Shortest Microlensing Event with a Bound Planet: KMT-2016-BLG-2605

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Journal Article
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Date
2021
Authors
Ryu Y-H
Hwang K-H
Gould A
Yee JC
Chung S-J
Han C
Jung YK
Kim H-W
Shin I-G
Shvartzvald Y
Abstract

KMT-2016-BLG-2605, with planet-host mass ratio q=0.012±0.001, has the shortest Einstein timescale, t\e=3.41±0.13days, of any planetary microlensing event to date. This prompts us to examine the full sample of 7 short (t\e<7day) planetary events with good q measurements. We find that six have clustered Einstein radii θ\e=115±20\muas and lens-source relative proper motions μ\rel≃9.5±2.5\masyr. For the seventh, these two quantities could not be measured. These distributions are consistent with a Galactic-bulge population of very low-mass (VLM) hosts near the hydrogen-burning limit. This conjecture could be verified by imaging at first adaptive-optics light on next-generation (30m) telescopes. Based on a preliminary assessment of the sample, "planetary" companions (i.e., below the deuterium-burning limit) are divided into "genuine planets", formed in their disks by core accretion, and very low-mass brown dwarfs, which form like stars. We discuss techniques for expanding the sample, which include taking account of the peculiar "anomaly dominated" morphology of the KMT-2016-BLG-2605 light curve.

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Citation
Ryu Y-H, Hwang K-H, Gould A, Yee JC, Albrow MD, Chung S-J, Han C, Jung YK, Kim H-W, Shin I-G, Shvartzvald Y, Zang W, Cha S-M, Kim D-J, Kim S-L, Lee C-U, Lee D-J, Lee Y, Park B-G, Pogge RW Shortest Microlensing Event with a Bound Planet: KMT-2016-BLG-2605.
Keywords
astro-ph.EP, astro-ph.GA, gravitational lensing: micro
Ngā upoko tukutuku/Māori subject headings
ANZSRC fields of research
Fields of Research::51 - Physical sciences::5101 - Astronomical sciences::510107 - Planetary science (excl. solar system and planetary geology)
Fields of Research::51 - Physical sciences::5101 - Astronomical sciences::510109 - Stellar astronomy and planetary systems
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