EDP Sciences
Free access
Volume 378, Number 1, October IV 2001
Page(s) L17 - L20
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20011223

A&A 378, L17-L20 (2001)
DOI: 10.1051/0004-6361:20011223

Binaries discovered by the SPY project

I. HE 1047-0436: A subdwarf B + white dwarf system
R. Napiwotzki1, H. Edelmann1, U. Heber1, C. Karl1, H. Drechsel1, E.-M. Pauli1 and N. Christlieb2

1  Dr. Remeis-Sternwarte, Astronomisches Institut der Universität Erlangen-Nürnberg, Sternwartstr. 7, 96049 Bamberg, Germany
2  Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany

(Received 14 August 2001 / Accepted 31 August 2001 )

In the course of our search for double degenerate binaries as potential progenitors of type Ia supernovae with the UVES spectrograph at the ESO VLT (ESO SN Ia Progenitor surveY -SPY) we discovered that the sdB star HE 1047-0436 is radial velocity variable. The orbital period of 1.213253 d, a semi-amplitude of 94 km s-1, and a minimum mass of the invisible companion of $0.44 M_\odot$ are derived from the analysis of the radial velocity curve. We use an upper limit on the projected rotational velocity of the sdB star to constrain the system inclination and the companion mass to $M> 0.71 M_\odot$, bringing the total mass of the system closer to the Chandrasekhar limit. However, the system will merge due to loss of angular momentum via gravitational wave radiation only after several Hubble times. Atmospheric parameters and metal abundances are also derived. The resulting values are typical for sdB stars.

Key words: stars: early-type -- binaries: spectroscopic -- stars: fundamental parameters -- white dwarfs

Offprint request: R. Napiwotzki, napiwotzki@sternwarte.uni-erlangen.de

SIMBAD Objects

© ESO 2001