An OH maser outburst in Cepheus A

Abstract

A remarkable outburst is reported in the OH maser emission from Cepheus A at 1665 MHz. A new flare feature at –8.9 km s – 1 has appeared in the spectrum. It increased in flux by a factor of over 250 in 16 months to reach a maximum in 1985 February and is now decaying at a slower rate. It is at least 98 per cent left-hand circularly polarized. Several weaker features have also appeared in the 1665-MHz spectrum, and one of the previously known features has undergone rapid variations in flux.