The nature of the massive stellar transient in DDO 68
Astronomical Institute, Ruhr-University Bochum, Germany
Astronomical Institute, Ruhr-University Bochum, Germany
Abstract
When measuring the metallicity of several H II regions in the very low metallicity dwarf galaxy DDO 68, Pustilnik et al. (2008) noted a spectral change of one H II region within 2 years. The lines in the residual spectrum and the brightening of the continuum lead them to interprete this transient event to be due to a variable massive star. Using archival and new imaging and spectroscopy of DDO 68, we present a study of the variability of the transient. Using the derived photometric variability and the properties of its spectrum, we noted that the transient appears to the very similar to V1 in NGC 2366, an exceptional LBV-like object. Together with results on massive variable stars in other nearby, low metallicity galaxies, this indicate interesting twists for the evolution of massive stars at metallicities below that of the Magellanic Clouds. Based on our compilation of nearby, very metal-poor galaxies, there are several objects suitable for observational studies of massive stars at very low metallicities with the current ground and space based instrumentation. This opens the window to derive observationally parameters of stars and their feedback on the interstellar medium critical for analyzing the galaxies at high redshift up to the time of reionization.