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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.
| On the Relation between Circular Velocity and Central Velocity Dispersion in High and Low Surface Brightness Galaxies
In order to investigate the correlation between the circular velocityVc and the central velocity dispersion of the spheroidalcomponent σc, we analyzed these quantities for a sampleof 40 high surface brightness (HSB) disk galaxies, eight giant lowsurface brightness (LSB) spiral galaxies, and 24 elliptical galaxiescharacterized by flat rotation curves. Galaxies have been selected tohave a velocity gradient <=2 km s-1 kpc-1 forR>=0.35R25. We used these data to better define theprevious Vc-σc correlation for spiralgalaxies (which turned out to be HSB) and elliptical galaxies,especially at the lower end of the σc values. We findthat the Vc-σc relation is described by alinear law out to velocity dispersions as low as σc~50km s-1, while in previous works a power law was adopted forgalaxies with σc>80 km s-1. Ellipticalgalaxies with Vc based on dynamical models or directlyderived from the H I rotation curves follow the same relation as the HSBgalaxies in the Vc-σc plane. On the otherhand, the LSB galaxies follow a different relation, since most of themshow either higher Vc or lower σc withrespect to the HSB galaxies. This argues against the relevance of baryoncollapse to the radial density profile of the dark matter halos of LSBgalaxies. Moreover, if the Vc-σc relation isequivalent to one between the mass of the dark matter halo and that ofthe supermassive black hole, then these results suggest that the LSBgalaxies host a supermassive black hole (SMBH) with a smaller masscompared to HSB galaxies with an equal dark matter halo. On the otherhand, if the fundamental correlation of SMBH mass is with the halocircular velocity, then LSB galaxies should have larger black holemasses for a given bulge dispersion. Elliptical galaxies withVc derived from H I data and LSB galaxies were not consideredin previous studies.Based on observations made with European Southern Observatory telescopesat the Paranal Observatory under programs 67.B-0283, 69.B-0573, and70.B-0171.
| Rotational Widths for Use in the Tully-Fisher Relation. I. Long-Slit Spectroscopic Data
We present new long-slit Hα spectroscopy for 403 noninteractingspiral galaxies, obtained at the Palomar Observatory 5 m Hale telescope,which is used to derive well-sampled optical rotation curves. Becausemany of the galaxies show optical emission features that aresignificantly extended along the spectrograph slit, a technique wasdevised to separate and subtract the night sky lines from the galaxyemission. We exploit a functional fit to the rotation curve to identifyits center of symmetry; this method minimizes the asymmetry in thefinal, folded rotation curve. We derive rotational widths using bothvelocity histograms and the Polyex model fit. The final rotational widthis measured at a radius containing 83% of the total light as derivedfrom I-band images. In addition to presenting the new data, we use alarge sample of 742 galaxies for which both optical long-slit and radioH I line spectroscopy are available to investigate the relation betweenthe H I content of the disks and the extent of their rotation curves.Our results show that the correlation between those quantities, which iswell established in the case of H I-poor galaxies in clusters, ispresent also in H I-normal objects: for a given optical size, starformation can be traced farther out in the disks of galaxies with largerH I mass.
