Search with UVES and X-Shooter for signatures of the low-mass secondary in the post common-envelope binary AA Doradus
Abstract
Context.
Aims: We aim to extract the secondary's contribution to the phase-dependent composite spectra. The spectrum and identified lines of the secondary decide on its nature.
Methods: In January 2014, we measured the phase-dependent spectrum of
Results: We identified 53 spectral lines of the secondary in the ultraviolet-blue, visual, and near-infrared X-Shooter spectra that are strongest close to its occultation. We identified 57 (20 additional) lines in available Ultraviolet and Visual Echelle Spectrograph (UVES) spectra from 2001. The lines are mostly from C ii-iii and O ii, typical for a low-mass star that is irradiated and heated by the primary. We verified the orbital period of P = 22 597.033201 ± 0.00007 s and determined the orbital velocity K_sec = 232.9+16.6-6.5 km s-1 of the secondary. The mass of the secondary is M_sec = 0.081+0.018-0.010 M_⊙ and, hence, it is not possible to reliably determine a brown dwarf or an M-type dwarf nature. Conclusions: Although we identified many emission lines of the secondary's irradiated surface, the resolution and signal-to-noise ratio of our UVES and X-Shooter spectra are not good enough to extract a good spectrum of the secondary's nonirradiated hemisphere.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 2015
- DOI:
- 10.1051/0004-6361/201526229
- arXiv:
- arXiv:1504.07750
- Bibcode:
- 2015A&A...578A.125H
- Keywords:
-
- stars: abundances;
- binaries: eclipsing;
- stars: low-mass;
- stars: individual: AA Dor;
- virtual observatory tools;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 17 pages, 19 figures