Interacting supernovae and supernova impostors. SN 2007sv: the major eruption of a massive star in UGC 5979

TL;DR

SN 2007sv was a supernova impostor resembling a luminous blue variable eruption, characterized by interaction with circumstellar material, and distinguished from true supernovae by its lower luminosity and spectral features.

Contribution

This study provides detailed photometric and spectroscopic analysis of SN 2007sv, confirming its classification as a supernova impostor rather than a genuine supernova.

Findings

SN 2007sv's luminosity suggests it is a supernova impostor.

Spectral features lack high-velocity ejecta typical of supernovae.

Light curve comparison supports similarity to known impostors like SN 1997bs.

Abstract

We report the results of the photometric and spectroscopic monitoring campaign of the transient SN 2007sv. The observables are similar to those of type IIn supernovae, a well-known class of objects whose ejecta interact with pre-existing circum-stellar material. The spectra show a blue continuum at early phases and prominent Balmer lines in emission, however, the absolute magnitude at the discovery of SN 2007sv (M_R = - 14.25 +/- 0.38) indicate it to be most likely a supernova impostor. This classification is also supported by the lack of evidence in the spectra of very high velocity material as expected in supernova ejecta. In addition we find no unequivocal evidence of broad lines of alpha - and/or Fe-peak elements. The comparison with the absolute light curves of other interacting objects (including type IIn supernovae) highlights the overall similarity with the prototypical impostor SN 1997bs. This supports our claim that SN 2007sv was not a genuine supernova, and was instead a supernova impostor, most likely similar to the major eruption of a luminous blue variable.