The Department for Physics of Stars and Galaxies - Achievements

MAIN SCIENTIFIC ACHIEVEMENTS

Galaxies with the active star formation

• Primary helium content is determined according to spectral observations of a large sample of dwarf galaxies. It is shown that in the era of primordial nucleosynthesis effective number of neutrino types N_eff=3.5б±0.3 magnitude greater than 3.046, which are for the standard model.
• Using a database view Sloan Digital Sky Survey (SDSS), containing almost a million spectra created 15,000 sample galaxies with active star formation, which is used for various studies and physical state of evolution of galaxies.
• A systematic search for galaxies with extremely low content of heavy elements using the SDSS database and own observations. Employees of the department discovered 12 galaxies with oxygen content of 12+logO/H < 7.35, representing over 70% of these galaxies, known in the world.
• Open glow highly ionized forbidden lines [Ne V] 342.6 nm in the spectra of blue compact dwarf galaxies, which excite the shock waves at a speed of 500 km / c. The world knows of eight galaxies, all of them open by the department.
• Discovered five dwarf galaxies with broad emission lines of hydrogen Hн±. This low metallicity galaxy, which is active core of black holes. By this time the world knew no such galaxies with black holes of intermediate mass.
• Two blue compact dwarf galaxies with extremely low content of heavy elements investigated temporal changes in brightness and size of broad emission lines H_нІ and H_н±hydrogen, resulting in heavy wind on bright blue variable stars, speed of over 1000 km / s. These stars are the brightest stars of galaxies. In our galaxy the stars with solar metallicity (eg н· Car and P Cyg) are well known, while the bright blue variable stars with low metallicity investigated first.
• For the first time in the world held determination of magnesium in 65 blue compact galaxies with low content of heavy elements. Proved that magnesium in a gaseous medium of these galaxies are moderately depleted as a result of its partial entry into dust particles.
• The nature of submillimeter emission excess based on the study of energy distribution in the spectra of dwarf galaxies with emission lines in the ultraviolet range of the radio. For the first time proved that this excess corresponds to free-free emission of ionized gas.
• Developed several variants of the method for determining the strong lines elekronnoyi temperature and chemical composition of extragalactic HII regions. Himchnoho of accuracy using the proposed method with comparable accuracy classical method. The advantage of the proposed methods is that they use only strong lines which are nearly all extragalactic HII regions.
• Observable studied chemical evolution (evolution with redshift) spiral and irregular galaxies. Found that the enrichment of oxygen and nitrogen massive galaxies (and, therefore, active star formation) occurred in the past, and low-mass galaxies in these processes occur in modern times.

Stars

• Completed original research on modeling of optical and infrared (IR) spectra of brown dwarfs and other low-mass objects. Their spectra formed at extremely low temperatures and the presence of radiation absorption polyatomic molecules and dust particles. The use of "Lithium test" possible to find among the set of low-mass stars young brown dwarfs. A new concept of "deuterium test" to separate populations of objects of planetary masses of ultracold massive population dwarfs.
• The method of determining the chemical composition of the stars in the later stages of evolution, allowing the quantitative analysis of their atomic and molecular spectra that are important to clarify the evolutionary status of stars. World recognition to the research vision of ultrashort scales of evolution: object Sakurai and V838 Mon.
• Introduced unique vision research with peculiar chemical composition, including vision, enriched with carbon and hydrogen even depleted. Or consider the study of spectra of red giants that form binary systems with the phenomenon of new stars.

Star clusters of the Galaxy

• The project MWSC (Milky Way Star Clusters) directory using 2MASS, which includes nearly 500 million vision to the limit Ks = 15.3, analyzed more than 4,000 cluster-like objects in the galaxy. It is shown that most of them are clusters, and clusters 3206 defined parameters: complex probability belonging to clusters of stars, the center coordinates, angular dimensions, proper motions, distance, excess color, age, tidal parameters, radiation speeds. For half of these clusters defined parameters first. Distance from the border areas where sampling is complete, is 2 kps and includes the spiral arms of Perseus and Sagittarius-Kylya. Limit the distance to the clusters in the sample are such that the Galaxy reached from the center and almost to the outskirts. Age clusters of 1-12.6 billion years and covers almost the entire existence of the Galaxy.