Contents
Images
Upload your image
DSS Images Other Images
Related articles
Active and Star-forming Galaxies and Their Supernovae
To investigate the extent to which nuclear starbursts or other nuclearactivity may be connected with enhanced star formation activity in thehost galaxy, we perform a statistical investigation of supernovae (SNe)discovered in host galaxies from four samples: the Markarian galaxiessample, the Second Byurakan Survey (SBS) sample, the north Galactic pole(NGP) sample of active or star-forming galaxies, and the NGP sample ofnormal galaxies. Forty-seven SNe in 41 Mrk galaxies, 10 SNe in six SBSgalaxies, 29 SNe in 26 NGP active or star-forming galaxies, and 29 SNein 26 NGP normal galaxies have been studied. We find that the rate ofSNe, particularly core-collapse (Types Ib/c and II) SNe, is higher inactive or star-forming galaxies in comparison with normal galaxies.Active or star-forming host galaxies of SNe are generally of latermorphological type and have lower luminosity and smaller linear sizethan normal host galaxies of SNe. The radial distribution of SNe inactive and star-forming galaxies shows a higher concentration toward thecenter of the active host galaxy than is the case for normal hostgalaxies, and this effect is more pronounced for core-collapse SNe.Ib/c-type SNe have been discovered only in active and star-forminggalaxies of our samples. About 78% of these SNe are associated with H IIregions or are located very close to the nuclear regions of these activegalaxies, which are in turn hosting AGNs or starburst nuclei. Besidesthese new results, our study also supports the conclusions of severalother earlier papers. We find that Type Ia SNe occur in all galaxytypes, whereas core-collapse SNe of Types Ib/c and II are found only inspiral and irregular galaxies. The radial distribution of Type Ib SNe intheir host galaxies is more centrally concentrated than that of Type IIand Ia SNe. The radial distances of Types Ib/c and II SNe, from thenuclei of their host galaxies, is larger for barred spiral hosts.Core-collapse SNe are concentrated in spiral arms and are often close toor in the H II regions, whereas Type Ia SNe show only a looseassociation with spiral arms and no clear association with H II regions.
| Measuring shapes of galaxy images - II. Morphology of 2MASS galaxies
We study a sample of 112 galaxies of various Hubble types imaged in theTwo Micron All Sky Survey (2MASS) in the near-infrared (NIR; 1-2 μm)J, H and Ks bands. The sample contains (optically classified)32 ellipticals, 16 lenticulars and 64 spirals acquired from the 2MASSExtended Source Catalogue (XSC).We use a set of non-parametric shape measures constructed from theMinkowski functionals (MFs) for galaxy shape analysis. We useellipticity (ɛ) and orientation angle (Φ) as shapediagnostics. With these parameters as functions of area within theisophotal contour, we note that the NIR elliptical galaxies withɛ > 0.2 show a trend of being centrally spherical andincreasingly flattened towards the edge, a trend similar to images inoptical wavelengths. The highly flattened elliptical galaxies showstrong change in ellipticity between the centre and the edge. Thelenticular galaxies show morphological properties resembling eitherellipticals or disc galaxies. Our analysis shows that almost half of thespiral galaxies appear to have bar-like features while the rest arelikely to be non-barred. Our results also indicate that almost one-thirdof spiral galaxies have optically hidden bars.The isophotal twist noted in the orientations of elliptical galaxiesdecreases with the flattening of these galaxies, indicating that twistand flattening are also anticorrelated in the NIR, as found in opticalwavelengths. The orientations of NIR lenticular and spiral galaxies showa wide range of twists.
| A CCD Study of the Environment of Seyfert Galaxies. III. Host Galaxies and the Nearby Environments
A technique is described that permits the robust decomposition of thebulge and disk components of a sample of Seyfert galaxies, as well as a(control) sample of nonactive galaxies matched to the Seyferts in thedistributions of redshift, luminosity, and morphological classification.The structural parameters of the host galaxies in both samples aremeasured. No statistically significant differences at greater than the95% level are found in these parameters according to aKolmogorov-Smirnov test. ``Companion galaxies''-defined as any galaxywithin a projected separation of 200 h-1 kpc from the centerof the host-are identified and their basic properties measured. Acomparison between the active and control samples in the distributionsof apparent R magnitude, absolute R magnitude (assuming the companionsare at the distance of the host), projected separation from the host,position angle relative to the host, magnitude difference between thecompanion and host, and strength of the tidal parameter shows nostatistically significant differences. Similarly, no statisticallysignificant differences are found between the control and active samplehost galaxies in terms of light asymmetries-bars, rings, isophotaltwisting, etc. The implications for a model in which interactions andmergers are responsible for inciting activity in galactic nuclei arediscussed briefly.
