A new extremely low-mass white dwarf in the NLTT catalogue

被引：30

作者：

Kawka, A. ^{[1
]}

Vennes, S. ^{[1
]}

机构：

[1] Akad Ceske Republiky, Astron Ustav, Ondrejov 25165, Czech Republic

来源：

ASTRONOMY & ASTROPHYSICS | 2009年 / 506卷 / 02期

基金：

美国国家航空航天局; 美国国家科学基金会;

关键词：

white dwarfs; stars: individual: NLTT 11748; stars: atmospheres; POPULATION SYNTHESIS; SOLAR NEIGHBORHOOD; STARS; COMPANION; SYSTEMS; COLORS;

D O I：

10.1051/0004-6361/200912954

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We report on the discovery of the extremely low-mass, hydrogen-rich white dwarf, NLTT 11748. Based on measurements of the effective temperature (8540 +/- 50 K) and surface gravity (log g = 6.20 +/- 0.15) obtained by fitting the observed Balmer line profiles with synthetic spectra, we derive a mass of 0.167 +/- 0.005 M(circle dot). This object is one of only a handful of white dwarfs with masses below 0.2 M(circle dot) that are believed to be the product of close binary evolution with an episode of Roche lobe overflow onto a degenerate companion (neutron star or white dwarf). Assuming membership in the halo population, as suggested by the kinematics and adopting a cooling age of 4.0-6.3 Gyr for the white dwarf, we infer a progenitor mass of 0.87-0.93 M circle dot. The likely companion has yet to be identified, but a search for radial velocity variations may help constrain its nature.

引用

页码：L25 / L28

页数：4

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