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|HI content in galaxies in loose groups|
Gas deficiency in cluster spirals is well known and ram-pressurestripping is considered the main gas removal mechanism. In some compactgroups too gas deficiency is reported. However, gas deficiency in loosegroups is not yet well established. Lower dispersion of the membervelocities and the lower density of the intragroup medium in small loosegroups favour tidal stripping as the main gas removal process in them.Recent releases of data from the HI Parkes All-Sky Survey (HIPASS) andcatalogues of nearby loose groups with associated diffuse X-ray emissionhave allowed us to test this notion. In this paper, we address thefollowing questions: (i) do galaxies in groups with diffuse X-rayemission statistically have lower gas content compared to the ones ingroups without diffuse X-ray emission? (ii) does HI deficiency vary withthe X-ray luminosity, LX, of the loose group in a systematicway? We find that (i) galaxies in groups with diffuse X-ray emission, onaverage, are HI deficient, and have lost more gas compared to those ingroups without X-ray emission; the latter are found not to havesignificant HI deficiency; (ii) no systematic dependence of the HIdeficiency with LX is found. Ram-pressure-assisted tidalstripping and evaporation by thermal conduction are the two possiblemechanisms to account for this excess gas loss.
|The 1000 Brightest HIPASS Galaxies: H I Properties|
We present the HIPASS Bright Galaxy Catalog (BGC), which contains the1000 H I brightest galaxies in the southern sky as obtained from the H IParkes All-Sky Survey (HIPASS). The selection of the brightest sourcesis based on their H I peak flux density (Speak>~116 mJy)as measured from the spatially integrated HIPASS spectrum. The derived HI masses range from ~107 to 4×1010Msolar. While the BGC (z<0.03) is complete inSpeak, only a subset of ~500 sources can be consideredcomplete in integrated H I flux density (FHI>~25 Jy kms-1). The HIPASS BGC contains a total of 158 new redshifts.These belong to 91 new sources for which no optical or infraredcounterparts have previously been cataloged, an additional 51 galaxiesfor which no redshifts were previously known, and 16 galaxies for whichthe cataloged optical velocities disagree. Of the 91 newly cataloged BGCsources, only four are definite H I clouds: while three are likelyMagellanic debris with velocities around 400 km s-1, one is atidal cloud associated with the NGC 2442 galaxy group. The remaining 87new BGC sources, the majority of which lie in the zone of avoidance,appear to be galaxies. We identified optical counterparts to all but oneof the 30 new galaxies at Galactic latitudes |b|>10deg.Therefore, the BGC yields no evidence for a population of``free-floating'' intergalactic H I clouds without associated opticalcounterparts. HIPASS provides a clear view of the local large-scalestructure. The dominant features in the sky distribution of the BGC arethe Supergalactic Plane and the Local Void. In addition, one can clearlysee the Centaurus Wall, which connects via the Hydra and Antlia Clustersto the Puppis Filament. Some previously hardly noticable galaxy groupsstand out quite distinctly in the H I sky distribution. Several newstructures, including some not behind the Milky Way, are seen for thefirst time.
