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|Flat Galaxies of the RFGC Catalog Detected in the HIPASS Survey|
Data from the H I Parkes All-Sky Survey (HIPASS) of the southern sky inthe neutral hydrogen line are used to determine the radial velocitiesand widths of the H I line for flat spiral galaxies of the RevisedFlat-Galaxy Catalog (RFGC) seen edge-on. The sample of 103 flat galaxiesdetected in HIPASS is characterized by a median radial velocity of +2037km/sec and a median width of the H I line at the level of 50% of maximumof 242 km/sec. For RFGC galaxies the 50% detection level in HIPASScorresponds to an apparent magnitude B t = 14 m .5 or an angulardiameter a = 2.9. The relative number of detected galaxies increasesfrom 2% for the morphological types Sbc and Sc to 41% for the type Sm.The median value of the ratio of hydrogen mass to total mass for RFGCgalaxies is 0.079. With allowance for the average internal extinctionfor edge-on galaxies, B t m .75, the median ratio of hydrogen mass toluminosity, M H I/L B = 0.74 M ȯ/L ȯ, is typical for late-typespirals. Because of its small depth, HIPASS reveals only a few RFGCgalaxies with previously unknown velocities and line widths.
|The Mass of the Centaurus A Group of Galaxies|
The mass M and the radius Rh of the Centaurus A group areestimated from the positions and radial velocities of 30 probablecluster members. For an assumed distance of 3.9 Mpc, it is found thatRh~640 kpc. The velocity dispersion in the Cen A group is114+/-21 km s-1. From this value and Rh=640 kpc,the virial theorem yields a total mass of 1.4x1013Msolar for the Cen A group. The projected mass method gives amass of 1.8x1013 Msolar. These values suggest thatthe Cen A group is about 7 times as massive as the Local Group. The CenA mass-to-light ratio is found to be M/LB=155-200(M/L)solar. The cluster has a zero-velocity radiusR0=2.3 Mpc.
|Surface BR Photometry of Newly Discovered Dwarf Elliptical Galaxies in the Nearby Sculptor and Centaurus A Groups|
Prompted by the recent finding of a large number of gas-rich dwarfirregular galaxies in the nearby southern galaxy groups Sculptor (Scl)and Centaurus A (Cen A) we carried out a complementary survey to searchfor members of the gas-poor dwarf elliptical (dE) galaxy family. Intotal 18 dE candidates were identified on SRC Sky Survey films coveringthe group regions. For five dE's in the Scl group and five in the Cen Agroup, membership information is available from surface brightnessfluctuations distance measurements; two dEs in each group also haveindependent redshift measurements. The remaining eight galaxies havebeen associated to the groups based on their morphology. We acquireddeep B- and R-band CCD images for all galaxies and determined theirphotometric and structural parameters. According to the magnitude rangecovered, -14
|Testing the Surface Brightness Fluctuations Method for Dwarf Elliptical Galaxies in the Centaurus A Group|
We have obtained deep B and R-band CCD photometry for five dwarfelliptical galaxies that were previously identified on Schmidt filmscovering the region of the Centaurus A (Cen A) group. From a Fourieranalysis of the R-band CCD images we determined the surface brightnessfluctuation (SBF) magnitude mR for each stellar system. Allmagnitudes are similar, and, given the small color spread, they suggestthat these low surface brightness galaxies lie approximately at the samedistance, regardless of the assumed SBF zero point. Long-slit spectrahave been acquired to derive redshifts for two of the dwarfs, ESO269-066 and ESO 384-016. The velocities, vsolar=784 kms-1 and vsolar=561 km s-1,respectively, identify them unambiguously as Cen A group members. An age(HδA)-metallicity(C2λ4668) analysis of the spectra reveals anunderlying old and metal-poor stellar population in both cases.Combining photometric and spectroscopic results we find strong evidencethat indeed all dwarf galaxies are Cen A group members. Based onCepheid, TRGB, and PNLF distances published for the two main Cen A groupgalaxies, NGC 5128 and NGC 5253, we adopted a mean group distance of3.96 Mpc to calibrate the apparent fluctuation magnitudes. The resultingabsolute SBF magnitudes MR of the dEs correlate with thedereddened colors (B-R)0 as predicted by Worthey's stellarsynthesis models, using the theoretical isochrones of Bertelli andcollaborators. This good agreement allows a calibration of the SBFmethod for dwarf ellipticals in the color range0.8<(B-R)0<1.5. However, two branches of stellar populationsappear in the MR-color plane, and care has to be taken todecide which branch applies to a given observed dwarf. For dwarfs with(B-R)0<1 there is very little color dependence(MR~-1.2), in accord with our previous SBF analysis of faint,blue Sculptor group dEs. For red dwarfs, (B-R)0>1.2, theMR-color relation is steep, and accurate colors are needed toachieve SBF distances with an uncertainty of only 10%. One of thedwarfs, ESO 219-010, is located slightly behind the core of the Cen Agroup at about 4.8 Mpc, while the remaining four recover the mean groupdistance of 3.96 Mpc that was put into the calibration. The depth of thegroup is only 0.5 Mpc, which identifies the Cen A group as a spatiallywell-isolated galaxy aggregate, in contrast to the nearby Sculptorgroup.
