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01101001
2008-Feb-18, 05:51 AM
NASA Spitzer Mission news: Many, Perhaps Most, Nearby Sun-Like Stars May Form Rocky Planets (http://www.nasa.gov/mission_pages/spitzer/news/spitzer-20080217.html)


Astronomers have discovered that terrestrial planets might form around many, if not most, of the nearby sun-like stars in our galaxy. These new results suggest that worlds with potential for life might be more common than we thought.

University of Arizona, Tucson, astronomer Michael Meyer and his colleagues used NASA's Spitzer Space Telescope to determine whether planetary systems like ours are common or rare in our Milky Way galaxy. They found that at least 20 percent, and possibly as many as 60 percent, of stars similar to the sun are candidates for forming rocky planets.

Meyer is presenting the findings at the annual meeting of the American Association for the Advancement of Science in Boston. The results appear in the Feb. 1 issue of Astrophysical Journal Letters.

Edit: Probably in Astrophysical Journal Letters, Feb. 1, Evolution of Mid-Infrared Excess around Sun-like Stars: Constraints on Models of Terrestrial Planet Formation; M. R. Meyer, J. M. Carpenter, et al (Abstract) (http://www.journals.uchicago.edu/doi/abs/10.1086/527470)

AAAS news release: Astronomers Look for Earth-Like Worlds (http://www.aaas.org/news/releases/2008/0217planets.shtml)


"I do not know exactly what a planet is, nor am I interested in a precise definition," Meyer said. "I am much more interested in finding the characteristics of bodies in space."

Deborah Fischer, a researcher at San Francisco State University, said extraterrestrial life is most likely to be found on planets of a certain mass and distance from a star. When a planet meets the two characteristics, Fischer said, it is possible the planet could support carbon-based life because the climate "will not be too hot or cold and water could pool."

Alan Stern, associate administrator for space exploration at NASA, said that searching space to find new planets and life is like "looking for a needle in a haystack."

"It's like we want to explore all of North America, and we are on the Eastern Seaboard and we only know about the first 100 kilometers," Stern said. "We really don't know what we will find."

Edit: See also earlier topic 'Hundreds of worlds' in Milky Way (http://www.bautforum.com/astronomy/70454-hundreds-worlds-milky-way.html).

Sitnalta
2008-Feb-18, 09:34 AM
Cool stuff, though not particularly surprising. I wouldn't be surprised if most, if not all main sequence stars had at least a Mars or Venus-like planet orbiting them.

What really impresses me is we all talk about exosolar planets as casually as we'd talk about the moons of Saturn. The galaxy is becoming a smaller place.

01101001
2008-Feb-18, 07:07 PM
I wouldn't be surprised if most, if not all main sequence stars had at least a Mars or Venus-like planet orbiting them.

All? That would be surprising, in that it would contradict the most optimistic of these findings (http://www.nasa.gov/mission_pages/spitzer/news/spitzer-20080217.html). It would be welcome news, but surprising.


"The correct answer probably lies somewhere between the pessimistic case of less than 20 percent and optimistic case of more than 60 percent," Meyer said.

Sitnalta
2008-Feb-18, 08:31 PM
Well "all" is an overstatement, since binary systems might be too hostile a gravitational environment for planets to dwell in for very long. But when you look at our solar system and see how insanely plentiful rocky planets/moons are, it seems that such formations are a very probably event.

cress
2008-Feb-18, 10:48 PM
As I recently said here (http://www.bautforum.com/1175200-post17.html), that depends very much on the binary.

In addition to the paper I mentioned there, which found stable orbits of large rocky bodies may be common, here's a case where ejection and capture are both possible outcomes (http://adsabs.harvard.edu/abs/2003MNRAS.345..233N). In this case the eccentricity of the binary seems to be significant.