Astrophysical Bulletin最新文献

We report the results of photometric and spectroscopic monitoring of CI Cam within 24 years since its outburst in 1998. Over this time, we found a system component emitting in the He II 4686 Å emission line, on an elliptical orbit with a period of (19overset{textrm{d}}{.}407) days and an eccentricity of 0.44–0.49. The variations of the optical brightness are observed with the same period and with an average amplitude of (0overset{textrm{m}}{.}04). The total amplitude of the He II radial velocity variations is about 380 km s({}^{-1}). The equivalent width of the line is variable on a time scale of tens of minutes as well as with the orbital period. Maximum equivalent widths of the He II line are observed when the component passes the descending node of the orbit. The intensity of the He II 4686 Å emission gradually increases with time. Slow radial velocity variations on a scale of decades were detected by means of high resolution spectroscopy in the iron emission lines and a forbidden nitrogen line formed in the circumstellar nebula. The B-type star turned out to be a pulsating variable. During the period between 2005 and 2009, pulsations were multiperiodic with the dominant periods (0overset{textrm{d}}{.}5223), (0overset{textrm{d}}{.}41539), and (0overset{textrm{d}}{.}26630) days. However, since 2012 it has pulsated in a single mode with a variable period in the (0overset{textrm{d}}{.}403{-}0overset{textrm{d}}{.}408) day range depending on the star’s luminosity. We identify the 2005–2009 pulsations as a resonance of the radial modes, and the residual stable mode as the first overtone. The pulsations are coherent on a scale of several months, and their average amplitudes are (0overset{textrm{m}}{.}02{-}0overset{textrm{m}}{.}04). The pulsation data constrain the spectral type of the main component to B0–B2 III, the distance to the system to 2.5–4.5 kpc, and the absolute visual magnitude (M_{V}) to the range of (-3overset{textrm{m}}{.}7) to (-4overset{textrm{m}}{.}9). The classification of the CI Cam main component as a B[e] supergiant is completely ruled out due to the observed pulsation periods. CI Cam may be a system at the stage after the first mass exchange and may be attributed to the FS CMa-type group of objects with the B[e] phenomenon.

The paper estimates the tidal distances (|xi_{c,1,2}|) between the components of wide binary stars (BS) in the Pleiades. We used data on the parameters of the Pleiades cluster and wide BSs in the Pleiades, obtained earlier from the Gaia DR2 data. Two models of a cluster are considered in the form of a gravitating sphere, homogeneous and inhomogeneous in density. Using the integrals of angular momentum and energy of the motion of the centers of mass of the BSs, two elliptical orbits and two open ‘‘rosette-like’’ trajectories of the centers of mass of the BSs relative to the center of mass of the three-body system (the BS components and the cluster) are constructed. For three bodies in a coordinate system nonuniformly rotating relative to their center of mass with the origin at the center of mass of the BS the equations of motion are written. For the model of a homogeneous cluster, a formula is obtained for the value (|xi_{c,1,2}|) for a BS moving along an elliptical orbit. The integrals of angular momentum and energy of motion of the components of the BS and three bodies of the system are obtained. The sizes of the area under the surface of zero velocities (SZV) of the BS components along the axes of the coordinate system with the origin in the center of mass of the BS are estimated. It is shown that in the model of a homogeneous cluster, the sizes of the area under the SZV of the BS components in the pericenters of the considered orbits are smaller than in the apocenters, and on the inner and outer parts of the BS orbits there are restrictions on the size of the area under the SZV of the BS components that differ in number and magnitude. For the model of an inhomogeneous cluster, an equation is obtained for the quantity (|xi_{c,1,2}|) for the BS moving along the ‘‘rosette’’ trajectory relative to the center of mass of three bodies. The quantities (|xi_{c,1,2}|) are numerically determined for the BS at different points of two such trajectories. With the help of the energy integral (E_{1,2,3}) of the motion of three bodies, the sizes of the area under the SZV of the BS components are determined. With an increase in the distance of the center of mass of the BS from the center of mass of three bodies in the model of an inhomogeneous cluster, an increase in the size of the area under the SZV of the BS components was noted, as well as the existence of more complex restrictions on the size of this area than in a homogeneous cluster. Mutual distances (r_{i,j}) between the components of wide BSs in the Pleiades are between the maximum and minimum values of (|xi_{c,1,2}|) for BSs on ‘‘rosette’’ trajectories. The increase in (r_{i,j}) with the distances (r_{i}) of the BS components from the center of the cluster is mainly due to the motion of the BS along its trajectories in the Pleiades. Other applications of the integral (E_{1,2,3}

The orbit of an active asteroid (457175) 2008 GO98/362P was obtained taking into account non-gravitational acceleration based on the Marsden model. The presence of systematic deviations was revealed in the 2016 observations prior to the cometary activity. The possibility of a collision with a minor body was considered. For this, the momenta of reaching the minimum distances (MOID, Minimum Orbit Intersection Distance) between the orbits of the asteroid (457175) and 585 961 numbered, and 536 561 unnumbered asteroids (according to the status in the Minor Planet Center catalogs of observations as of October 2021) were found. The maximum number of orbital rendezvouses falls on the time when the asteroid was passing in the vicinity of the ascending node, which suggests the possibility of a collision leading to the fragmentation of the main body. Two separation scenarios are considered and orbit variation of the main body and possible fragments are estimated. For the formed fragment, the heliocentric velocity variation amounted to (dv=0.148) m s({}^{-1}) and non-gravitational acceleration was (A_{3}=-12.5times 10^{-8}) AU day({}^{-2}). The main body dynamics did not vary significantly.