|The QDOT all-sky IRAS galaxy redshift survey|
We describe the construction of the QDOT survey, which is publiclyavailable from an anonymous FTP account. The catalogue consists ofinfrared properties and redshifts of an all-sky sample of 2387 IRASgalaxies brighter than the IRAS PSC 60-μm completeness limit(S_60>0.6Jy), sparsely sampled at a rate of one-in-six. At |b|>10deg, after removing a small number of Galactic sources, the redshiftcompleteness is better than 98per cent (2086/2127). New redshifts for1401 IRAS sources were obtained to complete the catalogue; themeasurement and reduction of these are described, and the new redshiftstabulated here. We also tabulate all sources at |b|>10 deg with noredshift so far, and sources with conflicting alternative redshiftseither from our own work, or from published velocities. A list of 95ultraluminous galaxies (i.e. with L_60μm>10^12 L_solar) is alsoprovided. Of these, ~20per cent are AGN of some kind; the broad-lineobjects typically show strong Feii emission. Since the publication ofthe first QDOT papers, there have been several hundred velocity changes:some velocities are new, some QDOT velocities have been replaced by moreaccurate values, and some errors have been corrected. We also present anew analysis of the accuracy and linearity of IRAS 60-μm fluxes. Wefind that the flux uncertainties are well described by a combination of0.05-Jy fixed size uncertainty and 8per cent fractional uncertainty.This is not enough to cause the large Malmquist-type errors in the rateof evolution postulated by Fisher et al. We do, however, find marginalevidence for non-linearity in the PSC 60-μm flux scale, in the sensethat faint sources may have fluxes overestimated by about 5per centcompared with bright sources. We update some of the previous scientificanalyses to assess the changes. The main new results are as follows. (1)The luminosity function is very well determined overall but is uncertainby a factor of several at the very highest luminosities(L_60μm>5x10^12L_solar), as this is where the remainingunidentified objects are almost certainly concentrated. (2) Thebest-fitting rate of evolution is somewhat lower than our previousestimate; expressed as pure density evolution with density varying as(1+z)^p, we find p=5.6+/-2.3. Making a rough correction for the possible(but very uncertain) non-linearity of fluxes, we find p=4.5+/-2.3. (3)The dipole amplitude decreases a little, and the implied value of thedensity parameter, assuming that IRAS galaxies trace the mass, isΩ=0.9(+0.45, -0.25). (4) Finally, the estimate of density varianceon large scales changes negligibly, still indicating a significantdiscrepancy from the predictions of simple cold dark matter cosmogonies.
|The Revised Flat Galaxy Catalogue.|
We present a new improved and completed version of the Flat GalaxyCatalogue (FGC) named the Revised Flat Galaxy Catalogue (RFGC)containing 4236 thin edge-on spiral galaxies and covering the whole sky.The Catalogue is intended to study large-scale cosmic streamings as wellas other problems of observational cosmology. The dipole moment ofdistribution of the RFGC galaxies (l = 273 degr; b =+19 degr) lieswithin statistical errors (+/-10 degr) in the direction of the LocalGroup motion towards the Microwave Background Radiation (MBR).
|New Galaxies Discovered in the First Blind H I Survey of the Centaurus A Group|
We have commenced a 21 cm survey of the entire southern sky(δ<0^deg, -1200 km s^-1-13.0), low surface brightness dwarf galaxies with H I profileline-widths suggestive of dynamics dominated by dark matter. The newgroup members add approximately 6% to the H I mass of the group and 4%to its light. The H I mass function, derived from all the known groupgalaxies in the interval 10^7 M_solar
|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 18.104.22.168 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.
|Ionised hydrogen at large galactocentric distances|
We summarize recent attempts to detect warm ionized gas at largegalactocentric distances. This includes searching for gas at the edgesof spirals, in between cluster galaxies, towards extragalactic HIclouds, and towards high velocity clouds and the Magellanic Stream inthe Galaxy. With the exception of extragalactic HI clouds, all of theseexperiments have proved successful. Within each class, we have onlyobserved a handful of objects. It is premature to assess what fractionof the missing baryonic mass fraction might be in the form of ionizedgas. But, in most cases, the detections provide a useful constraint onthe ambient ionizing flux, and in the case of spiral edges, can eventrace dark matter halos out to radii beyond the reach of radiotelescopes.
