Discovery in IC10 of the farthest known symbiotic star

Abstract

We report the discovery of the first known symbiotic star in IC10, a starburst galaxy belonging to the Local Group, at a distance of ~750 kpc. The symbiotic star was identified during a survey of emission-line objects. It shines at V = 24.62 ± 0.04, V - RC = 2.77 ± 0.05 and RC - IC = 2.39 ± 0.02, and suffers from EB-V = 0.85 ± 0.05 reddening. The spectrum of the cool component well matches that of solar neighbourhood M8III giants. The observed emission lines belong to Balmer series, [S II], [N II] and [O III]. They suggest a low electronic density, negligible optical depth effects and 35 000 < Teff < 90 000 K for the ionizing source. The spectrum of the new symbiotic star in IC10 is an almost perfect copy of that of Hen 2-147, a well-known Galactic symbiotic star and Mira. © 2008 The Authors. Journal compilation © 2008 RAS.