Conveners
Stellar astrophysics and interstellar medium
- Roman Akhmetshyn (Taras Shevchenko National University of Kyiv)
We review the study of variable stars using mathematical modeling of
their mean light curves. The simulation is carried out by various methods, using
the observational databases AAVSO, AFOEV, VSOLJ, TESS, ZTF, ASAS-SN,
etc. The purpose of the simulation is to "digitize" the light curves to determine
statistically optimal numerical parameters that characterize brightness...
We present the photometric and spectroscopic analysis of 9 W Uma type contact binaries. The studied targets are selected from the CRTS catalog. The photometric data is collected using the 1.3-m Devasthal Fast Optical Telescope (DFOT) and 1.04-m Sampurnanand Telescope (ST). We use the PHOEBE-legacy code for light curve modeling. The temperature is determined using different color-temperature...
Star formation is among the most intricate processes building the Universe and deep comprehensive studies of its low mass regime are crucial to understand the related processes like circumstellar disk evolution and its properties, brown dwarf formation. Since most of the star formation takes place in clusters, it is crucial to perform deep studies of low mass stellar population in young...
22.2 GHz water masers are generally associated with massive star formation. Recently, a very strong nuclear kilomaser, W1, has been found in a nearby galaxy (NGC 253) that is associated with a forming super star cluster. It has been proposed that kilomasers could arise from the accretion disc around supermassive stars (>1000 Msun). Such hypothetical stars are proposed candidates for polluters...
In this work, we consider the origin of the chemical element lithium (Li) in the Universe, and calculate its abundance in six solar-type stars.
Li is a very light, soft alkali metal. This is a special element, because it is one of the three elements created during the Big Bang. With the evolution of stars, lithium is modified by the process of nucleosynthesis inside and becomes hardly...
Close binary star system Cygnus X-1.
The subject matter of the research is studying and conducting relative and absolute photometry of Cygnus X-1 in optic range.
Relevance: the accretion of matter in the close binaries is an effective mechanism for releasing a huge amount of energy, because of which we observe many astrophysical objects that are at the late stages of their evolution.
...
Eclipsing dwarf novae are considered to be the perfect laboratories to study accretion. As high inclination systems, they allow to reconstruct the brightness distribution across the accretion disk using indirect techniques like Doppler tomography or eclipse mapping. However, such observations are very challenging. High quality data from large telescopes are needed and it is difficult to...
We report the results of long-term time series photometry on RX J2133.7+5107. Using data taken during 2007-2022 (15 yr), we confirmed and improved the results obtained by de Miguel et al. (2017). Due to longer time-base we obtained more accurate value of the spin-up time-scale $1.511(3)*10^5$ yr. The observed rate of spin-up is even faster then reported by de Miguel et al. (2017) and one of...
In this paper, we present astrophysical parameters of the open cluster King 13 based on the VI CCD and 2MASS JHK s photometric data. This is a poorly studied cluster, for which new results have been found in the present work. To identify probable members, we use proper motion data from Gaia DR2 catalogue. The mean proper motion of the cluster is determined as − 2.8±0.2 and − 0.88±0.14 mas yr −...
We analyzed the photometric data obtained for 4 short-period EW-type binary systems discovered at Astronomical Observatory at Kolonica Saddle using different instruments between 2009 and 2019. The stars USNO-B1.0 1411-0397871 (VSX J213321.5+510857) and USNO-B1.0 1411-0397855 (VSX J213320.0+510819) are W UMa type eclipsing binaries. These stars got GCVS names V2833 Cyg and V2832 Cyg...