| Ionized gas and stellar kinematics of seventeen nearby spiral galaxies
Ionized gas and stellar kinematics have been measured along the majoraxes of seventeen nearby spiral galaxies of intermediate to latemorphological type. We discuss the properties of each sample galaxy,distinguishing between those characterized by regular or peculiarkinematics. In most of the observed galaxies, ionized gas rotates morerapidly than stars and has a lower velocity dispersion, as is to beexpected if the gas is confined in the disc and supported by rotationwhile the stars are mostly supported by dynamical pressure. In a fewobjects, gas and stars show almost the same rotational velocity and lowvelocity dispersion, suggesting that their motion is dominated byrotation. Incorporating the spiral galaxies studied by Bertola et al.(\cite{Bertola1996}), Corsini et al. (\cite{Corsini1999},\cite{Corsini2003}) and Vega Beltrán et al. (\cite{Vega2001}) wehave compiled a sample of 50 S0/a-Scd galaxies, for which the major-axiskinematics of the ionized gas and stars have been obtained with the samespatial (≈1'') and spectral (≈50 km;s-1) resolution,and measured with the same analysis techniques. This allowed us toaddress the frequency of counter-rotation in spiral galaxies. It turnsout that less than 12% and less than 8% (at the 95% confidence level) ofthe sample galaxies host a counter-rotating gaseous and stellar disc,respectively. The comparison with S0 galaxies suggests that theretrograde acquisition of small amounts of external gas gives rise tocounter-rotating gaseous discs only in gas-poor S0s, while in gas-richspirals the newly acquired gas is swept away by the pre-existing gas.Counter-rotating gaseous and stellar discs in spirals are formed onlyfrom the retrograde acquisition of large amounts of gas exceeding thatof pre-existing gas, and subsequent star formation, respectively.Based on observations carried out at the European Southern Observatory,La Silla (Chile) (ESO 56.A-0684 and 57.A-0569).Tables 3 and 4 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/424/447Full Fig. \ref{fig:kinematics} and Figs. \ref{fig:gascomparison} and\ref{fig:starcomparison} are only available in electronic form athttp://www.edpsciences.org
| 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.
| 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.
| 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
| 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.
| Central Rotation Curves of Spiral Galaxies
We present high-resolution central-to-outer rotation curves for Sb, SBb,Sc, and SBc galaxies. We discuss their general characteristics,particularly their central behavior, as well as dependencies onmorphological types, activity, and peculiarity. The rotation curvesgenerally show a steep nuclear rise and high-velocity central rotation,followed by a broad maximum in the disk and then a flat rotation due tothe massive halo. Since the central high velocity and steep rise arecommon to all massive galaxies, they cannot be due to noncircularmotions. Disk rotation curves of barred galaxies show larger dispersionthan those of normal galaxies, probably because of noncircular motions.Interacting galaxies often show perturbed outer rotation curves, whiletheir central rotation shows no particular peculiarity. In addition,central activities, such as starbursts and active galactic nuclei,appear to show no particular correlation with the property of rotationcurves. This would suggest that the central activities are triggered bya more local effect than the global dynamical property.
| Nuclear-to-Disk Rotation Curves of Galaxies in the Hα and [N {II}] Emission Lines
We have obtained optical CCD spectroscopy along the major axes of 22nearby spiral galaxies of Sb and Sc types in order to analyze theirrotation curves. By subtracting the stellar continuum emission, we haveobtained position--velocity (PV) diagrams of the Hα and [N II]lines. We point out that the Hα line is often superposed by a broadstellar absorption feature (Balmer wing) in the nuclear regions, and,therefore, the [N II] line is a better tracer of kinematics in thecentral few hundred parsec regions. By applying the envelope-tracingtechnique to the Hα and [N II] PV diagrams, we have derivednucleus-to-disk rotation curves of the observed galaxies. The rotationcurves rise steeply within the central few hundred parsecs, indicating arapidly rotating nuclear disk and mass concentration near the nucleus.
