Contents
Images
Upload your image
DSS Images Other Images
Related articles
The Pattern Speeds of 38 Barred Galaxies
We estimate the pattern speeds of 38 barred galaxies by simulationmodeling. We construct the gravitational potentials of the galaxies fromnear-IR photometry by assuming that the mass-to-light ratio (M/L) isconstant in the H band and a single pattern speed dominates in thestellar disk. We use the response of gaseous and stellar particle disksto a rigidly rotating potential to determine the pattern speed. If ourassumptions are correct, then the pattern speed depends on themorphological type: the average value of the ratio of the corotationresonance radius to the bar radius, ℛ, increases from about 1.1 intype SB0/a to 1.4 in SBb and 1.7 in SBc. Within the error estimates, allthe bars in galaxies of type SBab or earlier are fast rotators, havingℛ<=1.4, whereas late-type galaxies include both fast and slowrotators.
| The Distribution of Bar and Spiral Arm Strengths in Disk Galaxies
The distribution of bar strengths in disk galaxies is a fundamentalproperty of the galaxy population that has only begun to be explored. Wehave applied the bar-spiral separation method of Buta and coworkers toderive the distribution of maximum relative gravitational bar torques,Qb, for 147 spiral galaxies in the statistically well-definedOhio State University Bright Galaxy Survey (OSUBGS) sample. Our goal isto examine the properties of bars as independently as possible of theirassociated spirals. We find that the distribution of bar strengthdeclines smoothly with increasing Qb, with more than 40% ofthe sample having Qb<=0.1. In the context of recurrent barformation, this suggests that strongly barred states are relativelyshort-lived compared to weakly barred or nonbarred states. We do notfind compelling evidence for a bimodal distribution of bar strengths.Instead, the distribution is fairly smooth in the range0.0<=Qb<0.8. Our analysis also provides a first look atspiral strengths Qs in the OSUBGS sample, based on the sametorque indicator. We are able to verify a possible weak correlationbetween Qs and Qb, in the sense that galaxies withthe strongest bars tend to also have strong spirals.
| Bar-induced perturbation strengths of the galaxies in the Ohio State University Bright Galaxy Survey - I
Bar-induced perturbation strengths are calculated for a well-definedmagnitude-limited sample of 180 spiral galaxies, based on the Ohio StateUniversity Bright Galaxy Survey. We use a gravitational torque method,the ratio of the maximal tangential force to the mean axisymmetricradial force, as a quantitative measure of the bar strength. Thegravitational potential is inferred from an H-band light distribution byassuming that the M/L ratio is constant throughout the disc. Galaxiesare deprojected using orientation parameters based on B-band images. Inorder to eliminate artificial stretching of the bulge, two-dimensionalbar-bulge-disc decomposition has been used to derive a reliable bulgemodel. This bulge model is subtracted from an image, the disc isdeprojected assuming it is thin, and then the bulge is added back byassuming that its mass distribution is spherically symmetric. We findthat removing the artificial bulge stretch is important especially forgalaxies having bars inside large bulges. We also find that the massesof the bulges can be significantly overestimated if bars are not takeninto account in the decomposition.Bars are identified using Fourier methods by requiring that the phasesof the main modes (m= 2, m= 4) are maintained nearly constant in the barregion. With such methods, bars are found in 65 per cent of the galaxiesin our sample, most of them being classified as SB-type systems in thenear-infrared by Eskridge and co-workers. We also suggest that as muchas ~70 per cent of the galaxies classified as SAB-types in thenear-infrared might actually be non-barred systems, many of them havingcentral ovals. It is also possible that a small fraction of the SAB-typegalaxies have weak non-classical bars with spiral-like morphologies.
| Circumnuclear Structure and Black Hole Fueling: Hubble Space Telescope NICMOS Imaging of 250 Active and Normal Galaxies
Why are the nuclei of some galaxies more active than others? If mostgalaxies harbor a central massive black hole, the main difference isprobably in how well it is fueled by its surroundings. We investigatethe hypothesis that such a difference can be seen in the detailedcircumnuclear morphologies of galaxies using several quantitativelydefined features, including bars, isophotal twists, boxy and diskyisophotes, and strong nonaxisymmetric features in unsharp-masked images.These diagnostics are applied to 250 high-resolution images of galaxycenters obtained in the near-infrared with NICMOS on the Hubble SpaceTelescope. To guard against the influence of possible biases andselection effects, we have carefully matched samples of Seyfert 1,Seyfert 2, LINER, starburst, and normal galaxies in their basicproperties, taking particular care to ensure that each was observed witha similar average scale (10-15 pc pixel-1). Severalmorphological differences among our five different spectroscopicclassifications emerge from the analysis. The H II/starburst galaxiesshow the strongest deviations from smooth elliptical isophotes, whilethe normal galaxies and LINERs have the least disturbed morphology. TheSeyfert 2s have significantly more twisted isophotes than any othercategory, and the early-type Seyfert 2s are significantly more disturbedthan the early-type Seyfert 1s. The morphological differences betweenSeyfert 1s and Seyfert 2s suggest that more is at work than simply theviewing angle of the central engine. They may correspond to differentevolutionary stages.
