Confirmation of the New Evolutionary Status of UU Cas

Abstract

A new spectral study of the close binary system (CBS) UU Cas with massive components was carried out, based on spectra obtained on the echelle spectrometer of the 1.2-m telescope of Kourovka Astronomical Observatory of UFU from 2017 to 2022. The results of this study confirm the new evolutionary status of UU Cas, previously determined by the author based on spectrophotometry of this system in 2017 and confirmed in a number of works by other researchers, according to which the system is in the final stage of the mass exchange process, and not at its beginning, as previously thought. Its components are not very massive, and the value of their mass ratio is the opposite of what was previously determined from photometry results. The values of the half-amplitudes of the radial velocities \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{K}_{1}} = 195.6$$\\end{document} km/s, \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{K}_{2}} = 106.5$$\\end{document} km/s and the masses of both components \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{M}_{1}} = 9.6\\;{{M}_{ \\odot }}$$\\end{document}, \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{M}_{2}} = 17.6\\;{{M}_{ \\odot }}$$\\end{document} obtained on a much more extensive observational material, for the orbital inclination angle i = 74.5°, given recently in the literature, as well as the orbital radius \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$A = 54\\;{{R}_{ \\odot }}$$\\end{document} of this close binary system are comparable with the values previously found by the author. The article is based on a talk presented at the astrophysical memorial seminar “Novelties in Understanding the Evolution of Binary Stars,” dedicated to the 90th anniversary of Professor M.A. Svechnikov.