DEPARTMENTS   

DEPARTMENT FOR PHYSICS OF STARS AND GALAXIES

The Department for Physics of Stars and Galaxies was organized in 1983 by Professor I. G. Kolesnyk on the basis of the Department of Astrophysics (it was created in 1958 by Dr.Sci. Sh. G. Gordeladze), and since 2000 it is headed by Dr.Sci., Member of NAS of Ukraine Yu. I. Izotov.

The Department includes also the Laboratory for Physics of Galaxies with Active Star Formation (the head is Dr.Sci., Member of NAS of Ukraine Yu. I. Izotov).

The Department has two specialized observational complexes at the 60-cm Zeiss telescope (High-Altitude Terskol Station) and at the 125-cm telescope (Crimean Astrophysical Observatory).

Investigations of the Department are concerned with

  • study of physical and evolutionary properties of blue compact dwarf galaxies with the use of different telescopes: 6-m Russian telescope, Hubble Space Telescope, MMT, etc.;

  • modeling the chemical evolution of irregular and late-type disk galaxies; modeling the stellar spectra with the NLTE effects taken into account and study of the chemical composition variations in the late-type stars; numerical simulations of the galaxy formation and evolution;

  • study of the evolutionary and physical properties of stars and stellar objects with the R CrB-type phenomena;

THE STAFF OF THE DEPARTMENT:

Laboratory for Physics of Galaxies with Active Star Formation:

Guseva, Nataliya G.

Dr.Sci.

guseva@mao.kiev.ua

Izotov, Yuriy I.

head, Dr.Sci., Member of NAS of Ukraine

izotov@mao.kiev.ua

Nikityuk, Tatiana V.

Ph.D.

nikita@mao.kiev.ua

Pilyugin, Leonid S.

Dr.Sci.

pilyugin@mao.kiev.ua

Shkvarun, Ruslan V.

Ph.D.

shkvarun@mao.kiev.ua

Agienko, Kateryna B.

Ph.D. student

agienko@mao.kiev.ua

Berczik, Peter

Dr.Sci.

berczik@mao.kiev.ua

Ivanyuk, Oleksiy M.

Ph.D. student

oi@mao.kiev.ua

Kaminskiy, Bogdan M.

 

bogdan@mao.kiev.ua

Khalack, Viktor R.

Ph.D.

khalack@mao.kiev.ua

Kovalchuk, George U.

Ph.D.

koval@mao.kiev.ua

Kravchuk, Sergey G.

Ph.D.

kravchuk@mao.kiev.ua

Lyubchik, Yuriy P.

Ph.D.

lyu@mao.kiev.ua

Mykhailytska, Nina G.

 

mykhail@mao.kiev.ua

Pavlenko, Yakiv V.

Dr.Sci.

yp@mao.kiev.ua

Petrov, Mykola I.

petrov@mao.kiev.ua

Polinovskyi, Grygorii O.

Ph.D. student

greg@mao.kiev.ua

Pugach, Alexandr F.

Ph.D.

pugach@mao.kiev.ua

Shavrina, Angelina V.

Ph.D.

shavrina@mao.kiev.ua

Sheminova Valentina A.

Dr.Sci.

shem@mao.kiev.ua

Shumakova, Tetiana O.

Ph.D. student

aphina@mao.kiev.ua

Yakobchuk, Taras M.

Ph.D.

yakobchuk@mao.kiev.ua

Yakovina, Larisa A.

Ph.D.

yakovina@mao.kiev.ua

Zinchenko, Igor A.

Ph.D. student

zinchenko@mao.kiev.ua


MAIN RESEARCH AREAS:

Laboratory for Physics of Galaxies with Active Star Formation:

  • Spectroscopic and photometric observations of the blue compact dwarf galaxies with ground-based and space telescopes (4m Kitt Peak telescope, Multiple Mirror Telescope, Very Large Telescope, Keck telescope, Hubble Space Telescope, Far Ultraviolet Spectroscopic Explorer and others).

  • The chemical abundances in HII regions.

  • The determination of the primordial 4He abundance and the baryonic mass of the Universe.

  • Search for and study of the properties of probable nearby young dwarf galaxies. Study of the stellar populations in the blue compact dwarf galaxies.

  • Chemical evolution of galaxies.

  • Study of the mass exchange (galactic winds, infall of metall-poor gas onto galaxies, mergers) between galaxies and their environments.

  • Search for and study of the correlations between chemical properties and other macroscopic characteristics of late-type galaxies. Investigation of the luminosity-metallicity relation for late-type galaxies. Study of the variation of properties of late-type galaxies along the Hubble sequence.

Individual Researchers and Groups of the Department:

Berczik P.P.

  • Development of multi-phase chemodynamical SPH code with the main purpose to implement the most recent multi-phase chemodynamical prescriptions of the stellar and gaseous (cold, warm, hot gas phase) components in galaxies and their interchanges into the widely applied general numerical treatment of hydrodynamics, the Smoothed Particle Hydrodynamics.

Khalack V.R.

  • Ap star atmospheres: physical properties and chemical abundance.

  • Surface magnetic field structure modeling for magnetic chemicaly peculiar stars.

Pavlenko Ya.V.

