A Candidate High-velocity Exoplanet System in the Galactic Bulge
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Date
2025-03
Open Access Location
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American Astronomical Society, Washington
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(c) 2025 The Author/s
CC BY 4.0
CC BY 4.0
Abstract
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 Mhost = 0.19 ± 0.03 M⊙ and mp = 28.92 ± 4.75 M⊕ at a distance of DL = 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 vL = 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.
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Keywords
. Unified Astronomy Thesaurus concepts: Exoplanets (498); Gravitational microlensing (672); High-resolution microlensing event imaging (2138); Adaptive optics (2281), Exoplanets, Gravitational microlensing, High-resolution microlensing event imaging, Adaptive optics
Citation
Terry SK, Beaulieu JP, Bennett DP, Bhattacharya A, Hulberg J, Huston MJ, Koshimoto N, Blackman JW, Bond IA, Cole AA, Lu JR, Ranc C, Rektsini NE, Vandorou A. (2025). A Candidate High-velocity Exoplanet System in the Galactic Bulge. Astronomical Journal. 169. 3.