Orbital periods of cataclysmic variables identified by the SDSS. VIII. A slingshot prominence in SDSS J003941.06+005427.5?
Abstract
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.
Reduced data (photometry and spectroscopy) are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/viz-bin/qcat?J/A+A/524/A86- Publication:
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Astronomy and Astrophysics
- Pub Date:
- December 2010
- DOI:
- 10.1051/0004-6361/201015633
- arXiv:
- arXiv:1009.5478
- Bibcode:
- 2010A&A...524A..86S
- Keywords:
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- stars: dwarf novae;
- binaries: spectroscopic;
- novae;
- cataclysmic variables;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Accepted for publication in A&