Vol 101, No 7 (2024)

Using a high-precision algorithm for interpreting transit light curves in a model of a classical eclipsing binary star-exoplanet system, we investigated the possibility of determining the system parameters in the absence of a priori knowledge of the orbital eccentricity. It was shown that it is impossible to determine the exact value of the eccentricity and periastron longitude based on the main minimum of the transit light curve alone. Also, with an observational accuracy of about 1% of the eclipse depth, the uncertainty in the eccentricity and periastron longitude together causes a significant uncertainty in the values of the component radii (an error of 2–3 times relative to the true values) and the orbital inclination angle. However, the ratios of the system component radii and the limb darkening coefficients are determined with good accuracy. With an increase in the observational accuracy to 0.1% of the eclipse depth, it becomes possible to determine the component radii and the orbital inclination angle when interpreting the light curve taking into account the eccentricity.

The analysis of parameters of radio pulsars with periods P > 5 sec has been carried out. It was found that there is not a clear dependence dP / dt on P on the diagram {dP / dt, P}. Such lack of any dependence can be explained in the frame of the disk model. It is shown that the pulse width decreases with increasing period for the sample considered. It is the opposite of the dependence in the generally accepted pulsar model. Such a behavior can be explained by the dependence of the level of radiation on the period, The alternative explanation is a non-dipole structure of magnetic field in the region of the generation of observed radiation. We consider the possibility of the description of extremely long intervals between successive pulses in pulsars J0901–4046 and J0250+5854 using the model of drift waves at the periphery of the magnetosphere. In the drift model rotation periods of these pulsars are several times shorter than the intervals between observed pulses.

Astrometric and multicolor photometric observations of near-Earth asteroids have been made at the SBG telescopes of the Kourovka Astronomical Observatory of the UrFU and the Zeiss-1000 telescope of the Simeiz Observatory in 2022–2023. Improved orbital elements were obtained for seven asteroids from astrometric observations at the SBG telescope. Axial rotation periods were estimated from photometric observations for seven asteroids. Color indices for six asteroids were obtained from photometric observations in B, V, R, and I filters.

A method has been developed for studying the secular evolution and stabilization of the shape of rings in small celestial bodies that do not have shepherd satellites. A model of a compound ring consisting of two close, generally non-coplanar elliptical Gaussian rings has been constructed. The self-gravitation of the ring is taken into account through the mutual gravitational energy of the boundary rings. The function is presented as a series with an accuracy of up to the 4th power of small eccentricities and mutual inclination of the rings. The secular evolution of a compound ring is described by differential equations in special (collective) variables. For rings without a central body (problem 1), a closed system of 8 differential equations is obtained using the mutual energy function. The evolution of rings in the azimuthally averaged potential of a rotating triaxial body is also studied (problem 2); a second system of eight differential equations is derived for it. In both problems, in addition to the general case, two particular ones are considered: i) the case of coplanar elliptical rings, and ii) the case of circular rings with a tilt. The theory is applied to study the recently discovered ring of the dwarf planet Haumea. It is shown that without taking into account self-gravity, the nodal precession time of the Haumea ring is equal to but taking into account the self-gravity of the ring can reduce this period. It is established that self-gravity does indeed contribute to the preservation of the ring shape without invoking the hypothesis of shepherd satellites. Criteria for the preservation of the ring shape are obtained, which made it possible to estimate the interval for the ratio of the ring mass to the mass of Haumea. Taking into account the optical thickness of the ring, it is shown that the Haumea ring with a mass can consist of ice particles of size $d_0\approx 0.7÷1$ m.