1,281 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
Spiral galaxies with large optical warps
As a result of our statistical study of 540 edge-on galaxies, we present here
the images and preliminary statistical analysis of a sub-sample of 60 galaxies,
that were selected to be S-type warped spirals. Computing the average volumic
density of galaxies from available redshift surveys, a first analysis suggests
that warped galaxies are found in denser environments. Only the clearest and
strongest warps have been extracted here, and therefore this sample of 60
objects gather the best candidates for future HI or optical works on galaxy
warps.Comment: 7 pages, 6 figures, accepted in Astronomy and Astrophysics Su
Polar-ring galaxies: the SDSS view on the symbiotic galaxies
Polar-ring galaxies are multi-spin systems, showing star formation in a blue
late-type component, perpendicular to a red early-type one, revealing how
galaxy formation can sometimes occur in successive steps. We perform
two-dimensional decomposition in the , , bandpasses of 50 polar-ring
galaxies (PRGs) from the Sloan Digital Sky Survey. Each object was fit with a
S\'ersic host galaxy and a S\'ersic ring. Our general results are: (i) The
central (host) galaxies of the PRGs are non-dwarf sub- galaxies with
colors typical for early-type galaxies. (ii) Polar structures in our sample
are, on average, fainter and bluer than their host galaxies. (iii) In most
galaxies, the stellar mass M of the polar component is not negligible in
comparison with that of the host. (iv) The distributions of the host galaxies
on the size -- luminosity and Kormendy diagrams are shifted by to
fainter magnitudes in comparison with E/S0 galaxies. It means that the PRGs
hosts are more similar to quenched disks than to ordinary early-type galaxies.
(v) All the PRGs in our sample are detected in mid-infrared by WISE, and we
derive from the 22m luminosity their star formation rate (SFR). Their
SFR/M ratio is larger than for the early-type galaxy sample of Atlas, showing that the star forming disk brings a significant contribution to
the new stars. Globally, PRGs appear frequently on the green valley in the
mass-color diagram, revealing the symbiotic character between a red-sequence
host and a blue cloud ring.Comment: 8 pages, 11 figures, accepted for publication in MNRA
Statistics of galaxy warps in the HDF North and South
We present a statistical study of the presence of galaxy warps in the Hubble
deep fields. Among a complete sample of 45 edge-on galaxies above a diameter of
1.''3, we find 5 galaxies to be certainly warped and 6 galaxies as good
candidates. In addition, 4 galaxies reveal a characteristic U-warp. Compared to
statistical studies of local warps, and taking into account the strong bias
against observing the outer parts of galaxies at high redshift, these numbers
point towards a very high frequency of warps at z \sim 1: almost all galaxy
discs might be warped. Furthermore, the amplitude of warps are stronger than
for local warps. This is easily interpreted in terms of higher galaxy
interactions and matter accretion in the past. This result supports these two
mechanisms as the best candidates for the origin of early warps. The mean
observed axis ratio of our sample of edge-on galaxies is significantly larger
in the high-z sample than is found for samples of local spiral galaxies. This
might be due to disk thickening due to more frequent galaxy interactions.Comment: 9 pages, 7 figures, accepted in A and
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