Contents
Images
Upload your image
DSS Images Other Images
Related articles
The Effects of Interactions on the Structure and Morphology of Elliptical/Lenticular Galaxies in Pairs
We present a structural and photometric analysis of 42elliptical/lenticular galaxies in E/S0 + S pairs observed in the BVRIcolor bands. The aim of the analysis is to empirically determine theeffects of interactions on the galaxies' morphology, structure, andstellar populations as seen from the CAS parameters (light concentrationC, asymmetry A, and clumpiness S). We further compare these values to acontrol sample of 67 mostly isolated noninteracting E/S0 galaxies. Wefind that the paired E/S0 galaxies occupy more scattered loci in CASspace than noninteracting E/S0s and that the structural effects ofinteractions on E/S0s are minor, in contrast to disk galaxies involvedin interactions. This suggests that observational methods forrecognizing interactions, such the CAS methodology of Conselice, wouldnot detect E/S0s involved in interactions (related to early phases ofthe so-called dry mergers), and that the majority of interactinggalaxies identified at high redshift must be gas-dominated systems.However, we find statistical differences in the asymmetry index whencomparing isolated and interacting E/S0s. On average, paired E/S0galaxies have A-values 2.96+/-0.72 times larger than those ofnoninteracting E/S0s. For the subset of presumably strongly interactingE/S0s, A and S can be several times larger than the typical values ofthe isolated E/S0s. We show that the asymmetries are consistent withseveral internal and external morphological distortions. We concludethat the subsample of interacting E/S0s should be dense, gas-poorgalaxies in systems spanning a wide range of interaction stages, withtypical merging timescales >~0.1-0.5 Gyr. We use the observedphenomenology of this subsample to predict the approximate loci of drypremergers in the CAS parameter space.
| BVRI Surface Photometry of Mixed Morphology Pairs of Galaxies. III. The Third Data Set
This is the third of a series of papers devoted to the study of thephotometric properties of spiral and elliptical galaxies in interactingpairs. We report broad band (BVRI) total magnitudes, as well as surfacebrightness, color and geometric (ɛ = 1 - b/a, PA, anda4/a) profiles for a sample of 10 mixed morphology (E/S0+S)pairs drawn from the Karachentsev Catalogue of Isolate Pairs of Galaxies(KPG). Most of the objects reported here have their photometricparameters derived for the first time. Surface photometry in combinationwith image processing and color diagrams are useful to test andreevaluate the morphological classification of each galaxy in thesepairs. We find 5 true (E+S) pairs in the present sample, 4lenticular-spiral (S0+S) systems and 1 spiral-spiral (S+S) pair. Wefound no clear evidence of a Holmberg effect in our sample of mixedpairs. The existence of a large number of isolated (E+S) pairs (50% in our sample) rises interesting questions for models of galaxyformation.
| The KPNO International Spectroscopic Survey. IV. Hα-selected Survey List 2
The KPNO International Spectroscopic Survey (KISS) is an objective-prismsurvey for extragalactic emission-line objects. It combines many of thefeatures of previous slitless spectroscopic surveys with the advantagesof modern CCD detectors and is the first purely digital objective-prismsurvey for emission-line galaxies. Here we present the second list ofemission-line galaxy candidates selected from our red spectral data,which cover the wavelength range 6400 to 7200 Å. In most cases,the detected emission line is Hα. The current survey list covers a1.6d-wide strip located at δ=43°30' (B1950) and spans theright ascension range 11h55m to16h15m. The survey strip runs through the centerof the Bootes void and has enough depth to adequately sample the farside of the void. An area of 65.8 deg2 is covered. A total of1029 candidate emission-line objects have been selected for inclusion inthe survey list (15.6 deg-2). We tabulate accuratecoordinates and photometry for each source, as well as estimates of theredshift and emission-line flux and equivalent width based onmeasurements of the digital objective-prism spectra. The properties ofthe KISS emission-line galaxies are examined using the availableobservational data. Although the current survey covers only a modestfraction of the total volume of the Bootes void, we catalog at least 12objects that appear to be located within the void. Only one of theseobjects has been recognized previously as a void galaxy.
| Properties of isolated disk galaxies
We 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
| Tidally Triggered Star Formation in Close Pairs of Galaxies. II. Constraints on Burst Strengths and Ages
Galaxy-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.