| Deprojecting spiral galaxies using Fourier analysis. Application to the Ohio sample
We use two new methods developed recently (Barberàet al.\cite{bar03}, A&A, 415, 849), as well as information obtained fromthe literature, to calculate the orientation parameters of the spiralgalaxies in the Ohio State University Bright Galaxy Survey. We comparethe results of these methods with data from the literature, and find ingeneral good agreement. We provide a homogeneous set of mean orientationparameters which can be used to approximately deproject the disks of thegalaxies and facilitate a number of statistical studies of galaxyproperties.Table 1 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/421/595
| Double-barred galaxies. I. A catalog of barred galaxies with stellar secondary bars and inner disks
I present a catalog of 67 barred galaxies which contain distinct,elliptical stellar structures inside their bars. Fifty of these aredouble-barred galaxies: a small-scale, inner or secondary bar isembedded within a large-scale, outer or primary bar. I providehomogenized measurements of the sizes, ellipticities, and orientationsof both inner and outer bars, along with global parameters for thegalaxies. The other 17 are classified as inner-disk galaxies, where alarge-scale bar harbors an inner elliptical structure which is alignedwith the galaxy's outer disk. Four of the double-barred galaxies alsopossess inner disks, located in between the inner and outer bars. Whilethe inner-disk classification is ad-hoc - and undoubtedly includes someinner bars with chance alignments (five such probable cases areidentified) - there is good evidence that inner disks form astatistically distinct population, and that at least some are indeeddisks rather than bars. In addition, I list 36 galaxies which may bedouble-barred, but for which current observations are ambiguous orincomplete, and another 23 galaxies which have been previously suggestedas potentially being double-barred, but which are probably not. Falsedouble-bar identifications are usually due to features such as nuclearrings and spirals being misclassified as bars; I provide someillustrated examples of how this can happen.A detailed statistical analysis of the general population of double-barand inner-disk galaxies, as represented by this catalog, will bepresented in a companion paper.Tables \ref{tab:measured} and \ref{tab:deproj} are only available inelectronic form at http://www.edpsciences.org
| The Visibility of Galactic Bars and Spiral Structure at High Redshifts
We investigate the visibility of galactic bars and spiral structure inthe distant universe by artificially redshifting 101 B-band CCD imagesof local spiral galaxies from the Ohio State University Bright SpiralGalaxy Survey. These local galaxy images represent a much fairerstatistical baseline than the galaxy atlas images presented by Frei etal. in 1995, the most commonly used calibration sample for morphologicalwork at high redshifts. Our artificially redshifted images correspond toHubble Space Telescope I814-band observations of the localgalaxy sample seen at z=0.7, with integration times matching those ofboth the very deep northern Hubble Deep Field (HDF) data and the muchshallower HDF flanking field observations. The expected visibility ofgalactic bars is probed in two ways: (1) using traditional visualclassification and (2) by charting the changing shape of the galaxydistribution in ``Hubble space,'' a quantitative two-parameterdescription of galactic structure that maps closely onto Hubble'soriginal tuning fork. Both analyses suggest that over two-thirds ofstrongly barred luminous local spirals (i.e., objects classified as SBin the Third Reference Catalogue) would still be classified as stronglybarred at z=0.7 in the HDF data. Under the same conditions, most weaklybarred spirals (classified SAB in the Third Reference Catalogue) wouldbe classified as regular spirals. The corresponding visibility of spiralstructure is assessed visually, by comparing luminosity classificationsfor the artificially redshifted sample with the corresponding luminosityclassifications from the Revised Shapley-Ames Catalog. We find that forexposure times similar to that of the HDF, spiral structure should bedetectable in most luminous (MB~M*) low-inclination spiralgalaxies at z=0.7 in which it is present. However, obvious spiralstructure is only detectable in ~30% of comparable galaxies in the HDFflanking field data using the Wide Field Planetary Camera 2. Our studyof artificially redshifted local galaxy images suggests that, whenviewed at similar resolution, noise level, and redshift-correctedwavelength, barred spirals are less common at z~0.7 than they are atz=0.0, although more data are needed to definitively rule out thepossibility that cosmic variance is responsible for much of this effect.
