Contenidos
Imágenes
Subir su imagen
DSS Images Other Images
Artículos relacionados
Classifications of the Host Galaxies of Supernovae, Set III
A homogeneous sample comprising host galaxies of 604 recent supernovae,including 212 objects discovered primarily in 2003 and 2004, has beenclassified on the David Dunlap Observatory system. Most SN 1991bg-likeSNe Ia occur in E and E/Sa galaxies, whereas the majority of SN1991T-like SNe Ia occur in intermediate-type galaxies. This differenceis significant at the 99.9% level. As expected, all types of SNe II arerare in early-type galaxies, whereas normal SNe Ia occur in all Hubbletypes. This difference is significant at the 99.99% level. A smallnumber of SNe II in E galaxies might be due to galaxy classificationerrors or to a small young-population component in these mainly oldobjects. No significant difference is found between the distributionsover the Hubble type of SNe Ibc and SNe II. This confirms that both ofthese types of objects have similar (massive) progenitors. The presentdata show that in order to understand the dependence of supernova typeon host-galaxy population, it is more important to obtain accuratemorphological classifications than it is to increase the size of thedata sample.
| 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.
| Near-infrared observations of galaxies in Pisces-Perseus. V. On the origin of bulges
We investigate the scaling relations of bulge and disk structuralparameters for a sample of 108 disk galaxies. Structural parameters ofindividual galaxies are obtained from two-dimensional bulge/diskdecomposition of their H-band surface brightness distributions. Bulgesare modelled with a generalized exponential (Sérsic) withvariable integer shape index n. We find that bulge effectivescalelengths reB and luminosity MBincrease with increasing n, but disk properties are independent of bulgeshape. As Hubble type T increases, bulges become less luminous and theirmean effective surface brightness <μeB>gets fainter; disk <μeD> shows a similar,but much weaker, trend. When bulge parameters(<μeB>, reB,MB) are compared with disk ones(<μeD>, reD,MD), they are tightly correlated for n=1 bulges. Thecorrelations gradually worsen with increasing n such that n=4 bulgesappear virtually independent of their disks. The Kormendy relation,<μeB> vs. reB, isshown to depend on bulge shape n; the two parameters are tightlycorrelated in n=4 bulges (r=0.8), and increasingly less so as ndecreases; disk <μeD> andreD are well correlated (r=0.7). Bulge-to-disksize ratios reB/reD areindependent of Hubble type, but smaller for exponential bulges; the meanreB/reD for n=1 bulges is 4times smaller than that for n=4, with a spread which is 9 times smaller.Strongly barred SB galaxies with exponential bulges are more luminousthan their unbarred counterparts. Exponential bulges appear to beclosely related to their underlying disks, while bulges with higher nvalues are less so; n=4 bulges and their disks apparently have norelation. We interpret our results as being most consistent with asecular evolutionary scenario, in which dissipative processes in thedisk are responsible for building up the bulges in most spirals.Based on observations at the TIRGO, NOT, and VATT telescopes. TIRGO(Gornergrat, CH) is operated by IRA-CNR, Arcetri, Firenze. NOT (LaPalma, Canary Islands) is operated by NOTSA, the Nordic ObservatoryScientific Association. VATT (Mt. Graham, AZ) is operated by VORG, theVatican Observatory Research Group.Full Table 1 is 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/414/905.
| Supernovae 2003hg, 2003hh, 2003hi, 2003hj, 2003hk, 2003hl
IAUC 8184 available at Central Bureau for Astronomical Telegrams.
| 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.
| 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: 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.
| Near-infrared observations of galaxies in Pisces-Perseus. I. vec H-band surface photometry of 174 spiral
We present near-infrared, H-band (1.65 $() μm), surface photometry of174 spiral galaxies in the area of the Pisces-Perseus supercluster. Theimages, acquired with the ARNICA camera mounted on various telescopes,are used to derive radial profiles of surface brightness, ellipticities,and position angles, together with global parameters such as H-bandmagnitudes and diameters Radial profiles in tabular form and images FITSfiles are also available upon request from gmorio@arcetri.astro.it.}.The mean relation between H-band isophotal diameter D_{21.5} and theB-band D25 implies a B-H color of the outer disk bluer than3.5; moreover, D_{21.5}/D25 depends on (global) color andabsolute luminosity. The correlations among the various photometricparameters suggest a ratio between isophotal radius D_{21.5}/2 and diskscale length of ~ m3.5 and a mean disk central brightness ~ meq 17.5H-mag arcsec^{-2}. We confirm the trend of the concentration indexC31$ with absolute luminosity and, to a lesser degree, withmorphological type. We also assess the influence of non-axisymmetricstructures on the radial profiles and on the derived parameters. Basedon observations at the TIRGO, NOT, and VATT telescopes. TIRGO(Gornergrat, CH) is operated by CAISMI-CNR, Arcetri, Firenze. NOT (LaPalma, Canary Islands) is operated by NOTSA, the Nordic ObservatoryScientific Association. VATT (Mt. Graham, Az) is operated by VORG, theVatican Observatory Research Group Table 3 and Fig. 4 are only availablein electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html.
