OGLE-2012-BLG-0724LB: A SATURN-MASS PLANET AROUND AN M DWARF
/ Authors
Y. Hirao, A. Udalski, T. Sumi, D. Bennett, I. Bond, N. Rattenbury, D. Suzuki, N. Koshimoto, F. Abe, Y. Asakura
and 28 more authors
A. Bhattacharya, M. Freeman, A. Fukui, Y. Itow, M. Li, C. Ling, K. Masuda, Y. Matsubara, T. Matsuo, Y. Muraki, M. Nagakane, K. Ohnishi, H. Oyokawa, T. Saito, A. Sharan, H. Shibai, D. Sullivan, P. Tristram, A. Yonehara, R. Poleski, J. Skowron, P. Mr'oz, M. Szyma'nski, S. Kozłowski, P. Pietrukowicz, I. Soszy'nski, Ł. Wyrzykowski, K. Ulaczyk
/ Abstract
We report the discovery of a planet by the microlensing method, OGLE-2012-BLG-0724Lb. Although the duration of the planetary signal for this event was one of the shortest seen for a planetary event, the anomaly was well covered thanks to high-cadence observations taken by the survey groups OGLE and MOA. By analyzing the light curve, this planetary system is found to have a mass ratio q = ( 1.58 ± 0.15 ) × 10 − 3 . By conducting a Bayesian analysis, we estimate that the host star is an M dwarf with a mass of M L = 0.29 − 0.16 + 0.33 M ☉ located at D L = 6.7 − 1.2 + 1.1 kpc away from the Earth and the companion’s mass is m P = 0.47 − 0.26 + 0.54 M Jup . The projected planet–host separation is a ⊥ = 1.6 − 0.3 + 0.4 AU . Because the lens–source relative proper motion is relatively high, future high-resolution images would detect the lens host star and determine the lens properties uniquely. This system is likely a Saturn-mass exoplanet around an M dwarf, and such systems are commonly detected by gravitational microlensing. This adds another example of a possible pileup of sub-Jupiters ( 0.2 < m P / M Jup < 1 ) in contrast to a lack of Jupiters ( ∼ 1 – 2 M Jup ) around M dwarfs, supporting the prediction by core accretion models that Jupiter-mass or more massive planets are unlikely to form around M dwarfs.
Journal: The Astrophysical Journal