| Multiwavelength Insights into Mixed-Morphology Binary Galaxies. I. ISOCAM, ISOPHOT, and Hα Imaging
We present Hα and ISO mid- and far-IR observations for a sample ofmixed-morphology galaxy pairs that reveal both the stellar andnonstellar signatures of the interaction process. A mixed-morphologypair is perhaps the simplest form of galaxy-galaxy interaction becauseit is expected to involve only a single rapidly rotating gas-richcomponent paired with a gas-poor elliptical or lenticular galaxy. Aprimary assumption that we address is whether spirals are the only IRemitter in these mixed (E+S) pairs. Our observations reveal that many ofthe early-type galaxies exhibit weak (low equivalent width) emission, asoften observed in field elliptical galaxies. These are the classicalmixed-morphology pairs. However, some of the early-type components,especially the lenticular galaxies, show evidence for significant starformation, with Hα equivalent widths and 15 μm luminositiescomparable to or exceeding those of their often much larger spiralcompanions. Our sample contains five Seyfert 2 nuclei, of which threecan be described as companions on the end of a spiral arm. The Seyfertnucleus is often accompanied by a starburst region, while other suchcompanions currently show only the starburst component. These pairs areamong the best candidates for direct interaction fuelling of bothstarbursts and active galactic nuclei.Based on observations with the Infrared Space Observatory (ISO), an ESAproject with instruments funded by ESA Member States (especially the PIcountries: France, Germany, the Netherlands and the United Kingdom) withthe participation of ISAS and NASA.
| The UZC-SSRS2 Group Catalog
We 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.
| Neutral hydrogen and optical observations of edge-on galaxies: Hunting for warps
We present 21-cm HI line and optical R-band observations for a sample of26 edge-on galaxies. The HI observations were obtained with theWesterbork Synthesis Radio Telescope, and are part of the WHISP database(Westerbork HI Survey of Spiral and Irregular Galaxies). We present HImaps, optical images, and radial HI density profiles. We have alsoderived the rotation curves and studied the warping and lopsidedness ofthe HI disks. 20 out of the 26 galaxies of our sample are warped,confirming that warping of the HI disks is a very common phenomenon indisk galaxies. Indeed, we find that all galaxies that have an extendedHI disk with respect to the optical are warped. The warping usuallystarts around the edge of the optical disk. The degree of warping variesconsiderably from galaxy to galaxy. Furthermore, many warps areasymmetric, as they show up in only one side of the disk or exhibitlarge differences in amplitude in the approaching and receding sides ofthe galaxy. These asymmetries are more pronounced in rich environments,which may indicate that tidal interactions are a source of warpasymmetry. A rich environment tends to produce larger warps as well. Thepresence of lopsidedness seems to be related to the presence of nearbycompanions. Full Fig. 13 is only available in electronic form athttp://www.edpsciences.org
| 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 130.79.128.5 orhttp://cdsweb.u-strasbg.fr/Abstract.html
| 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.
| A catalogue of spatially resolved kinematics of galaxies: Bibliography
We present a catalogue of galaxies for which spatially resolved data ontheir internal kinematics have been published; there is no a priorirestriction regarding their morphological type. The catalogue lists thereferences to the articles where the data are published, as well as acoded description of these data: observed emission or absorption lines,velocity or velocity dispersion, radial profile or 2D field, positionangle. Tables 1, 2, and 3 are proposed in electronic form only, and areavailable from the CDS, via anonymous ftp to cdsarc.u-strasbg.fr (to130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html
| Kinematical Observations of a Sample of Binary Galaxies
Not Available
| The fundamental plane of early-type galaxies: stellar populations and mass-to-light ratio.
We analyse the residuals to the fundamental plane (FP) of ellipticalgalaxies as a function of stellar-population indicators; these are basedon the line-strength parameter Mg_2_ and on UBVRI broad-band colors, andare partly derived from new observations. The effect of the stellarpopulations accounts for approximately half the observed variation ofthe mass-to-light ratio responsible for the FP tilt. The residual tiltcan be explained by the contribution of two additional effects: thedependence of the rotational support, and possibly that of the spatialstructure, on the luminosity. We conclude to a constancy of thedynamical-to-stellar mass ratio. This probably extends to globularclusters as well, but the dominant factor would be here the luminositydependence of the structure rather than that of the stellar population.This result also implies a constancy of the fraction of dark matter overall the scalelength covered by stellar systems. Our compilation ofinternal stellar kinematics of galaxies is appended.
| The reality of anomalous redshifts in the spectra of some QSOs and its implications.
