Volume 524, December 2010
|Number of page(s)||8|
|Section||Stellar structure and evolution|
|Published online||25 November 2010|
Orbital periods of cataclysmic variables identified by the SDSS
VIII. A slingshot prominence in SDSS J003941.06 + 005427.5?⋆
Astrophysics Group, Keele University,
2 Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
Received: 24 August 2010
Accepted: 27 September 2010
We present VLT spectroscopy and NTT photometry of the faint cataclysmic binary SDSS J003941.06 + 005427.5. This object shows triple-peaked Hα emission with all three peaks variable in both strength and velocity. We measure an orbital period of 91.395 ± 0.093 min from the velocity variations of the wings of the Hα emission line. Using the GALEX and SDSS photometry of this object, we determine a white dwarf temperature of 15 000 K and a very late (≳L2) spectral type for the companion star. These measurements, plus the relatively long orbital period, suggest that SDSS J003941.06 + 005427.5 may be a post-bounce cataclysmic variable. Doppler maps of the Hα and He I 6678 Å emission features show an accretion disc with a non-uniform brightness and departures from Keplerian flow. The third emission peak is detected only in Hα and at a relatively low velocity amplitude of 202 ± 3 km s-1. We are unable to explain this emission as arising from either the white dwarf, the secondary star, or the accretion disc. We tentatively attribute this mysterious central peak to a coronal loop anchored at the secondary star. If confirmed, this would be the first example of a slingshot prominence in a CV with a low mass-transfer rate and/or a fully convective secondary star.
Key words: stars: dwarf novae / binaries: spectroscopic / novae, cataclysmic variables
Reduced data (photometry and spectroscopy) are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsweb.u-strasbg.fr/viz-bin/qcat?J/A+A/524/A86
© ESO, 2010
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