| The NICMOS Snapshot Survey of Nearby Galaxies
We present ``snapshot'' observations with the Near-Infrared Camera andMulti-Object Spectrometer (NICMOS) on board the Hubble Space Telescope(HST) of 94 nearby galaxies from the Revised Shapley Ames Catalog.Images with 0.2" resolution were obtained in two filters, a broadbandcontinuum filter (F160W, roughly equivalent to the H band) and anarrowband filter centered on the Paα line (F187N or F190N,depending on the galaxy redshift) with the 51^''x51^'' field of view ofthe NICMOS camera 3. A first-order continuum subtraction is performed,and the resulting line maps and integrated Paα line fluxes arepresented. A statistical analysis indicates that the average Paαsurface brightness in the central regions is highest in early-type(Sa-Sb) spirals.
| Cosmic Masks Still Dance
The Hubble classification scheme of galaxies is based on their opticalappearance or `masks'. As one goes from early to late type spirals, bothbarred and unbarred, the optical appearance will be dominated more andmore by the young Population I, i.e., blue stars and dust. Atlasesreveal the rich variety of responses of the Population I component ofgas and dust (the mask) to the underlying, older, stellar population.However, the gaseous Population I component, may only constitute 5percent of the dynamical mass of the galaxy. Masks of negligible massmay conceal the human face - and that of galaxy. In the near-infrared,the morphology of older star-dominated disk indicates a simpleclassification scheme: the dominant Fourier m-mode in the dustpenetrated regime, and the associated pitch angle. A ubiquity of low m=1and m=2 modes is confirmed. On the basis of deprojected H (1.65 μm)and K' (2.1μm) images, we propose that the evolved stellar disks maybe grouped into three principal dust penetrated archetypes: those withtightly wound stellar arms characterised by pitch angles at K' of ~10^° (the α class), an intermediate group with pitch angles of~ 25^° (the β class) and thirdly, those with open spiralsdemarcated by pitch angles at K' of ~ 40^° (the γ bin). Flator falling rotation curves give rise to the tightly wound α class;rising rotation curves are associated with the open γ class. Theobserved dust penetrated classes are inextricably related to the rate ofshear in the stellar disk, as determined by A/ω. Here A is thefirst Oort constant andω denotes the angular velocity. There is nocorrelation between our dust penetrated classes and optical Hubblebinning; the Hubble tuning fork does not constrain the morphology of theold stellar Population II disks. NGC 3223 and NGC 7083 (both SbI-II andalmost the same absolute blue magnitude) have identical Hubble types andidentical luminosity classes; the dust penetrated disk of NGC 3223 hastightly wrapped arms of class α, whereas the near-infrared disk ofNGC 7083 has open arms of class γ. This is in turn associated withtheir very different rotation curve shapes yielding different rates ofshear A/ω in their stellar disks. Any specific dust penetratedarchetype may be the resident disk of both an early or late type galaxy.The number of arms and the pitch angle of the arms at K' of theearly-type `a' spiral NGC 718 are almost identical to those for thelate-type `c' spiral NGC 309. We demonstrate that galaxies on oppositeends of the tuning fork can display remarkably similar evolved diskmorphologies and belong to the same dust penetrated class. In thissense, there is no differentiation between an early and late typegalaxy: the Hubble tuning fork becomes a circle. Furthermore, aprototypically flocculent galaxy such as NGC 5055 (Elmegreen arm class3) can have an evolved disk morphology almost identical to that of NGC5861, characterised in the optical as having one of the most regularspiral patterns known and of Elmegreen class 12. Both opticallyflocculent or grand design galaxies can reside within the same dustpenetrated morphological bin. As was suggested by Block et al. (1994a),it is the gas dominated Population I component which determines theoptical types (a, b, c). This may be partially or even fully decoupledfrom the Population II disk. Those L=lopsided galaxies (where m=1 is adominant mode) are designated Lα, Lβ and Lγ accordingto the dust penetrated pitch angle; E=evensided galaxies (where m=2 isthe dominant Fourier mode) are classified into classes Eα, Eβand Eγ, according to our three principal dust penetratedarchetypes. The L and E modes are the most common morphologies in oursample, which spans a range of Hubble types from early (a) to late(irregular).
| 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.
