Massive White Dwarfs in the 100 pc Sample: Magnetism, Rotation, Pulsations, and the Merger Fraction
Abstract
We present a detailed model atmosphere analysis of massive white dwarfs with M > 0.9 M ⊙ and T eff ≥ 11,000 K in the Montreal White Dwarf Database 100 pc sample and the Pan-STARRS footprint. We obtained follow-up optical spectroscopy of 109 objects with no previous spectral classification in the literature. Our spectroscopic follow-up is now complete for all 204 objects in the sample. We find 118 normal DA white dwarfs, including 45 massive DAs near the ZZ Ceti instability strip. There are no normal massive DBs: the six DBs in the sample are strongly magnetic and/or rapidly rotating. There are 20 massive DQ white dwarfs in our sample, and all are found in the crystallization sequence. In addition, 66 targets are magnetic (32% of the sample). We use magnetic white dwarf atmosphere models to constrain the field strength and geometry using offset dipole models. We also use magnetism, kinematics, and rotation measurements to constrain the fraction of merger remnant candidates among this population. The merger fraction of this sample increases from 25% for 0.9–1 M ⊙ white dwarfs to 49% for 1.2–1.3 M ⊙. However, this fraction is as high as
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 2024
- DOI:
- 10.3847/1538-4357/ad6905
- arXiv:
- arXiv:2407.04827
- Bibcode:
- 2024ApJ...974...12J
- Keywords:
-
- Magnetic fields;
- Stellar evolution;
- White dwarf stars;
- 994;
- 1599;
- 1799;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 34 pages, 16 figures, accepted for publication in ApJ