CBA Center for Backyard Astrophysics

1RXS J232953.9+062814: A Dwarf Nova with a 64-minute Orbital Period and a Conspicuous Secondary Star

John Thorstensen, William Fenton, Joseph Patterson, Jonathan Kemp, Thomas Krajci, and Isabelle Baraffe

Astrophysical Journal, Letters

March 2002, Volume 567, Page 49

We present spectroscopy and time-series photometry of the newly discovered dwarf nova 1RXS J232953.9+062814. Photometry in superoutburst reveals a superhump with a period of 66.06(6) minutes. The low state spectrum shows Balmer and HeI emission on a blue continuum, and in addition shows a rich absorption spectrum of type K4±2. The absorption velocity is modulated sinusoidally at Porb=64.176(5) min, with semi-amplitude K=348(4) km s-1. The low-state light curve is double-humped at this period, and phased as expected for ellipsoidal variations. The absorption strength does not vary appreciably around the orbit. The orbital period is shorter than any other cataclysmic variable save for a handful of helium-star systems and V485 Centauri (59 minutes). The secondary is much hotter than main sequence stars of similar mass, but is well-matched by helium-enriched models, indicating that the secondary evolved from a more massive progenitor. A preliminary calculation in which a 1.2 Msolar star begins mass transfer near the end of H burning matches this system's characteristics remarkably well.

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Copyright © 2002 American Astronomical Society.