A New Luminous Blue Variable in the Giant Extragalactic H II Region NGC 2363

Abstract

We report the discovery of an erupting luminous blue variable (LBV) star in the giant H II region NGC 2363, the most massive star-forming region in the Magellanic irregular galaxy NGC 2366. This LBV, presently the visually brightest star in the galaxy (M_V ~ -10.2), was first noticed in Hubble Space Telescope Wide Field Planetary Camera 2 images taken in 1996 January. An archival search allowed us to determine the onset of the present outburst. This star was not visible in 1991 nor 1992, but appeared in late 1993. In early 1995, it became the brightest star in the galaxy. The spectrum of the LBV displays a strong Hα emission line, as well as blueshifted absorption lines of He I.

Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555.