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Публикации по объекту
Structural Parameters of Thin and Thick Disks in Edge-on Disk Galaxies
We analyze the global structure of 34 late-type, edge-on, undisturbed,disk galaxies spanning a wide range of mass. We measure structuralparameters for the galaxies using two-dimensional least-squares fittingto our R-band photometry. The fits require both a thick and a thin diskto adequately fit the data. The thick disks have larger scale heightsand longer scale lengths than the embedded thin disks by factors of ~2and ~1.25, respectively. The observed structural parameters agree wellwith the properties of thick and thin disks derived from star counts inthe Milky Way and from resolved stellar populations in nearby galaxies.We find that massive galaxies' luminosities are dominated by the thindisk. However, in low-mass galaxies (Vc<~120 kms-1) thick disk stars contribute nearly half the luminosityand dominate the stellar mass. Thus, although low-mass dwarf galaxiesappear blue, the majority of their stars are probably quite old.Our data are most easily explained by a formation scenario in which thethick disk is assembled through direct accretion of stellar materialfrom merging satellites while the thin disk is formed from accreted gas.The baryonic fraction in the thin disk therefore constrains the gasrichness of the merging pregalactic fragments. If we include the mass inH I as part of the thin disk, the thick disk contains <~10% of thebaryons in high-mass galaxies and ~25%-30% of the baryons in low-massgalaxies. Our data, therefore, indicate that the fragments were quitegas rich at the time of merging (fgas=75%-90%). However,because low-mass galaxies have a smaller fraction of baryons in theirthin disks, the pregalactic fragments from which they assembled musthave been systematically more gas poor. We believe this trend resultsfrom increased outflow due to supernova-driven winds in the lower masspregalactic fragments. We estimate that ~60% of the total baryonic massin these systems was lost due to outflows. Pushing the episode ofsignificant winds to early times allows the mass-metallicityrelationship for disks to be established early, before the main disk isassembled, and obviates the difficulty in driving winds from diffusedisks with low star formation efficiencies. We discuss otherimplications of this scenario for solving the G dwarf problem, forpredicting abundance trends in thick disks, and for removingdiscrepancies between semianalytic galaxy formation models and theobserved colors of low-mass galaxies.
| Structure and kinematics of edge-on galaxy discs - V. The dynamics of stellar discs
In earlier papers in this series we determined the intrinsic stellardisc kinematics of 15 intermediate- to late-type edge-on spiral galaxiesusing a dynamical modelling technique. The sample covers a substantialrange in maximum rotation velocity and deprojected face-on surfacebrightness, and contains seven spirals with either a boxy orpeanut-shaped bulge. Here we discuss the structural, kinematical anddynamical properties. From the photometry we find that intrinsicallymore flattened discs tend to have a lower face-on central surfacebrightness and a larger dynamical mass-to-light ratio. This observationsuggests that, at a constant maximum rotational velocity, lower surfacebrightness discs have smaller vertical stellar velocity dispersions.Although the individual uncertainties are large, we find from thedynamical modelling that at least 12 discs are submaximal. The averagedisc contributes 53 +/- 4 per cent to the observed rotation at 2.2 discscalelengths (hR), with a 1σ scatter of 15 per cent.This percentage becomes somewhat lower when effects of finite discflattening and gravity by the dark halo and the gas are taken intoaccount. Since boxy and peanut-shaped bulges are probably associatedwith bars, the result suggests that at 2.2hR the submaximalnature of discs is independent of barredness. The possibility remainsthat very high surface brightness discs are maximal, as these discs areunderrepresented in our sample. We confirm that the radial stellar discvelocity dispersion is related to the galaxy maximum rotationalvelocity. The scatter in this σ versus vmax relationappears to correlate with the disc flattening, face-on central surfacebrightness and dynamical mass-to-light ratio. Low surface brightnessdiscs tend to be more flattened and have smaller stellar velocitydispersions. The findings are consistent with the observed correlationbetween disc flattening and dynamical mass-to-light ratio and cangenerally be reproduced by the simple collapse theory for disc galaxyformation. Finally, the disc mass Tully-Fisher relation is offset fromthe maximum-disc scaled stellar mass Tully-Fisher relation of the UrsaMajor cluster. This offset, -0.3 dex in mass, is naturally explained ifthe discs of the Ursa Major cluster spirals are submaximal.
| Computing 2D images of 3D galactic disk models.
