2020/09/04 by Aparna Bhattacharya, D. P. Bennett, Bhattacharya, Aparna +25 · 2 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics of Galaxies (astro-ph.GA) #Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences #Gamma-ray bursts and supernovae #Instrumentation and Methods for Astrophysics (astro-ph.IM) #Solar and Stellar Astrophysics (astro-ph.SR) #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2009.02329
openalex publication_date 2020/09/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present Keck/NIRC2 adaptive optics imaging of planetary microlensing event\nMOA-2007-BLG-400 that resolves the lens star system from the source. We find\nthat the MOA-2007-BLG-400L planetary system consists of a 1.71\± 0.27 M rm\nJup planet orbiting a 0.69\± 0.04M odot K-dwarf host star at a distance\nof 6.89\± 0.77 ,kpc from the Sun. So, this planetary system probably resides\nin the Galactic bulge. The planet-host star projected separation is only weakly\nconstrained due to the close-wide light curve degeneracy; the 2\σ\nprojected separation range is 0.6--7.2 ,AU. This host mass is at the top end\nof the range of masses predicted by a standard Bayesian analysis that assumes\nthat all stars have an equal chance of hosting a star of the observed mass\nratio. This and the similar result for event MOA-2013-BLG-220 suggests that\nmore massive stars may be more likely to host planets with a mass ratio in the\n0.002 < q < 0.004 range that orbit beyond the snow line. These results also\nindicate the importance of host star mass measurements for exoplanets found by\nmicrolensing. The microlensing survey imaging data from NASA's Nancy Grace\nRoman Space Telescope (formerly WFIRST) mission will be doing mass measurements\nlike this for a huge number of planetary events. This host lens is the highest\ncontrast lens-source detected in microlensing mass measurement analysis (the\nlens being 10\× fainter than the source). We present an improved method\nof calculating photometry and astrometry uncertainties based on the Jackknife\nmethod, which produces more accurate errors that are \∼2.5 \× larger\nthan previous estimates.\n