AS 357 Is a New Symbiotic Star

Abstract

The article presents the results of spectroscopic observations of poorly studied variable star AS 357, proving that it is an S-type symbiotic star. The object’s spectrum contains TiO molecular bands; bright emission lines of H I, He I, [O II], [O III], [N II]; a weak line of He II; etc. Photometric observations show that the system is a long-period variable with a period of \( \sim {\kern 1pt} {850^d}\). This is likely the system’s orbital period. Estimates were obtained for the temperature of the hot component, \({T_{\text{h}}} \approx 55\,000\) K, and its luminosity, \({L_{\text{h}}} \approx 1300{\kern 1pt} {L_ \odot }\). The spectral class of the cold component is M3 III, with a luminosity of \({L_{\text{c}}} = (2500{-} 3400){\kern 1pt} {L_ \odot }\) and a radius of \({R_{\text{c}}} = (130{-} 150){\kern 1pt} {R_ \odot }\). There is excess radiation in the short-wavelength region of the spectrum that can be attributed to an accretion disk around the hot component. The study is partially based on a talk presented at the Modern Stellar Astronomy 2025 conference.