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Gliese 436 b -- a transiting hot Neptune, The first known "hot Neptune" became a lot more interesting |
 May 16 2007, 10:59 AM
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Member  Group: Members Posts: 249 Joined: 11-June 05 From: Finland (62°14′N 25°44′E) Member No.: 408  |
Detection of transits of the nearby hot Neptune GJ 436 b
QUOTE This Letter reports on the photometric detection of transits of the Neptune-mass planet orbiting the nearby M-dwarf star GJ 436. It is by far the closest, smallest and least massive transiting planet detected so far. Its mass is slightly larger than Neptune's at M = 22.6 +- 1.9 M_earth. The shape and depth of the transit lightcurves show that it is crossing the host star disc near its limb (impact parameter 0.84 +- 0.03) and that the planet size is comparable to that of Uranus and Neptune, R = 25200 +- 2200 km = 3.95 +- 0.35 R_earth. Its main constituant is therefore very likely to be water ice. If the current planet structure models are correct, an outer layer of H/He constituting up to ten percent in mass is probably needed on top of the ice to account for the observed radius. So it is apparently very Neptune-like, albeit a lot hotter. Therefore it must have migrated there beyond the snow line. The planet's eccentricity is anomalously high for such a closely-orbiting planet, so it is likely that there are more planets yet to be detected. Related systemic blog entry: QUOTE Gl 436 should be placed under constant photometric surveillance. If you’re capable of doing sub-1% photometry, please get out there on the sky whenever the night is clear and Gl 436 is at low air mass. If there are additional planets in the system, then it’s completely possible that they are transiting as well.
-------------------- The universe is not only stranger than we imagine, it is stranger than we can imagine.
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May 16 2007, 11:54 AM
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 Member Group: Members Posts: 813 Joined: 29-December 05 From: NE Oh, USA Member No.: 627 |
Fantastic!!!!!!
 how long now before we have a reported hot earth transit detection (Corot.. ground based???) These M dwarf systems are turning out to be really interesting ..... Craig |
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May 17 2007, 03:55 PM
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 Member Group: Members Posts: 160 Joined: 4-July 05 From: Irvine, CA, USA Member No.: 429 |
QUOTE (belleraphon1 @ May 16 2007, 07:54 AM)  how long now before we have a reported hot earth transit detection (Corot.. ground based???) If we don't stop global warming, we'll observe the transit every night
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Jyril Gliese 436 b -- a transiting hot Neptune May 16 2007, 10:59 AM
AndyG QUOTE ...it’s completely possible that they are tr... May 16 2007, 12:04 PM edstrick To a considerable extent, they can judge the incli... May 17 2007, 08:43 AM
Jyril In addition to the length of the transit, the shap... May 17 2007, 10:19 AM |
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