2023/08/19 by Maslennikova, N. A., Tatarnikov, A. M., Tatarnikova, A. A. +5
#FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Solar and Stellar Astrophysics (astro-ph.SR)
paper · doi:10.48550/arxiv.2308.10011
The results of photometric and spectral observations of T CrB obtained in a wide range of wavelengths in 2011-2023 are presented. We use the near-IR light curves to determine a new ephemeris JDmin = 2455828.9 + 227.55 × E for the times of light minima when the red giant is located between the observer and the hot component. The flux ratio Hα/Hβ varied from ∼ 3 to ∼ 8 in 2020-2023, which may be due to a change in the flux ratio between the X-ray and optical ranges. It is shown that the value of Hα/Hβ anticorrelates with the rate of accretion onto the hot component of the system. Based on high-speed follow-up observations obtained on June 8, 2023, we detected a variability of the HeII λ4686 line with a characteristic time-scale of ∼ 25 min, the amplitude of variability in the B-band was ∼ 0.07m. Simulations of the near-IR light curves accounting for the ellipsoidal effect allowed us to obtain the parameters of the binary system: the Roche lobe filling factor of the cool component μ=1.0, the mass ratio q=Mcool/Mhot ∈ [0.5, 0.77], the orbital inclination i ∈ [55^∘, 63^∘]. A comparison of the light curve obtained in 2005-2023 with the 1946 outburst template made it possible to predict the date of the upcoming outburst - January 2024.