The evidence for the physical association of close pairs involvingbright QSOs with large redshifts and bright nearby galaxies with smallredshifts, is reviewed and, in Table 1, a list of the best cases isgiven. It is shown that in a series of statistical studies usingcatalogs of QSOs and catalogs of galaxies, very strong correlations ofhigh redshift radio QSOs have been found successively with (o) [a.] TheShapley Ames Catalog of the brightest galaxies. Here the correlation iswith powerful radio QSOs with S>=9Jy (0.4GHz). The result issignificant at the 7-10σ level. (o) [b.] The Bright Galaxy Catalog(z<=0.05). Here the QSO sample is dominated by radio emitting QSOs,largely identified from the 3CR, Molonglo, Parkes, and 4C radiocatalogs. (o) [c.] The galaxies in the Lick Catalog (m<~17,z<~0.2). Again the sample of QSOs is a radio sample. (o) [d.] TheIRAS galaxy catalogs, where some fraction of the galaxies may have z upto 0.4, and where a few galaxies may be identical in position with theQSOs, but where the larger fraction have much smaller redshifts than theQSOs. Again the QSO sample is a radio sample. (o) [e.] Finally strongcorrelations on scales <~10' have been found between opticallybright, high redshift radio loud QSOs and the diffuse X-ray emissionseen by ROSAT. Bartelmann et al. (1994) believe that this diffuse X-rayemission is due to galaxy clusters at redshifts significantly less thanthe observed redshifts of the QSOs.
| Gaseous and stellar components in mixed pairs of galaxies. I. The data.
Isolated mixed morphology pairs are composed of an early and a late typegalaxy. They are an ideal laboratory for studying the response of gas toa gravitational instability. We present data from a kinematic andphotometric study of six mixed pairs. High resolution rotation andvelocity dispersion curves, for both gas and stellar components, arepresented. Slit orientations were along the major axis of the spiraland, in most of the cases, along the line connecting the galaxy nuclei.B and V luminosity and geometrical profiles are also presented.Photometric parameters including effective radius and disk scale lengthare also presented. Data on the [N II](6583)/Hα emission lineratio provide a further insight into physical conditions of the gas.Half of the early-type components show lenticular morphology involving awell defined disk. Most late-type components show Grand Design spiralstructure. Rotation curves of both members appear normal along the axesstudied. The nuclear region of NGC 5297 is the single case where thegaseous component shows evidence for an apparent counter rotationrelative to the stellar component, probably due to the presence of abar. There is evidence in the early type member NGC 5953, and possiblyalso in NGC 5296, that the gas component has been acquired from thespiral member of the pair. The gas in these objects is concentrated innuclear star forming regions as deduced from (B-V) color. This may beevidence for mass transfer induced activity (cross-fuelling) in thesepairs. The nuclear gas in NGC 5297, 6962 and E 297-G-8 shows a reversalof the [N II] to Hα emission line intensity ratio. This indicatoralong with the [O III](5007)/Hβ ratio suggests that these nucleishow low level (LINER) activity.
| 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.
| HI observations of galaxies in nearby Zwicky clusters
The results of a long term project of H I observations of galaxieswithin the boundaries of nearby Zwicky clusters are presented. Thedetection rate is rather low (233 out of 618, i.e., 38 percent) ascompared to other surveys carried out recently. Most of the radialvelocities of the detected galaxies are new determinations. The largespread in radial velocities for many of these clusters is a strongindication for the presence of several foreground and/or backgroundgalaxies.
| Imaging of the NGC 5296/7 system
The large spiral galaxy NGC 5297 has a small elliptical companion, NGC5296, with a much smaller, much higher-redshift galaxy nearby and aquasar farther off in the same direction. This system has been claimedas a strong argument in favor of noncosmological redshifts (Arp 1976,1987), especially as the unnamed galaxy shows signs of being silhouettedin front of NGC 5296. CCD images in B, V and H-alpha passbands (1)support the presence of extended material around the main galaxies; (2)deny the reality of the claimed silhouetting; but (3) reveal that NGC5296 is an unusual galaxy, with a bright off-center very red 'secondarynucleus'.
