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|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.
|An H_alpha catalogue of galaxies in Hickson compact groups. I. The sample|
We present H_alpha photometry for a sample of 95 galaxies in HicksonCompact Groups obtained from observations of 31 groups. The Cataloguelists isophotal and adaptive aperture (Kron aperture) flux measurementsfor about 75% of the accordant galaxies inside the observed HCGs, 22 outof which are upper limits. Non standard data reduction procedures havebeen used to obtain the continuum subtracted H_alpha images for each HCGof the target sample. Flux calibration has also been performed in orderto obtain H_alpha luminosities for the whole sample. Both the datareduction and calibration procedures are carefully described in thispaper. The new data listed in this Catalogue are of great importance inunderstanding the star formation rate inside HCG galaxies and in givingnew insights on its dependence on galaxy interactions. Tables 3 to 10and Figs. 6 to 11 are only available in electronic version athttp://www.edpsciences.com Tables 7, 8, 9 are also available inelectronic version form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (126.96.36.199) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
|An image database. II. Catalogue between δ=-30deg and δ=70deg.|
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
|Far infrared properties of Hickson compact groups of galaxies. I. High resolution IRAS maps and fluxes.|
The Far Infrared (FIR) properties of galaxies which are members ofcompact groups bear relevant information on the dynamical status and thephysical properties of these structures. All studies published so farhave been undermined by the poor sensitivity and spatial resolution ofthe IRAS-PSC and IRAS Sky Survey data. We used the HIRAS softwareavailable at the IRAS server at the Laboratory for Space Research inGroningen to fully exploit the redundancy of the IRAS data and toapproach the theoretical diffraction limit of IRAS. Among the 97 groupswhich were observed by IRAS, 62 were detected in at least one band,while reliable upper limits were derived for all the others. Among thedetected groups, 49 were fully or partially resolved, i.e. it waspossible to discriminate which member or members emit most of the FIRlight. At 60μm, for instance, 87 individual sources were detected in62 groups. In order to ease the comparison with data obtained at otherwavelengths - and in particular in the X and radio domains - we giveco-added and HIRAS maps for all the detected groups.
|Radio properties of spiral galaxies in high-density groups|
Radio-continuum observations with the Very Large Array (VLA) of 133spiral galaxies in 68 Hickson Compact Groups are used to investigatepossible enhancement of the effects of interactions among galaxies insuch high-density groups. In most of the 56 HCG spirals that weredetected the radio radiation is confined to slightly extended nuclearregions suggestive of starburst activity. It is found that the totalradio radiation from compact group spirals is significantly lower thanfrom a comparison sample of isolated spirals. However, the radioradiation from the nuclear regions is more than 10 times that fromcomparable regions in the comparison sample. This effect is moredominant in late-type spirals than it is in early-type spirals. Theobservations are interpreted in a scenario, suggested by numericalsimulation studies by a number of authors, in which galaxy interactionsare shown to cause both massive inflows of gas towards the centres ofgalaxies and outflows from the outer regions. The resultant starformation activity at the centre leads to the formation of supernovaeand the subsequent radio radiation. On the other hand, the outflow fromthe outer regions may be expected to remove the gas and magnetic fieldsfrom the disc, resulting in reduced disc radio emission. Observations ofgaseous and molecular line distributions may be expected to providekinematic information for modelling of specific interacting systems.
|The CfA Redshift Survey: Data for the NGP +36 Zone|
We have assembled redshifts for a complete sample of 719 galaxies withm_zw_ <= 15.5 in the declination range 32.5^deg^ <= δ <=38.5^deg^ and right ascension range 8^h^ <= α <= 17^h^. Wehave determined morphological types for all galaxies in the magnitudelimited sample by direct inspection of the POSS-O plates. 576 of theredshifts are measurements from Mount Hopkins, and 405 are newredshifts. We also include new redshifts for 77 fainter galaxies in thesame strip.
|A list of some corrections to Zwicky's Catalogue of Galaxies and Clusters of Galaxies|
|Dynamical properties of compact groups of galaxies|
Radial velocities are presented for 457 galaxies in the 100 Hicksoncompact groups. More than 84 percent of the galaxies measured havevelocities within 1000 km/s of the median velocity in the group.Ninety-two groups have at least three accordant members, and 69 groupshave at least four. The radial velocities of these groups range from1380 to 42,731 km/s with a median of 8889 km/s, corresponding to amedian distance of 89/h Mpc. The apparent space density of these systemsranges from 300 to as much as 10 exp 8 sq h/sq Mpc, which exceeds thedensities in the centers of rich clusters. The median projectedseparation between galaxies is 39/h kpc, comparable to the sizes of thegalaxies themselves. A significant correlation is found between crossingtime and the fraction of gas-rich galaxies in the groups, and a weakanticorrelation is found between crossing time and the luminositycontrast of the first-ranked galaxy.
|The luminosity function of compact groups of galaxies|
An analysis of the luminosity function of 68 compact groups of galaxiescataloged by Hickson (1982) is presented. The luminosities of compactgroup galaxies are consistent with their being drawn from a Schechterluminosity function. Individual morphological-type luminosity functionsare also determined. Both the total and morphological-type specificluminosity functions of compact group galaxies are significantlydifferent from those of field, loose-group, and cluster galaxies. Inparticular, the luminosity function of HCG elliptical galaxies has amean magnitude which is significantly brighter than the mean magnitudeof Virgo cluster elliptical galaxies. The mean luminosity density ofgalaxies in compact groups is estimated. The obtained result isconsistent with the conventional scenario in which compact groups mergeto form elliptical galaxies on a relatively short time scale.
|A photometric catalog of compact groups of galaxies|
The paper presents astrometry, photometry, and morphological types,derived from CCD images, for 463 galaxies in the 100 compact groupsselected by Hickson. Some minor revisions to the membership of theoriginal catalog are made, based on these new images. The completenessof the catalog is considered as a function of group magnitude andGalactic latitude. At high Galactic latitude the catalog is estimated tobe 90 percent complete for groups with total B(T) magnitude 13.0 orless. It is less complete at lower Galactic latitude because ofobscuration and high stellar density.
|Neutral hydrogen in compact groups of galaxies|
Integrated H I profiles were detected for 34 of 51 Hickson compactgroups (HCGs) of galaxies, and sensitive upper limits to the H I fluxdensity were measured for the other 17. About 60 percent of the galaxieswithin compact groups are spirals, and a significant tendency exists forthe fraction of elliptical galaxies to increase with group surfacebrightness. The amount of dark matter within the compact group region isnegligibly small. An HCG on average contains half as much neutralhydrogen as a loose group with a similar spectrum of galaxy luminositiesand morphological types, implying that compact groups are independentdynamical entities and not transient or projected configurations ofloose groups. The observed fraction of galaxies which are luminousenough to be possible merger products of compact groups is smallcompared with the fraction required by the theory of dynamical friction.A clear discrepancy thus exists between solid empirical evidence and astraightforward prediction of Newtonian dynamical theory in a settingwhich does not permit a dark matter explanation.
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