תוכן
תמונות
הוסף תמונה שלך
DSS Images Other Images
מאמרים קשורים
The connection between shear and star formation in spiral galaxies
We present a sample of 33 galaxies for which we have calculated (i) theaverage rate of shear from published rotation curves, (ii) thefar-infrared luminosity from IRAS fluxes, and (iii) theKs-band luminosity from the Two Micron All Sky Survey(2MASS). We show that a correlation exists between the shear rate andthe ratio of the far-infrared to Ks-band luminosity. Thisratio is essentially a measure of the star formation rate per unit mass,or the specific star formation rate. From this correlation we show thata critical shear rate exists, above which star formation would turn offin the discs of spiral galaxies. Using the correlation between shearrate and spiral arm pitch angle, this shear rate corresponds to thelowest pitch angles typically measured in near-infrared images of spiralgalaxies.
| M/L, Hα Rotation Curves, and H I Measurements for 329 Nearby Cluster and Field Spirals. I. Data
A survey of 329 nearby galaxies (redshift z<0.045) has been conductedto study the distribution of mass and light within spiral galaxies overa range of environments. The 18 observed clusters and groups span arange of richness, density, and X-ray temperature and are supplementedby a set of 30 isolated field galaxies. Optical spectroscopy taken withthe 200 inch (5 m) Hale Telescope provides separately resolved Hαand [N II] major-axis rotation curves for the complete set of galaxies,which are analyzed to yield velocity widths and profile shapes, extents,and gradients. H I line profiles provide an independent velocity widthmeasurement and a measure of H I gas mass and distribution. I-bandimages are used to deconvolve profiles into disk and bulge components,to determine global luminosities and ellipticities, and to checkmorphological classification. These data are combined to form a unifieddata set ideal for the study of the effects of environment upon galaxyevolution.
| A Dynamical Study of Galaxies in the Hickson Compact Groups
To investigate dynamical properties of spiral galaxies in the Hicksoncompact groups (HCGs), we present rotation curves of 30 galaxies in 20HCGs. We found as follows: (1) There is no significant relation betweendynamical peculiarity and morphological peculiarity in HCG spiralgalaxies. (2) There is no significant relation between the dynamicalproperties and the frequency distribution of nuclear activities in HCGspiral galaxies. (3) There are no significant correlations between thedynamical properties of HCG spiral galaxies and any group properties(i.e., size, velocity dispersion, galaxy number density, and crossingtime). (4) Asymmetric and peculiar rotation curves are more frequentlyseen in the HCG spiral galaxies than in field spiral galaxies or incluster ones. However, this tendency is more obviously seen in late-typeHCG spiral galaxies. These results suggest that the dynamical propertiesof HCG spiral galaxies do not strongly correlate with the morphology,the nuclear activity, and the group properties. Our results also suggestthat more frequent galaxy collisions occur in the HCGs than in the fieldand in the clusters.
| Arcsecond Positions of UGC Galaxies
We 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.
| The I-Band Tully-Fisher Relation for SC Galaxies: Optical Imaging Data
Properties derived from the analysis of photometric I-band imagingobservations are presented for 1727 inclined spiral galaxies, mostly oftypes Sbc and Sc. The reduction, parameter extraction, and errorestimation procedures are discussed in detail. The asymptotic behaviorof the magnitude curve of growth and the radial variation in ellipticityand position angle are used in combination with the linearity of thesurface brightness falloff to fit the disk portion of the profile. TotalI-band magnitudes are calculated by extrapolating the detected surfacebrightness profile to a radius of eight disk scale lengths. Errors inthe magnitudes, typically ~0.04 mag, are dominated by uncertainties inthe sky subtraction and disk-fitting procedures. Comparison is made withthe similar imaging database of Mathewson, Ford, & Buchhorn, both aspresented originally by those authors and after reanalyzing theirdigital reduction files using identical disk-fitting procedures. Directcomparison is made of profile details for 292 galaxies observed incommon. Although some differences occur, good agreement is found,proving that the two data sets can be used in combination with onlyminor accommodation of those differences. The compilation of opticalproperties presented here is optimized for use in applications of theTully-Fisher relation as a secondary distance indicator in studies ofthe local peculiar velocity field.
