Kepler Mission |
Kepler Mission |
Sep 24 2005, 04:23 PM
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#1
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Member Group: Members Posts: 147 Joined: 3-July 04 From: Chicago, IL Member No.: 91 |
This NASA Discovery mission is to be launched in June 2008 and will search for Earth-size and smaller planets. Launch was originally scheduled in 2007 but delayed by 8 months due to "funding constraints".
Here's the official web site: http://www.kepler.arc.nasa.gov/ |
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Guest_Zvezdichko_* |
Aug 7 2009, 02:44 PM
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#2
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Guests |
I'm extremely excited. But there's no way to detect the composition of the atmosphere, right?
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Aug 7 2009, 03:36 PM
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#3
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Senior Member Group: Members Posts: 1018 Joined: 29-November 05 From: Seattle, WA, USA Member No.: 590 |
But there's no way to detect the composition of the atmosphere, right? That came up in the press conference, and the answer is that Kepler can't do that, but some of the future missions being proposed would be able to. By the way, in case anyone missed it, this is what a Jovian planet looks like when you have four transits to work with. Had this been Earth and the Sun, the transit (the big drop) would have been about 2/3 the depth of the occultation (the little drop). So, yes, Earth-like planets should be detectable, but it's going to be close. Something else interesting from the conference and some of the links was that the light curves of the variable stars are often unlike anything in the literature. Apparently the atmospheric noise has been hiding significant behavior. This complicates finding planets, of course, since their models for spotting variable stars have to be reworked. --Greg |
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Aug 7 2009, 03:45 PM
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#4
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Senior Member Group: Members Posts: 1591 Joined: 14-October 05 From: Vermont Member No.: 530 |
ustrax's couple writeups were extremely interesting.
I thought it was cool that the warm Spitzer was mentioned as an observatory likely to follow up on new discoveries. I love it when old missions come in handy. |
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Aug 7 2009, 04:49 PM
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#5
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Member Group: Members Posts: 311 Joined: 31-August 05 From: Florida & Texas, USA Member No.: 482 |
ustrax's couple writeups were extremely interesting. I have some questions, if anyone can answer them. 1. Kepler's mission is only 3.5 years, barely enough time to confirm it's own initial discoveries. It sounds likely that the mission can be extended, so what is the expected longevity of the mission (assuming funding is not the problem)? 2. From the mission website: "Expected Results: From transits of terrestrial planets in one year orbits: About 50 planets if most are the same size as Earth (R~1.0 Re) and none larger, About 185 planets if most have a size of R~1.3 Re, About 640 planets if most have a size of R~2.2 Re, About 12% with two or more planets per system. " -- would these expected numbers scale linearly with mission extensions (i.e. would another 4 years of observing double these numbers)? Or is Kepler's field of view fixed to one region, so the sample set is difficult to change, and if this is the case, would most new planets found be longer orbital periods? 3. "Stellar evolution models are used to estimate the mass, radius and metalicity of the parent star" -- how reliable are these models? Is there any way to directly determine these values, or does it require an instrument like the Terrestrial Planet Finder? 4. For gas giants found within a habital zone of the star, would it be possible to search for large moons with either Kepler or astrometry of the gas giant using ground-based instruments? |
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Aug 8 2009, 10:15 PM
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#6
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Junior Member Group: Members Posts: 87 Joined: 9-November 07 Member No.: 3958 |
3. "Stellar evolution models are used to estimate the mass, radius and metalicity of the parent star" -- how reliable are these models? Is there any way to directly determine these values, or does it require an instrument like the Terrestrial Planet Finder? We can get masses for members of binary stars. The standard relations between mass and luminosity come from members of widely separated binaries, where the stars are too small compared to the orbits to have affected one another's evolution (yet). Here is a typical set of mass-luminosity and mass-radius relations for main-sequence stars. Eyeballing that scatter, it looks like 20% in luminosity if mass is known or 10% in mass if luminosity is known (since it's a steep function). Radius looks a bit worse; that often has to come from blackbody laws and the effective temperature and luminosity; which come from spectroscopy and from photometry plus parallax. That can be improved for stars not too distant; I saw a result from the CHARA interferometer in which they resolved the disk of one of the stars with a transiting planet, reducing its uncertainty in radius. (They are a long way from getting an interferometric signal from the dark planetary disk, alas). As has been posted already, we get metallicity from spectroscopy, calibrated to the Sun. (Kind of odd that the best-fitting spectroscopic oxygen abundance there is not the best-fitting one for helioseismology. A lot of other things may shift a bit when that gets sorted out). |
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