Araujo-Betancor, S., Gaensicke, B. T., Hagen, H.-J., Marsh, T. R., Harlaftis, E. T., Thorstensen, John Robert, Fried, R. E., Schmeer, P. and Engels, Dieter (2005) HS 2331+3905 : the cataclysmic variable that has it all. Astronomy & Astrophysics, Vol.430 (No.2). pp. 629-642. doi:10.1051/0004-6361:20041736 ISSN 0004-6361.

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Abstract

We report detailed follow-up observations of the cataclysmic variable HS 2331+3905, identified as an emissionline object in the Hamburg Quasar Survey. An orbital period of 81.08 min is unambiguously determined from the detection of eclipses in the light curves of HS 2331+3905. A second photometric period is consistently detected at P
83.38 min,∼2.8% longer than P orb , which we tentatively relate to the presence of permanent superhumps. High time resolution photometry exhibits short-timescale variability on time scales of 5−6 min which we interpret as non-radial white dwarf pulsations, as well as a coherent signal at 1.12 min, which is likely to be the white dwarf spin period. A large-amplitude quasi-sinusoidal radial
velocity modulation of the Balmer and Helium lines with a period ∼3.5 h is persistently detected throughout three seasons of time-resolved spectroscopy. However, this spectroscopic period, which is in no way related to the orbital period, is not strictly coherent but drifts in period and/or phase on time scales of a few days. Modeling the far-ultraviolet to infrared spectral energy
distribution of HS 2331+3905, we determine a white dwarf temperature of T eff 10 500 K (assuming M wd = 0.6 M ), close to the ZZ Ceti instability strip of single white dwarfs. The spectral model implies a distance of d = 90 ± 15 pc, and a low value for the distance is supported by the large proper motion of the system, µ = 0.14 yr −1 . The non-detection of molecular bands and the low J, H, and K fluxes of HS 2331+3905 make this object a very likely candidate for a brown-dwarf donor.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy
Divisions:	Faculty of Science, Engineering and Medicine > Science > Physics
Library of Congress Subject Headings (LCSH):	Cataclysmic variable stars
Journal or Publication Title:	Astronomy & Astrophysics
Publisher:	EDP Sciences
ISSN:	0004-6361
Official Date:	February 2005
Dates:	Date Event February 2005 Published
Volume:	Vol.430
Number:	No.2
Page Range:	pp. 629-642
DOI:	10.1051/0004-6361:20041736
Status:	Peer Reviewed
Access rights to Published version:	Open Access (Creative Commons)
Funder:	Space Telescope Science Institute (U.S.), United States. National Aeronautics and Space Administration (NASA), Particle Physics and Astronomy Research Council (Great Britain) (PPARC), Deutsche Forschungsgemeinschaft (DFG)
Grant number:	GO-9357 (STSI), GO-9724 (STSI), NAS5-26555 (NASA), Re 353/11 (DFG), Re 353/22 (DFG)

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