| 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
| 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
| Scaleheights of 486 southern spiral galaxies and some statistical correlation
Based on Peng's method (1988), we obtain scaleheights of 486 southernspiral galaxies, the images of which are taken from the Digitized SkySurvey at Xinglong Station of Beijing Astronomical Observatory. Thefitted spiral arms of 70 galaxies are compared with their images to gettheir optimum inclinations. The scaleheights of other 416 ones arelisted in Table A1 in Appendix. After compiling and analyzing the data,we find some statistical correlations. The most interesting results arethat a flatter galaxy is bluer and looks brighter, and galaxies becomeflatter along the Hubble sequence Sab -- Scd. Based on photographic dataof the National Geographic Society -- Palomar Observatory Sky Survey(NGS-POSS) obtained using the Oschin Telescope Palomar Mountain. TheNGS-POSS was funded by a grant from the National Geographic Society tothe California Institute of Technology. The plates were processed intothe present compressed digital form with their permission. The DigitizedSky Survey was produced at the Space Telescope Science Institute underUS Government grant NAG W-2166. Table A1 is available in electronic fromonly, via anonymous ftp 130.79.128.5 orhttp://cdsweb.u-strasbg.fr/Abstract.html
| An alternative view of flat rotation curves. II. The observations.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1994RMxAA..28...35S&db_key=AST
| Exponential bulges in late-type spirals: an improved description of the light distribution
In many cases the modeling of spiral galaxies by an exponential disc andan R1/4-law bulge does not satisfactorily describe the meanradial distribution of light. This is most evident in non-linearleast-squares fitting techniques in which the resulting effective radiusand surface brightness of the bulge are characterized by largeuncertainties and are scattered over large ranges, in sharp contrast totheir disc counterparts. We attempt to decompose the major-axis profilesof 34 late-type spirals in terms of an alternative model consisting ofan exponential disc and an exponential bulge, using seeing-convolvedmodels. The results of this decomposition show that this model issuperior in the statistical aspects of the fitting procedure, in thesense that the various goodness-of-fit indicators are better and theresiduals are smaller. The fact that it also confines the parameters ofthe bulge to a range whose narrowness is comparable to that of theparameters of the disc indicates that this model has the potential togive a better and more consistent description of the bulges of late-typespirals.
| A simple model to fit rotation curves.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993RMxAA..25..111M&db_key=AST
| H II regions in spiral galaxies: Positions, luminosity function and diameter distribution
For a sample of 22 spiral galaxies, most of which are in Virgo, wemeasure positions, diameters and relative magnitudes of the H IIregions. The diameter frequency integral distribution is found to followthe exponential law proposed by van den Bergh (1981) with no exceptions.The scale diameter, D0, (1) depends on the galactic absolutemagnitude with the law log(D0) = -0.123 +/- 0.007MB -0.33 +/- 0.14, (2) has a tendency to be larger at theperiphery than in the inner part of the galaxy and (3) is systematicallylarger along the arms than inter-arms. Although with a large dispersion,a cubic relationship between H II region luminosity and diameter,consistent with a radiation bounded geometry, is found for each galaxy.The differential luminosity function distribution is described by apower law with index in the range (1.3 less than or equal to alpha lessthan or equal to 2.4) and a mean index mean value of alpha = 1.8 +/- 0.3in agreement with previous works. The index alpha is found to depend onthe morphological type of the galaxy being steeper for early thanlate-type spirals. It sensibly changes if arm and inter-armdistributions are separately considered, but does not depend on thegalactocentric distance. The environment characterized by the localdensity of galaxies does not seem to play a role in the shape of the LFwhile the diameter scale of H II regions seems to be well defined in anarrow region of values at densities rho greater than or equal 1.2(galaxies/cubic Mpc) while at lower density the scale diameter showslarge fluctuations.
| The V-R Diagram - a Diagnostic Tool for the Dynamical Classification of Spiral Galaxies
The relations between the angular momentum (J) and the mass (M) for asample of spiral galaxies are discussed for galaxies distributed in therotational velocity (V) - size (R) plane. It is found that, for a givenmass, Sc galaxies have larger angular momentum (~20%) than Sa. Theabsence of segregation in the angular momentum (J) - mass (M) plane isexplained in terms of observational errors, which are greater than theexpected differences in J between galaxies of equal mass and differenttype. The distribution of lenticular and irregular galaxies in the V-Rplane is also discussed.
| Axial ratios of edge-on spirals
A diameter-limited sample of 888 normal Sa-Sc galaxies was compiled fromthe Uppsala General Catalog. New micrometer measures of the axial ratiosR of the disk components of 262 edge-on spirals in this sample were madeon copies of blue Palomar Sky Survey plates and calibrated againstphotometric standards. The distribution of isophotal axial ratios forthe whole sample was analyzed to give information on the true axialratios R0 of spiral disks. The mean value of logR0 is 0.95 +/- 0.03 and the dispersion about this mean is0.12 +/- 0.04. A similar mean value (0.90) was obtained from avolume-limited sub-sample of 348 spirals. The dispersion in logR0 is partly due to a dependence of R0 onmorphological type, and the mean value of log R0 for eachtype was estimated. Inclinations of 342 edge-on (R is greater than about3) spirals were determined from their isophotal axial ratios and types.No significant dependence of R0 on luminosity at each typewas found.