|Luminous Infrared Galaxies. II. NGC 4945: A Nearby Obscured Starburst/Seyfert Nucleus|
We have studied the physical conditions, reddening, and kinematics inthe nuclear and circumnuclear regions of the luminous IR source NGC4945. The I-band image shows a wide cone of radiation that emerges fromthe partially obscured nuclear region. The H alpha + [N II] imagereveals an extended nuclear region located at the same position as theI-band nucleus. Two extended filaments emerge from this region as well.Aperture optical spectroscopy of the nuclear region shows strongreddening in the continuum, and only the blends H alpha + [N II] and [SII] appear in emission. The long-slit spectroscopy at P.A. = 90 deg,coincident with the main H alpha filament, shows in the nuclear region aweak [O I] LINER or weak [O III] Seyfert spectrum and blueshifted broadcomponents in the [N II] and [S II] lines that are probably associatedwith superwinds. The velocity curve (at P.A. = 90 deg) is clearlyasymmetric, with the mean velocity shifted toward the obscured nuclearregion.
|Discovery of Numerous Dwarf Galaxies in the Two Nearest Groups of Galaxies.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....114.1313C&db_key=AST
|Massive Star Formation Along the Hubble Sequence|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....113..599D&db_key=AST
|Candidates for a southern extension of the Karachentsev catalogue of isolated pairs of galaxies.|
|Flat galaxy catalogue|
A systematic search for disklike edge-on-galaxies with a diameter largerthan a = 40 arcsec and a major-to-minor axis ratio a/b greater than 7was carried out by means of the Palomar Observatory Sky Survey and theESO/SERC survey. As a result, we present a new catalog of flat galaxies(FGC) containing 4455 objects and covering about 56 percent of the wholesky for the first time. The catalogue is assigned to study large-scalecosmic streamings and other problems of observational cosmology.
|On the central surface brightness problem in disk galaxies|
We have measured the diameters of a large number of disk galaxies onvarious Sky Surveys in order to examine the problem of the apparentuniformity of the central surface brightness in disk galaxies. From theratio of diameters on the various surveys we find that at least 55percent of the disk galaxies follow this rule. Another 26 percent of thegalaxies have only a very modest increase in diameters on the SRC-Jsurvey when compared to the Palomar survey prints, indicating thepresence of a cutoff in the outer disk. Nineteen percent of the galaxiesmeasured have a large increase in diameter. From their integrated H Iprofiles, these turn out to be mostly dynamically giant galaxies.Several examples are shown. The phenomenon of low surface brightnessextensions is greatly reduced for galaxies in the Virgo cluster. Fromfollow-up observations we conclude that the low surface brightnessgiants contain only about half the amount of luminous material as do'normal' spiral galaxies following the 21.65 law.
|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.
|Distribution and motions of atomic hydrogen in lenticular galaxies. X - The blue S0 galaxy NGC 5102|
Results of the mapping of the blue gas-rich S0 galaxy NGC 5102 in the21-cm H I line with a spatial resolution of 34 x 37 arcsec (delta(alpha)x Delta(delta)) and a velocity resolution of 12 km/s are presented. TheH I distribution has a pronounced central depression of 1.9 kpc radius,and most of the H I is concentrated in a 3.6 kpc wide ring with anaverage radius of 3.7 kpc, assuming a distance of 4 Mpc for NGC 5102.The maximum azimuthally averaged H I surface density in the ring is 1.4solar mass/sq pc, comparable to that found in other S0 galaxies. The HIvelocity field is quite regular, showing no evidence for large-scaledeviations from circular rotation, and the H I is found to rotate in theplane of the stellar disk. Both the H I mass/blue luminosity ratio andthe radial H I distribution are similar to those in early-type spirals.The H I may be an old disk or it may have been acquired through captureof a gas-rich smaller galaxy. The recent starburst in the nuclearregion, which gave the galaxy its blue color, may have been caused bypartial radial collapse of the gas disk, or by infall of a gas-richdwarf galaxy.
