太陽系最速の系外惑星候補を発見 (NASA Scientists Spot Candidate for Speediest Exoplanet System)

2025-02-10 NASA

＜関連情報＞

• https://www.nasa.gov/universe/nasa-scientists-spot-candidate-for-speediest-exoplanet-system/
• https://iopscience.iop.org/article/10.3847/1538-3881/ad9b0f/meta

銀河系バルジにおける高速太陽系外惑星候補系 A Candidate High-velocity Exoplanet System in the Galactic Bulge

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,…
The Astronomical Journal  Published: 2025 February 10
DOI:10.3847/1538-3881/ad9b0f

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 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.