The emission line galaxy TV Reticuli (research note) evidence for an ultraluminous supernova

Abstract

Aims. TV Ret was classified as a cataclysmic variable due to an outburst observed in 1977. We intended to confirm this classification and derive some basic properties of the system. Methods. Low resolution optical spectra were obtained for a spectral classification of the object. Results. We find that the object is not a cataclysmic variable but an emission line galaxy with a redshift z = 0.0964. An R-image taken in very good seeing conditions shows that the object is extended. Conclusions. We show that TV Ret is a blue dwarf galaxy, probably compact, with an absolute magnitude of MB = -17.5, a metallicity of 0.12 solar, and an average temperature of 1.3 × 10 4 K. The line ratios place it among the H II galaxies, although close to the border of the Seyfert 2s. The outburst, which was observed in 1977, could thus be explained by a supernova explosion. However, with an absolute magnitude around MB = -21, it was an extremely bright one. Show more