We present Keck/NIRC2 adaptive optics imaging of planetary microlensing event-2007-BLG-400 that resolves the lens star system from the source. We find the MOA-2007-BLG-400L planetary system consists of a 1.71\± 0.27 M\ planet orbiting a 0.69\± 0.04M\ K-dwarf host star at a distance 6.89\± 0.77\\,kpc from the Sun. So, this planetary system probably resides the Galactic bulge. The planet-host star projected separation is only weakly due to the close-wide light curve degeneracy; the 2\σ separation range is 0.6--$7.2\\,$AU. This host mass is at the top end the range of masses predicted by a standard Bayesian analysis that assumes all stars have an equal chance of hosting a star of the observed mass. This and the similar result for event MOA-2013-BLG-220 suggests that massive stars may be more likely to host planets with a mass ratio in the$0.002 < q < 0.004$ range that orbit beyond the snow line. These results also the importance of host star mass measurements for exoplanets found by. The microlensing survey imaging data from NASA's Nancy Grace Space Telescope (formerly WFIRST) mission will be doing mass measurements this for a huge number of planetary events. This host lens is the highest lens-source detected in microlensing mass measurement analysis (the being 10\× fainter than the source). We present an improved method calculating photometry and astrometry uncertainties based on the Jackknife, which produces more accurate errors that are \~2.5 \×$ larger previous estimates.
No takes yet. Share an insight, caveat, or question.
Bhattacharya et al. (2020) studied this question.