Upload your image
DSS Images Other Images
Submit a new article
|Near-infrared adaptive optics observations of galaxy clusters: Abell 262 at z=0.0157, J1836.3CR at z=0.414, and PKS 0743-006 at z=0.994|
We report on high angular resolution near-infrared (NIR) observations ofthree galaxy clusters at different redshifts using adaptive optics (AO).In the case of the barred spiral UGC 1347 in Abell262 we presented the first AO results obtained using a laser guide star.The observations have been carried out with the MPE/MPIA adaptive opticslaser guide star system ALFA and the ESO AO system ADONIS combined withthe SHARP II+ camera built at MPE. The three clusters are well suitedfor high resolution investigations since bright field stars for tip-tiltor wavefront sensing are located close to the line of sight to clustergalaxies. In summary our high angular resolution NIR data combined withother information clearly indicates star formation activity orinteraction between cluster members at all three redshifts. The resultsand implications for future high angular resolution adaptive opticsobservations are discussed in the framework of current galaxy andcluster evolution models. For two barred galaxies in the Abell 262cluster, UGC 1344 and UGC 1347, we interpret our NIRimaging results in combination with published radio, far-infrared, andHα data in the framework of a star formation model. In addition tothe star-forming resolved NIR nucleus in UGC 1347 we found a bright andcompact region of recent and enhanced star formation at one tip of thebar. The L_K/L_Lyc ratio as well as the V - K color of that region implya starburst that happened about 107 years ago. For UGC 1344we find that the overall star formation activity is low and that thesystem is deficient in fuel for star formation. The importance of starformation in galaxy clusters is also supported by a comparison of seeingcorrected nuclear bulge sizes of a sample of spiral galaxies within andoutside the central HI deficient zone of the Abell 262 andAbell 1367 clusters. We find that the galaxies insidethe Abell radii of both clusters show a tendency for more compact bulgesthan those outside. This phenomenon could be due to increased starformation activity triggered by interactions of cluster members insidethe Abell radius. The star formation activity in the two higher redshiftclusters J1836.3CR and PKS 0743-006 is investigated via comparison toGISSEL stellar population models in JHK two-color-diagrams. WhileJ1836.3CR is consistent with an evolved cluster, the objects in thefield of PKS 0743-006 show indications of more recent star formationactivity. The central object in J1836.3CR shows a radial intensityprofile that is indicative for cD galaxies in a rich clusterenvironment. Extended wings in its light distribution may be consistentwith recent or ongoing galaxy-galaxy interaction in this cluster.
|Arcsecond Positions of UGC Galaxies|
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
|General study of group membership. II - Determination of nearby groups|
We present a whole sky catalog of nearby groups of galaxies taken fromthe Lyon-Meudon Extragalactic Database. From the 78,000 objects in thedatabase, we extracted a sample of 6392 galaxies, complete up to thelimiting apparent magnitude B0 = 14.0. Moreover, in order to considersolely the galaxies of the local universe, all the selected galaxieshave a known recession velocity smaller than 5500 km/s. Two methods wereused in group construction: a Huchra-Geller (1982) derived percolationmethod and a Tully (1980) derived hierarchical method. Each method gaveus one catalog. These were then compared and synthesized to obtain asingle catalog containing the most reliable groups. There are 485 groupsof a least three members in the final catalog.
|Determination of the relative spectrophotometric gradients of galaxies. IV|
Relative spectrophotometric gradients of continua are determined for 195galaxies. The spectra have been obtained with the 70-cm meniscustelescope of the Abastumani Astrophysical Observatory using a 2-degpreobjective prism (the reverse linear dispersion was 1200 A/mm inH-gamma). The gradient values were reduced to the AO spectral class andcorrected for light absorption in the Galaxy.
|Gas deficiency in cluster galaxies - A comparison of nine clusters|
The available 21 cm line data in the literature for galaxies in nineclusters is combined with new high-sensitivity observations of 51galaxies in five of the nine clusters in order to test fordiscriminating circumstances between those clusters which show H Ideficiency among their spiral population and those which do not. An H Ideficiency for the complete cluster sample is derived employing acomparison sample of galaxies chosen from the Catalog of IsolatedGalaxies. The deficiency and its radial dependence is summarized foreach cluster and a composite. A comparison of the environments indifferent clusters leads to the conclusion that the occurrence of H Ideficiency is correlated with the presence of a hot X-ray intraclustermedium, and that an ongoing interaction process is active through thecores of X-ray clusters.
|A redshift survey of low-surface-brightness galaxies. I - The basic data|
Initial results from a 21 cm redshift survey of 375 very low surfacebrightness galaxies contained in the Uppsala General Catalog of Galaxiesare presented. The selection criteria and detection statistics as afunction of the sample optical properties are fully discussed. Theredshift distribution for the sample exhibits a pronounced peak at 5000km/s, corresponding to the well-studied Perseus-Pisces supercluster. Theoverall detection rate was 65 percent, and the bulk of the detectionsare genuine low surface brightness spiral galaxies, may with linewidthsin excess of 300 km/s, as opposed to true dwarf galaxies. It is arguedthat most of the nondetections are unlikely to be gas-poor dwarfs, butinstead are galaxies with velocities beyond 10,000 km/s. Taken as awhole, the sample demonstrates that optical surface brightness is notnecessarily a reliable indicator of intrinsic luminosity or mass.
|A 21 CM survey of the Pisces-Perseus supercluster. I - The declination zone +27.5 to +33.5 degrees|
Neutral-hydrogen 21 cm line data for a sample of galaxies in the regionbounded by 22 h less than R.A. less than 04h, + 27 deg 30 arcmin Dec.less than + 33 deg 30 arcmin are presented as the first installment of asurvey of galaxies in the region of the Pisces-Perseus supercluster. Ofthe 415 galaxies observed in this strip with the Arecibo 305 mtelescope, 342 have been detached in the 21 cm line; another ten haveuseful upper limits to their H I content. The sample includes mostspiral, irregular, and dwarf galaxies larger than 1 arcmin; in selectedareas, spirals to a limiting magnitude of + 15.7 have been observed. Thevelocity distribution of the 511 galaxies with known redshift in thiszone deviates markedly from that expected for a similar sample ofrandomly placed objects. The region contains significant clustering inall three dimensions.
Submit a new link
Member of following groups:
Observation and Astrometry data
Catalogs and designations: