Stellar physics and evolution galex and star formation




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Дата канвертавання24.04.2016
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THE STARFORMING CASCADE IN M17 AND ULTRAVIOLET

Dzhakusheva K.G., Mychelkin E.G.

Fesenkov Astrophysical Institute, Nat. Center of Space Researches&Technologies, Almaty 050020 Kazakhstan
The cascade process of star formation in M17 revealed by the world astronomical practice is considered beginning from the pioneer study of some peculiar active domain of that nebula executed in Fesenkov Astrophysical Institute. The different spectral and IR data including those obtained by space-craft telescopes are reviewed in connection with universal shock-waves mechanism of diffuse X-Rays and hard UV production exposed previously for M42 (Dzhakusheva K.G., Mychelkin E.G., in ‘UV Universe II, Moscow 2008’, P.294). The analogous region in M17 with exited diffuse UV is expected to be found, and a justification of that is performed on the grounds of related photometric and polarimetric data.
GALACTIC SPIRAL DENSITY WAVE PARAMETERS ON YOUNG OBJECTS

Bajkova Anisa.T., Bobylev Vadim.V., Stepanishchev Alexander. S.

Central (Pulkovo) Astronomical Observatory of RAS
Based on Bottlinger’s equations and currently available data on three-dimensional field of space velocities of young (≤50 Myr) open star clusters and 28 masers having trigonometric parallaxes we have found Galactic kinematics parameters. Fourier analysis of galactocentric radial velocities V(R) of the masers allowed us to estimate amplitude fR=4.0±1.0 km/s and wavelength λ=2.1±0.5 kpc of the density wave periodic perturbations, and phase of the Sun in the density wave χo=–118.8o±10o, what proofs that the Sun is located in the inter-arm space close to the Carina-Sagittarius arm. We revised the localization of the Perseus spiral arm and found its pitch angle i=–5o±1o. The solutions for spiral density wave parameters obtained directly from Bottlinger’s equations complemented by the terms in accordance with the density wave theory (Lin and Shu, 1964, APJ, 140, 646) are as follows: fR=5.5±1.1, fθ=3.8±0.8, i=–5.1o±0.8o, χo=–117.9o±11.7o, λ=2.2±0.3 kpc for data on young open star clusters.
NGC 4262: A VIRGO GALAXY WITH AN EXTENDED ULTRAVIOLLET RING

Buson Lucio

INAF, Italy
GALEX satellite has recently shown the presence of an extended, outer ring studded with UV-bright HII regions surrounding the otherwise normal lenticular galaxy NGC 4262. Such a structure is coupled with a ring of cold (HI) gas. Having structured UV-bright sources beyond its optical disc, NGC 4262 can be classified as a Type I extended ultraviolet disc (XUV).
GRAVITATIONALLY LENSED QSOS IN THE ISSIS/WSO-UV ERA

Luis Goicoechea,

Universidad de Cantabria, Spain
QSOs at 1 ≤ z ≤ 2 play a key role in understanding the cosmic evolution of the innermost parts of active galaxies. In this context, the gravitationally lensed QSO (GLQ) population is of particular interest, since about 50% of all well-identified GLQs are situated at a redshift between 1 and 2, and these are magnified with respect to normal QSOs at similar redshifts. With respect to studies of normal QSOs, GLQ programmes have several advantages. For example, a monitoring of GLQs may lead to unambiguous detections of intrinsic and extrinsic variations, accurate determinations of cosmological parameters, and valuable information on the structure and composition of lensing galaxies at intermediate redshifts. We describe some observation strategies to analyse the GLQ population at z ~ 1.5, using ISSIS (CfS) on board WSO-UV.
AN OBSCURED CLUSTER ASSOCIATED WITH THE HII REGION RCW173

Marco Amparo, Negueruela Ignacio

Universidad de Alicante, Spain
We present UBV photometry and spectroscopy of stars in the direction of the to HII region RCW173, located at l=25.3 degrees, projected towards Galactic Bar. We find evindence for several populations of early type stars at different distances. We identify the main ionization source of the HII region as a heavily reddened O7 II supergiant, which belongs to an obscured cluster that seems to be emerging from the molecular cloud associated with the bright nebulosity. We find several O and early-B members of this newly identified cluster, which we name as Alicante 6.
MOLECULE SUBLIMATION AND PHOTODISSOCIATION AROUND HII REGIONS

Kirsanova M., Wiebe D., Akimkin V.