We report eight new exoplanet candidates discovered at the SpecialAstrophysical Observatory of the Russian Academy of Sciences usingthe transit technique. Photometric observations were performedwith a 50-cm robotic telescope during the second half of 2020.Transits with depths of (Delta m=0overset{textrm{m}}{.}056{-}0overset{textrm{m}}{.}173) andperiods (P=18overset{textrm{h}}{.}8{-}8overset{textrm{d}}{.}3) weredetected in(m=14overset{textrm{m}}{.}3)–(18overset{textrm{m}}{.}8)stars. All the stars considered are dwarfs with radii (R_{*}=0.4{-}0.6R_{odot}) (with an uncertainty of up to(1.1 R_{odot}) for a single star). We use simulations to estimatethe candidate radii (all are greater than 1.4 times the Jovianradius), semi-major axes of their orbits (0.012–0.035 AU), andother orbital parameters. We report the transit light curves fortwo stars obtained in 2022 based on individual observations.

The paper presents the results of searching and studying magnetic fields of 4 chemically peculiar stars in the Pleiades open cluster and 21 CP stars in the kinematic group of the same name. Observations were carried out at the 6-m BTA SAO RAS telescope with a circular polarization analyzer. Four stars with anomalously strong silicon lines were previously specified in the Pleiades cluster. We did not find a magnetic field in any of them. The Pleiades group contains seven non-magnetic HgMn stars and 14 potentially magnetic Ap/Bp stars of various types. We detected or confirmed magnetic fields in eight objects. The fraction of magnetic CP stars is 57(%) relative to Ap/Bp. Not a single object was found in the group, in which the longitudinal magnetic field (B_{e}) would exceed 2 kG.

In this paper we present the RATAN-600 multi-frequency catalogue of blazars, an updated version of the BLcat: the RATAN-600 multi-frequency catalogue of BL Lacertae objects. The main novelty in the catalogue is an extension of the sample with flat-spectrum radio quasars (FSRQs), thus currently it contains more than 1700 blazars of different types. The main feature of the BLcat is a compilation of radio continuum data for blazars based on the RATAN-600 quasi-simultaneous measurements at frequencies of 1.2, 2.3, 4.7, 7.7/8.2, 11.2, and 21.7/22.3 GHz. We additionally supplement the catalogue with the radio data from external sources to provide an opportunity to more complete study of radio spectra and radio light curves. For the convenience of users, we developed tools to calculate the spectral index, variability index, and radio luminosity. We briefly describe basic radio properties of blazar subsamples of the catalogue: spectral classification, spectral indices, flux density variability, and radio luminosity.

We present a brief description of a joint Russian-Korean project abbreviated as EXPLANATION (EXoPLANet And Transient events InvestigatiON). The project is aimed at a massive photometric, speckle-interferometric, spectral, and radio bolometric search for non-stationary events in the Universe, as well as the study of exoplanets. The core of the project consists of several 0.07–2.5-m optical telescopes, 6-m telescope BTA and a six-hundred-meter radio telescope RATAN-600 of the Special Astrophysical Observatory of RAS (Russia), Moscow State University observatory (Russia), Kourovka Observatory (Russia), Crimean Astrophysical Observatory (Crimea), Korea Astronomy and Space Science Institute (Republic of Korea). We discuss the philosophy of the project and its instrumentation, as well as the first obtained results. In this paper we report the results related to the detection of several types of transient events and the study of exoplanets.

In this paper, we present results of refining the characteristics of the eclipsing pre-cataclysmic variable SDSS J162256.6+473051 based on a model analysis of its optical radiation. We used the spectra of the system obtained with the 6-m BTA telescope of SAO RAS and the data from its multi-band photometric observations with the 1.5-m Russian-Turkish telescope RTT150. Calculations of the optical radiation of SDSS J162256.6+473051 were carried out using the method of irradiated atmosphere models. When analyzing the spectra of the system at the minimum brightness, we found the following atmospheric parameter estimates of the sdB sub-dwarf: ({{T}_{{{text{eff}}}}} = 30{kern 1pt} 900 pm 700) K, (log {kern 1pt} g = 5.85 pm 0.12), [He/H] ( = - 0.57 pm 0.05). The light curves of SDSS J162256.6+473051 were modeled and a complete set of fundamental parameters of the system was obtained. Their satisfactory agreement with the literature data allows us to conclude that the characteristics of similar systems with weak reflection effects can be analyzed together, even when they are determined using different methods of radiation modeling.