Discovery of the first symbiotic star in NGC6822

Type Journal Article
Names Alexei Y. Kniazev, Petri Väisänen, Patricia A. Whitelock, John W. Menzies, Michael W. Feast, Eva K. Grebel, David A. H. Buckley, Yas Hashimoto, Nicola Loaring, Encarni Romero-Colmenero, Ramotholo Sefako, Eric B. Burgh, Kenneth Nordsieck
Publication Monthly Notices of the Royal Astronomical Society
Volume 395
Issue 2
Pages 1121-1126
Date May 1, 2009
URL http://adsabs.harvard.edu/abs/2009MNRAS.395.1121K
Library Catalog NASA ADS
Abstract We report the discovery of the first symbiotic star (V = 21.6, KS = 15.8mag) in the Local Group dwarf irregular galaxy NGC6822. This star was identified during a spectral survey of Hα emission-line objects using the Southern African Large Telescope during its performance-verification phase. The observed strong emission lines of HI and HeII suggest a high electron density and T* < 130000K for the hot companion. The infrared colours allow us to classify this object as an S-type symbiotic star, comprising a red giant losing mass to a compact companion. The red giant is an asymptotic giant branch (AGB) carbon star, and a semiregular variable, pulsating in the first overtone with a period of 142 d. Its bolometric magnitude is Mbol = -4.4mag. We review what is known about the luminosities of extragalactic symbiotic stars, showing that most, possibly all, contain AGB stars. We suggest that a much larger fraction of Galactic symbiotic stars may contain AGB stars than was previously realized. Based on observations made with the Southern African Large Telescope (SALT) and the Infrared Survey Facility (IRSF). E-mail: akniazev@saao.ac.za
Tags binaries: symbiotic, galaxies: individual: NGC6822, stars: mass-loss
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