The speckle polarimeter is a facility instrument of the 2.5-mSAIMSU telescope that combines the features of a speckle interferometer and a polarimeter. The speckle polarimeter is designed for ...observations in several visible bands in the following modes: speckle interferometry, polarimetry, speckle polarimetry, and polaroastrometry. In this paper we describe the instrument design and the procedures for determining the angular scale of the camera and the position angle of the camera and the polarimeter. Our measurements of the parameters for the binary star HD 9165 are used as an example to demonstrate the technique of speckle interferometry. For bright objects the accuracy of astrometry is limited by the error of the correction for the distortion caused by the atmospheric dispersion compensator. At zenith distances less than 45◦ the additional relative measurement error of the separation is 0.7%, while the additional error of the position angle is 0.3°. In the absence of a dispersion compensator the accuracy of astrometry is limited by the uncertainty in the scale and position angle of the camera, which are 0.15% and 0.06°, respectively. We have performed polarimetric measurements of unpolarized stars and polarization standards. The instrumental polarization at the Cassegrain focus in the
V
band does not exceed 0.01%. The instrumental polarization for the Nasmyth focus varies between 2 and 4% within the visible range; we have constructed its model and give a method for its elimination from the measurements. For stars with an intrinsic polarization of less than 0.2% during observations at the Cassegrain focus the error is determined mainly by the photon and readout noises and can reach 5 × 10
−5
.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract
The aim of this article is to determine the dynamical parameters of the asteroid (22) Kalliope with its satellite Linus, based on astrometric observations of this system. We use a model of ...the motion taking into account the gravitational influence of the primary’s axisymmetric non-sphericity. This factor leads to precession of the line of apsides of the satellite, as well as precession of its orbit around the primary’s axis of symmetry. The axisymmetric gravitational field of the primary is formed by the time-averaged field of the fast-rotating body of Kalliope. All available observations of the Kalliope–Linus system were divided into groups, each containing observations close in time. For each group, parameters of the fixed Keplerian orbit were determined. Thus, the behaviour of the satellite’s orbit axis over about 16-yr time intervals was studied. Contrary to the expected uniform precession of the orbital plane, we discovered abnormal prograde motion of the ascending node in the first seven years, which became retrograde in the next nine years. The amplitude of the change is about 120°. We make an attempt to explain such motion by effects not taken into account in the adopted dynamical model. It is shown that effects not taken into account cannot explain the oscillatory motion of the orbital node found. Using 121 available observations, two formal solutions for all fitted parameters were determined.
In 2011 and 2015–2018 the classical T Tauri star RW Aur A dimmed by 2–
. Previously, no such dimmings had been observed in historical observations since 1895: the variability amplitude did not exceed
.... During these eclipses the star showed evidence of UX Ori variability: a decrease in color index and an increase in polarization. To clarify the nature of the eclipses and the high polarization associated with them, we observed the object in the visible
bands by the method of differential speckle polarimetry with the 2.5-m telescope at the Caucasus Mountain Observatory of the Sternberg Astronomical Institute of the Moscow State University. The observations were carried out on October 23, 2016, at the end of a long and deep eclipse. As a simple geometric model shows, the polarized flux was reliably resolved. Using the MC3D radiative transfer simulation code, we have considered several three-dimensional dust envelope models. The two-component model that consists of a protoplanetary disk and a cone explains quantitatively the dimming and the shape of the resolved envelope. The typical size of the dust cone is 5–10 AU; this cone may be a dusty disk wind. However, our model does not reproduce the source of polarized radiation that coincides with the star and gives the bulk of the polarized flux from the object. The scattering envelope near the star unresolvable in our observations or the star itself, if its direct radiation is absorbed by aligned dust grains, can be this source.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In 2022 we carried out an upgrade of the speckle polarimeter (SPP)—the facility instrument of the 2.5-m telescope of the Caucasian Observatory of the SAI MSU. During the overhaul, CMOS Hamamatsu ...ORCA-Quest qCMOS C15550-20UP was installed as the main detector, some drawbacks of the previous version of the instrument were eliminated. In this paper, we present a description of the instrument, as well as study some features of the CMOS detector and ways to take them into account in speckle interferometric processing. Quantitative comparison of CMOS and EMCCD in the context of speckle interferometry is performed using numerical simulation of the detection process. Speckle interferometric observations of 25 young variable stars are given as an example of astronomical result. It was found that BM And is a binary system with a separation of 273 mas. The variability of the system is dominated by the brightness variations of the main component. A binary system was also found in NSV 16694 (TYC 120-876-1). The separation of this system is 202 mas.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The aim of this article is to analyze the dynamics of the Linus satellite of the asteroid (22) Kalliope. New results have been obtained, and now they are being published. New observations of the ...satellite were made at the Caucasian Mountain Observatory of Sternberg Astronomical Institute (SAI MSU) from October 2021 to March 2022. The obtained astrometric results are presented in the article. Based on the updated set of observations, the parameters of the satellite’s orbit were redetermined. With the addition of new observations an increase in the accuracy of ephemerides is shown. A new attempt was made to determine the precession of the satellite’s orbit caused by the compression of a rapidly rotating asteroid. The goal was to determine the dynamic compression of the central body. The entire observation interval is divided into groups. From the observations of each group the position of the axis of the satellite’s orbit was found. Changing the position of the axis gives the desired precession. Several case studies show that the axis position of such observation groups is determined very unreliable. The reason is strong correlation between the determinable parameters with limited observation accuracy. Ways of studying precession by jointly defining dynamic parameters based on all available observations have been identified.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The source BL Lac exhibited an enhanced activity from August 2020 to July 2022. This activity peaked in July–August 2021. In this period the source reached historic brightness maxima in various ...energy ranges. Observations of this nonstandard maximum were carried out by the SAI staff of the Crimean Station of SAI and with the telescopes of the Caucasus Mountain Observatory (CMO SAI MSU). Optical and near-infrared photometric data as well as optical polarimetric data were obtained. When investigating the correlation between the optical and gamma-ray fluxes and between the optical and infrared fluxes, its high degree with an almost zero lag was confirmed—this means that the emission regions spatially coincide or are very close together. The degree of linear polarization in the investigated period changed in a wide range, reaching 20
, with an anticorrelation between the degree of linear polarization and the brightness of the object having been observed. A similar pattern of variation was also observed in the preceding flares of this object. The changes in the electric vector position angle (EVPA) show a dependence on the rate of change of the object’s brightness. The EVPA changed greatly during flares and slowly at the times of a slow change in the intensity.
