Оглавление
Изображения
Загрузить ваше изображение
DSS Images Other Images
Публикации по объекту
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.
| Determination of the Thickness of Non-Edge-on Disk Galaxies
We propose a method to determine the thickness of non-edge-on diskgalaxies from their observed structure of spiral arms, based on thesolution of the truly three-dimensional Poisson's equation for alogarithmic disturbance of density and under the condition where theself-consistency of the density wave theory is no longer valid. Fromtheir measured number of arms, pitch angle and location of the innermostpoint of the spiral arms, we derive and present the thicknesses of 34spiral galaxies.
| Vertical Scale Parameter Estimates for 48 Non-edge-on Spiral Galaxies
In the first paper of this series, we directly studied the mathematicalforms, symmetry of spiral structure, and the projection of galacticdiscs on the images, and measured the pitch angles of the spiral armsand inclination angles of the galactic discs for 60 spiral galaxies. Inthis second paper, we estimate the vertical scale parameters of 48non-edge-on spiral galaxies based on the method proposed by Peng et al.and on the results given in Paper I. As we know, for edge-on discgalaxies we can obtain the vertical scale parameter from the photometry,once a mathematical form is specified for the vertical lightdistribution. For non-edge-on galaxies, some other methods have to beused. The statistical result was that the vertical scale parameter iscomparable for edge-on and non-edge-on galaxies, although it is obtainedfrom two very different methods.
| Beyond the Bulge: A Fundamental Relation between Supermassive Black Holes and Dark Matter Halos
The possibility that the masses MBH of supermassive blackholes (SBHs) correlate with the total gravitational mass of their hostgalaxy, or the mass MDM of the dark matter halo in which theypresumably formed, is investigated using a sample of 16 spiral and 20elliptical galaxies. The bulge velocity dispersion σc,typically defined within an aperture of size R<~0.5 kpc, is found tocorrelate tightly with the galaxy's circular velocity vc, thelatter measured at distances from the Galactic center at which therotation curve is flat, R~20-80 kpc. By using the well-knownMBH-σc relation for SBHs and a prescriptionto relate vc to the mass of the dark matter haloMDM in a standard ΛCDM cosmology, the correlationbetween σc and vc is equivalent to onebetween MBH and MDM. Such a correlation is foundto be nonlinear, with the ratio MBH/MDM decreasingfrom 2×10-4 for MDM~1014Msolar to 10-5 for MDM~1012Msolar. Preliminary evidence suggests that halos of masssmaller than ~5×1011 Msolar are increasinglyless efficient at forming SBHs-perhaps even unable to form them.
| Bar Galaxies and Their Environments
The prints of the Palomar Sky Survey, luminosity classifications, andradial velocities were used to assign all northern Shapley-Ames galaxiesto either (1) field, (2) group, or (3) cluster environments. Thisinformation for 930 galaxies shows no evidence for a dependence of barfrequency on galaxy environment. This suggests that the formation of abar in a disk galaxy is mainly determined by the properties of theparent galaxy, rather than by the characteristics of its environment.
| A Method of Obtaining the Pitch Angle of Spiral Arms and the Inclination of Galactic Discs
We investigate the mathematical form, the symmetry of spiral structureand the projected images of galactic discs. The measured pitch angles ofspiral arms and inclination angles of galactic discs for 60 spiralgalaxies are presented. The global spiral structure is emphasized in thestudy. It is found that, except for small-scale distortions, the spiralarms of those galaxies that were classified as AC 12 in the armclassification system of Elmegreen & Elmegreen, can be representedby the logarithmic spiral form.
| Nearby Optical Galaxies: Selection of the Sample and Identification of Groups
In this paper we describe the Nearby Optical Galaxy (NOG) sample, whichis a complete, distance-limited (cz<=6000 km s-1) andmagnitude-limited (B<=14) sample of ~7000 optical galaxies. Thesample covers 2/3 (8.27 sr) of the sky (|b|>20deg) andappears to have a good completeness in redshift (97%). We select thesample on the basis of homogenized corrected total blue magnitudes inorder to minimize systematic effects in galaxy sampling. We identify thegroups in this sample by means of both the hierarchical and thepercolation ``friends-of-friends'' methods. The resulting catalogs ofloose groups appear to be similar and are among the largest catalogs ofgroups currently available. Most of the NOG galaxies (~60%) are found tobe members of galaxy pairs (~580 pairs for a total of ~15% of objects)or groups with at least three members (~500 groups for a total of ~45%of objects). About 40% of galaxies are left ungrouped (field galaxies).We illustrate the main features of the NOG galaxy distribution. Comparedto previous optical and IRAS galaxy samples, the NOG provides a densersampling of the galaxy distribution in the nearby universe. Given itslarge sky coverage, the identification of groups, and its high-densitysampling, the NOG is suited to the analysis of the galaxy density fieldof the nearby universe, especially on small scales.
