Search Publications
Unusual objects in the spiral galaxy NGC 6946
Efremov, Yu. N.
Several strange objects in the spiral galaxy NGC 6946 are described. One of these objects is the giant stellar complex noted long ago; we suggested that its sharp semicircular western edge is a result of the ram pressure, arising owing to motion of this complex through the H I halo of NGC 6946. We found another enigmatic object, proposing for it t…
A young star cluster in the Leo A galaxy
Narbutis, D.; Vansevičius, V.; Bridžius, A. +2 more
We report a serendipitous discovery of a star cluster in the dwarf irregular galaxy Leo A. Young age ( ∼28 Myr) and low mass ( ∼510 M⊙) estimates are based on the isochrone fit assuming a metallicity derived for H II regions (Z=0.0007). The color-magnitude diagrams of the stars, located in and around the cluster area, and the results of…
Ultraviolet spectroscopic investigation of HU Aqr and AN UMa with the data from HST and IUE
Sanad, M. R.
We present ultraviolet spectroscopic study of two polar systems, HU Aqr and AN UMa, observed with the Hubble Space Telescope's Space Telescope Imaging Spectrograph (STIS) and Faint Object Spectrograph (FOS) and with the International Ultraviolet Explorer (IUE) during the period 1979--2003, to diagnose the ultraviolet fluxes of C IV 1550 Å and He I…
Structural and morphological properties of ultraluminous infrared galaxies at 1<z<3
Fang, Guanwen; Kong, Xu; Chen, Yang +1 more
Using the Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) near-infrared high-resolution imaging from the 3D-HST survey, we analyze the morphology and structure of 502 ultraluminous infrared galaxies (ULIRGs; LIR>1012L⊙) at 1<z< 3. Their rest-frame optical morphologies show that high-redshift ULIRGs…
Kinematic Modeling of Distant Galaxies
Kipper, Rain; Tempel, Elmo; Tamm, Antti
Evolution of galaxies is one of the most actual topics in astrophysics. Among the most important factors determining the evolution are two galactic components which are difficult or even impossible to detect optically: the gaseous disks and the dark matter halo. We use deep Hubble Space Telescope images to construct a two-component (bulge + disk) …
Hints on the Broad Line Region Structure of Quasars at High and Low Luminosities
Sulentic, Jack W.; Marziani, Paola; Dultzin, Deborah +2 more
Quasars show a considerable spectroscopic diversity. However, the variety of quasar spectra at low redshifts is non-random: a principal component analysis applied to large samples customarily identifies two main eigenvectors. In this contribution we show that the range of quasar optical spectral properties observed at low-z\ and associated with th…
Photometry of Star Clusters in the M 31 Galaxy. Aperture Size Effects
Narbutis, D.; Vansevičius, V.; Kodaira, K. +2 more
A study of aperture size effects on star cluster photometry in crowded fields is presented. Tests were performed on a sample of 285 star cluster candidates in the South-West field of the M 31 galaxy disk, measured in the Local Group Galaxy Survey mosaic images (Massey et al. 2006). In the majority of cases the derived UBVRI photometry errors repre…
Dust Distribution in [WR] Planetary Nebulae: a Case of M2-43
Szczerba, R.; Hajduk, M.; Gesicki, K.
Simultaneous presence of O- and C-rich molecules and/or dust is commonly known as mixed or dual chemistry. C-rich [WR] central stars show at the same time the presence of polycyclic aromatic hydrocarbons (PAHs) and crystalline silicates in their nebulae. We perform radiative transfer modeling of ISO spectrum for M2-43 to determine spatial location…
Eclipse Mapping of Symbiotic Binaries
Crowley, C.; Espey, B.
We describe an ultraviolet eclipse mapping of the symbiotic binary EG And. Analysis of FUSE and HST/STIS observations at differing orbital phases probe different layers of the chromosphere and wind of the red giant in absorption. Whilst the primary aim of the study is to examine the thermal and dynamic conditions at the base of these winds, much i…
New Insights Into the Dynamics and Expansion Parallax of Nebulae around Symbiotic Stars
Corradi, R. L. M.; Santander-García, M.
Currently, there are a dozen known spatially resolved nebulae around symbiotic stars. We summarize their properties, focusing on their dynamical ones. Then, new results about the determination of the expansion in the plane of the sky of the nebulae around Hen 2-104 and Hen 2-147, which allows us to gain important information about their dynamics a…