at Ohio State University, reported at a press conference titled "Exoplanet Demographics" that "We now know our place in the universe." Whenever I see or hear statements like this is I always get uneasy (rhymes with queasy), given how much we don't know about the universe in 2010.
But, to be fair, Mr. Gaudi also added this: "Solar systems like our own are not rare, but we're not in the majority, either."
The statement summarizes the latest findings from a worldwide informal consortium of astronomers participating in something called the Microlensing Follow-Up Network (MicroFUN)—well done!—which hunts for exoplanets using a technique called gravitational microlensing. Microlensing occurs when a star passes in front of another star as seen from Earth. As this happens the light from the farthest away star becomes magnified by the closer star. If any planets are orbiting the "lens star," they increase the magnification in a measurable way as they pass by. This technique works best in detecting gas giants.
Estimating the number of solar systems "like our own" is based on a statistical analysis of MicroFUN survey data. Only one system—having two gas giants similar to Jupiter and Neptune—has been identified so far. Gaudi's argument goes something like this: "We've only found this one system, and we should have found about six by now—if every star had a solar system like Earth's." In other words, not finding very many so far suggests a relatively small number of systems out there similar to the one we belong.
Gaudi admits this is pretty rough and the "final number could change a lot . . . With billions of stars out there, even narrowing the odds to 15 percent leaves a few hundred million systems that might be like ours."
An interesting idea, anyway.
Information about MicroFUN research is available at Ohio State University.