my recent articles |
| No sign of water on faraway planets |
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23 February 2007, for Nature Network Boston Astrophysicists have gotten the first direct glimpse of the atmospheres of planets outside our solar system, and their results are surprising. Based on accepted models of planet formation, they expected to see signs of water vapor but didn’t find any.  In two new studies, Boston researchers, using the Spitzer Space Telescope, measured a broad swath of wavelengths of infrared light emitted by two extrasolar planets. They were searching for the wavelengths of light absorbed by specific atmospheric components, such as water vapor. These studies are the first to directly analyze the light emitted by planets outside our solar system. A team co-led by David Charbonneau of the Harvard-Smithsonian Center for Astrophysics looked at one of these planets, HD 189733b, in a paper accepted by the Astrophysical Journal Letters. Another team, which includes Sara Seager of MIT, describes similar findings with a planet, HD 209458b, orbiting a different star, in this week’s Nature. The Nature paper provides a possible explanation for the unexpected results. The researchers saw signs of high levels of silicates, molecules containing silicon and oxygen, in the atmosphere. Their best guess is that these planets are shrouded in clouds of silicate—basically, rock dust—making them black all over and shrouding the signatures of other molecules in the atmosphere. |