Discovery of the Remarkably Red L/T Transition Object VHS J183135.58-551355.9
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.
- Publication:
-
The Astronomical Journal
- Pub Date:
- August 2024
- DOI:
- 10.3847/1538-3881/ad4b16
- arXiv:
- arXiv:2405.03849
- Bibcode:
- 2024AJ....168...66B
- Keywords:
-
- Brown dwarfs;
- L dwarfs;
- T dwarfs;
- Stellar associations;
- Moving clusters;
- 185;
- 894;
- 1679;
- 1582;
- 1076;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Earth and Planetary Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 14 pages, 4 figures