Multi-epoch radio imaging of γ-ray Nova V959 Mon

Abstract

V959 Mon (Nova Mon 2012) was first detected by the Fermi Large Area Telescope in June 2012, as a transient gamma-ray source. Subsequent optical observations showed that this gamma-ray emission was due to a classical nova explosion. Multifrequency observations of V959 Mon with the Very Large Array (VLA) between 2012 June and September revealed dramatic brightening, and a spectrum that steepened with increasing frequency. High-resolution radio images of V959 Mon using e-MERLIN are presented here, at six epochs between 2012 September and 2014 February that show morphological evolution of the source. While early e-MERLIN observations of V959 Mon showan east–west elongation in the ejecta morphology, subsequent observations suggest that the ejecta become elongated in the north–south direction.
Our high-resolution observations of this surprising evolution in the structure of V959 Mon can assist us in further understanding the behaviour and morphology of nova ejecta.