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Hydrodynamic models of a young binary system accreting matter from the remnants of a protostellar cloud have been calculated by the SPH method. It is shown that periodic variations in column density in projection onto the primary component take place at low inclinations of the binary plane to the line of sight. They can result in periodic extinction variations. Three periodic components can exist in general case. The first component has a period equal to the orbital one and is attributable to the streams of matter penetrating into the inner regions of the binary. The second component has a period that is a factor of 5-8 longer than the orbital one and is related to the density waves generated in a circumbinary (CB) disk. The third, longest period is attributable to the precession of the inner asymmetric region of CB disk. The relationship between the amplitudes of these cycles depends on the model parameters as well as on the inclination and orientation of the binary in space. We show that at a dust-to-gas ratio of 1:100 and and a mass extinction coefficient of 250 cm$^2$ g$^{-1}$, the amplitude of the brightness variations of the primary component in the V-band can reach $1^m$ at a mass accretion rate onto the binary components of $10^{-8} M_{odot}$ yr$^{-1}$ and a $10^{rm o}$ inclination of the binary plane to the line of sight. We discuss possible applications of the model to pre-main-sequence stars.
This paper presents an extensive overview of known and proposed RR Lyrae stars in binaries. The aim is to revise and extend the list with new Galactic field systems. We utilized maxima timings for eleven RRab type stars with suspicious behaviour from
Multiple star systems are commonly assumed to form coevally; they thus provide the anchor for most calibrations of stellar evolutionary models. In this paper we study the binary population of the Taurus-Auriga association, using the component positio
V582 Aur is an FU Ori-type young eruptive star in outburst since $sim$1985. The eruption is currently in a relatively constant plateau phase, with photometric and spectroscopic variability superimposed. Here we will characterize the progenitor of the
We report our analyses of the multi-epoch (2015-2017) ALMA archival data of the Class II binary system XZ Tau at Bands 3, 4 and 6. The millimeter dust continuum images show compact, unresolved (r <~ 15 au) circumstellar disks (CSDs) around the indivi
Recently Menard et al. detected a subtle but systematic change in the mean color of quasars as a function of their projected separation from foreground galaxies, extending to comoving separations of ~10Mpc/h, which they interpret as a signature of re