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

August 2024 • 2024AJ....168...66B

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

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 _S = 3.633 ± 0.277 mag; J ‑ W2 = 6.249 ± 0.245 mag) from the VISTA Hemisphere Survey and CatWISE2020 surveys. We obtain low-resolution near-infrared spectroscopy of VHS J1831‑5513 using the Magellan Folded port InfraRed Echellette spectrograph to confirm its extremely red nature and assess features sensitive to surface gravity (i.e., youth). Its near-infrared spectrum shows multiple CH₄ 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 _s -band magnitude, we find that VHS J1831‑5513 is a likely (∼85% probability) kinematic member of the β 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.

Links

• PDF https://iopscience.iop.org/article/10.3847/1538-3881/ad4b16/pdf
• PREPRINT http://arxiv.org/abs/2405.03849
• ELECTR https://doi.org/10.3847%2F1538-3881%2Fad4b16