Not Available
| Haloes around edge-on disc galaxies in the Sloan Digital Sky Survey
We present a statistical analysis of halo emission for a sample of 1047edge-on disc galaxies imaged in five bands by the Sloan Digital SkySurvey (SDSS). Stacking the homogeneously rescaled images of thegalaxies, we can measure surface brightnesses as deep asμr~ 31 mag arcsec-2. The results stronglysupport the almost ubiquitous presence of stellar haloes around discgalaxies, whose spatial distribution is well described by a power lawρ~r-3, in a moderately flattened spheroid (c/a~ 0.6). Thecolour estimates in g-r and r-i, although uncertain, give a clearindication for extremely red stellar populations, hinting at old agesand/or non-negligible metal enrichment. These results support the ideaof haloes being assembled via early merging of satellite galaxies.
| The Stellar Disk Thickness of Low Surface Brightness Galaxies
We present surface photometry results for a sample of 11 edge-ongalaxies observed with the 6 m telescope at the Special AstrophysicalObservatory, Russia. The photometric scale length, scale height, andcentral surface brightness of the stellar disks of our sample galaxiesare estimated. We show that four galaxies in our sample, which arevisually classified as objects of the lowest surface brightness class inthe Revised Flat Galaxy Catalog, have bona fide low surface brightness(LSB) disks. We find from a comparison of photometric scales that thestellar disks of LSB galaxies are thinner than those of high surfacebrightness (HSB) galaxies. There is a clear correlation between thecentral surface brightness of the stellar disk and itsvertical-to-radial scale ratio. The masses of spherical subsystems (darkhalo + bulge) and the dark halo masses are obtained for the samplegalaxies based on the thickness of their stellar disks. The LSB galaxiestend to harbor more massive spherical subsystems than the HSB objects,whereas no systematic difference in the dark halo masses is foundbetween LSB and HSB galaxies. At the same time, the inferredmass-to-luminosity ratio for the LSB disks appears to be systematicallyhigher than for HSB disks.
| Thick disks of lenticular galaxies. 3D-photometric thin/thick disk decomposition of eight edge-on s0 galaxies
Thick disks are faint and extended stellar components found aroundseveral disk galaxies including our Milky Way. The Milky Way thick disk,the only one studied in detail, contains mostly old disk stars (≈10Gyr), so that thick disks are likely to trace the early stages of diskevolution. Previous detections of thick disk stellar light in externalgalaxies have been originally made for early-type, edge-on galaxies butdetailed 2D thick/thin disk decompositions have been reported for only ascant handful of mostly late-type disk galaxies. We present in thispaper for the first time explicit 3D thick/thin disk decompositionscharacterising the presence and properties (e.g. scalelength andscaleheight) for a sample of eight lenticular galaxies by fitting 3Ddisk models to the data. For six out of the eight galaxies we were ableto derive a consistent thin/thick disk model. The mean scaleheight ofthe thick disk is 3.6 times larger than that of the thin disk. Thescalelength of the thick disk is about twice, and its central luminositydensity between 3-10% of, the thin disk value. Both thin and thick diskare truncated at similar radii. This implies that thick disks extendover fewer scalelengths than thin disks, and turning a thin disk into athick one requires therefore vertical but little radial heating. Allthese structural parameters are similar to thick disk parameters forlater Hubble-type galaxies previously studied. We discuss our data inrespect to present models for the origin of thick disks, either as pre-or post-thin-disk structures, providing new observational constraints.Based on observations obtained at the European Southern Observatory,Chile.Full appendices are only available in electronic form athttp://www.edpsciences.org
| A catalog of warps in spiral and lenticular galaxies in the Southern hemisphere
A catalog of optical warps of galaxies is presented. This can beconsidered complementary to that reported by Sánchez-Saavedra etal. (\cite{sanchez-saavedra}), with 42 galaxies in the northernhemisphere, and to that by Reshetnikov & Combes(\cite{reshetnikov99}), with 60 optical warps. The limits of the presentcatalog are: logr 25 > 0.60, B_t< 14.5, delta (2000) <0deg, -2.5 < t < 7. Therefore, lenticular galaxies havealso been considered. This catalog lists 150 warped galaxies out of asample of 276 edge-on galaxies and covers the whole southern hemisphere,except the Avoidance Zone. It is therefore very suitable for statisticalstudies of warps. It also provides a source guide for detailedparticular observations. We confirm the large frequency of warpedspirals: nearly all galaxies are warped. The frequency and warp angle donot present important differences for the different types of spirals.However, no lenticular warped galaxy has been found within the specifiedlimits. This finding constitutes an important restriction fortheoretical models.