| 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.
| On the local radio luminosity function of galaxies. II. Environmental dependences among late-type galaxies
Using new extensive radio continuum surveys at 1.4 GHz (FIRST and NVSS),we derive the distribution of the radio/optical and radio/NIR luminosity(RLF) of late-type (Sa-Irr) galaxies (m_p<15.7) in 5 nearby clustersof galaxies: A262, Cancer, A1367, Coma and Virgo. With the aim ofdiscussing possible environmental dependences of the radio properties,we compare these results with those obtained for relatively isolatedobjects in the Coma supercluster. We find that the RLF of Cancer, A262and Virgo are consistent with that of isolated galaxies. Conversely weconfirm earlier claims that galaxies in A1367 and Coma have their radioemissivity enhanced by a factor ~ 5 with respect to isolated objects. Wediscuss this result in the framework of the dynamical pressure sufferedby galaxies in motion through the intra-cluster gas (ram-pressure). Wefind that the radio excess is statistically larger for galaxies in fasttransit motion. This is coherent with the idea that enhanced radiocontinuum activity is associated with magnetic field compression. TheX-ray luminosities and temperatures of Coma and A1367 imply that thesetwo clusters have significantly larger intracluster gas density than theremaining three studied ones, providing a clue for explaining the higherradio continuum luminosities of their galaxies. Multiple systems in theComa supercluster bridge (with projected separations smaller than 300kpc) have radio luminosities significantly larger than isolatedgalaxies. Table~1 is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html}
| A CCD Study of the Environment of Seyfert Galaxies. I. The Survey
Large-format, R-band CCD data are presented for a spectroscopicallycomplete sample of 34 Seyfert galaxies and a control sample of 45nonactive galaxies that are well matched to the Seyfert sample inredshift, luminosity, and morphological type. Gray-scale images of thelocal environment are included for all of the host galaxies, as well asfigures showing the surface brightness, ellipticity, and position angleof the major axis as a function of radius. These data will be used tostudy the environments of these galaxies and hence to test the"interaction hypothesis" that, over the past two decades, has beenimplicated as the triggering mechanism for nuclear activity. While thereare no dramatic differences in most parameters between the active andnonactive samples, the distributions of ellipticities and major-axisposition-angle excursions of the Seyfert host galaxies and the controlgalaxies are marginally different. A higher proportion of Seyfertgalaxies appear to be involved in late-stage mergers. A similar fractionof the control sample, however, displays significant light asymmetriesthat could be evidence for recent interactions. Moreover, a small butsubstantial number of the Seyfert galaxies show no evidence for recentinteractions as judged by the absence of light asymmetries.
| The far-infrared properties of the CfA galaxy sample. I - The catalog
IRAS flux densities are presented for all galaxies in the Center forAstrophysics magnitude-limited sample (mB not greater than 14.5)detected in the IRAS Faint Source Survey (FSS), a total of 1544galaxies. The detection rate in the FSS is slightly larger than in thePSC for the long-wavelength 60- and 100-micron bands, but improves by afactor of about 3 or more for the short wavelength 12- and 25-micronbands. This optically selected sample consists of galaxies which are, onaverage, much less IR-active than galaxies in IR-selected samples. Itpossesses accurate and complete redshift, morphological, and magnitudeinformation, along with observations at other wavelengths.
| Near-infrared observations of galaxies in the Coma supercluster
Near-IR magnitudes have been obtained for 136 galaxies in the Coma/A1367supercluster region, and near-IR colors (J-H) and (H-K) for 90 and 87objects, respectively. The near-IR colors are contained in a small rangeand do not depend on morphological types, galaxy inclination, orenvironment. Optical-to-IR colors depend strongly on a galaxy'smorphological type and inclination. There is a dependence of therelative excess of radio, and to a lesser degree, of far-IR emission onrecent star formation activity. The magnitude-line width relation forgalaxies in Coma and A1367 obtained with these data has a larger spreadthan previously found with smaller samples. The data suggest a distancemodulus to Coma of about 35, regardless of the choice of primarycalibrators.
