HST & VLA Imaging of the Symbiotic Star HM Sge

Abstract

Symbiotic stars are a heterogenous group of interacting binaries, where the combination of a mass-losing giant and a hot compact companion create conditions ideal for studying interacting winds, dust formation, nebular shaping and accretion phenomena. We present HST and VLA observations of the symbiotic nova HM Sge as an example of our work. In this case, we characterise hot and cool parts of the extended nebula, determine the angular binary separation to be 40±9 milli-arcsec, and the interstellar reddening to be no more than E(B-V) = 0.35. Comparison with a suggested binary separation of 50 au gives a distance of 1250±280 pc, consistent with the sparsely-sampled distance-extinction mapping in the direction of HM Sge. A number of other observations of additional high spatial-resolution observations of symbiotic stars have been completed or are being planned.