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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Aug 16 2009, 05:23 AM
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#2
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Junior Member Group: Members Posts: 24 Joined: 29-May 08 From: Seattle, USA Member No.: 4162 |
I think "resolultion" in this case refers to time. According to the mission website, Kepler samples a star's brightness every fifteen minutes. I don't know how long a typical Kepler transit will be but in the preliminary list of COROT candidates the transits ranged from an hour up to sixteen hours, with perhaps three hours being the norm. So if we assume a transit takes three hours, we have only about a dozen samples per transit. That is a pretty small sample size from which to try and weed out moon data, and it is a reasonable question whether it will be possible. It seems to me that, if we have a particularly long, slow transit (say 8 hours), an unusually large moon (approaching Earth sized or at least larger than Mars), and a bit of luck, it will be possible, but won't be obvious in the raw data. However, over time Kepler will obviously accumulate observations of multiple transits for each planet detected by Kepler, so that with rigorous analysis it might be possible even with less extreme examples. This is more believable after seeing how clean and noise-free the data were at the Aug. 6 news conference.
As for a ring: Doug, I hadn't thought of it, but it will obviously wreak havoc with density assumptions at first, as first contact of the rings will be difficult to differentiate from the planet itself, giving a grossly inflated diameter estimate. I imagine the difference will become apparent over time, as more samples are added to the data set, but in the meantime someone will publish a paper they'll have to retract. |
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Aug 16 2009, 06:54 AM
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#3
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Dublin Correspondent Group: Admin Posts: 1799 Joined: 28-March 05 From: Celbridge, Ireland Member No.: 220 |
Hmmh - it seems to me then that a number of the extremely low density exoplanets already discovered might actually have ring systems, it's just that we have (as yet) no mechanism (other than a very low apparent density) for making that case. I'm specifically thinking about such oddities as TrES-4 (1.67 Jupiter radii but 1/6th the density) although from the discussions I've seen so far the smart money on all of these appears to be on tidal heating.
Although this does also get me thinking that surely it would be nearly impossible for any large moon ( certainly anything earth sized ) or significant ring system to survive around any of the hot Jupiter class of planets? Tidal forces would be immense and since the numbers indicate these are probably enough to inflate the Hot Jupiters by 10-20% in any case then surely they would be more than enough to rip any significant moon apart and lead to environments far to chaotic for rings to form? Or is there a possibility for a class of "Trojan\Greek" style co-orbital dust clouds rather than rings that might be more stable in such an aggressive environment? |
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