| The Asiago Supernova Catalogue
A Catalogue of Supernovae (SNe) is presented which tabulates the maindata relative to all extragalactic SNe discovered up to 1988 December31, and to their parent galaxies. In total 661 SNe are listed of which267 are classified. For an easier consultation, two lists are givenwhere the SNe are ordered chronologically and by Right Ascension,respectively. The overall distribution of classified supernovae over themorphological types of their parent galaxies is also presented in asummary table.
| 21 centimeter study of spiral galaxies in the Coma supercluster
High-sensitivity, 21 cm line observations of 130 galaxies in theComa/A1367 Supercluster region are presented and used to study thelarge-scale distribution of galaxies in the direction of the ComaSupercluster and the H I content in spiral galaxies as a function of thelocal galaxy density. Groups of galaxies are found to form aquasi-continuous structure that connects the Local Supercluster to theComa Supercluster. This structure is composed of real filaments only inthe vicinity of the Coma Cluster. Spiral galaxies in the surveyed groupsand multiple systems have H I content not dissimilar from that ofisolated galaxies. Galaxies within about 1 Abell radius from the ComaCluster contain about three times less hydrogen on average than isolatedgalaxies. There is a strong tendency for galaxies that are more severelyH I-depleted to be redder and of earlier Hubble type. In the ComaCluster a considerable fraction of late-type, blue galaxies have largedeficiency parameters.
| Taxonomical analysis of superclusters. II - The A1367/Coma supercluster
The nonhierarchical taxonomical method has been applied to a sample of185 galaxies, complete to m not greater than 15, in the A1367/Comaregion. Once the fore- and background galaxies have been identified, theanalysis of the A1367 cluster shows it composed by two gravitationallybound clumps at essentially the same redshift, 6396 km/s and 6562 km/s,respectively. Central Coma is traced by three different groups whosegravitational binding does not appear clearly. However, accepting theunique dynamical entity of Central Coma, some other neighboring groupswould be part of the cluster. In that case, the average radial velocityand dispersion of the Coma cluster would be 7013 and 423 km/s,respectively. The M/L ratios for the groups evidenced by the taxonomyrange from 13 to 170. The missing mass problem only appears when all thegalaxies in the sample are considered as members of a unique dynamicalstructure. The relationship found in other systems between the redshift,the morphological type and the radioemissivity is also present in thesample.
| A Checklist of Supernovae in the NGC and IC Galaxies Through 1985
This Checklist of Supernovae in the NGC and IC Galaxies Through 1985 ispresented to assist those interested in undertaking a visual orphotographic search for extragalactic supernovae. Some galaxies appearto have had more than one or two supernovae, and these should bemonitored closely for any new outbursts.
| 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 revised supernova catalogue
Essential data for 568 supernovae, discovered since 1885 up to 1983, andtheir parent galaxies are presented. This catalogue updates and revisesprevious listings, and some of its information is summarized in tabularand graphical form and briefly discussed. An appendix listing the mainreferences to observations of supernovae outside the optical range isprovided.
| 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.
| Inner ring structures in galaxies as distance indicators. III - Distances to 453 spiral and lenticular galaxies
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1983ApJS...51..149B&db_key=AST
| 21 centimeter observations of supercluster galaxies - The bridge between Coma and A1367
21 cm observations of galaxies in the region of the Coma-A1367supercluster are presented. It is shown that galaxies near the clustercenter are hydrogen deficient, while galaxies which are in between thetwo clusters have a normal hydrogen content. A crossing time of about1.7 x 10 to the 9th yr is defined by the radius of the region oftransition between deficient and nondeficient galaxies and the cluster'svelocity dispersion. The gas removed by stripping is a small fraction ofthe gas observed in the X-ray region.
| A distance scale from the infrared magnitude/H I velocity-width relation. III - The expansion rate outside the local supercluster
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980ApJ...239...12A&db_key=AST
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
Catalogs and designations:
|