|Galaxy interactions - poor starburst triggers. III. A study of a complete sample of interacting galaxies|
We report on a study of tidally triggered star formation in galaxiesbased on spectroscopic/photometric observations in the optical/near-IRof a magnitude limited sample of 59 systems of interacting and merginggalaxies and a comparison sample of 38 normal isolated galaxies. From astatistical point of view the sample gives us a unique opportunity totrace the effects of tidally induced star formation. In contrast toresults from previous investigations, our global UBV colours do notsupport a significant enhancement of starforming activity in theinteracting/merging galaxies. We also show that, contrary to previousclaims, there is no significantly increased scatter in the colours ofArp galaxies as compared to normal galaxies. We do find support formoderate (a factor of ~ 2-3) increase in star formation in the verycentres of the interacting galaxies of our sample, contributingmarginally to the total luminosity. The interacting and in particularthe merging galaxies are characterized by increased far infrared(hereafter FIR) luminosities and temperatures that weakly correlate withthe central activity. The LFIR/LB ratio however,is remarkably similar in the two samples, indicating that truestarbursts normally are not hiding in the central regions of the FIRluminous cases. The gas mass-to-luminosity ratio in optical-IR ispractically independent of luminosity, lending further support to thepaucity of true massive starburst galaxies triggered byinteractions/mergers. We estimate the frequency of such cases to be ofthe order of ~ 0.1% of the galaxies in an apparent magnitude limitedsample. Our conclusion is that interacting and merging galaxies, fromthe global star formation aspect, generally do not differ dramaticallyfrom scaled up versions of normal, isolated galaxies. No drastic changewith redshift is expected. One consequence is that galaxy formationprobably continued over a long period of time and did not peak at aspecific redshift. The effects of massive starbursts, like blowoutscaused by superwinds and cosmic reionization caused by starburstpopulations would also be less important than what is normally assumed.Based on observations collected at the European Southern Observatory, LaSilla, Chile.
|Homogenization of the Stellar Population along Late-Type Spiral Galaxies|
We present a study of the broadband UBV color profiles for 257 Sbcbarred and nonbarred galaxies, using photoelectric aperture photometrydata from the literature. Using robust statistical methods, we haveestimated the color gradients of the galaxies, as well as the total andbulge mean colors. A comparative photometric study using CCD images wasdone. In our sample, the color gradients are negative (reddish inward)in approximately 59% of the objects, are almost null in 27%, and arepositive in 14%, considering only the face-on galaxies, which representapproximately 51% of the sample. The results do not change, essentially,when we include the edge-on galaxies. As a consequence of this study wehave also found that barred galaxies are overrepresented among theobjects having null or positive gradients, indicating that bars act as amechanism of homogenization of the stellar population. This effect ismore evident in the U-B color index, although it can also be detected inthe B-V color. A correlation between the total and bulge colors wasfound that is a consequence of an underlying correlation between thecolors of bulges and disks found by other authors. Moreover, the meantotal color is the same irrespective of the gradient regime, whilebulges are bluer in galaxies with null or positive gradients, whichindicates an increase of the star formation rate in the central regionsof these objects. We have also made a quantitative evaluation of theamount of extinction in the center of these galaxies. This was doneusing the Wide Field Planetary Camera 2 (WFPC2) and the Near InfraredCamera and Multi-Object Spectrometer (NICMOS) Hubble Space Telescope(HST) archival data, as well as CCD B, V, and I images. We show thatalthough the extinction in the V-band can reach values up to 2 mag inthe central region, it is unlikely that dust plays a fundamental role inglobal color gradients. We found no correlation between color and O/Habundance gradients. This result could suggest that the color gradientsare more sensitive to the age rather than to the metallicity of thestellar population. However, the absence of this correlation may becaused by dust extinction. We discuss this result by considering apicture in which bars are a relatively fast, recurrent phenomenon. Theseresults are not compatible with a pure classical monolithic scenario forbulge and disk formation. On the contrary, they favor a scenario inwhich both these components are evolving in a correlated process inwhich stellar bars play a crucial role. Based partly on observationsmade at the Pico dos Dias Observatory (PDO/LNA-CNPq), Brazil.
|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.
|Total magnitude, radius, colour indices, colour gradients and photometric type of galaxies|
We present a catalogue of aperture photometry of galaxies, in UBVRI,assembled from three different origins: (i) an update of the catalogueof Buta et al. (1995) (ii) published photometric profiles and (iii)aperture photometry performed on CCD images. We explored different setsof growth curves to fit these data: (i) The Sersic law, (ii) The net ofgrowth curves used for the preparation of the RC3 and (iii) A linearinterpolation between the de Vaucouleurs (r(1/4) ) and exponential laws.Finally we adopted the latter solution. Fitting these growth curves, wederive (1) the total magnitude, (2) the effective radius, (3) the colourindices and (4) gradients and (5) the photometric type of 5169 galaxies.The photometric type is defined to statistically match the revisedmorphologic type and parametrizes the shape of the growth curve. It iscoded from -9, for very concentrated galaxies, to +10, for diffusegalaxies. Based in part on observations collected at the Haute-ProvenceObservatory.
