Spectral classification and estimation of distances to the Be/X-ray binaries 1H1936+541 and 1H2202+501

1Simon, AO, 2Metlova, NV, 3Godunova, VG, 1Vasylenko, VV
1Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
2Sternberg Astronomical Institute, Moscow State University, Moscow, Russia
3International Center for Astronomical, Medical and Ecological Research of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2019, 35(1):57-69
Start Page: Physics of Stars and Interstellar Medium
Language: Russian

Results of spectral and photometric studies of the two Be/X-ray binaries 1H1936+541 and 1H2202+501 are presented. The spectral class of the optical component of the 1H1936 + 541 system was first determined and the spectral class of the optical component of the 1H2202 + 501 system was refined. The results obtained allowed us to state that the optical components of the systems 1H1936 + 541 and 1H2202 + 501 are Be stars of the spectral type B1Ve and B3Ve, respectively. These findings, as well as the well-known spectral type distribution of Be stars can testify to the fact that the object 1H1936 + 541 belongs to X-ray binary systems. At the same time, taking into account the fact that Be / X-ray binaries of spectral type B3 are still very little known, the object 1H2202 + 501 can not be unambiguously classified as a Be / X-ray binary. The rotational speeds of the main components of these systems are 246 ± 11 km/s for 1H1936 + 541 and 111 ± 8 km/s for 1H2202 + 501, and the range of the angles of their rotation axes is within 49...82° and 21...28°, respectively. Additionally, using the B and V band photometric observations and spectral classes obtained, we estimated interstellar extinction values E(В – V), as well as distances to the objects. In particular, for 1H2202 + 501, the value of E(В – V) is 0.36 ± 0.03m, and the distance r ranges from 0.8 to 1.6 kpc. For the 1H1936 + 541 system, the following values were obtained: E(В – V) = 0.23 ± 0.03m and r = 2.1...3.6 kpc. Comparison of the distances to the objects with data from the GAIA DR2 catalog (http://gea.esac.esa.int/archive/) revealed the coincidence of the corresponding values within the limits of errors.

Keywords: Be/X-ray binaries, distances to stars, interstellar extinction, light curves, photometric and spectral observations, stellar color-indices, stellar spectral classification

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