TY - JOUR
T1 - MOA-2009-BLG-387Lb
T2 - a massive planet orbiting an M dwarf
AU - Batista...[et al.], V.
AU - Gould, A.
AU - Dieters, S.
AU - Dong, S.
AU - Harpsøe, Kennet Bomann West
AU - Jørgensen, Uffe Gråe
PY - 2011/5/1
Y1 - 2011/5/1
N2 - Aims. We report the discovery of a planet with a high planet-to-star mass ratio in the microlensing event MOA-2009-BLG-387, which exhibited pronounced deviations over a 12-day interval, one of the longest for any planetary event. The host is an M dwarf, with a mass in the range 0.07 M ⊙ < Mhost < 0.49 M1 at 90% confidence. The planet-star mass ratio q = 0.0132 ± 0.003 has been measured extremely well, so at the best-estimated host mass, the planet mass is mp = 2.6 Jupiter masses for the median host mass, M = 0.19 M ⊙. Methods. The host mass is determined from two "higher order" microlensing parameters. One of these, the angular Einstein radius θE = 0.31 ± 0.03 mas has been accurately measured, but the other (the microlens parallax πE, which is due to the Earth's orbital motion) is highly degenerate with the orbital motion of the planet. We statistically resolve the degeneracy between Earth and planet orbital effects by imposing priors from a Galactic model that specifies the positions and velocities of lenses and sources and a Kepler model of orbits. Results. The 90% confidence intervals for the distance, semi-major axis, and period of the planet are 3.5 kpc < DL < 7.9 kpc, 1.1 AU < a < 2.7 AU, and 3.8 yr < P < 7.6 yr, respectively.
AB - Aims. We report the discovery of a planet with a high planet-to-star mass ratio in the microlensing event MOA-2009-BLG-387, which exhibited pronounced deviations over a 12-day interval, one of the longest for any planetary event. The host is an M dwarf, with a mass in the range 0.07 M ⊙ < Mhost < 0.49 M1 at 90% confidence. The planet-star mass ratio q = 0.0132 ± 0.003 has been measured extremely well, so at the best-estimated host mass, the planet mass is mp = 2.6 Jupiter masses for the median host mass, M = 0.19 M ⊙. Methods. The host mass is determined from two "higher order" microlensing parameters. One of these, the angular Einstein radius θE = 0.31 ± 0.03 mas has been accurately measured, but the other (the microlens parallax πE, which is due to the Earth's orbital motion) is highly degenerate with the orbital motion of the planet. We statistically resolve the degeneracy between Earth and planet orbital effects by imposing priors from a Galactic model that specifies the positions and velocities of lenses and sources and a Kepler model of orbits. Results. The 90% confidence intervals for the distance, semi-major axis, and period of the planet are 3.5 kpc < DL < 7.9 kpc, 1.1 AU < a < 2.7 AU, and 3.8 yr < P < 7.6 yr, respectively.
U2 - 10.1051/0004-6361/201016111
DO - 10.1051/0004-6361/201016111
M3 - Journal article
SN - 0004-6361
VL - 529
SP - A102
JO - Astronomy and Astrophysics Supplement Series
JF - Astronomy and Astrophysics Supplement Series
ER -