| The Fueling of Nuclear Activity. I. A Near-Infrared Imaging Survey of Seyfert and Normal Galaxies
We present near-infrared, modified K-band images of a sample of Seyfertand control galaxies. Our sample includes all known Seyfert galaxies inthe Revised Shapely-Ames Catalog and Sandage & Tammann's 1987extension to the RSA with recessional velocities less than 5000 km s-1and logarithmic axial ratios less than 0.2 (excluding the two early-typeSeyfert galaxies Centaurus A and Perseus A). A control sample of normalgalaxies, matched to the Seyfert sample in Hubble type, redshift,inclination, and blue luminosity, has also been observed. To quantifythe incidence of bars in both samples, elliptical fits to the isophotesof each galaxy have been performed. In agreement with earlier studies,we find that many galaxies classified as unbarred in the optical,display evidence for bars in the near-infrared.
| Molecular Gas, Morphology, and Seyfert Galaxy Activity
We probe the cause of the elevated star formation in host galaxies ofSeyfert 2 nuclei compared with Seyfert 1 hosts and with field galaxies.12CO (1--0) observations of a large sample of Seyfert galaxies indicateno significant difference in the total amount of molecular gas as afunction of the Seyfert nuclear type, nor are Seyfert galaxiessignificantly different in this regard from a sample of field galaxiesonce selection effects are accounted for. Therefore, the total amount ofmolecular gas is not responsible for the enhanced star-forming activityin Seyfert 2 hosts. To probe how this gas is being converted moreefficiently into stars in Seyfert 2 hosts than in the other galaxies, weinvestigate the occurrence of bars, interactions, and distortedmorphologies among Seyfert galaxies. We find a significantly higher rateof asymmetric morphologies for Seyfert 2 galaxies with respect toSeyfert 1 galaxies and field galaxies. Relative to field galaxies, theeffect is at a greater than 99.9% confidence level. The presence ofasymmetric morphologies in individual Seyfert galaxies is correlatedwith their tendency to exhibit enhanced star-forming activity. Theseresults suggest that asymmetric morphologies are an important cause forthe link between Seyfert type and star-forming activity: bars anddistortions in Seyfert 2 hosts are likely both to enhance star-formingactivity and to funnel gas into the nuclear region, thus obscuring andpossibly contributing to the feeding of the active nucleus.
| 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.
| 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.
| 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.
| Population studies in groups and clusters of galaxies. III - A catalog of galaxies in five nearby groups
Five nearby groups of galaxies have been surveyed using large-scaleplates from the 2.5 m duPont Telescope at Las Campanas Observatory.Catalogs of galaxies brighter than B(T) = 20 are presented for the Leo,Dorado, NGC 1400, NGC 5044, and Antlia groups. A total of 1044 galaxiesare included, from visual inspection of 14 plates, covering 31 degsquare. Galaxies have been classified in the extended Hubble system, andgroup memberships have been assigned based on velocity (where available)and morphology. About half the galaxies listed are likely members of oneof the nearby groups. The catalogs are complete to B(T) = 18, althoughthe completeness limits vary slightly from group to group. Based on Kingmodel fits to the surface density profiles, the core radii of the groupsrange from 0.3 to 1 Mpc, and central densities range from 120 to 1900galaxies Mpc exp-3 brighter than M(BT) = -12.5. Dynamical analysisindicates that all of the groups are likely to be gravitationally bound.
| A millimeter-wave survey of CO emission in Seyfert galaxies
Emission in the 115 GHz 1-0 line of CO has been detected in 18 Seyfertgalaxies in a sample of 43. The CO properties of 29 Seyferts in theRevised Shapley Ames Catalog (RSA) are compared with the CO propertiesof normal galaxies of the same Hubble type. These RSA type 2 Seyfertshave an average ratio of CO-to-blue luminosity that is about twice aslarge as that of the normal galaxies, but the RSA type 1 Seyferts havenormal CO luminosities. The RSA type 2 Seyfert galaxies have anunusually large average ratio of CO luminosity-to-H I mass compared tonormal disk galaxies. The RSA type 2 Seyferts have an average far-IRluminosity that is about four times larger than a non-Seyfert comparisonsample, while the RSA type 1 Seyferts are not significantly moreluminous than the non-Seyferts. The result imply that the two classes ofSeyferts are intrinsically different from one another and that one classcannot evolve into another in less than a few million years.
| Study of a complete sample of galaxies. II - Spectroscopy of the nuclei
Spectroscopic observations of a complete sample of 320 galaxies (fromthe Revised Shapley Ames Catalog of Sandage and Tammann, 1981) withdeclination less than or equal to +20 deg, galactocentric velocity lessthan 3000 km/s, and absolute magnitude brighter than M(B) = -21.0 arereported. The 400-700-nm spectra were obtained with resolution about 1nm using the Boller and Chivens spectrograph and image-dissector scannerat the Cassegrain focus of the 1.52-m telescope at ESO on 36 nightsduring 1980-1983. The data are presented in extensive tables and spectraand briefly characterized. The majority of the spectra are classified asH II regions ionized by hot stars or as Seyfert-like nebulosities.
| Southern Galaxy Catalogue.