|Homogeneous Velocity-Distance Data for Peculiar Velocity Analysis. III. The Mark III Catalog of Galaxy Peculiar Velocities|
This is the third in a series of papers in which we assemble and analyzea homogeneous catalog of peculiar velocity data. In Papers I and II, wedescribed the Tully-Fisher (TF) redshift-distance samples thatconstitute the bulk of the catalog and our methodology for obtainingmutually consistent TF calibrations for these samples. In this paper, wesupply further technical details of the treatment of the data andpresent a subset of the catalog in tabular form. The full catalog, knownas the Mark III Catalog of Galaxy Peculiar Velocities, is available inaccessible on-line databases, as described herein. The electroniccatalog incorporates not only the TF samples discussed in Papers I andII but also elliptical galaxy Dn- sigma samples originally presentedelsewhere. The relative zero pointing of the elliptical and spiral datasets is discussed here. The basic elements of the Mark III Catalog arethe observables for each object (redshift, magnitude, velocity width,etc.) and inferred distances derived from the TF or Dn- sigma relations.Distances obtained from both the forward and inverse TF relations aretabulated for the spirals. Malmquist bias--corrected distances arecomputed for each catalog object using density fields obtained from theIRAS 1.2 Jy redshift survey. Distances for both individual objects andgroups are provided. A variety of auxiliary data, including distancesand local densities predicted from the IRAS redshift surveyreconstruction method, are tabulated as well. We study the distributionsof TF residuals for three of our samples and conclude that they are wellapproximated as Gaussian. However, for the Mathewson et al. sample wedemonstrate a significant decrease in TF scatter with increasingvelocity width. We test for, but find no evidence of, a correlationbetween TF residuals and galaxy morphology. Finally, we derivetransformations that map the apparent magnitude and velocity width datafor each spiral sample onto a common system. This permits theapplication of analysis methods that assume that a unique TF relationdescribes the entire sample.
|Parameters of 2447 Southern Spiral Galaxies for Use in the Tully-Fisher Relation|
I-band luminosities, rotational velocities, and redshifts of 1092 spiralgalaxies have been measured by CCD photometry and Hα spectroscopyusing the 1 m and 2.3 m telescopes at Siding Spring Observatory,respectively. The results are tabulated. Luminosity profiles andHα rotation curves are given for the galaxies. When these resultsare combined with similar data for 1355 spiral galaxies publishedpreviously (Mathewson, Ford, & Buchhorn, hereafter Paper I), itprovides a large, uniform, and unique data set with which to measure,via the Tully-Fisher relation, the peculiar velocities of galaxies inthe local universe to a distance of 11,000 km s^-1^ (Mathewson &Ford). Taking advantage of the opportunity for publishing this data inmachine-readable form, in the CD-ROM, we have also included similar datafor the 1355 galaxies in Paper I.
|The Absence of X-Ray Flashes from Nearby Galaxies and the Gamma-Ray Burst Distance Scale|
If typical gamma-ray bursts (GRBs) have X-ray counterparts similar tothose detected by Ginga, then sensitive-focusing X-ray telescopes willbe able to detect GRBs 3 orders of magnitude fainter than the detectionlimit of the Burst and Transient Source Experiment (BATSE). If asubstantial portion of the burst population detected by BATSE originatesin a Galactic halo at distances greater than or equal to 150 kpc,existing X-ray telescopes will be able to detect GRBs in externalgalaxies out to a distance of at least 4.5 Mpc. As reported in Gotthelf,Hamilton, & Helfand, the imaging proportional counter (IPC) on boardthe Einstein Observatory detected 42 transient events with pointlikespatial characteristics and timescales of less than 10 s. These eventsare distributed isotropically on the sky; in particular, they are notconcentrated in the directions of nearby external galaxies. For halomodels of the BATSE bursts with radii of 150 kpc or greater, we wouldexpect to see several burst events in observations pointed toward nearbygalaxies. We see none. We therefore conclude that if the Gingadetections are representative of the population of GRBs sampled byBATSE, GRBs cannot originate in a Galactic halo population with limitingradii between 150 and 400 kpc. Inasmuch as halos with limiting radiioutside of this range have been excluded by the BATSE isotropymeasurements, our result indicates that all halo models are excluded.This result is independent of whether the flashes we do detect have anastronomical origin.