| Kinematics of the local universe. VII. New 21-cm line measurements of 2112 galaxies
This paper presents 2112 new 21-cm neutral hydrogen line measurementscarried out with the meridian transit Nan\c cay radiotelescope. Amongthese data we give also 213 new radial velocities which complement thoselisted in three previous papers of this series. These new measurements,together with the HI data collected in LEDA, put to 6 700 the number ofgalaxies with 21-cm line width, radial velocity, and apparent diameterin the so-called KLUN sample. Figure 5 and Appendices A and B forcorresponding comments are available in electronic form at thehttp://www.edpsciences.com
| Near-infrared surface photometry of early-type spiral galaxies. I. Bulge and disk decomposition
We present near-infrared (NIR) surface photometry of a sample of 14early-type spirals with observed rotation curves. In this first paper,we report the results of two-dimensional parametric and non-parametricdecompositions to separate the bulge and disk components; the parametricbulge is modeled with a generalized exponential law of integer index n,and the disk with a simple exponential. We find that the derived bulgeparameters, for a given galaxy, vary systematically with the bulge shapeindex n. The mean early-type bulge has a best-fit n = 2.6, and 80% ofthe sample has best n of 2 or 3. Bulges are rarely spherical; the medianbulge intrinsic ellipticity is 0.33. The median early-type disk has(J-K)_d more than 0.1 mag bluer than the bulge, and a NIR disk surfacebrightness more than 1 mag arcsec(-2) brighter than later-type disks.Our data are consistent with the well-established correlation of bothbulge and disk surface brightness with physical scale length, and wenote that the location of bulges within this projection of thefundamental plane depends on their shape index n. In agreement withprevious work, the ratios of bulge and disk scale lengths are consistentwith a constant value r_e/r_d = 0.3; however, such value again dependson the bulge index n, implying that claims for a scale-free Hubblesequence may be premature. Based on observations taken at TIRGO(Gornergrat, Switzerland). TIRGO is operated by CAISMI--CNR, Arcetri,Firenze, Italy.
| 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
| Near-infrared surface photometry of early-type spiral galaxies. II. M/L ratios and dark halos
We present mass distributions obtained from near-infrared (NIR) surfacebrightness decompositions and rotation curve fitting of a sample ofearly-type spiral galaxies. Bulge and disk mass-to-light (M/L) ratios,dark halo parameters, and the modified Newtonian dynamics (MOND)acceleration parameter are derived. We find that the mean disk NIR M/Lis higher than that of the bulge, and comparison with stellar populationsynthesis models implies that early-type spiral bulges are, on average,younger and more metal rich than disks. NIR disk M/L is found to dependon disk luminosity, consistently with previously reported trends inellipticals and spirals, and with cold dark matter models for diskformation. Within the optical radius, the mean ratio of stellar to darkmatter is 2 and the typical dark halo mass is 10(11) M_sun. The value ofthe MOND acceleration parameter that best accommodates the sample as awhole is 1.3*10(-8) cm s(-2) . Based on observations taken at TIRGO(Gornergrat, Switzerland). TIRGO is operated by CAISMI--CNR, Arcetri,Firenze, Italy
| 21 CM H1 Line Spectra of Galaxies in Nearby Clusters
A compilation of HI line fluxes, systemic velocities and line widths ispresented for \Ndet detected galaxies, mostly in the vicinities of 30nearby rich clusters out to a redshift of z ~ .04, specifically for usein applications of the Tully-Fisher distance method. New 21 cm HI lineprofiles have been obtained for ~ 500 galaxies in 27 Abell clustersvisible from Arecibo. Upper limits are also presented for \Nnod galaxiesfor which HI emission was not detected. In order to provide ahomogeneous line width determination optimized for Tully-Fisher studies,these new data are supplemented by the reanalysis of previouslypublished spectra obtained both at Arecibo and Green Bank that areavailable in a digital archive. Corrections for instrumental broadening,smoothing, signal-to-noise and profile shape are applied, and anestimate of the error on the width is given. When corrected forturbulent broadening and viewing angle, the corrected velocity widthspresented here will provide the appropriate line width parameter neededto derive distances via the Tully-Fisher relation.