Not Available
| The Antlia cluster of galaxies and its environment - The Hydra I-Centaurus supercluster
The small Antlia cluster of galaxies was investigated by measuring manyradial velocities for galaxies from the Lauberts catalog in the Antliaregion. Apart from the Antlia cluster itself, four more small groupswere identified. These five systems form a tiny but not bound Antliamini-supercluster. The mini-supercluster consists of small groups andclusters and of a dispersed component of field galaxies. The five galaxysystems are also part of the large Hydra I-Centaurus supercluster. Thislarge supercluster belongs now to the class of well observed ones. Ithas a chain-like filamentary structure. This supercluster seems to beconnected to the Local Supercluster via two very extended but very loosegroups. The total structure is the triangle-shaped Virgo-HydraI-Centaurus supercluster.
| The plume phenomenon in barred spirals
Observational data on 341 barred spiral galaxies in the revisedShapley-Ames Catalog (Sandage and Tammann, 1981) are analyzed todetermine the relative frequency and characteristics of plumelikestructures similar to those seen in the theta spiral NGC 1433. The dataare presented in tables, and images of several galaxies with plumes areshown. A total of 16 additional barred spirals, mainly objects of typesSab to Sbc with inner rings or pseudorings, are found to have plumestructures, which are less clearly defined and developed than those inNGC 1433 and which 'lead' the bars by 10-20 deg and lie at 1.4-2.5 timesthe inner-ring radius in the galaxies which are seen face-on. The originof the plumes is examined in the light of theoretical models, and it issuggested that they are secondary compressions located near thecorotation radius and possibly related to arm doubling just beyond theinner second-harmonic resonance, consistent with the model of Schwarz(1979 and 1981).
| The dependence on distance and redshift of the velocity vectors of the sun, the Galaxy, and the Local Group with respect to different extragalactic frames of reference
The solar apex S is confirmed to move steadily from S-prime toS-asterisk, when the mean redshift of the reference frame increases fromsmall to large values, on the basis of a new analysis of the solarmotion and Hubble ratio. Most of the change takes place in the 0-4000km/sec interval. The velocity vectors increase steadily, and thedirections of the apexes drift progressively as the mean distance orredshift of the reference frame increases. The frame of referencedefined by galaxies at z greater than 0.01 is essentially at rest withrespect to background radiation, suggesting that any intrinsic dipolaranisotropy of the background radiation is probably less than about0.0001.
| Study of a complete sample of galaxies. I - UBV aperture photometry
UBV photometry was performed over the period September 1979-February1984 on 320 galaxies in the Revised Shapely-Ames catalog of galaxies(1981). The galaxies chosen had radial velocities under 3000 km/sec,declinations of no more than +20 deg and absolute magnitudes of at most-21.0. V, B-V and U-B data are provided for all the objects, along withdata for other galaxies which were either Seyfert galaxies or had astarburst nucleus.
| Inner ring structures in galaxies as distance indicators. III - Distances to 453 spiral and lenticular galaxies
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1983ApJS...51..149B&db_key=AST
| UBV photometry of 262 southern galaxies
Multiaperture photometry of 262 bright southern galaxies in the JohnsonUBV system is given. Most of these are south of -30 deg declination,although some northward to -10 deg are included. A total of 169 objectshave published radial-velocity determinations. These provide distancesand enable construction of color-magnitude diagrams for this subset ofobjects through a physical diameter of 2.0 kpc (with H = 100). Thetwo-color diagrams for the inner regions of the galaxies differ fromthose of integrated galaxies due to the color changes towards theircenters. Comparison with theoretical models of Larson and Tinsley (1978)suggest that the colors of the inner portions of most ellipticals andlenticulars are consistent with their having all stars formed at nearlyone epoch with little subsequent star formation, while for spiralslarger amounts of star formation, either in bursts or continuously, aresuggested. This simple picture is complicated by the presence of certainobjects having peculiar colors indicative of large amounts of recentstar formation.
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
Catalogs and designations:
|
