Search Publications
Crossmatching of high-proper motion L, T, and Y brown dwarfs with large photometric surveys
Avdeeva, Aleksandra S.; Karpov, Sergey V.; Malkov, Oleg Yu.
L, T, and Y brown dwarf (BD) exploration is a topical issue. First, the transition boundary between planets and BDs is not fully understood yet. Second, there is a phenomenon called the L/T-transition. The observed properties of cooler BDs differ significantly from the less cool ones, namely, colors of BDs shift much bluer and, simultaneously, dwa…
A holistic study of the systems V0487 Lac, V0566 Hya, and V0666 Lac
Alenazi, Moqbil S.; Elkhateeb, Magdy M.
A comprehensive photometric study and evolutionary state for the systems V0487 Lac, V0566 Hya, and V0666 Lac were carried out by means of their first photometric observations. New times of minima were estimated from the observed light curves, and first (O-C) curves were established for all systems. The radiative treatment was carried out using a W…
Light curve analysis of main belt asteroids 4747, 5255, 11411, 15433, 17866
Eglitis, Ilgmars; Kristers, Nagainis
The main belt asteroids 4747, 5255, 11411, 15433, and 17866 were studied at the Baldone Astrophysical Observatory in the time span range 2018-2022. The obtained light curve data together with published Minor Planet Center data are analyzed with Fourier series, Lomb-Scargle periodogram, and phase dispersion minimization methods. A plan of analysis …
Wide binary stars with non-coeval components
Malkov, Oleg; Kniazev, Alexey
We have the estimated masses of components of visual binaries from their spectral classification. We have selected pairs in which the less massive component looks more evolved. Spectral observations of some of these pairs were made, and at least one pair, HD 156331, was confirmed to have components of different ages. Since mass exchange is exclude…
Parameterization of long-period eclipsing binaries
Malkov, Oleg; Kniazev, Alexei; Berdnikov, Leonid +2 more
One of the important sources for independent determination of stellar masses is eclipsing binaries with components on the main sequence, and with observable spectral lines of both components. The parameters of such stars are used to construct the mass-luminosity relation for stars of high and intermediate masses. Among them, the type of long-perio…
Observational data and orbits of the comets discovered at the Vilnius Observatory in 1980-2006 and the case of the comet 322P
Włodarczyk, Ireneusz; Černis, Kazimieras
This article is devoted to the discovery of comets at the Vilnius Observatory together with the orbital analysis of dynamically interesting comets, namely 322P. We studied the orbital evolution of comet 322P with and without non-gravitational effects. It turned out that many of the comet's orbital clones go into and out of retrograde orbits, somet…
Absolute magnitudes of white dwarfs and discovery of new white dwarfs from FBS Blue Stellar Objects by means of Gaia EDR3 data
Malkov, Oleg Yu.; Mickaelian, Areg M.; Mikayelyan, Gor A. +2 more
This article is a presentation of a project which is a statistical study of white dwarfs' properties carried out based on the sample of the First Byurakan Survey Blue Stellar Objects (FBS BSOs) and the Catalogue of White Dwarfs. Using these results, we have searched and will continue to search for new white dwarfs by means of Gaia accurate astrome…
Comparing results of real-scale time MHD modeling with observational data for first flare M 1.9 in AR 10365
Borisenko, Alexey Vasilevich; Podgorny, Igor Maksimovich; Podgorny, Alexander Igorevich
As shown in the first results of MHD simulations in the real scale of time, above the active region (AR) 10365, during the first flare M 1.9 (05/26/2003 05:34) at a height of 16-18 mm (lower corona), a singular line of magnetic field appears. The local maximum of the current density is situated on this singular line. The magnetic field in the vici…
Possibilities of velocity field analysis from Hinode SOT/SP data
Mozharovsky, Sergei G.
The possibility of analyzing the line of sight (LOS) velocity and its gradient at each point of the Hinode SOT/SP maps using bisector analysis is revealed. A technique for obtaining such gradient is described. To estimate the velocity gradient, it is necessary to know both the velocity value and the layer height to which the bisector point is resp…
The New Ephemeris and Light Curve Analysis of V870 Ara by the Ground-Based and TESS Data
Davoudi, Fatemeh; Poro, Atila; Blackford, Mark G. +4 more
New CCD photometric observations and their investigation of the W UMa-type binary, V870 Ara, are presented. Light curves of the system were taken through BVIfilters from the Congarinni Observatory in Australia. The new ephemeris is calculated based on seven new determined minimum times, together with the TESS data and others compiled from the lite…