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Daugėjant įrodymų, kad žvaigždės formuojasi spiečiais, jų masių funkcijos ir evoliucijos savybes kol kas galima nustatyti empiriniais stebėjimais. Tačiau tirti žvaigždėdaros procesą mūsų Galaktikoje galima ribotai. Andromedos galaktika (M31) yra artimiausia žvaigždžių sistema, panaši į Galaktiką. Todėl ji tinkamiausia žvaigždžių spiečių populiacijai tirti, tačiau ilgą laiką buvo tirta ribotai dėl tankių žvaigždžių laukų stebėjimo sudėtingumo. Naudojant „Subaru“ teleskopo Suprime-Cam plataus lauko nuotraukas, buvo ištirti žvaigždžių spiečiai M31 galaktikos disko srityje, kuri pagal cheminę sudėtį, žvaigždinį tankį ir mažą žvaigždėdaros spartą yra analogiška Saulės aplinkai mūsų Galaktikoje. Buvo sukurti, išbandyti ir pritaikyti duomenų analizės metodai ir programos tankiems plataus lauko vaizdams apdoroti ir pusiau išskiriamų žvaigždžių spiečių evoliuciniams parametrams nustatyti. Pagrindiniai rezultatai: (1) žvaigždžių spiečių formavimosi spartos sustiprėjimas M31 galaktikoje įvyko prieš ~70 mln. m.; (2) maždaug 10% žvaigždžių spiečių gyvena ilgiau nei 100 mln. m.; (3) būdingoji ~10^4 Saulės masių spiečiaus gyvavimo trukmė yra ~300 mln. m.; (4) žvaigždžių spiečių masių pasiskirstymas panašus į kitų mažos žvaigždėdaros spartos galaktikų žvaigždžių spiečių pasiskirstymą ir jį gerai nusako Schechter'io funkcija, kurios charakteringoji masė ~2x10^5 Saulės masių. Tai rodo, kad M31 galaktikoje yra gausi vidutinės masės žvaigždžių spiečių populiacija, kuri mūsų Galaktikoje yra... [toliau žr. visą tekstą] Observational evidence that star formation proceeds in a clustered manner raises a question on the mass function of star clusters and their evolution. However, we have a limited scope of these processes in the Milky Way galaxy. The M31 galaxy is the nearest stellar system similar to our Galaxy, therefore, it is the most suitable one to provide clues for understanding the star cluster population and the evolution of galactic structures. However, detailed study of stellar populations and star clusters is a challenging task for ground-based observations due to crowded stellar fields. Using Subaru telescope Suprime-Cam wide-field images, a survey of clusters was carried out in the disk region of the M31 galaxy southwest field, which is a close analogue to that of the Solar neighborhood in terms of chemical composition, stellar density, and quiescent star formation. Data analysis methods and programs were developed, tested, and applied for crowded wide-field image reduction and evolutionary parameter determination of semi-resolved star clusters. The main results are: (1) enhanced star cluster formation activity in M31 occurred ~70 Myr ago; (2) approximately 10% of stars born in star clusters remain there at 100 Myr age; (3) the characteristic lifetime of a cluster of ~10^4 solar masses mass is ~300 Myr; (4) the mass function of star clusters in M31 is similar to that in other low star formation activity galaxies and it is best described by the Schechter's function with a... [to full text]

We assume a large-scale feature of the Galactic background, the North Polar Spur (NPS), being a jet of the Milky Way galaxy. The suggested interpretation explains the visible circular structure of NPS. The jet may be enveloped by an extended cocoon of a jet-long diameter. The hypothesis is supported by analysis of the physical parameters of NPS.

The space distribution of stars of various types is investigated in a 1.5 square degree area at the Galactic equator (l = 146 degrees, b = +2.6 degrees) in Camelopardalis, in the direction of the association Cam OB3. The study is based on photometric classification, interstellar extinction and distance determination of 1303 stars down to 15.5 mag (in the violet). The limiting distance of the study is about 5 kpc, thus our line of sight crosses the Perseus and the Outer spiral arms. The space density of stars of different spectral types and the luminosity function are determined.

Powerful radio galaxies often display regions of enhanced optical/ UV emission, elongated and aligned with the radio jet axis. The expanding radio source strongly affects the surrounding IGM, and the properties of the aligned emission regions vary considerably with both radio source properties and cosmic epoch. The results of deep rest-frame UV and optical imaging of high redshift 6C radio galaxies are discussed, considering the influence of radio power on the strength of the observed alignment effect, the galaxy colors and the dominant emission mechanisms.

The time evolution of giant (D > 1 Mpc) lobe-dominated galaxies is analyzed on the basis of dynamical evolution of the entire FR II-type population.

Very deep 4.9 GHz observations with the VLA are used to supplement available radio maps at the frequencies of 325 MHz (WENSS, survey) and 1.4 GHz (NVSS survey) in order to study the synchrotron spectra and radiative ages of relativistic particles in the extended lobes of distant giant radio galaxies selected from the sample of Machalski et al. (2001).

If the transverse jet B fields observed in BL Lac objects on parsec-scales represent the toroidal component of the jet B fields, this should give rise to rotation-measure gradients across the jets, due to the systematic change in the line-of-sight component of the jet B field. We have found evidence for such rotation-measure gradients in one-third to one-half of the 1 Jy BL Lac objects we have analyzed. We present and discuss these new results, together with some of their implications for our understanding of the parsec-scale jets of AGN.