EDP Sciences
Free access
Volume 410, Number 2, November I 2003
Page(s) 663 - 669
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20031278

A&A 410, 663-669 (2003)
DOI: 10.1051/0004-6361:20031278

Binaries discovered by the SPY project

III. HE 2209-1444: A massive, short period double degenerate
C. A. Karl1, R. Napiwotzki1, G. Nelemans2, N. Christlieb3, D. Koester4, U. Heber1 and D. Reimers3

1  Dr.-Remeis-Sternwarte, Astronomisches Institut der Universität Erlangen-Nürnberg, Sternwartstr. 7, 96049 Bamberg, Germany
2  Institute of Astronomy, Madingley Road, CB3 0HA, Cambridge, UK
3  Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
4  Institut für Theoretische Physik und Astrophysik, Universität Kiel, 24098 Kiel, Germany

(Received 20 March 2003 / Accepted 12 August 2003 )

In the course of our search for double degenerate (DD) binaries as potential progenitors of type Ia supernovae with the UVES spectrograph at the ESO VLT (ESO SN Ia Progenitor surveY - SPY) we discovered HE 2209-1444 to be a double-lined system consisting of two DA white dwarfs. From the analysis of the radial velocity curve we determined the period of the system to be $P = 6^{\rm h}38^{\rm m}47^{\rm s}$. The semi-amplitudes for both individual components are 109 km s -1 each. A model atmosphere analysis enabled us to derive individual temperatures for both components (8490 K and 7140 K, resp.) and masses of $0.58~M_\odot$ for each component. The total mass of the system is $1.15\pm 0.07~M_\odot$. The system will lose angular momentum due to gravitational wave radiation and therefore will merge within 5 Gyrs - less than a Hubble time. HE 2209-1444 is the second massive, short period double degenerate detected by SPY. Its total mass is about 20% below the Chandrasekhar mass limit and therefore it does not qualify as a potentional SN Ia progenitor. However, together with our previous detections it supports the view that Chandrasekhar mass systems do exist.

Key words: stars: binaries: close -- stars: supernovae: general -- stars: white dwarfs

Offprint request: C. A. Karl, karl@sternwarte.uni-erlangen.de

SIMBAD Objects

© ESO 2003