A Candidate High-velocity Exoplanet System in the Galactic Bulge

A Candidate High-velocity Exoplanet System in the Galactic Bulge

We present an analysis of adaptive optics images from the Keck I telescope of the microlensing event MOA-2011-BLG-262. The original discovery paper by Bennett et al. reports two possibilities for the lens system: a nearby gas giant lens with an exomoon companion or a very low-mass star with a planet...

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Main Authors: Sean K. Terry, Jean-Philippe Beaulieu, David P. Bennett, Aparna Bhattacharya, Jon Hulberg, Macy J. Huston, Naoki Koshimoto, Joshua W. Blackman, Ian A. Bond, Andrew A. Cole, Jessica R. Lu, Clément Ranc, Natalia E. Rektsini, Aikaterini Vandorou
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astronomical Journal
Subjects:
Exoplanets
Gravitational microlensing
High-resolution microlensing event imaging
Adaptive optics
Online Access:https://doi.org/10.3847/1538-3881/ad9b0f
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Summary:We present an analysis of adaptive optics images from the Keck I telescope of the microlensing event MOA-2011-BLG-262. The original discovery paper by Bennett et al. reports two possibilities for the lens system: a nearby gas giant lens with an exomoon companion or a very low-mass star with a planetary companion in the Galactic bulge. The ∼10 yr baseline between the microlensing event and the Keck follow-up observations allows us to detect the faint candidate lens host (star) at K = 22.3 mag and confirm the distant lens system interpretation. The combination of the host star brightness and light curve parameters yields host star and planet masses of M _host = 0.19 ± 0.03 M _⊙ and m _p = 28.92 ± 4.75 M _⊕ at a distance of D _L = 7.49 ± 0.91 kpc. We perform a multiepoch cross reference to Gaia Data Release 3 and measure a transverse velocity for the candidate lens system of v _L = 541.31 ± 65.75 km s ^−1 . We conclude this event consists of the highest-velocity exoplanet system detected to date, and also the lowest-mass microlensing host star with a confirmed mass measurement. The high-velocity nature of the lens system can be definitively confirmed with an additional epoch of high-resolution imaging at any time now. The methods outlined in this work demonstrate that the Roman Galactic Exoplanet Survey will be able to securely measure low-mass host stars in the bulge.
ISSN:1538-3881

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