RS Ophiuchi: radio lightcurve development following the 2006 outburst

Abstract

We report GHz observations beginning 4.5 days after the discovery of RS Ophiuchi undergoing its 2006 recurrent nova outburst. Observations over the first 60 days are included, enabling us to follow spectral development throughout the three phases of the remnant development. We see dramatic brightening on days 4 to 7 at 6 GHz and an accompanying increase in other bands, particularly 1.46 GHz, consistent with transition from the initial phase to the adiabatic expansion phase. This is complete by day 13 when the brightness at 5 GHz is apparently declining from an early maximum (compared with 1985 observations). The flux recovered to a second peak by approximately day 40, consistent with behaviour observed in 1985. At all times the spectral index is consistent with combined thermal and non-thermal components. The emission requires at least 4±2×10/sup−7M of ejecta.