[phys4phys] Seminar Katedre za astronomiju - 31. mart 2026.

[Katedra za astronomiju]

                     Seminar iz astronomije i astrofizike

                             Prof. dr Sergei B. Popov
       (Sternberg Astronomical Institute, Moscow State University, Rusija)

           "Wide astrometric low-mass binaries with compact objects:
                 neutron stars' evolution and appearance"

            utorak, 31. mart 2026. godine, u 18 sati, u ucionici 809.


Abstract: 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.

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