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Sunday, May 27, 2007
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Friday, March 30, 2007
NASA Telescope Finds Planets Thrive Around Stellar Twins
Previously, astronomers knew that planets could form in exceptionally wide binary systems, in which stars are 1,000 times farther apart than the distance between Earth and the sun, or 1,000 astronomical units. Of the approximately 200 planets discovered so far outside our solar system, about 50 orbit one member of a wide stellar duo.
The new Spitzer study focuses on binary stars that are a bit more snug, with separation distances between zero and 500 astronomical units. Until now, not much was known about whether the close proximity of stars like these might affect the growth of planets. Standard planet-hunting techniques generally don't work well with these stars, but, in 2005, a NASA-funded astronomer found evidence for a planet candidate in one such multiple-star system (http://www.jpl.nasa.gov/news/news.cfm?release=2005-115).
Trilling and his colleagues used Spitzer's infrared, heat-seeking eyes to look not for planets, but for dusty disks in double-star systems. These so-called debris disks are made up of asteroid-like bits of leftover rock that never made it into rocky planets. Their presence indicates that the process of building planets has occurred around a star, or stars, possibly resulting in intact, mature planets.
In the most comprehensive survey of its kind, the team looked for disks in 69 binary systems between about 50 and 200 light-years away from Earth. All of the stars are somewhat younger and more massive than our middle-aged sun. The data show that about 40 percent of the systems had disks, which is a bit higher than the frequency for a comparable sample of single stars. This means that planetary systems are at least as common around binary stars as they are around single stars.
In addition, the astronomers were shocked to find that disks were even more frequent (about 60 percent) around the tightest binaries in the study. These coziest of stellar companions are between zero and three astronomical units apart. Spitzer detected disks orbiting both members of the star pairs, rather than just one. Extra-tight star systems like these are where planets, if they are present, would experience Tatooine-like sunsets.
NASA Spitzer News Release
Posted @ 10:40 AM by kinzi
Thursday, February 22, 2007
Spitzer Captures Feeble Lights from Distant Worlds
Spitzer, a space-based infrared telescope, obtained the detailed data, called spectra, for two different gas exoplanets. Called HD 209458b and HD 189733b, these so-called "hot Jupiters" are, like Jupiter, made of gas, but orbit much closer to their suns.
The data indicate the two planets are drier and cloudier than predicted. Theorists thought hot Jupiters would have lots of water in their atmospheres, but surprisingly none was found around HD 209458b and HD 189733b. According to astronomers, the water might be present but buried under a thick blanket of high, waterless clouds.
Those clouds might be filled with dust. One of the planets, HD 209458b, showed hints of tiny sand grains, called silicates, in its atmosphere. This could mean the planet's skies are filled with high, dusty clouds unlike anything seen around planets in our own solar system.
Source: NASA's Spitzer News Release
Posted @ 7:34 PM by kinzi
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ryan
kinzi
Nightsky calendar (a brief version) by Skymaps & NASA's Space Calendar | Image of FCO - credit: NASA. Hosting generously provided by Site Design Magazine Design & page layout © kinzi - 2008 | Contact me? kinzikuta@(no-spam)gmail.com |
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