Based on observations collected at the European Southern Observatory, Chile. ESO No. 072.D-0362.
On the origin of the ultramassive white dwarf GD 50★
Article first published online: 6 OCT 2006
Monthly Notices of the Royal Astronomical Society: Letters
Volume 373, Issue 1, pages L45–L49, November 2006
How to Cite
Dobbie, P. D., Napiwotzki, R., Lodieu, N., Burleigh, M. R., Barstow, M. A. and Jameson, R. F. (2006), On the origin of the ultramassive white dwarf GD 50. Monthly Notices of the Royal Astronomical Society: Letters, 373: L45–L49. doi: 10.1111/j.1745-3933.2006.00240.x
- Issue published online: 6 OCT 2006
- Article first published online: 6 OCT 2006
- Accepted 2006 August 29. Received 2006 August 24; in original form 2006 July 24
- stars: individual: GD 50;
- stars: individual: PG 0136 + 251;
- white dwarfs;
- open clusters and associations: individual: Pleiades
We argue on the basis of astrometric and spectroscopic data that the ultramassive white dwarf GD 50 is associated with the star formation event that created the Pleiades and is possibly a former member of this cluster. Its cooling age (∼60 Myr) is consistent with it having evolved essentially as a single star from a progenitor with a mass M > 6 M⊙, so we find no need to invoke a white dwarf–white dwarf binary merger scenario to account for its existence. This result may represent the first direct observational evidence that single-star evolution can produce white dwarfs with M > 1.1 M⊙, as predicted by some stellar evolutionary theories. On the basis of its tangential velocity, we also provisionally identify the ultramassive (M∼ 1.2 M⊙) white dwarf PG 0136 + 251 as being related to the Pleiades. These findings may help to alleviate the difficulties in reconciling the observed number of hot nearby ultramassive white dwarfs with the smaller number predicted by binary evolution models under the assumption that they are the products of white dwarf mergers.