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arXiv · 2405.03849

Discovery of the Remarkably Red L/T Transition Object VHS J183135.58-551355.9

Thomas P. Bickle·Adam C. Schneider·Jonathan Gagné·Jacqueline K. Faherty·Austin Rothermich·Johanna M. Vos·Genaro Suárez·J. Davy Kirkpatrick·Aaron M. Meisner·Marc J. Kuchner·Adam J. Burgasser·Federico Marocco·Sarah L. Casewell·Dan Caselden·Daniella Bardalez Gagliuffi·The Backyard Worlds·:·Planet 9 Collaboration
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Abstract

We present the discovery of VHS J183135.58$-$551355.9 (hereafter VHS J1831$-$5513), an L/T transition dwarf identified as a result of its unusually red near-infrared colors ($J-K_{\rm S}=3.633\pm0.277$ mag; $J-W2=6.249\pm0.245$ mag) from the VISTA Hemisphere Survey and CatWISE2020 surveys. We obtain low resolution near-infrared spectroscopy of VHS J1831$-$5513 using Magellan/FIRE to confirm its extremely red nature and assess features sensitive to surface gravity (i.e., youth). Its near-infrared spectrum shows multiple CH$_{\rm 4}$ absorption features, indicating an exceptionally low effective temperature for its spectral type. Based on proper motion measurements from CatWISE2020 and a photometric distance derived from its $K_{\rm S}$-band magnitude, we find that VHS J1831$-$5513 is a likely ($\sim$85$\%$ probability) kinematic member of the $\beta$ Pictoris moving group. Future radial velocity and trigonometric parallax measurements will clarify such membership. Follow-up mid-infrared or higher resolution near-infrared spectroscopy of this object will allow for further investigation as to the cause(s) of its redness, such as youth, clouds, and viewing geometry.

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Thomas P. Bickle, Adam C. Schneider, Jonathan Gagné, Jacqueline K. Faherty, Austin Rothermich, Johanna M. Vos, Genaro Suárez, J. Davy Kirkpatrick, Aaron M. Meisner, Marc J. Kuchner, Adam J. Burgasser, Federico Marocco, Sarah L. Casewell, Dan Caselden, Daniella Bardalez Gagliuffi, The Backyard Worlds, :, Planet 9 Collaboration. 2024-05-06. Discovery of the Remarkably Red L/T Transition Object VHS J183135.58-551355.9. https://arxiv.org/abs/2405.03849

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