Upload your image
DSS Images Other Images
Submit a new article
|Gas-rich Dwarfs from the PSS-II. III. H I Profiles and Dynamical Masses|
We present Arecibo neutral hydrogen data on a sample of opticallyselected dwarf galaxies. The sample ranges in H I mass from106 to 5×109 Msolar, with a meanof 7.9×108 Msolar. Using estimated H Iradii, the H I surface densities range from 0.6 to 20 Msolarpc-2, all well below the critical threshold for starformation (Kennicutt 1998). MH I/L values of the LSB dwarfsrange from 0.3 to 12 with a mean value of 2.0. Dynamical masses,calculated from the H I profile widths, range from 108 to1011 Msolar. There is a strong correlation betweenoptical luminosity and dynamical mass for LSB dwarfs implying that thedark matter (whether baryonic or nonbaryonic) follows the detectablebaryonic matter.
|Nearby Optical Galaxies: Selection of the Sample and Identification of Groups|
In this paper we describe the Nearby Optical Galaxy (NOG) sample, whichis a complete, distance-limited (cz<=6000 km s-1) andmagnitude-limited (B<=14) sample of ~7000 optical galaxies. Thesample covers 2/3 (8.27 sr) of the sky (|b|>20deg) andappears to have a good completeness in redshift (97%). We select thesample on the basis of homogenized corrected total blue magnitudes inorder to minimize systematic effects in galaxy sampling. We identify thegroups in this sample by means of both the hierarchical and thepercolation ``friends-of-friends'' methods. The resulting catalogs ofloose groups appear to be similar and are among the largest catalogs ofgroups currently available. Most of the NOG galaxies (~60%) are found tobe members of galaxy pairs (~580 pairs for a total of ~15% of objects)or groups with at least three members (~500 groups for a total of ~45%of objects). About 40% of galaxies are left ungrouped (field galaxies).We illustrate the main features of the NOG galaxy distribution. Comparedto previous optical and IRAS galaxy samples, the NOG provides a densersampling of the galaxy distribution in the nearby universe. Given itslarge sky coverage, the identification of groups, and its high-densitysampling, the NOG is suited to the analysis of the galaxy density fieldof the nearby universe, especially on small scales.
|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.
|Catalogue of HI maps of galaxies. I.|
A catalogue is presented of galaxies having large-scale observations inthe HI line. This catalogue collects from the literature the informationthat characterizes the observations in the 21-cm line and the way thatthese data were presented by means of maps, graphics and tables, forshowing the distribution and kinematics of the gas. It containsfurthermore a measure of the HI extension that is detected at the levelof the maximum sensitivity reached in the observations. This catalogueis intended as a guide for references on the HI maps published in theliterature from 1953 to 1995 and is the basis for the analysis of thedata presented in Paper II. The catalogue is only available inelectronic form at the CDS via anonymous ftp 22.214.171.124 orhttp://cdsweb.u-strasbg.fr/Abstract.html
|Gas-rich Dwarfs from the Second Palomar Sky Survey. I. Catalog and Characteristics|
This project is a visual search for field dwarf galaxies using SecondPalomar Sky Survey photographic plates. A morphologically selectedsample of 310 objects yielded 145 detections of true dwarfs within aredshift search window of 0 to 10,000 km s-1. We confirm the low-mass,dwarf nature of the same by comparison of luminosity, isophotal size, HI mass and H I profile width distribution of other dwarf samples. Thegoal of this project is to use these newly discovered dwarf galaxies tomap large-scale structure as a test of biased galaxy formation. Initialindicators are that the large-scale distribution of dwarf galaxies isidentical to that of bright, high-mass galaxies, in contradiction totheory using biasing. The full analysis of the sample will be reportedin the final paper of our series.
|Gas-Rich Dwarf Galaxies from the Second Palomar Sky Survey. II. Optical Properties|
We describe the optical properties of a sample of 101 gas-rich fielddwarf galaxies found on Second Palomar Sky Survey plates, most newlydiscovered as part of a survey to investigate the clustering propertiesof dwarf galaxies relative to giants. These galaxies have low surfacebrightnesses and are relatively distant, with recession velocitiesranging up to 104 km s-1. They have bluer V-I colors (median value of0.75) than either actively star-forming giant galaxies orlow-metallicity globular clusters, implying that these dwarfs have bothlow metallicities and little past star formation. These galaxies arealso extremely gas-rich, with a median H I mass--to--V luminosity ratioof approximately 2 in solar units. We divide the sample into two groups:true dwarfs with diameters (at 25 I mag arcsec-2) less than 7.5 kpc andMagellanic dwarfs with diameters greater than that value. The truedwarfs have greater H I mass--to--V luminosity ratios and slightly bluerV-I colors than the Magellanic dwarfs. Overall, the optical propertiesof our sample of dwarf galaxies point toward their being quiescentobjects that have undergone little star formation over the age of theuniverse. They are not faded objects but instead may be going throughone of their first periods of weak star formation.