|Nuclei of Nearby Disk Galaxies.I.A Hubble Space Telescope Imaging Survey|
We present deconvolved images of the central regions of 20 nearby diskgalaxies, obtained with the original Planetary Camera of the HubbleSpace Telescope. The galaxies span a range in Hubble type from S0 to Sm.We have measured surface brightness profiles, and inverted these toestimate luminosity-density profiles. Surface brightness profiles in thecentral regions show a variety of forms, sometimes clearly affected byheavy dust obscuration. All galaxies in the sample earlier than type Scshow a continuing rise in surface brightness up to the resolution limitin the deconvolved images. Later types show shallower slopes, consistentwith exponential disks either continuing into the center or elseflattening in the central regions. These galaxies often, but not always,exhibit an unresolved nucleus which is likely a dense nuclear starcluster. Luminosity densities in the earlier-type galaxies reach orexceed 10^4^ L_sun_,V_ pc^-3^, and the nuclei of the later-type galaxiesoccasionally approach the same level. The dS0 galaxies in our samplehave central characteristics most closely resembling the late-typegalaxies. A comparison of the central luminosity and central surfacebrightness of our galaxies with elliptical galaxies and nucleated dwarfssupports an association of late-type disks systems and such dwarfs.
|Recalibration of the H-0.5 magnitudes of spiral galaxies|
The H-magnitude aperture data published by the Aaronson et al.collaboration over a 10 year period is collected into a homogeneous dataset of 1731 observations of 665 galaxies. Ninety-six percent of thesegalaxies have isophotal diameters and axial ratios determined by theThird Reference Cataloque of Bright Galaxies (RC3; de Vaucouleurs et al.1991), the most self-consistent set of optical data currently available.The precepts governing the optical data in the RC3 are systematicallydifferent from those of the Second Reference Catalogue (de Vaucouleurs,de Vaucouleurs, & Corwin 1976), which were used by Aaronson et al.for their original analyses of galaxy peculiar motions. This in turnleads to systematic differences in growth curves and fiducialH-magnitudes, prompting the present recalibration of the near-infraredTully-Fisher relationship. New optically normalized H-magnitude growthcurves are defined for galaxies of types SO to Im, from which new valuesof fiducial H-magnitudes, Hg-0.5, are measured forthe 665 galaxies. A series of internal tests show that these fourstandard growth curves are defined to an accuracy of 0.05 mag over theinterval -1.5 less than or equal to log (A/Dg) less than orequal to -0.2. Comparisons with the Aaronson et al. values of diameters,axial ratios, and fiducial H-magnitudes show the expected differences,given the different definitions of these parameters. The values ofHg-0.5 are assigned quality indices: a qualityvalue of 1 indicates an accuracy of less than 0.2 mag, quality 2indicates an accuracy of 0.2-0.35 mag, and quality 3 indicates anaccuracy of more than 0.35 mag. Revised values of corrected H I velocitywidths are also given, based on the new set of axial ratios defiend bythe RC3.
