http://arxiv.org/abs/1804.10136
Context. Extrasolar planets found by gravitational microlensing often require assumptions on the source star distance and relative proper motion. Only in a few cases has it been possible to confirm these findings with space-based observations or high-resolution follow-up. 25 planetary microlensing events can be positionally cross-matched with the second Gaia data release containing parallax and proper motion measurements Aims. In this work we subject all microlensing planets listed in the NASA’s Exoplanet Archive to a consistency check by comparing them with Gaia data release 2 measurements. The resulting list is supposed to serve as a reference for the microlensing community and to test if standard assumptions that are made in microlensing studies hold. Methods. Gravitational microlensing can constrain the physical parameters lens mass and lens distance based on fit parameters, such as the event timescale, the microlensing parallax, and the source star crossing time. If some of these parameters are not available one needs to resort to indirect means of assessing the events, often involving a Galactic model. In this work, we seek to make an assessment of those parameters solely based on Gaia DR2. Results. We find that 19 of 25 planets are consistent within 2-sigma of their published lens and source distances. Changing the lens distance of the remaining 6 published planets could lead to revised parameter values that are accordingly compatible with the published ones. We expect the incompatible planet mass estimates to belong to a blend star.
K. Nikolaus and M. Hundertmark
Fri, 27 Apr 18
-50/64
Comments: 5 pages, 2 figures