| The New Galaxy: Signatures of Its Formation
The formation and evolution of galaxies is one of the great outstandingproblems of astrophysics. Within the broad context of hierachicalstructure formation, we have only a crude picture of how galaxies likeour own came into existence. A detailed physical picture whereindividual stellar populations can be associated with (tagged to)elements of the protocloud is far beyond our current understanding.Important clues have begun to emerge from both the Galaxy (near-fieldcosmology) and the high redshift universe (far-field cosmology). Here wefocus on the fossil evidence provided by the Galaxy. Detailed studies ofthe Galaxy lie at the core of understanding the complex processesinvolved in baryon dissipation. This is a necessary first step towardachieving a successful theory of galaxy formation.
| 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.
| A Catalog of H I-Selected Galaxies from the South Celestial Cap Region of Sky
The first deep catalog of the H I Parkes All Sky Survey (HIPASS) ispresented, covering the south celestial cap (SCC) region. The SCC areais ~2400 deg2 and covers δ<-62°. The average rmsnoise for the survey is 13 mJy beam-1. Five hundredthirty-six galaxies have been cataloged according to their neutralhydrogen content, including 114 galaxies that have no previous catalogedoptical counterpart. This is the largest sample of galaxies from a blindH I survey to date. Most galaxies in optically unobscured regions of skyhave a visible optical counterpart; however, there is a small populationof low-velocity H I clouds without visible optical counterparts whoseorigins and significance are unclear. The rms accuracy of the HIPASSpositions is found to be 1.9′. The H I mass range of galaxiesdetected is from ~106 to ~1011 Msolar.There are a large number of late-type spiral galaxies in the SCC sample(66%), compared with 30% for optically selected galaxies from the sameregion in the NASA Extragalactic Database. The average ratio of H I massto B luminosity of the sample increases according to optical type, from1.8 Msolar/Lsolar for early types to 3.2Msolar/Lsolar for late-type galaxies. The HI-detected galaxies tend to follow the large-scale structure traced bygalaxies found in optical surveys. From the number of galaxies detectedin this region of sky, we predict the full HIPASS catalog will contain~5000 galaxies, to a peak flux density limit of ~39 mJy (3 σ),although this may be a conservative estimate as two large voids arepresent in the region. The H I mass function for this catalog ispresented in a subsequent paper.
| Outer edges of face-on spiral galaxies. Deep optical imaging of NGC 5923, UGC 9837 and NGC 5434
We present deep optical imaging of three face-on disk galaxies togetherwith a detailed description of the reduction and calibration methodsused, in order to measure the intrinsic shape of their outer stellaredges. Whereas it is now well accepted that disks of spiral galaxies arenot infinite exponential beyond galactocentric distances of about 3-5radial scalelengths, the genuine structure of the truncation region isnot yet well known. Our data quantitatively establish a smoothtruncation behaviour of the radial surface brightness profiles and isbest described by a two-slope model, characterised by an inner and outerexponential scalelength separated at a relatively well defined breakradius. This result disagrees with the frequently assumed sharplytruncated nature of the radial surface brightness profiles and impliesthe presence of stars and even star-formation beyond the break radius.In addition, we do not find a strong influence of a nearby companion onthe ratio of the break radius to the radial scalelength. Our resultsdenote new observational constraints for the search of the physicalexplanation for these smooth disk truncations. Based on observationsobtained at the German-Spanish Astronomical Center (DSAZ), Calar Alto,jointly operated by the Max-Planck-Institut für AstronomieHeidelberg and the Spanish National Commission for Astronomy.