| 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.
| 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.
| The I-Band Tully-Fisher Relation for SC Galaxies: 21 Centimeter H I Line Data
A compilation of 21 cm line spectral parameters specifically designedfor application of the Tully-Fisher (TF) distance method is presentedfor 1201 spiral galaxies, primarily field Sc galaxies, for which opticalI-band photometric imaging is also available. New H I line spectra havebeen obtained for 881 galaxies. For an additional 320 galaxies, spectraavailable in a digital archive have been reexamined to allow applicationof a single algorithm for the derivation of the TF velocity widthparameter. A velocity width algorithm is used that provides a robustmeasurement of rotational velocity and permits an estimate of the erroron that width taking into account the effects of instrumental broadeningand signal-to-noise. The digital data are used to establish regressionrelations between measurements of velocity widths using other commonprescriptions so that comparable widths can be derived throughconversion of values published in the literature. The uniform H I linewidths presented here provide the rotational velocity measurement to beused in deriving peculiar velocities via the TF method.
| 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.
| 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.
| Extensive Spiral Structure and Corotation Resonance
Spiral density wave theories demand that grand-design spiral structurebe bounded, at most, between the inner and outer Lindblad resonances ofthe spiral pattern. The corotation resonance lies between the outer andthe inner Lindblad resonances. The locations of the resonances are atradii whose ratios to each other are rather independent of the shape ofthe rotation curve. The measured ratio of outer to inner extent ofspiral structure for a given spiral galaxy can be compared to thestandard ratio of corotation to inner Lindblad resonance radius. In thecase that the measured ratio far exceeds the standard ratio, it islikely that the corotation resonance is within the bright optical disk.Studying such galaxies can teach us how the action of resonances sculptsthe appearance of spiral disks. This paper reports observations of 140disk galaxies, leading to resonance ratio tests for 109 qualified spiralgalaxies. It lists candidates that have a good chance of having thecorotation resonance radius within the bright optical disk.
| Bulge-Disk Decomposition of 659 Spiral and Lenticular Galaxy Brightness Profiles
We present one of the largest homogeneous sets of spiral and lenticulargalaxy brightness profile decompositions completed to date. The 659galaxies in our sample have been fitted with a de Vaucouleurs law forthe bulge component and an inner-truncated exponential for the diskcomponent. Of the 659 galaxies in the sample, 620 were successfullyfitted with the chosen fitting functions. The fits are generally welldefined, with more than 90% having rms deviations from the observedprofile of less than 0.35 mag. We find no correlations of fittingquality, as measured by these rms residuals, with either morphologicaltype or inclination. Similarly, the estimated errors of the fittedcoefficients show no significant trends with type or inclination. Thesedecompositions form a useful basis for the study of the lightdistributions of spiral and lenticular galaxies. The object base issufficiently large that well-defined samples of galaxies can be selectedfrom it.
| The Southern Sky Redshift Survey
We report redshifts, magnitudes, and morphological classifications for5369 galaxies with m_B <= 15.5 and for 57 galaxies fainter than thislimit, in two regions covering a total of 1.70 sr in the southerncelestial hemisphere. The galaxy catalog is drawn primarily from thelist of nonstellar objects identified in the Hubble Space TelescopeGuide Star Catalog (GSC). The galaxies have positions accurate to ~1"and magnitudes with an rms scatter of ~0.3 mag. We compute magnitudes(m_SSRS2) from the relation between instrumental GSC magnitudes and thephotometry by Lauberts & Valentijn. From a comparison with CCDphotometry, we find that our system is homogeneous across the sky andcorresponds to magnitudes measured at the isophotal level ~26 magarcsec^-2. The precision of the radial velocities is ~40 km s^-1, andthe redshift survey is more than 99% complete to the m_SSRS2 = 15.5 maglimit. This sample is in the direction opposite that of the CfA2; incombination the two surveys provide an important database for studies ofthe properties of galaxies and their large-scale distribution in thenearby universe. Based on observations obtained at Cerro TololoInter-American Observatory, National Optical Astronomy Observatories,operated by the Association of Universities for Research in Astronomy,Inc., under cooperative agreement with the National Science Foundation;Complejo Astronomico El Leoncito, operated under agreement between theConsejo Nacional de Investigaciones Científicas de laRepública Argentina and the National Universities of La Plata,Córdoba, and San Juan; the European Southern Observatory, LaSilla, Chile, partially under the bilateral ESO-ObservatórioNacional agreement; Fred Lawrence Whipple Observatory;Laboratório Nacional de Astrofísica, Brazil; and the SouthAfrican Astronomical Observatory.
