RS Ophiuchi — first radio detection of a recurrent nova outburst

Abstract

Recurrent novae and classical novae belong to the cataclysmic variable class of objects. Of these, only classical novae outbursts have been hitherto observed at radio wavelengths, and then no earlier than 50 days after the outburst. Here we report the first radio detection of an outburst from a recurrent nova (RS Ophiuchi). The observations begin only 18 days after the optical maximum and show a radio ‘Light’ curve which is different from that of classical novae. The brightness temperature of ∼107 K, calculated for this event, greatly exceeds the 104 K, seen in classical novae, and suggests a non-thermal origin for the radio emission from RS Ophiuchi. Although the later emission has a classical (t–t0) ‘light’ curve, the radio emission mechanism appears not to turn on until 14 days after the optical nova and takes a further 10 days to reach the (t–t0)curve. Analogies may be drawn between the radio development of RS Ophiuchi and that of young super-novae.