Discovery of the first halo white dwarf + L subdwarf wide binary
Contributors
- 1. Universitat Politécnica de Catalunya
-
2.
University of California, San Diego
-
3.
University of Leicester
-
4.
National Institute for Astrophysics
-
5.
University of Hertfordshire
-
6.
Instituto de Astrofísica de Canarias
- 7. Centro de Astrobiologia
-
8.
University of Zielona Góra
-
9.
Nanjing University
Description
We present a white dwarf + L subdwarf wide binary discovered in the Gaia DR3. It is a gravitationally bound system with a projected separation of 1375 au. The system has a total space velocity of 406 km/s, which suggests it is a member of the Galactic halo. The secondary is an L subdwarf with metallicity of [Fe/H] = -0.81+/-0.10 and Teff = 2298+45/-43 K according to atmospheric model fitting to its optical to NIR spectrum. The L subdwarf is just above the stellar substellar boundary, and is the lowest mass halo star. Such a lowest mass star has low-rate hydrogen fusion, thus its initial thermal energy has a significant fraction of contribution to its luminosity. Its temperature has dropped significantly in the last 10 Gyr, due to the dissipation of its initial thermal energy. The primary is a cool DC WD with a cooling time of 8.5 Gyr and a total age of 10.5+3.3/-2.1 Gyr according to white dwarf model fitting. With age constrain from the WD companion, the secondary companion becomes the first age benchmark L subdwarf of the Galactic halo.
Files
Zenghua_Zhang_cs22.jpg
Files
(1.4 MB)
| Name | Size | Download all |
|---|---|---|
|
md5:bab69748dd3951ba1f64600b2868b3a9
|
1.4 MB | Preview Download |
Additional details
Related works
- Is published in
- Journal article: 10.1093/mnras/stae1851 (DOI)
Dates
- Accepted
-
2024-07-26MNRAS