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CSS100603:112253−111037: a helium-rich dwarf nova with a 65 min orbital period

Breedt, E. and Gänsicke, B. T. and Marsh, T. R. and Steeghs, D. and Drake, A. J. and Copperwheat, C. M. (2012) CSS100603:112253−111037: a helium-rich dwarf nova with a 65 min orbital period. Monthly Notices of the Royal Astronomical Society, 425 (4). pp. 2548-2556. ISSN 0035-8711. doi:10.1111/j.1365-2966.2012.21724.x.

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We present time-resolved optical spectroscopy of the dwarf nova CSS100603:112253−111037. Its optical spectrum is rich in helium, with broad, double-peaked emission lines produced in an accretion disc. We measure a line flux ratio He i λ5876/Hα = 1.49 ± 0.04, a much higher ratio than is typically observed in dwarf novae. The orbital period, as derived from the radial velocity of the line wings, is 65.233 ± 0.015  min. In combination with the previously measured superhump period, this implies an extreme mass ratio of M_2/M_1 = 0.017 ± 0.004. The Hα  and He i λ 6678 emission lines additionally have a narrow central spike, as is often seen in the spectra of AM CVn-type stars. Comparing their properties with cataclysmic variables (CVs), AM CVn systems and hydrogen binaries below the CV period minimum, we argue that CSS100603:112253−111037 is the first compelling example of an AM CVn system forming via the evolved CV channel. With the addition of this system, evolved CVs now account for 7 per cent of all known semidetached white dwarf binaries with P_orb < 76 min. Two recently discovered binaries may further increase this figure. Although the selection bias of this sample is not yet well defined, these systems support the evolved CV model as a possible formation channel for ultracompact accreting binaries. The orbital periods of the three ultracompact hydrogen accreting binaries overlap with those of the long-period AM CVn stars, but there are currently no known systems in the period range of 67–76  min.

Item Type:Article
Related URLs:
URLURL TypeDescription
Breedt, E.0000-0001-6180-3438
Gänsicke, B. T.0000-0002-2761-3005
Marsh, T. R.0000-0002-2498-7589
Additional Information:© 2012 The Authors. Monthly Notices of the Royal Astronomical Society © 2012 RAS. Accepted 2012 July 13. Received 2012 July 12; in original form 2012 June 20. Article first published online: 30 Aug. 2012. We thank our referee, M. Wood, for his suggestions and comments on this paper. EB, BTG, TRM, DS and CMC acknowledge support from the UK STFC in the form of a Rolling Grant. This paper is based on observations made with the ESO’s VLT, as part of programme 086.D-0243B. The CSS survey is funded by the National Aeronautics and Space Administration under Grant No. NNG05GF22G issued through the Science Mission Directorate Near-Earth Objects Observations Programme. The CRTS survey is supported by the U.S. National Science Foundation under grant AST-0909182.
Funding AgencyGrant Number
STFC (United Kingdom) Rolling GrantUNSPECIFIED
Subject Keywords:binaries: close; stars: dwarf novae; stars: individual: CSS100603:112253; 111037; novae, cataclysmic variables
Issue or Number:4
Record Number:CaltechAUTHORS:20121012-112709174
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Official Citation:Breedt, E., Gänsicke, B. T., Marsh, T. R., Steeghs, D., Drake, A. J. and Copperwheat, C. M. (2012), CSS100603:112253−111037: a helium-rich dwarf nova with a 65 min orbital period. Monthly Notices of the Royal Astronomical Society, 425: 2548–2556. doi: 10.1111/j.1365-2966.2012.21724.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:34875
Deposited By: Jason Perez
Deposited On:12 Oct 2012 20:52
Last Modified:09 Nov 2021 23:11

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