Katedra za astronomiju Matematičkog fakulteta Univerziteta u Beogradu organizuje seminar iz astronomije i astrofizike, koji će se održati u utorak, 31. marta 2026. godine, u 18 časova, u učionici 809.

Predavanje pod nazivom „Wide astrometric low-mass binaries with compact objects: neutron stars’ evolution and appearance” održaće prof. dr Sergei B. Popov (Sternberg Astronomical Institute, Moscow State University, Rusija).

Pozivamo sve zainteresovane studente i nastavnike da prisustvuju seminaru.

Apstrakt: Precise astrometric measurement with the Gaia satellite resulted in the discovery of tens of wide binary systems consisting of a Sun-like star and an invisible component. The latter can be a white dwarf, a neutron star, or a black hole. In the talk, I briefly review these systems and present our model of magneto-rotational evolution of neutron stars in wide low-mass binaries, accounting for the orbital eccentricity. We aim to calculate when neutron stars in such systems can start to accrete matter from the stellar wind of the companion. We show that the transition from the ejector to the propeller stage occurs earlier in more eccentric systems, thus increasing the time that neutron stars can spend accreting matter. Our calculations show that in the case of efficient spin-down at the propeller stage, a neutron star in an eccentric orbit with e\gtrsim0.6 and a standard magnetic field B=10^{12} G can start accreting within a few Gyr. For neutron stars with B=10^{13} G, the onset of accretion occurs earlier regardless of the orbital eccentricity. Otherwise, with a lower spin-down rate, such a neutron star will remain at the propeller stage for most of its life.
Finally, I present the results of radio observations of several of these systems and discuss the detected burst from  2MASS J1527+3536 (arXiv:2509.03001). Some preliminary results about recently discovered high-velocity X-ray sources are also presented.