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…
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…
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…
Application of clustering algorithm to wide stellar pairs for unsupervised search of parts of disrupting clusters
Kovaleva, Dana; Sapozhnikov, Sergei
We introduce the application of the clustering algorithm to the preliminary compiled list of probable wide pairs of co-moving stars. The main aim of such development is a possibility of unsupervised blind search of coeval loose stellar structures over significant regions in space. Using Gaia EDR3 data, we investigated the application of the method…
Fitting procedure for estimating interstellar extinction at high galactic latitudes
Malkov, Oleg; Kovaleva, Dana; Avdeeva, Aleksandra +1 more
We determine the interstellar extinction in the selected high-latitude areas of the sky based on Gaia EDR3 astrometry and photometry and spectroscopic data from RAVE survey. We approximate the results with the cosecant law in each area thus deriving the parameters of the barometric formula for different lines of sight. The distribution of the para…
Spectral energy distributions and colours of hot subluminous stars
Irrgang, Andreas; Heber, Ulrich; Schaffenroth, Johannes
Photometric surveys at optical, ultraviolet, and infrared wavelengths provide ever-growing datasets as major surveys proceed. Colour-colour diagrams are useful tools to identify classes of star and provide large samples. However, combining all photometric measurements of a star into a spectral energy distribution will allow quantitative analyses t…
Meet the family - the catalog of known hot subdwarf stars
Gänsicke, Boris T.; Telting, John H.; Østensen, Roy H. +6 more
In preparation for the upcoming all-sky data releases of the Gaia mission, we compiled a catalog of known hot subdwarf stars and candidates drawn from the literature and yet unpublished databases. The catalog contains 5613 unique sources and provides multi-band photometry from the ultraviolet to the far infrared, ground based proper motions, class…