Exoplanet Discoveries, discussion of the latest finds |
Exoplanet Discoveries, discussion of the latest finds |
Guest_PhilCo126_* |
Apr 21 2009, 11:10 AM
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Guests |
Well-known exoplanet researcher Dr Michel Mayor ( discoverer of Peg 51b with Dr Didier Queloz in 1995 ) today announced the discovery of the lightest exoplanet found so far. The planet, “e”, in the famous system Gliese 581, is only about twice the mass of our Earth. The team also refined the orbit of the planet Gliese 581 d, first discovered in 2007, placing it well within the habitable zone, where liquid water oceans could exist:
http://www.eso.org/public/outreach/press-r...9/pr-15-09.html |
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Feb 22 2017, 06:16 PM
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Director of Galilean Photography Group: Members Posts: 896 Joined: 15-July 04 From: Austin, TX Member No.: 93 |
-------------------- Space Enthusiast Richard Hendricks
-- "The engineers, as usual, made a tremendous fuss. Again as usual, they did the job in half the time they had dismissed as being absolutely impossible." --Rescue Party, Arthur C Clarke Mother Nature is the final inspector of all quality. |
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Feb 22 2017, 06:57 PM
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Member Group: Members Posts: 684 Joined: 24-July 15 Member No.: 7619 |
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Feb 22 2017, 08:06 PM
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
This is quite an interesting and – IMO – surprising discovery for the sheer number of planets packed so tightly together. Six of the planets have orbital periods between 1.51 and 12.35 days. Not surprisingly, there are small-integer ratios galore between orbital periods. In terms of the shortest period, the next four are 8:5, 8:3, 4:1, and 6:1.
In terms of bolometric luminosity, the second, third, and fourth ones get about the same thermal input as Venus, Earth, and Mars. There's no doubt that whatever one considers to be earthlike context in terms of that alone, at least one of these planets has it. And here's one of the interesting consequences: There are about 500 red dwarfs closer than this system. The probability of a transit for a single planet in the "habitable zone" of such stars is about 2.5%, which would mean 12.5 such systems. But if there are multiple planets per system, then the number of planets we can see transiting will be higher than ~12.5, perhaps double that. And that'll increase the bounty when the time comes that we can do serious follow-up science by examining spectra. A decade or so from now, we may have spectra for something like 20-50 sub-Neptune-sized planets in the HZ of red dwarfs. That's a nice future set of results to look forward to. |
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Feb 22 2017, 09:03 PM
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
Not surprisingly, there are small-integer ratios galore between orbital periods. And, if the Jovian system is anything to go by, these resonances will be evolving over time with each planet experiencing different episodes of orbital forcing, eccentricity change and tidal heating. So once the orbital/thermal history of the Galilean moons has been definitively settled the dynamicists will then have this diabolically complex and even more crowded planetary system to chew over. Another curiosity is that the system lies within one degree of our ecliptic plane. Does this mean that seen from there our Sun would also exhibit planetary transits? |
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