| Dark-to-luminous mass ratio in spiral galaxies
We have calculated the mass-to-light ratios of spiral galaxies in theblue band and the H-band by using a chemical and photometric evolutionmodel with a two-component bulge-disc system. The slopes of thetheoretical M/L(b) vs. (B-V) and M/L(h) vs. (B-H) relations are muchsmaller than those of Larson and Tinsley (1978), which were adopted inprevious studies. The model predictions agree with the data of Rubin etal. (1982, 1985) and Burstein et al. (1982); the masses referred to arethose within a radius corresponding to the isophotal level of surfacebrightness at 25th B mag/sq arcsec. We find no evidence which supportsthe previous claims that bluer galaxies have relatively more massivedark halos. We conclude that the ratio of dark-to-luminous mass isuniform among spiral galaxies, contrary to the conventional view.
| 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.
| The Disc Contribution to Rotation Curves of Spiral Galaxies
We formulate analytically the maximum disc hypothesis (MDH) in theframework of a disc/halo mass decomposition, and apply it to a sample ofsuitably selected optical rotation curves. We find that the resultingdisc-to-total mass ratios show a definite trend of increasingdark-to-luminous mass ratio with decreasing luminosity, in very goodagreement with our previous results obtained by means of differentdecomposition techniques (Persic & Salucci). The same trend is alsoclearly discernible when the mass ratios (at the same radius in disclength-scale units) obtained from published MDH models are correlatedwith luminosity. We discuss possible reasons why previous studies whichhave assumed a similar framework have missed this fundamentalsystematics of dark matter.
| On the Stability of Gaseous Disks of Galaxies
Not Available
| Mass discrepancies in galaxies - Dark matter and alternatives
This paper discusses the observed systematics of the mass discrepancy ingalaxies (in particular, the spiral galaxies, for which the most preciseobservations exist) and presents arguments to account for thesesystematics both in the context of dark matter and the non-Newtoniangravity. It is argued that the standard picture of the spiral galaxyhalo and disc formation in the context of cold dark matter cannotaccount for the observed systematics of the discrepancy. On the otherhand, the suggestion of Milgrom (1983), in which the force law becomesessentially 1/r below a critical acceleration, can account for most ofthe observed systematics of galaxy rotation curves, and significantly,leads to the observed luminosity-velocity relationship in spiralgalaxies.
| 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.
| Systematics of the central velocity gradients of spiral galaxies
Using the central velocity gradient as a representative parameter of thecentral masses of spiral galaxies, a preliminary comparison has beenmade with the most imortant properties defining the Hubbleclassification scheme. Significant correlations with the bulge-to-diskratio and the pitch angle of spiral arms have been found for 39 and 30spiral galaxies, respectively. These preliminary results are anadditional evidence that (1) the light distribution reflects propertieslike central mass and density and (2) the arm shapes strongly depend onthe central mass concentration as expected from the density wave theory.Although it will be desirable to confirm the present results as soon asa larger sample of data would become available, it already appears thatthe central velocity gradient can be regarded as a classificationparameter accounting for morphological and kinematical properties ofspiral galaxies.
| The kinematic effects on the rotation curve of a galaxy
This paper considers the kinematic effects on the rotation curve of agalaxy, with special consideration given to an extreme case in which allpositive (or negative) gradients of velocity of the rotation curve arecaused by the kinematic effect of revolving. The periods of revolutionand the ratio of tidal force to self-gravitating force were calculatedfor 44 rotation curves of Sb and Sc galaxies. The revolution periodswere found to be in the range of one billion years, and the tidal forcewas always less than the gravitational force, indicating that theresults of calculations are in a reasonaable region. It is concludedthat a part of the velocity gradient of the rotation curve could becaused by the kinematic effect of revolution.
| 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.
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