November
2025
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2025AJ....170..272U
Authors
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Uyama, Taichi
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Kuzuhara, Masayuki
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Beichman, Charles
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Hirano, Teruyuki
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Kotani, Takayuki
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An, Qier
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Brandt, Timothy D.
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Janson, Markus
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Mawet, Dimitri
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Mori, Mayuko
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Sato, Bun'ei
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Stoeva, Denitza
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Tamura, Motohide
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Aizawa, Masataka
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Cale, Bryson
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Henning, Thomas
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Ishikawa, Hiroyuki Tako
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Narita, Norio
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Ogihara, Masahiro
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Sanghi, Aniket
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Trifonov, Trifon
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Xuan, Jerry
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Akiyama, Eiji
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Harakawa, Hiroki
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Hodapp, Klaus
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Ishizuka, Masato
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Jacobson, Shane
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Kokubo, Eiichiro
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Konishi, Mihoko
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Kudo, Tomoyuki
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Kurokawa, Takashi
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Kwon, Jungmi
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Nishikawa, Jun
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Omiya, Masashi
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Serizawa, Takuma
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Teng, Huan-Yu
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Ueda, Akitoshi
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Vievard, Sebastien
Abstract
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We report the discovery of a new directly imaged brown-dwarf companion with Keck/NIRC2+pyWFS around a nearby mid-type M-dwarf LSPM J1446+4633 (hereafter J1446). The L' -band contrast (4.5 × 10−3) is consistent with a ∼20─60 MJup object at 1─10 Gyr and our two-epoch NIRC2 data suggest a ∼30% (∼3.1σ) variability in its L' -band flux. We incorporated Gaia DR3 non-single-star catalog into the orbital fitting by combining the Subaru/IRD radial velocity monitoring results, NIRC2 direct imaging (DI) results, and Gaia proper motion acceleration. As a result, we derive 59.8−1.4+1.5MJup and ≍4.3 au for the dynamical mass and the semimajor axis of the companion J1446B, respectively. J1446B is one of the intriguing late-T dwarfs showing variability at L' -band for future atmospheric studies with the constrained dynamical mass. Because the J1446 system is accessible with various observation techniques such as astrometry, DI, and high-resolution spectroscopy including radial velocity measurement, it has a potential as a great benchmark system to improve our understanding for cool dwarfs.
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