A Dwarf Nova in the Core of 47 Tucanae

Abstract

The Faint Object Camera on the Hubble Space Telescope detected an outburst of a star (V2) located in the core of the Galactic globular cluster 47 Tucanae that occured in 1993 October. The instrumental magnitudes at 220 and 342 nm at outburst were 15.4 and 16.2, respectively. Observations of the same object made a year before and 2 weeks later gave an instrumental magnitude at 200 nm of 19.5 and 19.3, respectively. The continuum spectrum of the nova at outburst in the 195-370 nm range can be reasonably well fitted by a power law with an index of 2.3. These characteristics are all consistent with the hypothesis that V2 is a dwarf nova, the first clearly identifiable object of this type in the core of a globular cluster.