SKY-MAP.ORG
 Home Getting Started To Survive in the Universe News@Sky Astro Photo The Collection Forum Blog New! FAQ Press Login

# NGC 3993

Contents

### Images

DSS Images   Other Images

### Related articles

 The SCUBA Local Universe Galaxy Survey - III. Dust along the Hubble sequenceWe present new results from the Submillimetre Common-User BolometerArray (SCUBA) Local Universe Galaxy Survey (SLUGS), the first largesystematic submillimetre (submm) survey of the local Universe. Since ourinitial survey of a sample of 104 IRAS-selected galaxies we have nowcompleted a survey of a sample of 81 optically selected galaxies,observed with the SCUBA camera on the James Clerk Maxwell Telescope.Since SCUBA is sensitive to the 90 per cent of dust too cold to radiatesignificantly in the IRAS bands our new sample represents the firstunbiased SCUBA survey of dust in galaxies along the whole length of theHubble sequence.We find little change in the properties of dust in galaxies along theHubble sequence, except a marginally significant trend for early-typegalaxies to be less-luminous submm sources than late types. Wenevertheless detected six out of 11 elliptical galaxies, although someof the emission may possibly be synchrotron rather than dust emission.As in our earlier work on IRAS galaxies we find that the IRAS and submmfluxes are well fitted by a two-component dust model with dustemissivity index β= 2. The major difference from our earlier workis that we find the ratio of the mass of cold dust to the mass of warmdust is much higher for our optically selected galaxies and can reachvalues of ~1000. Comparison of the results for the IRAS and opticallyselected samples shows that there is a population of galaxies containinga large proportion of cold dust that is unrepresented in the IRASsample.We derive local submm luminosity and dust mass functions, both directlyfrom our optically selected SLUGS sample, and by extrapolation from theIRAS Point Source Catalogue Redshift Survey (PSCz) survey using themethod of Serjeant and Harrison (by extrapolating the spectral energydistributions of the IRAS PSCz survey galaxies out to 850μm we probea wider range of luminosities than probed directly by the SLUGSsamples), and find excellent agreement between the two. We find them tobe well fitted by Schechter functions except at the highestluminosities. We find that as a consequence of the omission of coldgalaxies from the IRAS sample the luminosity function presented in ourearlier work is too low by a factor of 2, reducing the amount of cosmicevolution required between the low-z and high-z Universe. Properties of isolated disk galaxiesWe present a new sample of northern isolated galaxies, which are definedby the physical criterion that they were not affected by other galaxiesin their evolution during the last few Gyr. To find them we used thelogarithmic ratio, f, between inner and tidal forces acting upon thecandidate galaxy by a possible perturber. The analysis of thedistribution of the f-values for the galaxies in the Coma cluster leadus to adopt the criterion f ≤ -4.5 for isolated galaxies. Thecandidates were chosen from the CfA catalog of galaxies within thevolume defined by cz ≤5000 km s-1, galactic latitudehigher than 40o and declination ≥-2.5o. Theselection of the sample, based on redshift values (when available),magnitudes and sizes of the candidate galaxies and possible perturberspresent in the same field is discussed. The final list of selectedisolated galaxies includes 203 objects from the initial 1706. The listcontains only truly isolated galaxies in the sense defined, but it is byno means complete, since all the galaxies with possible companions underthe f-criterion but with unknown redshift were discarded. We alsoselected a sample of perturbed galaxies comprised of all the diskgalaxies from the initial list with companions (with known redshift)satisfying f ≥ -2 and \Delta(cz) ≤500 km s-1; a totalof 130 objects. The statistical comparison of both samples showssignificant differences in morphology, sizes, masses, luminosities andcolor indices. Confirming previous results, we found that late spiral,Sc-type galaxies are, in particular, more frequent among isolatedgalaxies, whereas Lenticular galaxies are more abundant among perturbedgalaxies. Isolated systems appear to be smaller, less luminous and bluerthan interacting objects. We also found that bars are twice as frequentamong perturbed galaxies compared to isolated galaxies, in particularfor early Spirals and Lenticulars. The perturbed galaxies have higherLFIR/LB and Mmol/LB ratios,but the atomic gas content is similar for the two samples. The analysisof the luminosity-size and mass-luminosity relations shows similartrends for both families, the main difference being the almost totalabsence of big, bright and massive galaxies among the family of isolatedsystems, together with the almost total absence of small, faint and lowmass galaxies among the perturbed systems. All these aspects indicatethat the evolution induced by interactions with neighbors would proceedfrom late, small, faint and low mass Spirals to earlier, bigger, moreluminous and more massive spiral and lenticular galaxies, producing atthe same