|Galaxy shredding. I - Centaurus A, NGC 5237, and the Fourcade-Figueroa shred|
Numerical simulations of galaxy shredding are presented together with acase study of the nearby active galaxy Centaurus A. It is suggested thata shred-forming encounter with a spiral galaxy (about the same size asthe Milky Way) took place some 5 x 10 exp 8 yr ago. The captured diskmaterial now forms the conspicuous ring of gas and dust which girdlesCentaurus A, and probably provides the fuel that powers the radioemission seen today. The present shredding model provides a consistentpicture of many aspects of the Centaurus A system, including: therelative positions and velocities of Centaurus A, NGC 5237, and theFourcade-Figueroa shred; the orientation and sense of rotation of thedust lane in Centaurus A; the peculiar nature of the interacting dwarfelliptical galaxy NGC 5237; and the orientation and observed nonrotationof the Fourcade-Figueroa shred.
|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.
|The supergalactic plane redshift survey|
Redshift measurements, about 1000 of which are new, are presented for1314 galaxies in a survey toward the apex of the large-scale streamingflow for ellipticals. The velocity histogram shows that the excess ingalaxy number counts in this area is due to a substantial concentrationof galaxies with discrete peaks at V about 3000 km/s and V about 4500km/s. After correction for the sampling function, the centroid of thedensity distribution is found to be near V about 4500 km/s.Normalization to the more extensive SSRS survey, which was selected bythe same criteria, shows that the region studied contains a considerableoverdensity of galaxies from 2000 to 6000 km/s. This result is in goodagreement with the 'great attractor' model suggested by Lynden-Bell etal. (1988) which attributes the peculiar motions of elliptical galaxiesover a large region of space to an extensive mass overdensity whichincludes the Hydra-Centaurus and Pavo-Indus superclusters. The centroidof the density enhancement is also consistent with new data by Dresslerand Faber (1990) of peculiar motions of elliptical and spiral galaxies,both of which show a zero crossing of the Hubble line at approximately4500-5000 km/s.
|Thin edge-on galaxies as a tool for the investigation of large-scale streaming motions in the universe|
A sample of 324 galaxies observed at Arecibo is used to demonstrate thatthin edge-on galaxies can be used to study large-scale streaming motionsin the universe. It is found that the scatter of galaxies in theTully-Fisher (TF) diagram steadily decreases when the axial ratio a/bincreases, and that for the flattest and most inclined galaxies (a/b ofgreater than 7), the scatter in the TF diagram yields a rms error indistance estimates of 10 exp + or - 0.09. A proposed catalogue of flatgalaxies is described.
|A catalog of IRAS observations of large optical galaxies|
A catalog is presented of IRAS observations of 85 galaxies withblue-light isophotal diameters greater than 8 arcmin. The observations,data processing, and data measurement techniques are described, andtotal IRAS flux densities and integrated infrared emission properties ofthe sample are reported. Infrared brightness profiles of the detectedgalaxies and infrared surface brightness contour maps of the galaxiesfor which structural features were resolved are displayed. Aclassification scheme based on the degree of central concentration andspatial structure of the 60 micron emission of the best-resolvedgalaxies is proposed. The 60 micron and blue-light isophotal diametersof the largest galaxies are compared.
|Southern Galaxy Catalogue.|
|Is there a unique relation between absolute (blue) luminosity and total 21 CM linewidth of disk galaxies?|
Twenty-one-cm line observations for a sample of 130 galaxies in nearbygroups and in the Virgo cluster were used together with well-establishedvalues from the literature for a discussion of the blue Tully-Fisherrelation (TFR). Known distances of galaxies from the local group and theM81 group were used to calibrate the zeropoint of the TFR. Within theobservational errors the slope of the TFR was the same for the wholesample, and was only weakly dependent on: (1) the correction used forinternal extinction in the galaxies and (2) the inclusion of a galaxiantype dependence of the TFR. The correlation coefficients between theslope of the TFR and the distance moduli are significant and alwayspositive; distances derived via the TFR do depend on the adopted slope.Known H I profiles of Virgo cluster galaxies were used to check fordifferences in the TFR between group and cluster galaxies. The resultingdistance of the Virgo cluster is 24.0 + or - 3.3 Mpc.
|Distance of M83 and of the Centaurus group|
The distances of eight probable or possible bright members of theCentaurus group of galaxies are derived from secondary and tertiaryindicators and from redshifts. The best determined distance is that ofM83, and this group centered at supergalactic coordinates L = 154 degand B = -2 deg covers an elongated area parallel to the supergalacticplane, and has a depth of approximately 2 Mpc in the line of sight. TheFourcade-Figueroa galaxy is probably a background object and theCircinus galaxy is probably a field galaxy, but additional membersbetween it and the group may be hidden near the galactic plane. Thevelocity dispersion may be interpreted as evidence for stability (boundgroup) or instability (expanding association or accidental grouping).The presence of three early-type systems in a group dominated bylate-type spirals and magellanic irregulars is unusual and suggestive ofa chance encounter.
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