Department of Physics, University of Warwick, Coventry CV4 7AL, UK e-mail: Pablo.Rodriguez-Gil@warwick.ac.uk
2 Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
3 Institute of Space Applications and Remote Sensing, National Observatory of Athens, PO Box 20048, Athens 11810, Greece
4 Institute of Astronomy and Astrophysics, National Observatory of Athens, PO Box 20048, Athens 11810, Greece
Accepted: 28 September 2004
We report the discovery of a new, non-eclipsing SU UMa-type dwarf nova, HS 2219+1824. Photometry obtained in quiescence () reveals a double-humped light curve from which we derive an orbital period of 86.2 min. Additional photometry obtained during a superoutburst reaching clearly shows superhumps with a period of 89.05 min. The optical spectrum contains double-peaked Balmer and He I emission lines from the accretion disc as well as broad absorption troughs of , , and from the white dwarf primary star. Modelling of the optical spectrum implies a white dwarf temperature of , a distance of , and suggests that the spectral type of the donor star is later than M 5. Phase-resolved spectroscopy obtained during quiescence reveals a narrow emission line component which has a radial velocity amplitude and phase consistent with an origin on the secondary star, possibly on the irradiated hemisphere facing the white dwarf. This constitutes the first detection of line emission from the secondary star in a quiescent SU UMa star.
Key words: accretion, accretion disks / stars: binaries: close / stars: individual: HS 2219+1824 / stars: novae, cataclysmic variables / stars: dwarf novae
Based in part on observations obtained at the German-Spanish Astronomical Center, Calar Alto, operated by the Max-Planck-Institut für Astronomie, Heidelberg, jointly with the Spanish National Commission for Astronomy; on observations made with the IAC80 and OGS telescopes, operated on the island of Tenerife by the Instituto de Astrofísica de Canarias (IAC) and the European Space Agency (ESA), respectively, in the Spanish Observatorio del Teide of the IAC; on observations made at the 1.2 m telescope, located at Kryoneri Korinthias, and owned by the National Observatory of Athens, Greece; and on observations made with the William Herschel Telescope, which is operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the IAC.
© ESO, 2005