| Warps and correlations with intrinsic parameters of galaxies in the visible and radio
From a comparison of the different parameters of warped galaxies in theradio, and especially in the visible, we find that: a) No large galaxy(large mass or radius) has been found to have high amplitude in thewarp, and there is no correlation of size/mass with the degree ofasymmetry of the warp. b) The disc density and the ratio of dark toluminous mass show an opposing trend: smaller values give moreasymmetric warps in the inner radii (optical warps) but show nocorrelation with the amplitude of the warp; however, in the externalradii is there no correlation with asymmetry. c) A third anticorrelationappears in a comparison of the amplitude and degree of asymmetry in thewarped galaxies. Hence, it seems that very massive dark matter haloeshave nothing to do with the formation of warps but only with the degreeof symmetry in the inner radii, and are unrelated to the warp shape forthe outermost radii. Denser discs show the same dependence.
| Kinematics and dynamics of the ``superthin'' edge-on disk galaxy IC 5249
We present spectroscopic observations of the stellar motions in the diskof the superthin edge-on spiral galaxy IC 5249 and re-analyse synthesisobservations of the HI. We find that the HI rotation curve risesinitially to about 90-100 km s-1, but contrary to theconclusion of Abe et al. (\cite{Abe99}) flattens well before the edge ofthe optical disk. Over most part of the optical disk we have been ableto establish that the (tangential) stellar velocity dispersion is 25-30km s-1. We argue that the central light concentration in thedisk is not a bulge in the classical Population II sense, but mostlikely represents structure in the disk component. From earlier surfacephotometry we adopt a value for the radial scalelength of the disk of 7+/- 1 kpc, a vertical scaleheight of 0.65 +/- 0.05 kpc and a disktruncation radius of 17 +/- 1 kpc. The HI disk has a measurablethickness but from our analysis we conclude that this is due to a smallinclination away from perfectly edge-on. The very thin appearance of IC5249 on the sky is the result of a combination of a low (face-on)surface brightness, a long scalelength and a a sharp truncation at onlyabout 2.5 scalelengths. In terms of the ratio of the radial scalelengthand the vertical scaleheight of the disk, IC 5249 is not very flat; infact it is slightly fatter than the disk of our Galaxy. From variousarguments we derive the stellar velocity dispersions at a position oneradial scalelength out in the disk (R ~ 7 kpc) as respectively sigmaR ~ 35 km s-1, sigma theta ~ 30 kms-1 and sigma z ~ 20 km s-1. This iscomparable to the values for the disk of our Galaxy in the solarneighborhood. Near the edge of the disk the ratio of radial to verticalvelocity dispersion is probably higher. Presumably the angular momentumdistribution of the gas that formed the disk in IC 5249 was such that,compared to the Galaxy, a much more extended distribution resulted inspite of the lower overall rotation and mass. The low surface densitythat arose from that resulted in a thicker HI layer in which starformation proceeded at a much slower rate, but disk heating proceeded ata similar pace.
| A list of peculiar velocities of RFGC galaxies
A list of radial velocities, HI line widths and peculiar velocities of1327 galaxies from the RFGC catalogue has been compiled using actualobservations and literature data. The list can be used for studying bulkmotions of galaxies, construction of the field of peculiar velocitiesand other tasks.
| Box- and peanut-shaped bulges. I. Statistics
We present a classification for bulges of a complete sample of ~ 1350edge-on disk galaxies derived from the RC3 (Third Reference Catalogue ofBright Galaxies, de Vaucouleurs et al. \cite{rc3}). A visualclassification of the bulges using the Digitized Sky Survey (DSS) inthree types of b/p bulges or as an elliptical type is presented andsupported by CCD images. NIR observations reveal that dust extinctiondoes almost not influence the shape of bulges. There is no substantialdifference between the shape of bulges in the optical and in the NIR.Our analysis reveals that 45% of all bulges are box- and peanut-shaped(b/p). The frequency of b/p bulges for all morphological types from S0to Sd is > 40%. In particular, this is for the first time that such alarge frequency of b/p bulges is reported for galaxies as late as Sd.The fraction of the observed b/p bulges is large enough to explain theb/p bulges by bars. Partly based on observations collected at ESO/LaSilla (Chile), DSAZ/Calar Alto (Spain), and Lowell Observatory/Flagstaff(AZ/U.S.A.). Tables 6 and 7 are only available in electronic form at CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| 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).
| Properties of the Stellar Velocity Ellipsoid and Stability in Disks of Spiral Galaxies
Disks of spiral galaxies are characterized by effectively exponentialbrightness and presumably density distributions in both the radial andvertical directions. It is to be expected that the ratio between thescalelength and -height bears a relation to the axis ratio of thestellar velocity ellipsiod. Hydrostatic equilibrium connects thevertical velocity dispersion to the scaleheight. In the radial directionthe velocity dispersion relates to the scalelength through conditions oflocal stability. Preliminary applications are presented.
