Evolutionary Increase of the orbital Separation and Change of the Roche Lobe Size in SS433

Anatol Cherepashchuk; Alexander Belinski; Alexander Dodin; Konstantin Postnov

doi:10.1016/j.newast.2023.102060

paper

Evolutionary Increase of the orbital Separation and Change of the Roche Lobe Size in SS433

arXiv:2305.07093 · doi:10.1016/j.newast.2023.102060

Abstract

We present results of long-term photometric monitoring of SS433 which proves a secular evolutionary increase of the orbital period of SS433 at a rate of $(1.14 \pm 0.25) \times 1 0^{- 7}$ s~s $^{- 1}$ . Using a physical model of non-conservative mass transfer in SS433 through a supercritical accretion disc around the compact companion, we reliably confirm that the binary mass ratio in SS433, $q = M_{x} / M_{v}$ is $≳ 0.8$ . For an optical star mass $M_{v} \sim 10 M_{⊙}$ the compact object in SS433 is a black hole with mass $M_{B H} ≳ 8 M_{⊙}$ . We discuss evolutionary implications of the found orbital period increase in SS433 -- a secular change in the orbital separation and a size of the Roche lobe of the optical star. We show that for the mass-loss rate $d M_{v} / d t \sim 1 0^{- 4} - 3 \times 1 0^{- 5} M_{⊙}$ per year and an optical star mass $M_{v} \sim 10 - 15 M_{⊙}$ the found orbital period increase implies the corresponding orbital separation increase while the Roche lobe size can shrink or expand around a mean constant value depending on the optical star mass-loss rate which may be modulated with the precessional period.

19 pages, 3 figures, accepted for publication in New Astronomy

Evolutionary Increase of the orbital Separation and Change of the Roche Lobe Size in SS433

Abstract

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