| Associations between quasi-stellar objects and galaxies
A table is presented here listing all close pairs of QSOs and galaxiesthat were found in a computer-aided search of catalogs of QSOs andbright galaxies and an extensive search of the literature. There is alarge excess of pairs with separations of 2 arcmin lor less, or about 60kpc, over the numbers expected if the configurations were accidental.The angular separation for 392 pairs adds to the evidence for physicalassociation, and it is shown that selection effects are not important. Ageneral rule is stated that QSOs tend to lie in the vicinity of normalgalaxies much more often than is expected by chance whether or not thegalaxies and the QSOs have the same redshifts. It is emphasized thatthis rule cannot be explained in terms of gravitational microlensing,and it is concluded that some part of the redshift of all classes ofactive nuclei is not associated with the expansion of the universe.
| Quasar redshifts and nearby galaxies
Results of a statistical investigation are presented showing thatquasars close on the sky to bright galaxies show a stronger tendency togroup around certain redshifts than do quasars in general. Theseparticular redshifts form a series with a distance between consecutivepeaks of 0.089 in log(1+z) (the matematical solution discovered byKarlsson, 1971, 1973, 1977). The difference between quasars close tonearby galaxies and other quasars was found to persist when differentsamples of QSOs close to galaxies were compared to their respective'parent populations' (i.e., all known quasars found by the same method).It is concluded that there might exist different types of quasars.
| Observations requiring a non-standard approach
Six different lines of evidence that quasars are much closer than theirredshift distances are presented. The evidence concerns multiple quasarsassociated with nearby galaxies, quantization of quasar redshifts,single quasars associated with nearby galaxies, quasars visiblyconnected to no galaxies, and galaxies with many associated quasars.Evidence is reviewed that many galaxies have small, non-Dopplercomponents of redshift and that the more a galaxy resembles a quasar,the greater the nonvelocity redshift it usually has.
| Individual and orbital masses of double galaxies
A list is given of individual estimates of the masses of 124 componentsof isolated pairs of galaxies from Turner's catalog for which there arepublished data on the velocity dispersions in the central parts of thegalaxies, on the width of the 21-cm radio line profile, and on theamplitude of the rotation curve of the galaxies. From the comparison ofthe orbital estimates of the mass with the sum of the individual massesof the double galaxies it is concluded that the bulk of the mass of thegalaxies is situated within their standard optical diameter A(25). Theconsidered observational data for the Turner galaxy pairs do not containany arguments for the hypothesis of massive halos. Good agreementbetween the orbital and individual estimates of the mass is observed foralmost circular motions of the galaxies in pairs with mean orbitaleccentricity 0.25.
| H I line studies of galaxies. IV - Distance moduli of 468 disk galaxies
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985A&AS...59...43B&db_key=AST
| Double galaxies - Redshift measurements, error analysis, and mean mass/luminosity ratio
New radial velocities for 44 double galaxy systems are presented. Theratio k between the internal and external errors in the redshift data isestimated by comparing data from catalog galaxies with a sample fromWhite et al. (1983). This ratio is found to increase from 1.0 to 2.1from galaxies with strong emission lines to absorption-line objects. Thedisparity between the absolute and internal errors diminishes for theredshift differentials of pair components, because the individual errorsin the redshifts measured for the members of a given pair are observedto be positively correlated. The average value of k for the whole sampleis estimated by considering the values of the first four moments of themass/luminosity ratio as functions of k. The absolute error in theredshift differential is 1.4 times the internal error, bringing the meanratio of orbital mass to luminosity for 490 pairs into good agreementwith the values determined from the differential rotation of galaxies.
| Observational tests of QSO amplification by condensed objects in galactic halos.
Not Available
| A quasar near a companion galaxy, NGC 5296
An inspection of National Geographic-Palomar Sky Atlas prints revealed aspiral galaxy NGC 5297 and a smaller companion galaxy NGC 5296. A quasarof redshift 0.963 was spectroscopically determined to be in the vicinityof the companion galaxy. In addition, deep photographic plates of thesystem obtained later revealed a luminous extension from the companionpointing to the quasar. A compact, disturbed galaxy of redshift 25,900km/s (that of the other two galaxies is about 2500 km/s) was found to beinteracting with NGC 5296.
| Binary galaxie. I. A well-defined statistical sample.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976ApJ...208...20T&db_key=AST
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
Catalogs and designations:
|
