OGLE-2011-BLG-0265Lb: a Jovian Microlensing Planet Orbiting an M Dwarf

TL;DR

This paper reports the discovery of a Jupiter-mass planet orbiting an M-dwarf star via microlensing, providing rare insights into planetary systems around low-mass stars and their formation.

Contribution

The discovery of a Jovian planet orbiting an M-dwarf through microlensing adds valuable data to planetary formation theories, especially for systems beyond the snow line.

Findings

Planet mass approximately 0.9 Jupiter masses

Host star mass around 0.22 solar masses

System located 3-4 kpc in the Galactic disk

Abstract

We report the discovery of a Jupiter-mass planet orbiting an M-dwarf star that gave rise to the microlensing event OGLE-2011-BLG-0265. Such a system is very rare among known planetary systems and thus the discovery is important for theoretical studies of planetary formation and evolution. High-cadence temporal coverage of the planetary signal combined with extended observations throughout the event allows us to accurately model the observed light curve. The final microlensing solution remains, however, degenerate yielding two possible configurations of the planet and the host star. In the case of the preferred solution, the mass of the planet is $M_{\rm p} = 0.9\pm 0.3\ M_{\rm J}$, and the planet is orbiting a star with a mass $M = 0.22\pm 0.06\ M_\odot$. The second possible configuration (2$\sigma$ away) consists of a planet with $M_{\rm p}=0.6\pm 0.3\ M_{\rm J}$ and host star with $M=0.14\pm 0.06\ M_\odot$. The system is located in the Galactic disk 3 -- 4 kpc towards the Galactic bulge. In both cases, with an orbit size of 1.5 -- 2.0 AU, the planet is a "cold Jupiter" -- located well beyond the "snow line" of the host star. Currently available data make the secure selection of the correct solution difficult, but there are prospects for lifting the degeneracy with additional follow-up observations in the future, when the lens and source star separate.