The sdA problem - II. Photometric and spectroscopic follow-up
Abstract
The spectral classification `subdwarf A' (sdA) is given to stars showing H-rich spectra and sub-main-sequence surface gravities, but effective temperature lower than the zero-age horizontal branch. Their evolutionary origin is an enigma. In this work, we discuss the results of follow-up observations of selected sdAs. We obtained time-resolved spectroscopy for 24 objects and time-series photometry for another 19 objects. For two targets, we report both spectroscopy and photometry observations. We confirm seven objects to be new extremely low-mass white dwarfs (ELMs), one of which is a known eclipsing star. We also find the eighth member of the pulsating ELM class.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- July 2018
- DOI:
- 10.1093/mnras/sty1101
- arXiv:
- arXiv:1804.09059
- Bibcode:
- 2018MNRAS.478..867P
- Keywords:
-
- subdwarfs;
- binaries: general;
- stars: evolution;
- white dwarfs;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Accepted for publication in MNRAS. 19 pages, 30 figures, 6 tables