Том 101, № 10 (2024)

The problem of the formation of exoplanets in inclined orbits relative to the equatorial plane of the parent star or the main plane of the protoplanetary disk can be solved by introducing a smaller inclined disk. However, the question of the nature of such an internal disk remains open. In the paper, we successfully tested the hypothesis about the formation of an inclined inner disk in a protoplanetary disk near a T Tau type star as a result of a gas stream falling on it. To test the hypothesis, three-dimensional gas-dynamic calculations were performed taking into account viscosity and thermal conductivity using the PLUTO package. In the course of the analysis of calculations, it was shown that a single intersection of the matter stream with the plane of the disk cannot ensure the formation of an inclined disk near the star, while a double intersection can. In addition, in the case of a retrograde fall of matter, the angle of inclination of the resulting inner disk is significantly greater. An analysis of the observational manifestations of this event was also carried out: the potential change in the brightness of the star, the distribution of optical thickness in angles, the evolution of the accretion rate. It is shown that the decrease in brightness can reach up to 5^m, taking into account scattered light, and such a decrease in brightness will last several decades. In addition, a sharp increase in the accretion rate by two orders of magnitude could potentially trigger an FU Ori-like outburst.

In this article we analyze the properties of the photometric and spectral variability of the young star V718 Per, a member of the cluster IC 348, in terms of its possible binarity. The most realistic is the model where the main component of the system V718 Per A — with an effective temperature of 5200 K — is periodically shielded by two extended dust periods structures consisting of large particles and moving around the star in resonance with two planets. Their orbital periods are 4.7 years and 213 days. Their ratio with high accuracy is 1:8, and the ratio of the large semi-axes is 1:4. The masses of the planets do not exceed 6 М_Jup. At the moments of total eclipses of V718 Per A, the radiation of the system is dominated by a colder component with an effective temperature of 4150 ± 100 K, which explains the reddening of the star observed in the brightness minima, as well as its spectral changes during brightness weakening. Speckle interferometric observations performed on the 2.5-m telescope of the CMO of SAI MSU made it possible to estimate the upper limit of the angular distance between the components of the system: 0.1′′, which is equivalent to a projection distance of 30 a.u. The unique feature of this system is that the planes of the planetary orbits practically coincide with the line of sight. Such an orientation of the system is most favorable for measuring fluctuations in the radial velocity of a star caused by the orbital motion of planets, as well as for observing planetary transits along the disk of the main component of the system.

The aim of the work is to derive a new dynamic formula for the angular velocity of rotation of equilibrium figures of a gravitating fluid with a polytropic equation of state. In this formula, the angular velocity of rotation depends not only on the polytropic index 0 ≤ n ≤ 5, but, and this is the main thing, on the components of the internal and external gravitational energy of the figure. When solving the problem, the integration constant in the full potential was expressed through three global characteristics: mass, full gravitational energy and rotation energy of the equilibrium figure. The validity of the new formula was confirmed by the limiting transition at n = 0 to classical homogeneous Maclaurin spheroids and Jacobi ellipsoids. The results of the work expand the scope of application of the theory of equilibrium figures.