Publications
Section: PZ: main journal
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We present an analysis of new infrared photometric data in YJHK bands for the poorly studied hot variable post-AGB star IRAS 21546+4721. The observations were carried out with the 2.5-m telescope at the Caucasian Mountain Observatory of the Sternberg Astronomical Institute, Lomonosov Moscow State University during 2021 - 2022. We detected brightness variations with a maximum amplitude of 0.3 mag in all bands, as well as discrepancies between our average magnitudes and those from the 2MASS catalog. We constructed the spectral energy distribution of the object in the wavelength range 0.36 - 0.60 micrometers and calculated a model of the circumstellar dust shell. Our model consists of three components, formed by isotropic wind and superwind at the AGB stage, as well as during the post-AGB phase.
We present a new Name-List of variable stars containing information on 1315 variable stars in 23 globular star clusters, mainly in ten constellations (Scorpius - Virgo; several variables in NGC 6496, its center being in Scorpius, belong to Corona Austrina). With this Name-list, we have finished merging catalogs of variable stars in globular clusters with the General Catalogue of Variable Stars (GCVS). In the five parts of our globular-cluster Name-lists, we have added 6346 variable stars in 121 globular clusters into the GCVS. Also in the present Name-list, GCVS names are assigned to 9 recent Novae and one rare-type variable star in our Galaxy.
We present the results of our analysis of the light curves of the star TIC 372275195 based on observations from the TESS mission. Our frequency analysis has revealed the fundamental frequency, f_0, and the subharmonic frequency, f_1, while f_2 and f_3 correspond to higher harmonics. The star TIC 372275195 pulsates in the radial p-mode at the fundamental frequency f_0 = 7.614 day^{-1}, corresponding to the period P_0 = 0.1313 days, and is located on the main sequence of the Hertzsprung - Russell diagram. The star exhibits a relatively low metallicity index and belongs to the delta Scuti type. The light curve of TIC 372275195 has an asymmetric shape. Using the value of the pulsation constant, a physical model of the star was constructed. The pulsation constant Q was found to be about 0.087 days, which is larger than the characteristic values of the pulsation constant for typical delta Scuti stars.
Photometric observations of SN Ia 2016coj spanning the time interval from -10 to 165 days with respect to the B-band maximum are reported. SN 2016coj occurred in an elliptical galaxy, and our results confirm negligible host galaxy extinction. We determine basic photometric parameters and show that SN 2016coj exhibits normal photometric evolution for objects of this class. The distance estimates to the host galaxy, derived using the relations between luminosity and photometric parameters of SN 2016coj, are consistent with independent results.
We report significant consistent systematic errors in the equatorial coordinates alpha(1950.0) and delta(1950.0) of 10 variables (V1 - V10) in the young LMC cluster NGC 1866 in the discovery paper by Storm et al. (1988). The authors incorrectly mark one of these variables in their finding chart. We provide correct Gaia DR3 identifications for the stars considered here, together with the corrected finding chart.
We present 691 magnitude measurements in the B, V, and I_c filters acquired for the ultra-long-period Cepheid V729 Car. The shape of the light curve of V729 Car remained constant for 25 years, the star may really be a classical Cepheid. If this status is confirmed, V729 Car will be the first ultra-long-period Cepheid found in our Galaxy.
I present my photometric observations of a field in Orion, 47' x 31' in size, centered at RA J2000 = 06h11m59.7s, Dec J2000 = +18deg30'45", where I studied 27 variable stars, 15 of them discovered by me. Among them, there are DSCT and GDOR stars with multiperiodicity, a UV-Ceti type flare variable star, and other variables. The most interesting among program stars are discussed in detail.
A correction is suggested to the html/pdf version of the 84th Name-list of Variable Stars published in Peremennye Zvezdy/Variable Stars in 2021. Because of a technical error, three variable stars were missing in Table 1 for the globular cluster NGC 4833. No mistake was contained in the database of the General Catalogue of Variable Stars.
The optical transient MASTER OT J095321.02+202721.2, discovered in 2014, was not classified or confirmed as a supernova. We present the light curve of this object which allows us to classify it as a type II-L supernova with the absolute magnitude at maximum brightness M_R about -19.4 mag.
We present our analysis of new photometric and spectroscopic data for a poorly studied star with an uncertain variability type (BY Dra or EW), ZTF J021857.72+585950.1. The observations were carried out with the 0.6-m and 2.5-m telescopes of the Caucasian Mountain Observatory and the 1.25-m telescope of the Crimean Astronomical Station of the Sternberg Astronomical Institute (Lomonosov Moscow State University) in 2019 - 2024. We found a period of 0.279 d and demonstrated that brightness variations resulted from rotation of a spotted chromospherically active star of the BY Dra type, which is consistent with the AAVSO classification. Based on our low-resolution spectra, we classified the star as K1V and found profile variations of the Halpha line both from night to night and during a single night. We also estimated the interstellar extinction A_V = 0.27 mag and distance to the star d = 154 pc. |
