Kepler Mission |
Kepler Mission |
Sep 24 2005, 04:23 PM
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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_PhilCo126_* |
Aug 17 2009, 03:52 PM
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Guests |
Also, though, as the planet/moon gets farther from the star, you might just get two or three separate transits.... what would Jupiter+Callisto or Saturn+Titan look like 200 light years away? Do they resolve as separate transits? Well, I've read that for a distant observer, a Jupiter transit would have a duration of 30 hours, a Saturn transit about 40 hours... Exo-moons could be detected with more accurate detectors, , a Planet-Moon system would have a characteristic transit timing variation, for instance a Jupiter-Europa system would have a variation in the order of 10 seconds, a Saturn-Titan system in the order of 30 seconds... Ring system might be easier to detect |
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Aug 18 2009, 08:51 PM
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#3
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Junior Member Group: Members Posts: 24 Joined: 29-May 08 From: Seattle, USA Member No.: 4162 |
Well, I've read that for a distant observer, a Jupiter transit would have a duration of 30 hours, a Saturn transit about 40 hours... Exo-moons could be detected with more accurate detectors, , a Planet-Moon system would have a characteristic transit timing variation, for instance a Jupiter-Europa system would have a variation in the order of 10 seconds, a Saturn-Titan system in the order of 30 seconds... Ring system might be easier to detect By "transit timing variation," are you referring to delays or advances in the transit time due to the planet's motion around a planet-moon barycenter? This is the method described in the discussion earlier in the thread. It would seem to me that, in order for such a system to be detectable with Kepler, the moon would need to be more massive, relative to the planet. We've found larger planets than Jupiter; it's only reasonable to assume that larger moons than Ganymede also exist. And such larger moons--if they indeed exist--could be detectable by their own transits across the star as well, I should think, especially if their presence was already suspected from the timing data. Helvick's concern about the stability of moon orbits for hot Jupiters due to tides is notable, but again, if we tweak our hypothetical we might avoid it. Wouldn't there be more available stable orbits for a large moon of a planet in a 24-day orbit than of one in a 3-day orbit? As a bonus, the 24-day planet will have lower orbital speed and thus a longer transit, giving a longer sample of planet-moon interaction. I haven't heard anyone talk about work on direct detection of moons transiting their planets. Any graduate students looking for a thesis idea? One other possible source of noise occurs to me; it's also an opportunity for stellar studies, I suppose. If a planet crosses a large starspot, the variation in total light will be similar to its eclipsing a large moon. There are of course differences; the region surrounding a starspot is usually brighter than the average star surface, no? Has such an event been modeled? What would the resulting light curve look like? |
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