| Catalogue of HI maps of galaxies. I.
A catalogue is presented of galaxies having large-scale observations inthe HI line. This catalogue collects from the literature the informationthat characterizes the observations in the 21-cm line and the way thatthese data were presented by means of maps, graphics and tables, forshowing the distribution and kinematics of the gas. It containsfurthermore a measure of the HI extension that is detected at the levelof the maximum sensitivity reached in the observations. This catalogueis intended as a guide for references on the HI maps published in theliterature from 1953 to 1995 and is the basis for the analysis of thedata presented in Paper II. The catalogue is only available inelectronic form at the CDS via anonymous ftp 130.79.128.5 orhttp://cdsweb.u-strasbg.fr/Abstract.html
| Total magnitude, radius, colour indices, colour gradients and photometric type of galaxies
We present a catalogue of aperture photometry of galaxies, in UBVRI,assembled from three different origins: (i) an update of the catalogueof Buta et al. (1995) (ii) published photometric profiles and (iii)aperture photometry performed on CCD images. We explored different setsof growth curves to fit these data: (i) The Sersic law, (ii) The net ofgrowth curves used for the preparation of the RC3 and (iii) A linearinterpolation between the de Vaucouleurs (r(1/4) ) and exponential laws.Finally we adopted the latter solution. Fitting these growth curves, wederive (1) the total magnitude, (2) the effective radius, (3) the colourindices and (4) gradients and (5) the photometric type of 5169 galaxies.The photometric type is defined to statistically match the revisedmorphologic type and parametrizes the shape of the growth curve. It iscoded from -9, for very concentrated galaxies, to +10, for diffusegalaxies. Based in part on observations collected at the Haute-ProvenceObservatory.
| 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
| 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.
| Optical Rotation Curves and Linewidths for Tully-Fisher Applications
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....114.2402C&db_key=AST
| The universal rotation curve of spiral galaxies - I. The dark matter connection
We use a homogeneous sample of about 1100 optical and radio rotationcurves (RCs) and relative surface photometry to investigate the mainmass structure properties of spirals, over a range of 6 mag and out to<~1.5 and 2 optical radii (for the optical and radio data,respectively). We confirm the strong dependence on luminosity for boththe profile and the amplitude of RCs claimed by Persic & Salucci.Spiral RCs show the striking feature that a single global parameter,e.g. luminosity, dictates the rotational velocity at any radius for anyobject, so revealing the existence of a universal RC. At highluminosities, there is a slight discrepancy between the profiles of RCsand those predicted from the luminous matter (LM) distributions: thisimplies a small, yet detectable, amount of dark matter (DM). At lowluminosities, the failure of the LM prediction is much more severe, andthe DM is the only relevant mass component. We show that the universalRC implies a number of scaling properties between dark and luminousgalactic structure parameters: (i) the DM/LM mass ratio scales inverselywith luminosity; (ii) the central halo density scales as L^-0.7 (iii)the halo core radius is comparable to the optical radius, but shrinksfor low luminosities; (iv) the total halo mass scales as L^0.5. Suchscaling properties can be represented as a curve in the(luminosity)-(DM/LM mass ratio)-(DM core radius)-(DM central density)space, which provides a geometrical description of the tight couplingbetween the dark and the luminous matter in spiral galaxies.
| 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 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.