|The Catalog of Southern Ringed Galaxies|
The Catalog of Southern Ringed Galaxies (CSRG) is a comprehensivecompilation of diameters, axis ratios, relative bar position angles, andmorphologies of inner and outer rings, pseudorings, and lenses in 3692galaxies south of declination -17 deg. The purpose of the catalog is toevaluate the idea that these ring phenomena are related to orbitalresonances with a bar or oval in galaxy potentials. The catalog is basedon visual inspection of most of the 606 fields of the Science ResearchCouncil (SRC) IIIa-J southern sky survey, with the ESO-B, ESO-R, andPalomar Sky surveys used as auxiliaries when needed for overexposed coreregions. The catalog is most complete for SRC fields 1-303 (mostly southof declination -42 deg). In addition to ringed galaxies, a list of 859mostly nonringed galaxies intended for comparison with other catalogs isprovided. Other findings from the CSRG that are not based on statisticsare the identification of intrinsic bar/ring misalignment; bars whichunderfill inner rings; dimpling of R'1pseudorings; pointy, rectangular, or hexagonal inner or outer ringshapes; a peculiar polar-ring-related system; and other extreme examplesof spiral structure and ring morphology.
|Multiwavelength Energy Distributions and Bolometric Luminosities of the 12 Micron Galaxy Sample|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ...453..616S&db_key=AST
|Total and effective colors of 501 galaxies in the Cousins VRI photometric system|
Total color indices (V-R)T, (V-I)T and effectivecolor indices (V-R)e, (V-I)e in the Cousins VRIphotometric system are presented for 501 mostly normal galaxies. Thecolors are computed using a procedure outlined in the Third ReferenceCatalogue of Bright Galaxies (RC3) whereby standard color curvesapproximated by Laplace-Gauss integrals are fitted to observedphotoelectric multiaperture photometry. 11 sources of such photometrywere used for our analysis, each source being assigned an appropriateweight according to a rigorous analysis of residuals of the data fromthe best-fitting standard color curves. Together with the integrated B-Vand U-B colors provided in RC3, our analysis widens the range ofwavelength of homogeneously defined colors of normal galaxies of allHubble types. We present color-color and color-type relations that canbe modeled to understand the star formation history of galaxies.
|Photometrically distinct nuclei in elliptical and early-type disks galaxies.|
|The Montreal Blue Galaxy survey. 2: Second list of UV-bright candidates|
We present and discuss the second list of the Montreal Blue Galaxysurvey. Following the inspection of 71 plates, we found 237 newcandidates with B less than 15.5. 73 percent of them are also detectedby Infrared Astronomy Satellite (IRAS). Spectrophotometry was carriedout, at medium resolution, for a subset of 40 objects leading to theidentification of three new AGNs and producing 13 new radial velocities.Spectral classification of our candidates confirms our previous findingthat the majority of our candidates are starburst nucleus galaxiessimilar to the objects studied by Balzano in 1983. Our survey is biasedagainst the high excitation starburst H II galaxies and the LINERgalaxies. Metallicities of our galaxies are found to be from log(O/H)=8.4 to 9.0, which suggests galaxies in advanced stages of chemicalevolution.
|The extended 12 micron galaxy sample|
We have selected an all-sky (absolute value of b greater than or equalto 25 deg) 12 micron flux-limited sample of 893 galaxies from the IRASFaint Source Catalog, Version 2 (FSC-2). We have obtained accurate totalfluxes in the IRAS wavebands by using the ADDSCAN procedure for allobjects with FSC-2 12 micron fluxes greater than 0.15 Jy and increasingflux densities from 12 to 60 microns, and defined the sample by imposinga survey limit of 0.22 Jy on the total 12 micron flux. Its completenessis verified, by means of the classical log N - log S andV/Vmax tests, down to 0.30 Jy, below which we have measuredthe incompleteness down to the survey limit, using the log N - log Splot, for our statistical analysis. We have obtained redshifts (mostlyfrom catalogs) for virtually all (98.4%) the galaxies in the sample.Using existing catalogs of active galaxies, we defined a subsample of118 objects consisting of 53 Seyfert 1s and quasars, 63 Seyfert 2s, andtwo blazars (approximately 13% of the full sample), which is the largestunbiased sample of Seyfert galaxies ever assembled. Since the 12 micronflux has been shown to be about one-fifth of the bolometric flux forSeyfert galaxies and quasars, the subsample of Seyferts (includingquasars and blazars) is complete not only to 0.30 Jy at 12 microns butalso with respect to a bolometric flux limit of approximately 2.0 x10-10 ergs/s/sq cm. The average value of V/Vmaxfor the full sample, corrected for incompleteness at low fluxes, is 0.51+/- 0.04, expected for a complete sample of uniformly distributedgalaxies, while the value for the Seyfert galaxy subsample is 0.46 +/-0.10. We have derived 12 microns and far-infrared luminosity functionsfor the AGNs, as well as for the entire sample. We extracted from oursample a complete subsample of 235 galaxies flux-limited (8.3 Jy) at 60microns. The 60 micron luminosity function computed for this subsampleis in satisfactory agreement with the ones derived from the brightgalaxy sample (BGS) and the deep high-galactic latitude sample, bothselected at 60 microns.
