Radio Emission from V723 Cas

摘要

V723 Cas (Nova Cassiopeiae 1995) is an unusually slow nova discovered on 1995 August 24. MERLIN has been used to follow the evolution of the radio emission from this nova providing ten epochs of data and nine radio maps between 1996 and 2001. The radio light curve shows an initial optically thick rise followed by a turn-over into optically thin emission and a corresponding decline in flux as the shell expands. The shell is resolved in the radio by 1998 March and subsequently breaks up into several compact components. Later maps display an unusual effect involving a 90 degree change in the preferential emission axis between successive epochs. A simple radiative transfer model is applied to the light curve in order to determine physical parameters for the shell. These results are presented together with a discussion of the radio maps in terms of an expanding non-uniform shell with varying optical depth.