time a larger fraction of barred galaxies but preserving thesame relations between global parameters. The properties we found forour sample of isolated galaxies appear similar to those of high redshiftgalaxies, suggesting that the present-day isolated galaxies could bequietly evolved, unused building blocks surviving in low densityenvironments.Tables \ref{t1} and \ref{t2} are only available in electronic form athttp://www.edpsciences.org Infrared Observations of Galaxies in the Local Universe. II. 391 Calibrated Images with Photometric and Structural MeasurementsThis paper presents empirical results from a deep imaging survey ofgalaxies in the local universe at the J and Ks wavelengths.Three hundred ninety-one images have been obtained and calibrated usingthe same camera and filter set with the Steward Observatory 1.6 m KuiperTelescope on Mount Bigelow and the 2.3 m Bok Telescope on Kitt Peak. Thelimiting magnitude is typically 22 mag arcsec-1 at J and 21mag arcsec-1 at Ks. The central surfacebrightness, apparent magnitudes, sizes, scale lengths, and inclinationsare tabulated from measurements made using these data. The purpose ofthis paper is to provide basic near-infrared data on a variety of galaxytypes. Tidally Triggered Star Formation in Close Pairs of Galaxies. II. Constraints on Burst Strengths and AgesGalaxy-galaxy interactions rearrange the baryons in galaxies and triggersubstantial star formation; the aggregate effects of these interactionson the evolutionary histories of galaxies in the universe are poorlyunderstood. We combine B- and R-band photometry and optical spectroscopyto estimate the strengths and timescales of bursts of triggered starformation in the centers of 190 galaxies in pairs and compact groups.Based on an analysis of the measured colors and EW(Hα), wecharacterize the preexisting and triggered populations separately. Thebest-fitting burst scenarios assume stronger reddening corrections forline emission than for the continuum and continuous star formationlasting for >~100 Myr. The most realistic scenarios require aninitial mass function that is deficient in the highest mass stars. Thecolor of the preexisting stellar population is the most significantsource of uncertainty. Triggered star formation contributessubstantially (probably >~50%) to the R-band flux in the centralregions of several galaxies; tidal tails do not necessarily accompanythis star formation. Many of the galaxies in our sample have bluercenters than outskirts, suggesting that pre- or nonmerger interactionsmay lead to evolution along the Hubble sequence. These objects wouldappear blue and compact at higher redshifts; the older, redder outskirtsof the disks would be difficult to detect. Our data indicate thatgalaxies with larger separations on the sky contain weaker, and probablyolder, bursts of star formation on average. However, confirmation ofthese trends requires further constraints on the colors of the olderstellar populations and on the reddening for individual galaxies. A new catalogue of ISM content of normal galaxiesWe have compiled a catalogue of the gas content for a sample of 1916galaxies, considered to be a fair representation of normality''. Thedefinition of a normal'' galaxy adopted in this work implies that wehave purposely excluded from the catalogue galaxies having distortedmorphology (such as interaction bridges, tails or lopsidedness) and/orany signature of peculiar kinematics (such as polar rings,counterrotating disks or other decoupled components). In contrast, wehave included systems hosting active galactic nuclei (AGN) in thecatalogue. This catalogue revises previous compendia on the ISM contentof galaxies published by \citet{bregman} and \citet{casoli}, andcompiles data available in the literature from several small samples ofgalaxies. Masses for warm dust, atomic and molecular gas, as well asX-ray luminosities have been converted to a uniform distance scale takenfrom the Catalogue of Principal Galaxies (PGC). We have used twodifferent normalization factors to explore the variation of the gascontent along the Hubble sequence: the blue luminosity (LB)and the square of linear diameter (D225). Ourcatalogue significantly improves the statistics of previous referencecatalogues and can be used in future studies to define a template ISMcontent for normal'' galaxies along the Hubble sequence. The cataloguecan be accessed on-line and is also available at the Centre desDonnées Stellaires (CDS).The catalogue is available in electronic form athttp://dipastro.pd.astro.it/galletta/ismcat and at the CDS via anonymousftp to\ cdsarc.u-strasbg.fr (130.79.128.5) or via\http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/405/5 The UZC-SSRS2 Group CatalogWe apply a friends-of-friends algorithm to the combined Updated ZwickyCatalog and Southern Sky Redshift Survey to construct a catalog of 1168groups of galaxies; 411 of these groups have five or more members withinthe redshift survey. The group catalog covers 4.69 sr, and all groupsexceed the number density contrast threshold, δρ/ρ=80. Wedemonstrate that the groups catalog is homogeneous across the twounderlying redshift surveys; the catalog of groups and their membersthus provides a basis for