Institute of Astronomy, RAS
Chemical composition of gas and dust mantles in a cold dense cloud during the expansion of an HII region is studied with a chemo-dynamical model. We found that photoevaporation of molecules, rather than thermal or cosmic ray evaporation, is the main way to bring species to the gas phase from dust icy mantles. Sharp evaporation fronts are formed in a molecular cloud with high initial gas density. They are close to each other and to the shock front, so in fact we have a single evaporation front for various species. In a cloud with moderate gas density, desorption from icy mantles occurs gradually rather than in a jump-like fashion. The distances between evaporation fronts are significant in this case, so the overall distributions of various gas-phase species in the cloud are also different. Various molecular components reside in regions with different kinematics, which would result in different spectral signatures. Photoreactions are another important factor determining the chemical composition in the vicinity of a young star. Cross sections of these photoreactions are largest in the UV band. We discuss how important it is to know accurate values of the cross sections.
AGN IN UV LIGHT: TESTING THE MODELS OF MATTER OUTFLOW

E.Y. Vilkoviskij and S.N. Yefimov

Fesenkov Astrophysical Institute, Almaty, Kazakhstan)
We present a theoretical model of the matter outflow from AGN. The model includes the hot gas dynamics calculations, the calculation of dynamics of the cold clouds embedded in the hot gas flow, and the radiation transfer calculations in the two-phase medium. The model permits numerical simulations of the absorption spectra of AGN in the UV and X-ray bands. We used the model for calculation of the ultraviolet spectrum of the quasars q1303+308. Our model calculations permits to obtain some thin details seen in the observed absorption spectrum, which confirms the validity of the main issues of our theory and model of the two-phase medium dynamics in the radiation field for the sake of interpretation of the absorption spectra of the matter outflow from AGN.

The WSO-UV mission provides us with the opportunities to further testing and developing of this model.


VARIATION OF DUST SIZE DISTRIBUTION TRANSPORTED INTO IGM.

Shaginyan Alexey

Southern Federal University, Russia
Radiation pressure is thought to be an efficient mechanism of dust transport from galactic disks through their halos into the intergalactic space. The forces governing dust motion are: radiation pressure, gravitation, Lorentz force, friction through Coulomb and direct collisions. While radiation pressure and friction in direct collisions are proportional to the square of dust radius, gravitational force is proportional to the radius cube, and Lorentz and Coulomb forces depend on dust charge. This therefore means that dust motion is selective, and when transported into the intergalactic medium they change their size distribution: the heaviest particles are bound to the gravitating (stellar and dark matter) disk, while the lightest are collisionally coupled to the gaseous disk. As a results, the size distribution becomes narrower and flatter, however, depends strongly on exact distribution of gravitational potential, gas density profile, and magnetic field configuration. We show several examples of variations of the dust size spectrum.
DYNAMICS OF GALAXIES CLUSTER IN THE WSO-UV PROJECT

Chechin Leonid

AFIF, Kazakhstan
Number of space telescopes can detect hundreds of thousands galaxies that locate on sky at distances about 10-12 billions light years of order. That is why one of the WSO-UV scientific priorities is the processes of galaxies creation and their clusters searching for - that allowed to lighting the dark matter phenomena, for example. It relates to the practically absence of such searching due to deficiency of deep UV; images. They plan to realize by UV- cameras of WSO-UV that allowed search galaxies at relatively small distances corresponded to, where - small value. As example of such galaxy cluster is the cluster Abell 2218, that locates at distance about three billions light years ( ) in Draco constellation. The theory of stationary galactic system on the nonbaryonic matter background is presents. The basic kinetic equation for distribution function of system gravitating galaxies with general potential was deduced for this Where - is the density of gravitating baryonic substance, and - are the density and pressure of antigravitating nonbaryonic substance. Some dynamical consequences of this equation for the spherical galaxies distribution are discussed.
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