  • Model atmospheres of chemically peculiar stars.

  • NLTE effects in stellar spectra.

  • Abundances of light elements in stellar atmospheres.

  • Investigation of the M-L and brown dwarfs.

Pugach A.F.

Kovalchuk G.U.

  • Investigation of a small (n~20) subgroup of ALIVARS (Algol-like or Alpha-Line Irregular Variable Stars) which are members of more ample group of the classic Herbig Ae/Be Stars (HAEBES). The problem concerned is to solve an evident contradiction between the age supposed for the ALIVARS and their features observed. The stars are often supposed to be young objects whereas many observed data point out their rather evolved status.

Rosenbush A.E.

  • Stars with the R Coronae Borealis type variability, novae.

Yakovina L.A.

  • Numerical analysis of stellar spectra. Synthetic spectra and spectral energy distributions of cool stars.


SIGNIFICANT RESULTS OBTAINED BY THE DEPARTMENT RESEARCHERS:

Laboratory for Physics of Galaxies with Active Star Formation:

  • Comprehensive spectroscopic studies of the samples of blue compact dwarf galaxies from the First and Second Byurakan, Hamburg and Case surveys.

  • Discovery of several very low-metallicity blue compact dwarf galaxies, including SBS 0335-052, the second most metal-deficient blue compact dwarf galaxy after I Zw 18.

  • Determination of the primordial helium abundance from the observations with large telescopes of large sample of low-metallicity blue compact dwarf galaxies.

  • Determination with high precision of the heavy element abundances in the most metal-deficient blue compact dwarf galaxies in both Northern and Southern hemispheres. Discovery of the constancy with very low dispersion of the nitrogen-to-oxygen abundance ratio in these galaxies.

  • Discovery of Wolf-Rayet stars in two most metal-deficient blue compact dwarf galaxies I Zw 18 and SBS 0335-052.

  • Comprehensive study of the large sample of Wolf-Rayet galaxies.

  • Discovery of the emission lines of high ionized species in spectra of two galaxies SBS 0335-052 and Tol 1214-277. The presence of these lines implies that fast shocks with velocities of several hundred km/s are present in the interstellar medium of these galaxies.

  • Development of numerical nonuniform models for the chemical evolution of irregular and spiral galaxies. The study of the influence of self-enrichment of HII regions, galactic winds, and episodic gas infall onto galaxy (successive micromerging) on the chemical properties of galaxies. Modification of the analytical model of chemical evolution of galaxies taking selective heavy-elements loss into account.

  • Investigation of the origin of luminosity-metallicity relationship for late-type galaxies. Examination of the transition from spirals to irregulars.

  • Development of the method of the oxygen abundance determination in HII regions. Only strong oxygen lines are used in the method.

Individual Researchers and Groups of the Department:

Berczik P.P.

  • Our recent project is aimed to develop, test and compare results of multi-phase chemodynamical SPH code in the field of the numerical simulation of the formation and evolution of galaxies, in particular for disk and dwarf galaxies.

Khalack V.R.

  • Detection of the REE ring-structure around the spots with enhanced lithium abundance at the surface of some roAp stars.

  • The new approuch is developed for the surface magnetic field modeling in the magnetic Ap stars.

  • The link between the surface magnetic field structure and the lithium spots location is revealed for some roAp stars.

Pavlenko Ya.V.

  • Methods and procedure of computations of hydrogen-deficient, carbon-rich atmosphere models were developed. Temporary changes of spectral energy distributions of Sakurai's object (V4334 Sgr) were modeled to obtain its evolutionary model.

  • NLTE effects in lithium lines were studied for a sample of late-type stars using a sophisticated NLTE approach.

  • Li, B, C, N, O abundances were obtained for the late-type stars with different ages, metallicities and luminosities.

  • Models of formation of the coolest dwarfs were developed to interpret observed spectra. Spectral energy distributions were computed for a sample of coolest stars and brown dwarfs.

Pugach A.F.

Kovalchuk G.U.

  • We have managed to prove that ALIVARS are not the Main Sequence stars for many reasons. Main of them are as follows:

    • their location on the H-R diagram is above the Main Sequence;

    • they have gravity parameters lgg (lgg less than 3.5) which are common for giants and more luminous stars;

    • they have weakened hydrogen absorption lines and several ALIVARS demonstrate clear signs of hydrogen deficiency;

    • all ALIVARS show the correlation between Teff  and H-alpha luminosity, in contrast to all other HAEBES which do not;

    • projected rotation velocity (Vsini = 107 km/s) is markedly less than that for the main sequence stars (approximately 130 km/s).

Rosenbush A.E.

  • Expansion of absolute magnitudes of stars with the R Coronae Borealis variability from -5 mag to 0 mag, suggesting the broad class of objects demonstrating such variability.

  • The distribution of the matter around the stars with the RCB variability is shown to be uniform, not clumpy.

  • The influence of permanent dust shell on the observable characteristics of stars with the RCB variability is established.

  • The grounds for a new classification of classical novae are proposed.

  • It is shown that the Sakurai's object (V4334 Sgr) and V605 Aql (Nova Aquilae 1919) recurrent outbursts of classical novae.


Main publications of the Department for Physics of Stars and Galaxies

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