| Large-Scale Structure at Low Galactic Latitude
We have extended the CfA Redshift Survey to low galactic latitudes toinvestigate the relation between the Great Wall in the North GalacticCap and the Perseus-Pisces chain in the South Galactic Cap. We presentredshifts for 2020 galaxies in the Catalogue of Galaxies and of Clustersof Galaxies (Zwicky et al. 1961-68, CGCG) in the following regions: 4^h^<= α <= 8^h^, 17^h^ <= α <= 20^h^, 0^deg^ <=δ <= 45^deg^. In these regions, the redshift catalogue includes1664 galaxies with B(0) <= 15.5 (of which 820 are newly measured) andis 97% complete. We also include redshifts for an additional 356galaxies in these regions with B(O) > 15.5; of these, 148 werepreviously unmeasured. The CGCG samples the galaxy distribution down tob_II_ = 10^deg^. In this paper, we discuss the acquisition and reductionof the spectra, and we examine the qualitative features of the redshiftdistribution. The Great Wall and the Perseus-Pisces chain are not simplyconnected across the Zone of Avoidance. These structures, which at firstappear to be coherent on scales of ~100 h^-1^ Mpc or more, actually formthe boundaries of neighboring voids of considerably smaller scale,approximately 50h^-1^ Mpc. The structures delineated by ouroptically-selected sample are qualitatively similar to those detected bythe far-infrared-selected IRAS 1.2 Jansky Survey (Fisher et al. 1995).Although the IRAS survey probes more deeply into the Zone of Avoidance,our optically-selected survey provides better sampling of structures atb_II_ >= 10^deg^.
| Near-Infrared Low-Resolution Mapping of Early-Type Spirals
We present low-resolution near-infrared (NIR: J,H,K) radial brightnessand color profiles of a sample of eight early-type spirals. Thebrightness distribution was sampled along the major axis by shifting afixed 28" aperture in steps of 14" using a single-element InSbphotometer. We first examine the J- H and H- K radial profiles: (i)there is no evidence for large-scale radial gradients in the NIR colors;(ii) the distribution of (central) colors is remarkably tight, withstandard deviation of ~0.05 mag; (iii) NIR colors do not show any cleardependence on galaxy inclination; (iv) H- K colors are similar to thoseobserved in late-type spirals, while J - H is significantly redder.Second, we fit a composite model of bulge+ disk to the radial brightnessprofiles. In the cases where the decomposition is successful we findthat: (i) bulge-to- disk ratios tend to be higher than at opticalwavelengths; (ii) disk scale lengths are shorter than in the optical, aswe previously observed in a sample of Sc spirals; (iii) early-typespiral disks tend to be brighter, in terms of central surfacebrightness, than those of later types; (iv) by comparing our NIR bulgeeffective brightness with the optical one, as measured by other authors,we derive quite red colors, r - J~2. Third, we calculate NIRmass-to-light (M/L) ratios for the central regions. When compared withthose for a sample of Sc's studied in a previous paper, Sa's tend tohave smaller NIR M/L ratios than Sc's, at least in their centralregions. We attribute these properties to the presence of a metal-richbulge population combined with the effect of extinction for which weinfer an average value τ_B_(0) ~ 3. Finally, we find significantcorrelations of J - K with both central and total mass content,confirming that metallicity is mainly governed by galaxy mass.
| Optical and I-band surface photometry of spiral galaxies. I. The data.
We present V- and I-band CCD surface photometry on 234 inclined Sa-Sdgalaxies, completed by similar data in B and R for a reduced subsample.In this first paper of a series, the reduction of the data is discussed,and several comparisons are made with other recent works. Radialprofiles are presented for the surface brightness and thecharacteristics of ellipses fitted to isophotes; global, effective, andisophotal parameters are listed. All the results are available inelectronic form.
| 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.
| A Catalog of Stellar Velocity Dispersions. II. 1994 Update
A catalog of central velocity dispersion measurements is presented,current through 1993 September. The catalog includes 2474 measurementsof 1563 galaxies. A standard set of 86 galaxies is defined, consistingof galaxies with at least three reliable, concordant measurements. It issuggested that future studies observe some of these standard galaxies sothat different studies can be normalized to a consistent system. Allmeasurements are reduced to a normalized system using these standards.
