COROT Discoveres Its First Exoplanet

woohoo. though over 230 extrasolar planets have been discovered since 1995, this is still impressive: ESA's (and CNES - the french space agency) COROT mission, the first mission whose primary objective is the detection of extra-solar planets, announced its first exoplanet discovered today! the planet was discovered using the transit method (developed by dear professor sasselov at the cfa), has a radius of around 1.78 times that of jupiter, and orbits a sun-like star located around 1500 lightyears away from us with an orbital period of around 1.5 days (for comparison, jupiter's orbital period is 4333 days). most impressively, given the success of this first discovery, the researchers on the project believe that COROT will be able to detect earth-sized planets using the transit method, which was not the original plan. (image credit: esa)

Planets Around Binary Stars

it's been quite common for astronomers to complain about the above scene in star wars, where luke skywalker observes the double sunset (of stars tatoo I and tatoo II) on his home planet of tatooine (which, by the way, was named after the city of tatouine in tunisia, where many scenes for the movie were shot). it was previously believed to be impossible (or at least highly unlikely) for planetary systems to form around binary stars because of gravitational instabilities. then, when more extensive searches for extrasolar planets were embarked upon, planets were found around quite a few binary systems, though these binary systems tended to be extremely "wide" (where the separation between the two stars was on the order of thousands of astronomical units). now, astronomers have used the spitzer space telescope to look for debris disks around stars in binary systems, whose presence would suggest that the planet-building material is there, even if planets haven't actually formed. out of a sample of 69 binary systems, 40 percent were found to have these disks, which is higher than the percentage for single star systems. very cool. (and, we might actually get some reliable numbers into the drake equation.) (image "credit": here)

No Water on Two Exoplanets

good news from spitzer space telescope: for the first time, astronomers have been able to analyze chemical signatures in the atmospheres of planets outside of our solar system. the image above demonstrates the basic idea behind how the planetary spectra were obtained: the spectrum of the star (obtained when the planet was passing behind the star) was subtracted from the combined spectrum of the planet and star (obtained when the planet was transiting the star). the most surprising result of the analysis? neither of the two exoplanets that were observed - both gas giants and with such inspiring names as HD 189733b and HD 209458b - showed evidence of water in their atmospheres, though most theories of planetary formation predict the contrary. one of the planets was found to have a very dusty atmosphere full of silicates, suggesting that water may simply be hidden from view (in fact, there are plenty of other reasons why water, even if present, would not show up in the planets' spectra). either way, these observations represent a critical step ahead in our search for life outside of the solar system. here is the nytimes article, and here is the spitzer press release. (image credit: spitzer)