other statistical studies of the large-scaledistribution of groups and their physical properties. The medianphysical properties of the groups are similar to those for groupsderived from independent surveys, including the ESO Key Programme andthe Las Campanas Redshift Survey. We include tables of groups and theirmembers. Lick Observatory Photographic Supernova SpectraSeventy-eight photographic spectra of 18 bright supernovae that wereobtained by various observers at the Lick Observatory between 1937 and1971 are presented and briefly discussed. Microphotometer transmissiontracings of the photographic plates have been digitized and plotted on acommon scale with a linear wavelength axis. The spectra were prismatic,with a nonlinear dispersion, in their original form. These spectra areuseful for classification purposes and for comparative studies of theblueshifts of absorption features. Nearby Optical Galaxies: Selection of the Sample and Identification of GroupsIn 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 GalaxiesWe 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. Galaxy coordinates. II. Accurate equatorial coordinates for 17298 galaxiesUsing images of the Digitized Sky Survey we measured coodinates for17298 galaxies having poorly defined coordinates. As a control, wemeasured with the same method 1522 galaxies having accurate coordinates.The comparison with our own measurements shows that the accuracy of themethod is about 6 arcsec on each axis (RA and DEC). Infrared Observations of Galaxies in the Local Universe. I. The Survey and Some Representative ResultsThis paper introduces a continuing survey of galaxies in the localuniverse. Consistent deep images are being acquired for a representativesample of 321 galaxies in the Uppsala General Catalogue down to 21.7 magarcsec-2 at Ks (2.16 mu m) and 22.4 mag arcsec-2 at J (1.25 mu m) usinga NICMOS camera with a 3.'8 x 3.'8 field of view attached to the 61 inch(1.5 m) telescope on Mount Bigelow. We provide some examples of theresults being obtained by employing 64 deep images of a subset of 44galaxies. Bulge-to-disk ratios are tabulated for 30 galaxies. Thebrightness of the central region of 44 galaxies declines approximately 5mag from Hubble type S0 to Sm. An exponential vertical scale height atKs is found to be 500 pc for the disk of UGC 5173. Arm amplitudes offour nearly face-on spiral galaxies are found to range between 11% and88% compared to the interarm region. There is some evidence that the armamplitude is larger at Ks than it is at J. Color gradients are measuredfor 15 galaxies with only one showing a significant nonzero result. Ameasurement of galactic symmetry applied to 64 deep images reveals anaverage asymmetry of 7.6% ( sigma = 4.6%) for these galaxies. Peculiar Velocities for Galaxies in the Great Wall.II.AnalysisWe analyze the peculiar velocity field in the vicinity of the Great Wall(GW) using a sample of 172 spiral galaxies with reliable IRTF distanceestimates (Dell'Antonio et al. 1996). We examine three main issues: (1)the infall onto the GW, (2) large-scale flow, and (3) shear. We use aMonte Carlo method to remove selection-based biases from the peculiarvelocity sample. For the GW sample, the velocity bias is small (<150km s^-1^). We use the bias-corrected velocities to constrain the infalltowards the Great Wall. We thus have the first limits on the truespatial thickness of this structure. The data are best fit by an infallvelocity <= 150 km s^-1^. The 90% upper limit on the mean infallvelocity is ~500 km s^-1^. Consequently, the upper limit on thereal-space full width of the GW is d<11.2h^-1^ Mpc. Thus, the GreatWall is a thin, two- dimensional structure in real space as well as inredshift space. We calculate the best-fit estimate of the motion of theLocal Group with respect to the galaxy distribution: ν_flow_ ~725+/-400 km s^-1^ towards a 11.7 +/- 1.5 hr, δ =36.8deg^+/-55^deg^. Because our δ constraints are quiteweak, this flow is consistent with the CMB dipole (Smoot et al. 1992)and with the flow vector of Riess et al. (1995). The data are alsoconsistent at the 25% confidence level with the direction of large-scaleflow reported by Lauer & Postman (1994). We calculate theimprovement in sensitivity expected for a sample extending over the fulldeclination range of the GW. We also calculate the shear across theright ascension range of the GW. The GW region is quiet: the detectedthe shear across the range of the GW is -70+/-210 km s^-1^. The absenceof large shear constrains the amplitude of large-scale densityfluctuations (Feldman & Watkins 1995). 