| Dark Matter Particles and the Flat Rotation Curves of Spiral Galaxies
Not Available
| Integrated photoelectric magnitudes and color indices of bright galaxies in the Johnson UBV system
The photoelectric total magnitudes and color indices published in theThird Reference Catalogue of Bright Galaxies (RC3) are based on ananalysis of approximately equals 26,000 B, 25,000 B-V, and 17,000 U-Bmultiaperture measurements available up to mid 1987 from nearly 350sources. This paper provides the full details of the analysis andestimates of internal and external errors in the parameters. Thederivation of the parameters is based on techniques described by theVaucouleurs & Corwin (1977) whereby photoelectric multiaperture dataare fitted by mean Hubble-type-dependent curves which describe theintegral of the B-band flux and the typical B-V and U-B integrated colorgradients. A sophisticated analysis of the residuals of thesemeasurements from the curves was made to allow for the random andsystematic errors that effect such data. The result is a homogeneous setof total magnitudes BTA total colors(B-V)T and (U-B)T, and effective colors(B-V)e and (U-B)e for more than 3000 brightgalaxies in RC3.
| A CCD survey of galaxies. III. Observations with the Loiano 1.5m telescope.
Continuing a CCD survey of galaxies belonging or projected onto the Comaand Hercules Superclusters and to the A262, Virgo and Cancer clusters,we present isophote maps and photometric profiles in the Johnson systemof 127 galaxies (126 taken in the V, 28 of which also in the B band, oneonly in B). For the objects in common we compare our results with thosein the RC3.
| The proto-galaxy, globular clusters, and quasars
Metallicities and horizontal-branch population gradients are used todistinguish between two populations of Galactic halo globular clusters.The beta population of clusters appears to be almost coeval and occursmainly at R less than R(solar). Clusters of the beta population wereprobably formed during a rapid Eggen, Lynden-Bell, and Sandage-typecollapse of the inner proto-Galaxy. Clusters of the alpha population alloccur at R greater than 8 kpc. Many of these objects are found to lie onplunging retrograde orbits. This suggests that clusters of the alphapopulation formed during an extended Searle-Zinn-type merger andcollapse phase. The relative ages, metallicities, and locations of thealpha and beta populations indicate that the Galaxy formed inside out,with the dense proto-Galactic core forming stars and clusters before itslower density halo. In a massive galaxy the quasar phenomenon probablytakes place after the bulk of its globular cluster system has formed. Aquasar outburst may have guillotined cluster formation in the nearby S0galaxy NGC 3115, thus preventing the formation of a thick-disk globularcluster population.
| Flat rotation curves of spiral galaxies and the dark matter particles
It is shown that a gas of massive bosonic particles (m approximatelyequal to or greater than 70 eV), e.g. Higgs particles, surrounding thedisk galaxies is able to generate flat rotation curves without internaldifficulties with physical principles.
| An X-ray catalog and atlas of galaxies
An X-ray catalog and atlas of galaxies observed with the EinsteinObservatory imaging instruments (IPC and HRI) are presented. The catalogcomprises 493 galaxies, including targets of pointed observations, andRSA or RC2 galaxies serendipitously included in Einstein fields. A totalof 450 of these galaxies were imaged well within the instrumentalfields, resulting in 238 detections and 2123 sigma upper limits. Theother galaxies were either at the edge of the visible field of view orconfused with other X-ray sources. For these a rough measure of theirX-ray emission is also given. The atlas shows X-ray contour maps ofdetected galaxies superposed on optical photographs and givesazimuthally averaged surface brightness profiles of galaxies detectedwith a high signal-to-noise ratio.
| The mass-to-light ratio in spiral galaxies
The galactocentric variation of the dynamical mass-to-light ratio for alarge sample of field and Hickson compact group spirals has beenexamined in a systematic way. The majority of galaxies in this sample donot have a constant M/LR, but rather one that increases with radius. Thegradient in M/LR between 0.2 and 0.6 R25 is correlated with totalluminosity, in that faint galaxies have a higher proportion of darkmatter at large radii. The absolute value of M/LR at 0.5 R25 isconsistent with early type spirals having more dark matter. Highermetallicity gas is found in galaxies with a deeper gravitationalpotential.
| The neutral hydrogen content of early type disk galaxies
This paper presents the results of a sensitive 21-cm survey of massiveearly type galaxies made with the Arecibo radio telescope. Of the 81galaxies observed, the detections comprise 48 percent of the S0s, 73percent of the S0a's, and 96 percent of the Sa's. The values of thehybrid, distance-independent H I surface densities of the S0 galaxies inthe sample ranged continuously from amounts comparable to the mostgas-rich Sa galaxies to low estimated upper limts of the H I content.CCD images of most of the gas-rich S0s revealed either faint spiralfeatures or patchy structure in the disks. While no firm correlationbetween H I content and environmental density is apparent for thegalaxies in the sample, two-sample statistics suggest a differencebetween the highest and the lowest density bins. Early-type diskgalaxies within low density environments tend to have higher gas surfacedensities than those within high-density environments.