|Influence of a partial incompleteness of the sample on the determination of the Hubble constant.|
This paper presents a study of the Malmquist bias effect in thedetermination of the Hubble constant from the method of "sosies"(look-alike) galaxies. It is shown that a bias appears when a partialincompleteness exists in the sample. A new method, based on the use ofthe completeness curve, is proposed to correct for such a bias. Afterthis correction, the Hubble constant drops of about 20% just because ofthe existence of the partial incompleteness. From the present resultsand on the acceptance of the distance modulus of primary calibrators,the value of the Hubble constant would be: H_0_=~60km/s/Mpc with aninternal statistical error of about 2km/s/Mpc.
|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.
|H I 21 centimeter observations and I-band CCD surface photometry of spiral galaxies behind the Virgo Cluster and toward its antipode|
Sample selection, radio and optical data acquisition and reduction, andobservation results are presented for spiral galaxies behind the VirgoCluster and toward its antipode. I-band CCD photometry was obtained forall the bright galaxies and part of the sample of faint galaxies in thetwo local volumes was studied. The statistical properties of the galaxysamples are discussed.
|Dynamics of Binary Galaxies. I. Wide Pairs|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993ApJ...419...30C&db_key=AST
|A study of the large-scale structure in the distribution of galaxies in a region centered about the Cancer cluster. III - Further observational results|
Further observational results are presented from a study of thelarge-scale structure in the distribution of galaxies in anapproximately 4000 sq deg region nominally centered about the Cancercluster. The criteria used in defining the galaxy sample and theobservational methods used in its study are reviewed. The H I spectraand the associated measured parameters and derived properties for the134 sample galaxies are presented.
|Arecibo H I data for 136 spiral galaxies|
The results of observations of the neutral hydrogen emission of 136spiral galaxies observed using the 21 cm spectral-line system of theArecibo Observatory are presented. Most of the 114 detected objects havebeen mapped along the major axis, and cumulative spectra andposition-velocity contour maps for each of them are presented. The dataare used to determine the overall H I content, systemic velocity, linewidths, and scale-length H I diameters. Data are also presented, indetailed tabular form, for each of the positions observed on thedetected objects.
|A survey of galaxy redshifts. IV - The data|
The complete list of the best available radial velocities for the 2401galaxies in the merged Zwicky-Nilson catalog brighter than 14.5mz and with b (II) above +40 deg or below -30 deg ispresented. Almost 60 percent of the redshifts are from the CfA surveyand are accurate to typically 35 km/s.
|A catalog of hierarchical subclustering in the Turner-Gott groups|
Information on the substructure, to four levels of hierarchy, ispresented for the 103 groups listed by Turner and Gott (TG) in theircatalog of groups of galaxies. All galaxies brighter than Mpg= 14.0 in the region delta is 0 deg or greater and b(II) is 40 deg orgreater that have been assigned group memberships by TG are included.Also listed is the local environmental information for each of thegalaxies, giving the surface density enhancement beta in the galaxy'sneighborhood, calculated at 15 levels in the range beta = 4.6 to 10,000.
|Flocculent and grand design spiral structure in field, binary and group galaxies|
A 12-division morphological system emphasizing arm continuity, lengthand symmetry has been developed for the classification of all spiralgalaxies according to the regularity of their spiral arm structure. Armclassifications were tabulated for 305 barred and nonbarred spiralgalaxies; of these, 79 are isolated, 52 are binary and 174 are ingroups. Among the isolated SA galaxies, 68 + or - 10% have irregular andfragmented, or 'flocculent', spiral structures. Only 32 + or - 10% havesymmetric spiral arms in the classic grand design pattern. Flocculentspirals are the most common structures of galaxies without companions orbars. Since flocculent galaxies may have bars and companions, and granddesign galaxies may have neither bars nor companions, such perturbationsare neither perfectly effective nor always necessary in the driving ofgrand design patterns.
Submit a new link
Member of following groups:
Observation and Astrometry data
Catalogs and designations: