Open AccessThe triple degenerate star WD 1704+481
Author(s) -
Maxted P. F. L.,
Marsh T. R.,
Moran C. K. J.,
Han Z.
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03343.x
Subject(s) - white dwarf , physics , astrophysics , degenerate energy levels , astronomy , visual binary , surface gravity , binary star , redshift , binary number , mass ratio , effective temperature , stars , galaxy , quantum mechanics , arithmetic , mathematics
WD 1704+481 is a visual binary in which both components are white dwarfs. We present spectra of the H α line of both stars which show that one component (WD 1704+481.2=Sanduleak B=GR 577) is a close binary with two white dwarf components. Thus, WD 1704+481 is the first known triple degenerate star. From radial velocity measurements of the close binary we find an orbital period of 0.1448 d, a mass ratio, q M bright M faint , of 0.70±0.03 and a difference in the gravitational redshifts of 11.5±2.3 km s −1 . The masses of the close pair of white dwarfs predicted by the mass ratio and gravitational redshift difference combined with theoretical cooling curves are 0.39±0.05 and 0.56±0.07 M ⊙ . WD 1704+481 is therefore also likely to be the first example of a double degenerate in which the less massive white dwarf is composed of helium and the other white dwarf is composed of carbon and oxygen.