| Kinematical observations of ordinary spiral galaxies - A bibliographical compilation
Data extracted from 280 papers reporting observations of the kinematicsof 245 nonbarred spiral galaxies are presented. Information is providedon the type of observations (instruments, spectral lines used, etc.) andthe derived geometrical and kinematical parameters of the galaxies(major axis position angle, inclination, heliocentric systemic velocity,maximum extension of the kinematical measurements, etc.). In addition,whenever possible, a 'mean' rotation curve has been considered, fromwhich the maximum rotational velocity of the galaxy and a parameterdescribing the essential shape of the rotation curve within r25 havebeen derived. Histograms illustrating the distribution of morphologicaltypes, inclinations, extensions of the kinematical measurements, andmaximum rotational velocities account for the statistical properties ofthis sample of spiral galaxies.
| Does the dark component influence the shape of the inner rotation curves of spiral galaxies?
A statistical analysis of the relation between the essential shape ofthe rotation curve, the morphology, and the absolute luminosity ofspiral galaxies is presented for a sample of 167 objects. At variancewith Burstein and Rubin's (1985) results, it is found that the shape ofrotation curves of spirals inside the 'optical' region correlates withthe Hubble type. This fact reflects a correlation between light and massdistributions in the inner galaxian regions, showing that the lineardynamics is not usually controlled by the dark component.
| The distribution of mass for spiral galaxies in clusters and in the field
A comparison is made between the mass distributions of spiral galaxiesin clusters and in the field using Burstein's mass-type methodology.Both the H-alpha emission-line rotation curves and more extended H Irotation curves are used. The fitting technique for determining masstypes used by Burstein and coworkers has been replaced by an objectivechi-sq method. Mass types are shown to be a function of both the Hubbletype and luminosity, contrary to earlier results. The present data showa difference in the distribution of mass types for spiral galaxies inthe field and in clusters, in the sense that mass type I galaxies, wherethe inner and outer velocity gradients are similar, are generally foundin the field rather than in clusters. This can be understood in terms ofthe results of Whitmore, Forbes, and Rubin (1988), who find that therotation curves of galaxies in the central region of clusters aregenerally failing, while the outer galaxies in a cluster and fieldgalaxies tend to have flat or rising rotation curves.
| H I observations of galaxies in the Hercules supercluster
An H-I survey of the Hercules supercluster region was conducted using21-cm line observations of galaxies listed in the Uppsala GeneralCatalog of Galaxies (Nilson, 1973). It is found that thethree-dimensional distribution of the sample deviates markedly from thatexpected for a randomly distributed sample, and that the sample volumecontains an underdense region in front of the supercluster. An upperlimit to the expansion velocity of this underdense region of 400 km/s isobtained.
| Dark matter in spiral galaxies. III - The SA galaxies
Luminosity profiles have been obtained for 14 Sa galaxies with opticalrotation curves measured by Rubin et al. (1985). The rotation curves andbulge dynamics for about half of the galaxies were found to agree withtheoretical predictions assuming a typical mass/light ratio. The otherhalf have slow-rising rotation curves that are inconsistent with thelight distribution and bulge dynamics. The proposed explanation for thisinconsistency is that the rotation curves in the bulge-dominated partsof these galaxies are not measuring their true velocities. Central bulgevelocity dispersions are computed by using the measured bulge lightdistribution and a mass profile given by the rotation curves. For the'normal' velocities, the predicted dispersions match the observed valuesreasonably well, while for the 'massless bulge' galaxies the predicteddispersion is always low, by a factor of 3 in the worst case.
| Central velocity gradients and the classification of spiral galaxies
Measurements of the central velocity gradient are presented for 94spiral galaxies with existing rotation curves. The central velocitygradient is used as a representative dynamical parameter of the galaxycentral mass. This parameter in a galaxy is shown to be correlated withHubble type. This result provides an additional evidence that theluminosity classification reflects structural properties such as centralmass and density of spirals.
|
הכנס מאמר חדש
לינקים קשורים
הכנס לינק חדש
משמש של הקבוצה הבאה
|
תצפית ומידע אסטרומטרי
קטלוגים וכינוים:
|
