2013ApJ...771L...2H -
Astrophys. J., 771, L2 (2013/July-1)
Discovery of an ultramassive pulsating white dwarf.
HERMES J.J., KEPLER S.O., CASTANHEIRA B.G., GIANNINAS A., WINGET D.E., MONTGOMERY M.H., BROWN W.R. and HARROLD S.T.
Abstract (from CDS):
We announce the discovery of the most massive pulsating hydrogen-atmosphere white dwarf (WD) ever discovered, GD 518. Model atmosphere fits to the optical spectrum of this star show it is a 12, 030±210 K WD with a log g =9.08 ±0.06, which corresponds to a mass of 1.20±0.03 M☉. Stellar evolution models indicate that the progenitor of such a high-mass WD endured a stable carbon-burning phase, producing an oxygen-neon-core WD. The discovery of pulsations in GD 518 thus offers the first opportunity to probe the interior of a WD with a possible oxygen-neon core. Such a massive WD should also be significantly crystallized at this temperature. The star exhibits multi-periodic luminosity variations at timescales ranging from roughly 425 to 595 s and amplitudes up to 0.7%, consistent in period and amplitude with the observed variability of typical ZZ Ceti stars, which exhibit non-radial g-mode pulsations driven by a hydrogen partial ionization zone. Successfully unraveling both the total mass and core composition of GD 518 provides a unique opportunity to investigate intermediate-mass stellar evolution, and can possibly place an upper limit to the mass of a carbon-oxygen-core WD, which in turn constrains Type Ia supernovae progenitor systems.
Abstract Copyright:
∼
Journal keyword(s):
stars: evolution - stars: individual: GD 518 - stars: oscillations - stars: variables: general - supernovae: general - white dwarfs
Simbad objects:
3
Full paper
View the references in ADS
To bookmark this query, right click on this link: simbad:2013ApJ...771L...2H and select 'bookmark this link' or equivalent in the popup menu