321 research outputs found
Photometric structure of polar-ring galaxies
The results of B, V, R surface photometry of three polar-ring galaxies (PRGs)
-- A0017+2212, UGC1198, UGC4385 -- are presented. The data were acquired at the
6-m telescope of the Special Astrophysical Observatory of the Russian Academy
of Sciences. It was shown that all three galaxies are peculiar late-type
spirals in the state of ongoing interaction or merging. We discuss available
photometric properties of the PRGs with spiral hosts and consider the
Tully-Fisher relation for different types of PRGs. In agreement with Iodice et
al. (2003), we have shown that true PRGs demonstrate ~1/3 larger maximum
rotation velocities than spiral galaxies of the same luminosity. Peculiar
objects with forming polar structures satisfy, on average, the Tully-Fisher
relation for disk galaxies but with large scatter.Comment: 12 pages, A&A accepte
Tidal Tails and Galaxy Evolution
We review recent results on the tidal structures of spiral galaxies. Topics
included are general characteristics of tails; kinematics of tidal structures
and dark haloes of host galaxies; frequency of tidal distortions at z~1.Comment: 5 pages, "Morphology and Dynamics of Stellar Systems: Star Clusters,
Galactic Arms and Rings", Proc. JENAM-2000, in pres
Sky surveys and deep fields of ground-based and space telescopes
Selected results obtained in major observational sky surveys (DSS, 2MASS,
2dF, SDSS) and deep field observations (HDF, GOODS, HUDF, etc.) are reviewed.
Modern surveys provide information on the characteristics and space
distribution of millions of galaxies. Deep fields allow one to study galaxies
at the stage of formation and to trace their evolution over billions of years.
The wealth of observational data is altering the face of modern astronomy: the
formulation of problems and their solutions are changing and all the previous
knowledge, from planetary studies in the solar system to the most distant
galaxies and quasars, is being revised.Comment: 22 pages, 18 figure
The polar-ring galaxies NGC 2685 and NGC 3808B (VV 300)
Polar-ring galaxies (PRG) are among the most interesting examples of interaction between galaxies. A PRG is a galaxy with an elongated main body surrounded by a ring (or a disk) of stars, gas, and dust rotating in a near-polar plane (Schweizer, Whitmore, and Rubin, 1983). Accretion of matter by a massive lenticular galaxy from either intergalactic medium or a companion galaxy is usually considered as an explanation of the observed structure of PRG. In the latter case there are two possibilities: capture and merging of a neighbor galaxy, and accretion of mass from a companion galaxy during a close encounter. Two PRG formation scenarios just mentioned are illustrated here by the results of our observations of the peculiar galaxies NGC 2685 and NGC 3808B
UGC 7388: a galaxy with two tidal loops
We present the results of spectroscopic and morphological studies of the
galaxy UGC7388 with the 8.1-m Gemini North telescope. Judging by its observed
characteristics, UGC7388 is a giant late-type spiral galaxy seen almost
edge-on. The main body of the galaxy is surrounded by two faint (\mu(B) ~ 24
and \mu(B) ~ 25.5) extended (~20-30 kpc) loop-like structures. A large-scale
rotation of the brighter loop about the main galaxy has been detected. We
discuss the assumption that the tidal disruption of a relatively massive
companion is observed in the case of UGC7388. A detailed study and modeling of
the observed structure of this unique galaxy can give important information
about the influence of the absorption of massive companions on the galactic
disks and about the structure of the dark halo around UGC7388.Comment: 8 pages, 5 figure
On the global structure of distant galactic disks
Radial and vertical profiles are determined for a sample of 34 edge-on disk
galaxies in the HDFs, selected for their apparent diameter larger than 1.3
arcsec and their unperturbed morphology. The thickness and flatness of their
galactic disks are determined and discussed with regard to evolution with
redshift. We find that sub-L* spiral galaxies with z \sim 1 have a relative
thickness or flatness (characterized by h_z/h the scaleheight to scalelength
ratio) globally similar to those in the local Universe. A slight trend is
however apparent, with the h_z/h flatness ratio larger by a factor of \sim 1.5
in distant galaxies if compared to local samples. In absolute value, the disks
are smaller than in present-day galaxies. About half of the z \sim 1 spiral
disks show a non-exponential surface brightness distribution.Comment: 13 pages, 8 figures, accepted in A and
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