|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.
|A southern sky survey of the peculiar velocities of 1355 spiral galaxies|
The paper presents data from photometric and spectroscopic observationsof 1355 southern spiral galaxies and uses them to determine theirdistances and peculiar velocities via the Tully-Fisher (TF) relation.I-band CCD surface photometry was carried out using the 1-m and 3.9-mtelescopes at Siding Spring Observatory. H-alpha rotation curves for 965galaxies and 551 H I profiles are presented. The physical parameters,photometric and velocity data, distances, and peculiar velocities of thegalaxies are presented in tabular form. The mean distance, systemicvelocity, and average peculiar velocity of 24 clusters in the sample aregiven. TF diagrams are presented for each cluster.
|Nearby galaxy flows modeled by the light distribution - Distances, model, and the local velocity anomaly|
Tables giving measured galaxy distances used to construct a map ofobserved peculiar velocities, and giving a grid of the distribution oflight used to construct a map of expected peculiar velocities arepresented. A preferred model was developed which yielded a best fitbetween these maps, and this model was used to generate output kinematicdistances which are recorded for groups and individual galaxies withV0 of less than 3000 km/s. In terms of the ratio ofpeculiar-to-systemic velocities, the local velocity anomaly is the mostimportant perturbation involving substantial numbers of galaxies forthis case. The ratio of these quantities in this case is larger than forthe more famous cases of the Virgocentric or Great Attractorperturbations. Maps which illustrate the fit of the present mass modelto the velocity data in the local region are provided. A graphicaldemonstration of the relative importance of large-scale streaming tolocal motions within the context of this model is presented.
|Groups of galaxies within 80 Mpc. II - The catalogue of groups and group members|
This paper gives a catalog of the groups and associations obtained bymeans of a revised hierarchical algorithm applied to a sample of 4143galaxies with diameters larger than 100 arcsec and redshifts smallerthan 6000 km/s. The 264 groups of galaxies obtained in this way (andwhich contain at least three sample galaxies) are listed, with the looseassociations surrounding them and the individual members of eachaggregate as well; moreover, the location of every entity among 13regions corresponding roughly to superclusters is specified. Finally,1729 galaxies belong to the groups, and 466 to the associations, i.e.,the total fraction of galaxies within the various aggregates amounts to53 percent.
|Southern Sky Redshift Survey - The catalog|
The catalog of radial velocities for galaxies which comprise thediameter-limited sample of the Southern Sky Redshift Survey ispresented. It consolidates the data of observations carried out at theLas Campanas Observatory, Observatorio Nacional, and South AfricanAstronomical Observatory. The criteria used for the sample selection aredescribed, as well as the observational procedures and the techniqueutilized to obtain the final radial velocities. The intercomparisonbetween radial velocity measurements from different telescopes indicatesthat the final data base is fairly homogeneous with a typical error ofabout 40 km/s. The sample is at present 90 percent complete, and themissing galaxies are predominantly objects with very low surfacebrightness for which it is very difficult to obtain optical redshifts.
|Dark matter in spiral galaxies|
The Tully-Fisher relation is used to probe dark matter (DM) in theoptical regions of spiral galaxies. By establishing it at severaldifferent isophotal radii in an appropriate sample of 58 galaxies withgood B-band photometry and rotation curves, it is shown that some of itsattributes (such as scatter, residuals, nonlinearity, and bias)dramatically decrease moving from the disk edge inward. This behaviorchallenges any mass model which assumes no DM or aluminosity-independent DM mass fraction interior to the optical radiusof spiral galaxies.
