Modulation of Circumstellar Extinction in a Young Binary System with a Low-Mass Companion in a Noncoplanar Orbit

TL;DR

This study models how noncoplanar orbits and disk interactions in young binary systems cause cyclic variations in circumstellar extinction and light curves, aiding understanding of UX Ori stars' activity.

Contribution

It introduces hydrodynamics models of young binary systems with noncoplanar disks, showing how orbital and system orientation affect observed light variations.

Findings

Light curve shapes and amplitudes vary with system orientation.

Mass accretion rate depends on orbital phase.

Models can explain cyclic activity in UX Ori stars.

Abstract

The cyclic activity model of a young star with the low-mass secondary component (q = M2/M1 <= 0.1) accreting a matter from circumbinary disk is considered. It is assumed that the orbit is circular and the disk and orbital planes are non-coplanar. Sets of hydrodynamics models of such a system have been calculated by the SPH method and then the variations of the circumstellar extinction and phase light curves were determined. The calculations showed that depending on the model parameters and orientation of the system in regards to an observer the different in shape and amplitude light curves can be observed. An important property of the considered models is also the dependence of the mass accretion rate onto the components on the phase of the orbital period. The results of the calculation can be used for analysis of the cyclic activity of UX Ori stars and young stars with the long-lasting eclipses.