Photometric and Spectroscopic Observations of MV Lyrae from 1968 to 1991

• Published in: Publications of the Astronomical Society of the Pacific 1993-01, Vol.105 (683), p.51-58
• Main Authors: Rosino, L., Romano, G., Marziani, P.
• Format: Article
• Language: English
• Subjects: Accretion disks; Astronomical magnitude; Astronomy; Cataclysmic variables; Earth, ocean, space; Emission spectra; Exact sciences and technology; Light curves; Line spectra; Mathematical minima; Novae, dwarf novae, recurrent novae, and other cataclysmic (eruptive) variables; Optical bursts; Spectroscopy; Stars; Variable and peculiar stars (including novae); White dwarfs
• ISSN: 0004-6280; 1538-3873
• DOI: 10.1086/133126

We report results of a program to monitor the peculiar variable star MV Lyrae, carried out at Asiago since 1968. MV Lyrae is a cataclysmic variable formed by a white dwarf and an M5 V companion, with an orbital period near the 2-3-h "period gap" and other unusual characteristics. The light curve shows that MV Lyr passes at times from its normal "high state" of maximum to a deep minimum (low state) in which it can remain for months or even years. The optical spectra of MV Lyr at minimum are characterized by the presence of narrow emission lines of H, He i, and very weak Ca ii K. The same lines are observed in the course of outbursts, but the presence in this phase of He ii 4686 indicates an increased degree of excitation. At maximum, He ii 4686 disappears and some of the He i lines are found in absorption. The continuum rises toward the blue, like that of a blackbody with temperature of about 15,000 K. The color index B–V is always negative, slightly higher at maximum (~–0.2) than at minimum (~–0.3). We compare MV Lyr with other typical members of the VY Sculptoris subclass of cataclysmic variables. MV Lyr, uniquely among these stars, remained in the low state for about 10 years (1979 September-1989 June). During this period of time MV Lyr was moderately active displaying several outbursts before returning to its high state.