On the Orbital Period and Models of V Sge

The orbital period of V Sge is decreasing at a rate which increased from dP/dt=-(4.11±0.33)×10-10 in 1962 to -(5.44±0.61)× 10-10 in 2022. This implies that the mass transfer from the secondary component is accelerating. From the evidence based on the orbital period variations, combined with estimates of the mass loss from the system based on radio observations, it follows that (1) the mass transfer rate from the secondary component is larger than M2=-5×10-6 M☉/yr, possibly as large as M2=-2.5×10-5 M☉/yr, and (2) the mass loss rate from the primary component is M1=-4×10-7 M☉/yr or larger. Close similarity of V Sge to binary Wolf-Rayet stars supports the model with primary component being a hot, evolved star loosing its mass. Several arguments are presented which exclude the alternative model with primary component being a white dwarf with an accretion disk.

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Opracowanie rekordu ze środków MEiN, umowa nr SONP/SP/546092/2022 w ramach programu "Społeczna odpowiedzialność nauki" - moduł: Popularyzacja nauki i promocja sportu (2022-2023)