A planet-sized transiting star around OGLE-TR-122. Accurate mass and radius near the hydrogen-burning limit
Abstract
We report the discovery and characterisation of OGLE-TR-122b, the smallest main-sequence star to date with a direct radius determination. OGLE-TR-122b transits around its solar-type primary every 7.3-days. With M=0.092±0.009 M_⊙ and R=0.120+0.020-0.013 R_⊙, it is by far the smallest known eclipsing M-dwarf. The derived mass and radius for OGLE-TR-122b are in agreement with the theoretical expectations. OGLE-TR-122b is the first observational evidence that stars can indeed have radii comparable or even smaller than giant planets. In such cases, the photometric signal is exactly that of a transiting planet and the true nature of the companion can only be determined with high-resolution spectroscopy.
Based on observations collected with the VLT/UT2 Kueyen telescope (Paranal Observatory, ESO, Chile) using the FLAMES+UVES spectrograph (program ID 072.C-191).- Publication:
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Astronomy and Astrophysics
- Pub Date:
- April 2005
- DOI:
- 10.1051/0004-6361:200500025
- arXiv:
- arXiv:astro-ph/0501611
- Bibcode:
- 2005A&A...433L..21P
- Keywords:
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- stars: low-mass;
- brown-dwarfs;
- stars: fundamental parameters;
- stars: binaries;
- binaries: eclipsing;
- Astrophysics
- E-Print:
- 4 pages, 3 figures, A&