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. Observational status and excitation mechanisms of beta-Cephei variables.Not Available A CCD survey of galaxies. II. Observations with the 2.1 M telescope at San Pedro MartirAs a part of a CCD survey of galaxies belonging or projected onto theComa and Hercules Superclusters and to the A262, Virgo and Cancerclusters, we present isophote maps and photometric profiles of 87galaxies (85 taken with the V, 25 with the B and 3 with the U Johnsonfilters). For the objects in common we compare our results with those inthe RC3. The velocity field of clusters of galaxies within 100 megaparsecs. II - Northern clustersDistances and peculiar velocities for galaxies in eight clusters andgroups have been determined by means of the near-infrared Tully-Fisherrelation. With the possible exception of a group halfway between us andthe Hercules Cluster, we observe peculiar velocities of the same orderas the measuring errors of about 400 km/s. The present sample is drawnfrom the northern Galactic hemisphere and delineates a quiet region inthe Hubble flow. This contrasts with the large-scale flows seen in theHydra-Centaurus and Perseus-Pisces regions. We compare the observedpeculiar velocities with predictions based upon the gravity fieldinferred from the IRAS redshift survey. The differences between theobserved and predicted peculiar motions are generally small, except neardense structures, where the observed motions exceed the predictions bysignificant amounts. Kinematic models of the velocity field are alsocompared with the data. We cannot distinguish between parameterizedmodels with a great attractor or models with a bulk flow. General study of group membership. II - Determination of nearby groupsWe 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. Galaxies possibly resembling M82-type galaxiesA list of 298 galaxies with possible features of M82 galaxies ispresented. This list contains those Irr II candidates whose images onPalomar photographs shown no trace of dust although the objects are redand suspected to be peculiar. KISO survey for ultraviolet-excess galaxies. X.Presented here are the tenth list and identification charts of theultraviolet-excess galaxies which have been detected on the multi-colorplates taken with the Kiso Schmidt telescope for 10 survey fields. Inthe sky area of some 300 square degrees 490 objects are catalogued downto the photographic magnitude of about 18. Near-infrared observations of galaxies in the Coma superclusterNear-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. Radio-continuum survey of the Coma/A1367 supercluster. IV - 1.4 GHz observations of CGCG galaxies1.4 GHz radio-continuum observations of 148 CGCG galaxies in the Comasupercluster region were obtained with the VLA in C array configuration.Comparison with previous measurements at 0.6 GHz leads to an averagespectral index of 0.8. The structures of 29 galaxies in this regiondetermined with high-resolution VLA (A array) observations arepresented. A VLA 20 CM survey of poor groups of galaxiesThe paper reports on VLA 20 cm observations of an extensive sample ofgalaxies in 139 poor groups. These groups, composed of galaxies down tothe limit of the Zwicky et al. (CGCG) catalog, were chosen using apercolation algorithm set at a high surface-density threshold.Approximately 50 percent of the groups have measured redshifts. Thesegroups were surveyed using a 'snapshot' mode of the VLA with aresolution of about 13 arcsec. Analysis of the resulting radio andoptical properties reveals that the presence of a nearby companiongalaxy has an important role in generating radio emission in a galaxy.CCD observations of two radio-loud, disturbed galaxies with companionsare presented and are used to discuss models of radio-source production.Nine tailed radio galaxies are found in the poor groups, which is muchmore than had been expected from previous work on rich clusters and fromtheoretical models. The paper discusses previous statistical biases andproposes a method for bending head-tail sources in poor groups. From theconfinement of extended radio features associated with tailed sources,the presence of a substantial intracluster medium that should radiatesignificantly at soft-X-ray energies is predicted. The NGC 4005 group - A rotating system of galaxies?H I line observations with the Arecibo 305 m telescope were made of 23galaxies within a 7 square degree region centered on the NGC 4005 group,a system of galaxies located in Zw 127-10. Accurate radial velocitiesand direct mass estimates derived from the 21 cm line profiles of thegalaxies in this region are reported. A systematic trend in the radialvelocities is found along the major axis of the NGC 4005 group. Thiscorrelation between position and velocity is fitted to a simple linearregression relation with a slope significantly different from zero. Oneexplanation for this effect is that the NGC 4005 group is rotating witha period no longer than four billion yr. Other possible interpretationsof this systematic effect are discussed. The mass of the group isestimated by applying the harmonic law, the virial theorem, and theprojected mass method. The masses obtained from the three methods areall consistent. Radio continuum survey of the Coma/A1367 supercluster. I - 610 MHz observations of CGCG galaxies in four groupsRadio continuum observations obtained with the Westerbork RadioSynthesis Telescope (WSRT) at 0.6 GHz of four groups of galaxies in theComa/A1367 supercluster area are presented. Ninety-nine CGCG galaxieswere surveyed, yielding the detection of 21 objects. A wide-angle-tailradio galaxy, NGC 4061, in the NGC 4065 group is found. Analysis of thissource suggests a relatively low value (n(e) T approximately 1000 per cucm K) for the intracluster gas pressure in this group.
Submit a new article