|A study of a complete sample of interacting galaxies. I - Presentation of the sample and the UBVRIJHK photometry|
An investigation is presented on what effects galaxy-galaxy interactionhas on the properties of the involved galaxies. A magnitude limitedsample of interacting galaxies is presented, together with a controlsample of isolated galaxies. The Cousins UBVRI and Johnson JHKphotometry of all galaxies included in the samples is also presented.
|Neutral hydrogen observations of southern galaxies|
21-cm neutral hydrogen observations, made using the 64-m Parkes radiotelescope, are presented for 48 galaxies, 39 of which are cleardetections. The HI properties and homogeneous optical data, includingnew photometry, are tabulated for the galaxies. A high signal-to-noiseratio subset of these observations is used to demonstrate that theoverall flux-density scale is within a few per cent of northern (JodrellBank, and Green Bank) scales. HI-optical diameter correlations are shownto be a useful discriminant between competing diameter systems andindicate that the Lauberts ESO(B) catalogue is the most useful currentlyavailable source of southern galaxy diameters.
|A catalog of southern groups of galaxies|
A catalog of groups of galaxies identified in the southern Galactic capis presented. This catalog was constructed utilizing the group-findingalgorithm developed by Huchra and Geller (1982) to analyze galaxysamples with well-defined selection criteria and complete velocityinformation.
|Revised supernova rates in Shapley-Ames galaxies|
Observations of 855 Shapley Ames galaxies made from November 1, 1980 toOctober 31, 1988, together with improved supernova luminosities, havebeen used to derive the frequency of supernovae of different types, andthe results are presented in tables. From a uniform database of 24supernovae discovered, the following SN rates are found, expressed in SNper century per 10 to the 10th L(B)(solar): SN Ia, 0.3; SN Ib, 0.3; andSN II, 1.0. The present data confirm the relatively high frequency of SNII in late-type galaxies that has been found by many previousinvestigators.
|The 12 micron galaxy sample. I - Luminosity functions and a new complete active galaxy sample|
An all-sky 12 micron flux-limited sample of active galaxies was selectedfrom the IRAS Point Source Catalog. Most of the sample galaxies are inexisting catalogs, and 99 percent have measured redshifts. The 12-micronand the far-infrared luminosity functions of active and normal galaxiesare derived using IRAS co-added data. A total of 22 percent of thesample galaxies harbor active nuclei. The sample consists almost equallyof Seyfert 1, Seyfert 2, and LINER nuclei. The derived luminosityfuctions for Seyfert 1 and Seyfert 2 galaxies are indistinguishable fromthose of the optically selected CfA sample. Thus, 12 micron selection isthe most efficient available technique for finding complete activegalaxy samples.
|The local extragalactic velocity field as a test of the explosion and gravitational instability pictures|
Various models for the origin of large-scale structure were tested andconstrained using the local galaxy velocity field derived from theAaronson et al. (1982) catalog of IR magnitudes and H I velocity widthsfor nearby galaxies, together with the IR Tully-Fisher calibration ofthese data (Aaronson et al.,1986). The assumptions and the tests of theVirgocentric flow model, the pancake model, and, particularly, thesimple explosion model based on the work of Ostriker and Cowie (1981)and Ostriker et al. (1986) are discussed. It is concluded that theobservations of the local peculiar velocity field do not support thesimple explosion model.
|The Malmquist bias in the extragalactic distance scale - Controversies and misconceptions|
Several critical statements about the authors' work on the Malmquistbias in the Tully-Fisher (TF) relation are examined. Theoreticalproblems with the bias and evidence for the bias are reviewed, and theconcept of the normalized distance is discussed. The determination ofH(0) from the plateau data is addressed, and the slope of the B-band TFrelation is examined. The cluster population incompleteness bias isdiscussed. It is shown that the criticisms are unjustified.
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