| On the Origin of the Hubble Sequence
I discuss some items which may be relevant to the origin of the Hubblesequence. The emphasis is on the broad properties of disk galaxies. Themain topics include the structure and dynamics of dark halos, theformation of large and small bulges, and some brief comments about disksand S0 galaxies.
| The Extraordinary ``Superthin'' Spiral Galaxy UGC 7321. I. Disk Color Gradients and Global Properties from Multiwavelength Observations
We present B- and R-band optical imaging and photometry, Hαnarrowband imaging, near-infrared H-band imaging, and H I 21 cmspectroscopy of the nearby (Vh=407 km s-1), Sdspiral galaxy UGC 7321. UGC 7321 exhibits a remarkably thin stellar diskwith no discernible bulge component. The galaxy has a very diffuse, lowsurface brightness disk, which appears to suffer relatively littleinternal extinction in spite of its nearly edge-on geometry(i~88deg). If seen face-on, UGC 7321 would have an observedcentral B-band surface brightness of only ~23.4 mag arcsec-2.The UGC 7321 disk shows significant B-R color gradients in both theradial and vertical directions: Δ(B-R)>=0.80 mag along thegalaxy major axis, and Δ(B-R) as large as 0.45 mag is observedparallel to the galaxy minor axis. These color gradients cannot beexplained solely by dust and are indicative of changes in the mix ofstellar ages and/or metallicity as a function of both radius and heightabove the galaxy plane. The outer regions of the UGC 7321 disk are tooblue to be explained by low metallicity alone (B-R<=0.6) and must berelatively young. However, the galaxy also contains stellar populationswith B-R>1.1, indicating it is not a young or recently formed galaxy.The disk of UGC 7321 is not a simple exponential but exhibits a lightexcess at small radii, as well as distinct surface brightness zones.Despite its organized disk structure, many of the global properties ofUGC 7321 (MB=-17.0 MHI=1.1x109MHI/LB=1.1 Msolar/LsolarW20=233 km s-1 hr=2.1 kpc) arereminiscent of a dwarf galaxy. Together the properties of UGC 7321 implythat it is an underevolved galaxy in both a dynamical and in a starformation sense.
| Observation of the Halo of the Edge-On Galaxy IC 5249
Optical photometry and H I synthesis observations of the southernedge-on Sc/Sd galaxy IC 5249 are reported. The rotation curve riseslinearly out to a radius of 7 kpc and then appears to flatten out at~100 km s^-1. The H I mass out to 24.5 kpc is ~6x10^9 M_solar, or 10% ofthe total mass out to this radius. The color, central surfacebrightness, scale height, and scale length of the disk of IC 5249 areR-I~0.4, mu=20.6+/-0.1R_C mag arcsec^-2, 600+/-40 pc, and 11+/-2 kpc,respectively. Additional light to that predicted by an exponential diskis present at distances greater than 3 kpc from the disk. At 5 kpc thesurface brightness is 27-28R_C mag arcsec^-2. The measured distributionof surface brightness is used to constrain the abundance of low-massmain-sequence stars in the halo of the galaxy. A halo made up entirelyof main-sequence stars heavier than 0.13 M_solar is excluded. We alsofind that less than 20% of the halo can be composed of main-sequencestars heavier than 0.30 M_solar. Further observations are required todetermine the rotation curve of IC 5249 to large radii and to determineprecisely the abundance of low-mass main-sequence stars in the halo ofthe galaxy.
| 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.
| 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 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.
| Galaxy properties in different environments. 1: The sample
This paper presents two galaxy samples, respectively in a high and in alow local density environments, that were generated from the SouthernSky Redshift Survey (SSRS) catalog using objective criteria. Apreliminary comparison of physical properties in these two samplesreveals that galaxies in high-density environments tend to be under ahigher starbursting activity, have a deficiency of the neutral hydrogencontent, present a higher fractional Seyfert population and a higherfraction of barred spirals as well. The present samples are intended tobe used in future spectroscopic observations for more detailedinvestigation.
| 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.
| 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.
| 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.
| Southern Galaxy Catalogue.
Not Available
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