Candidate transiting M dwarf planets from OGLE

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Candidate transiting M dwarf planets from OGLE

Post by Sirius_Alpha on 27th April 2010, 8:47 pm

Characterization of extrasolar planetary transiting candidates II
http://arxiv.org/abs/1004.4667

Abstract wrote:We present a second paper of fully characterization of a sample of stars whose low-depth transits were discovered by the OGLE-III campaign in order to select the most promising candidates for spectroscopic confirmation, following the same analysis done in Gallardo et al. (2005). We present new optical and near-IR photometry, deriving physical parameters like effective temperature (Teff), distance (d), the stellar radii (R*) and the companion radii (Rc). We selected eight M (2800 K \le Teff \le 3850 K) or K (3850 K \le Teff \le 5150 K) spectral type stellar objects as potential candidates to host exoplanets, even though, considering the radii of their companions, only stars OGLE-TR-61, OGLE-TR-74, OGLE-TR-123 and OGLE-TR-173 are the most promising M-type transit candidates to host planets. Confirmation of the planetary nature of any of these objects will yield another transiting extrasolar planet orbiting a M-type star, or even more interesting, the first extrasolar planets orbiting a late M-type dwarf of effective temperature about 2900 K.

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Re: Candidate transiting M dwarf planets from OGLE

Post by Edasich on 28th April 2010, 3:58 am

Seems It's time for transiting candidates around red dwarfs. Go for it Laughing

However wasn't OGLE-TR-123 a G-type star with planet-sized low-mass star?
Here it seems cooler and with quite a smaller companion. Same orbital period though (1.8 days).

Radius and mass of a transiting M dwarf near the hydrogen-burning limit. OGLE-TR-123.

The system OGLE-TR-123, detected by the OGLE planetary transit survey in Carina, was shown by subsequent spectroscopic follow-up to be an eclipsing binary with a very low mass companion (M2~0.07M☉). Neither the light curve nor the radial velocity data were sufficient to constrain the parameters more precisely and to exclude alternative explanations in terms of a triple system. In this paper, new HARPS radial velocity data and a precise photometric monitoring of the transit with VLT/FORS2 are presented, resulting in an improved mass and radius determination for OGLE-TR-123b and the rejection of alternative scenarios. We find M2=0.0850.011M☉ and R2=0.1330.009R☉ for the transiting companion, confirming its nature as a small M dwarf near the hydrogen-burning limit. Its mass-radius relation corresponds to expectations for a relatively young object. The primary is an F dwarf that does not rotate synchronously with the orbital motion. Asynchronous rotation is unexpected in such a close binary (P=1.8-days) but could be explained by the small mass of the secondary, the young age for the system, and the absence of convective envelope in the primary. OGLE-TR-123b is one of only two known objects below 0.1M☉ with directly determined radii, after a similar object was characterised around OGLE-TR-122. The characterisation of OGLE-TR-123 provides another example of the type of system that can closely mimic planetary transits and contaminate transit surveys.
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Re: Candidate transiting M dwarf planets from OGLE

Post by Lazarus on 28th April 2010, 4:12 pm

So correct me if I'm wrong here, but currently there are only 2 known transiting planets around M dwarfs: GJ 1214b and Gliese 436b.
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Re: Candidate transiting M dwarf planets from OGLE

Post by Sirius_Alpha on 28th April 2010, 4:47 pm

As far as I know that is accurate.

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Re: Candidate transiting M dwarf planets from OGLE

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