| Rotation Curves of 967 Spiral Galaxies
We present the rotation curves of 967 southern spiral galaxies, obtainedby deprojecting and folding the raw Hα data originally publishedby Mathewson, Ford, & Buchhorn (1992). For 900 objects, we alsopresent, in figures and tables, the rotation curves smoothed on scalescorresponding to 5%-20% of the optical size; of these, 80 meet objectiveexcellence criteria and are suitable for individual detailed massmodeling, while 820, individually less compelling mainly because of themoderate statistics and/or limited extension, are suitable forstatistical studies. The remaining 67 curves suffer from severeasymmetries, small statistics, and large internal scatter that maylargely limit their use in galaxy structure studies. The deprojectedfolded curves, the smoothed curves, and various related quantities areavailable via anonymous ftp at galileo.sissa.it in the directory/users/ftp/pub/psrot.
| Dark Matter Particles and the Flat Rotation Curves of Spiral Galaxies
Not Available
| 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.
| Infrared imaging of spiral galaxies: Colors and luminosity profiles
We present surface photometry of 43 SO and spiral galaxies in the K bandwith a subset also observed in J. Most of the data are photometricallycalibrated. We combine our data with published optical major-axisprofiles to construct a set of galaxies with rJK colors, divide themajor-axis profiles into bulge-dominated and disk-dominated regions, andcompute mean colors and color gradients separately for bulges and disks.Typically the disk colors are measured from 0.8 to 1.8 scale lengths.The colors of the bulge and disk components are strongly correlated,indicating that both components have a red stellar content that issimilar in both age and metallicity. In the mean the disks are 0.1 magbluer in r - K than bulges; this color difference would arise if thedisks are 2-4 x 109 yr younger or have lower metallicities byDelta(Fe/H) is approximately equal to -0.1 to -0.2. Many of the bulgesexhibit negative color gradients (bluer outward), which indicate thatmetallicity gradients of order Delta(Fe/H) is approximately -0.2 may becommon in bulges. Bulges of late-type galaxies are bluer on average thanthose of early types, probably a consequence of lower metallicity. About25% of the galaxies have especially red bulge and disk colors, which weinterpret as arising from large internal extinction rather than from anenhanced star-formation rate.
| CCD calibration of the magnitude scale for the SSRS2 sample: The equatorial region
In this paper we continue our investigation on the isophotal nature,accuracy, and uniformity of the magnitude system adopted in the SouthernSky Redshift Survey extension (SSRS2). Extending our earlier work, weexamine galaxies in the equatorial region, primarily in the declinationrange delta greater than or equal to -17.5 deg and less than or equal to0 deg, over a large range of right ascension, covering the southern andnorthern Galactic caps. For this purpose, we have obtained CCD isophotalmagnitudes in the B and R bands for 265 galaxies of differentmorphological types. Using the larger sample we confirm our earlierclaim that the mSSRS2 magnitudes are very nearly themagnitude measured within the isophote muB = 26 mag/sqarcsec, with a dispersion of about 0.30 mag. The relative zero-pointoffset between our mSSRS2 magnitudes and the CCD photometryis -0.02 mag from all data we have obtained. However, we detect avariation of the zero-point across different regions of the sky of +/-0.10 mag for regions at large angular separations. We also estimate thatthe zero-point offset between the mSSRS2 and Zwicky systemsis relatively small (approximately 0.10 mag), which should allow us tocombine the data from the SSRS2 and the CfA2 Redshift Survey.
| The morphological catalogue of galaxies equatorial survey
We present 865 redshifts of galaxies located in the equatorial stripdelta between -17.5 deg and -2.5 deg in the right ascension rangebetween 20 h and 5 h. Redshifts have been obtained for the completesample of all 833 galaxies in the Morphological Catalog of Galaxies withmagnitudes brighter than m = 14.5 (corresponding approximately tom(Zwicky) = 15.0). This sample also includes three galaxies from othersources with more reliable magnitudes, satisfying this limit, and 29fainter galaxies, usually companions of the galaxies in the magnitudelimited sample. Our maps of a very large volume of nearby spacedemonstrate a variety of coherent large scale structures which includelarge voids, 20-50/h Mpc in diameter and large walls at least 70/h Mpcacross.
|
Добавить новую статью
Внешние ссылки
- - Внешних ссылок не найдено -
Добавить внешнюю ссылку
Группы:
|
Наблюдательные данные и астрометрия
Каталоги и обозначения:
|
