Low-resolution Optical Spectroscopy of Recently Discovered Accreting-only Symbiotic Star THA 15–31

Abstract

Recently, the discovery and characterization of a new accreting-only symbiotic star THA 15–31 was presented. Motivated by the suggestion that the optical spectrum of the star might show the emission lines with higher ionization potential in comparison with previously studied epochs, we have obtained a low-resolution spectrum of this target. The spectrum does not reveal the presence of suggested He ii emission lines. Moreover, the near-UV excess seems to be even less prominent now in comparison with the previous observations, suggesting a decrease in mass transfer and accretion rate. The search for He ii emission lines should be repeated when the accretion rate is higher.