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Orenburg oblast is situated in the steppe zone. The climate is continental, characterized by a large amplitude of fluctuations in both summer and winter air temperatures, and insufficient ...precipitation. Due to such low climate potential, the development of agricultural production in the region needs constant improvement (increasing soil fertility, erosion control, planting sustainable crops). Therefore, optimization of agricultural production in order to restore the productive potential of land is one of the most actual problems in the region. Orenburg oblast due to its geographical location is characterized by dry winds, which not only dry up the soil, but also sharply reduce its fertility, effect on the water balance, and reduce yield. Therefore, the creation of forest protection treestands in this case is a priority method that contributes to the preservation of soil fertility in the region and, consequently, to the increased rate of agricultural production. In this article, we consider some species of plants belonging to the genera Sorbus L., Crataegus L., Aronia Pers., Syringa L., which have a number of positive ecological and biological characteristics, compared to plants that are widely used in forest protection plantations in the region today (Betula pendula Roth., Pinus sylvestris L., etc.). Using plants that have significant advantages in creating protective forests, it becomes possible to solve the problem of sustainable development of the land fund, and, consequently, to increase the rate of agricultural production. This will allow regulating land use processes not only at the regional level, but also at the state level.
The results of photometric, polarimetric, and spectroscopic observations of the young star ZZ Tau IRS in the visible and near-infrared bands are presented. Against the continuum of an M spectral type ...star about 50 emission lines of allowed (H I, He I, Na I, S II) and forbidden (O I, O II, O III, N I, N II, S II, Ca II, Fe II, Ni II) transitions were identified. It was found that from the autumn of 2020 to the beginning of 2023, the brightness of the star in the visible region decreased
) and then began to return to the initial level. As the visible brightness of the star declined, its color indices decreased in the visible region, but increased in the near-IR bands. At light minimum, the degree of polarization in the
band reached approx 13
, and the equivalent widths of, e.g., the H
and S II
6731 lines increased to 376 and 79
, respectively. Arguments are given in favor of ZZ Tau IRS being a UX Ori type star, and its variability being due to eclipses by dust clouds, which are inhomogeneities in the dusty disk wind. Forbidden lines are formed both in the disk wind and in the jet, the axis of what is oriented along
. The jet mass-loss rate exceeds
yr
, what is abnormally large for a star with a mass less than
. Apparently, the disk wind of ZZ Tau IRS is not axially symmetric, probably due to the azimuthal asymmetry of the protoplanetary disk found earlier from ALMA observations.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The morphology and kinematics of the matter in the vicinity of young stars ZZ Tau and ZZ Tau IRS are studied. It has been found that the emission nebula (the H
filament) located southwest of these ...stars, as well as the Herbig–Haro object HH 393 projected onto it are moving away from ZZ Tau and ZZ Tau IRS with a radial velocity of about 50 km s
. On the inner edge of the western part of the H
filament, there is a cooler filament emiting in the molecular hydrogen line (
m) and in the dust continuum. In the northeastern part of the studied region, a new Herbig–Haro object is discovered and assigned the number HH 1232. The presence of several more new emission nebulae is suspected. The electron density in the studied regions of the H
filament, as well as HH 393 and HH 1232
cm
. Arguments are presented in favor of the fact that the dusty disk wind has created a gas-and-dust nebula around ZZ Tau IRS, along the symmetry axis of which there is a jet moving in the direction of HH 393.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
V CVn is a red semiregular variable star with an amplitude of its
V
-band brightness variations of ≈2
m
. An unusually high amplitude of its polarization variability, up to 6%, a noticeable inverse ...correlation between polarization and total flux, and relative constancy of the angle of polarization distinguish this star from other semiregular variables. To clarify the nature of these peculiarities, we have observed the object with the 2.5-m telescope at the Caucasian Observatory of the Sternberg Astronomical Institute of the Moscow State University using differential speckle polarimetry at wavelengths of 550, 625, and 880 nm. The observations were performed on 20 dates distributed over three pulsation periods. We have detected an asymmetric reflection nebula around the star at a distance of ≈35 mas. Three regions that change their brightness with the same characteristic time scale as the star, but with different phase shifts are identified in the nebula. We consider several hypotheses that could explain this behavior.
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