| Near-infrared observations of galaxies in Pisces-Perseus. III. Global scaling relations of disks and bulges
We determine the parameters of scaling relations analogous to theFundamental Plane of elliptical galaxies for the bulges and disks of asample of 40 spiral galaxies. To this end we derive structuralparameters (scalelengths and surface brightnesses) from near infrared Hband images, and kinematical parameters (rotational velocities) fromoptical rotation curves. In the case of the disks, we test the accuracyof the derived relation as a distance indicator by comparing its scatterto that of the H band Tully-Fisher relation for the same sample, andfind that the accuracy attained by the latter is slightly higher (thedispersion is 19% versus 23% for this sample). It is speculated that thedifference is due to the more robust character of global parameters,rather than those associated with the inner parts of disks. It alsoapperas that (a) either the stellar mass-to-light ratios of bulge anddisk increase with the size of the components, or (b) the bulge and diskrelative contributions to the overall rotation of the galaxy (and, as aconsequence, to its total mass) become steadily smaller with increasingsize.
| 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.
| Groups of galaxies. III. Some empirical characteristics.
Not Available
| 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
| 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
| The I band Tully-Fisher relation for cluster galaxies: data presentation.
Observational parameters which can be used for redshift-independentdistance determination using the Tully-Fisher (TF) technique are givenfor \ntot spiral galaxies in the fields of 24 clusters or groups. I bandphotometry for the full sample was either obtained by us or compiledfrom published literature. Rotational velocities are derived either from21 cm spectra or optical emission line long-slit spectra, and convertedto a homogeneous scale. In addition to presenting the data, a discussionof the various sources of error on TF parameters is introduced, and thecriteria for the assignment of membership to each cluster are given.
| 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.
| Large-Scale Structures in the Zone of Avoidance: The Galactic Anticenter Region
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ...449..527L&db_key=AST
| Dark Matter Particles and the Flat Rotation Curves of Spiral Galaxies
Not Available
| 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.
| Dark matter in spiral galaxies and the Arimoto-Jablonka photometric model
We use the recent stellar population synthesis models by Arimoto &Jablonka (1991), which by introducing the bulge into the calculation ofgalaxy masses mark a significant improvement over previous one-componentmodels, to show that low-luminosity spiral galaxies have a higher darkmatter fraction within the optical radius than high-luminosity spirals.In fact, the derived dark-to-visible mass ratio increases withdecreasing luminosity, approximately as 1/(square root ofLB). This conclusion agrees with previous results based ondynamical disk halo decompositions of galaxy rotation curves (e.g.Persic & Salucci 1988). On the other hand, we do not find any strongtrend between dark matter content and galaxy B - V colors, although wecannot exclude a weak one. Our results agree with Jablonka &Arimoto's (1992) conclusion that colors are not a primary indicator ofthe dark matter content of spiral galaxies. Instead, we confirm that theluminosity is a fundamental indicator of the dark mass fraction ofspiral galaxies.
| 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.
| A survey of small-scale extremes in extinction at low Galactic latitudes using IRAS galaxies
Optical CCD and 21 cm H I data are combined here via the Tully-Fisherrelation to study the Galactic extinction in the V an I bands over anangular scale of a few arcmin at absolute Galactic latitudes between 2and 16 deg. Extinctions in V and I bands are found to be linearlycorrelated with A(I) about 0.58 A(V), with no noticeable environmentaldependence and consistent with existing results of Galactic reddening.There is a large scatter in the simple linear relation with csc /b/,confirming the existence of 'holes' and patches at low Galacticlatitudes. The mean correlation between Galactic extinction and H Icolumn density over a comparable angular scale is also found to beconsistent with those at high latitudes over large angular scales.Correlation is also found between optical extinction and the IRAS 100micron sky brightness, and this sky brightness is only slightly worsethan H I column density as an indicator for optical extinction.
| The far-infrared properties of the CfA galaxy sample. I - The catalog
IRAS flux densities are presented for all galaxies in the Center forAstrophysics magnitude-limited sample (mB not greater than 14.5)detected in the IRAS Faint Source Survey (FSS), a total of 1544galaxies. The detection rate in the FSS is slightly larger than in thePSC for the long-wavelength 60- and 100-micron bands, but improves by afactor of about 3 or more for the short wavelength 12- and 25-micronbands. This optically selected sample consists of galaxies which are, onaverage, much less IR-active than galaxies in IR-selected samples. Itpossesses accurate and complete redshift, morphological, and magnitudeinformation, along with observations at other wavelengths.
| 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.
| 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.
| The dark matter content of spiral galaxies
A novel technique for calculating the fraction of dark material withinthe optical radius of spiral galaxies is presented. Disk luminositiesare converted to disk masses, and the latter are compared to dynamicalmasses. The method employs the well-established observational resultthat spiral galaxies have similar central surface brightnesses, as wellas published stellar-synthesis evolutionary models, color-magnituderelations, and optical rotation curves. No assumptions about the darkmatter distribution are necessary. It is found that the ratio ofdisk-to-dynamical mass within the optical radius increases roughly asLB exp 0.4. This is in good agreement with the results ofPersic and Salucci (1991) which are derived from independentconsiderations.
| Correlation functions of matter from galaxy rotation curves
Based on the disk-halo decomposition method introduced by Persic andSalucci (1988, 1990), 58 spiral rotation curves are used to measure thegalaxy-background correlation function in the range 3-350 kpc for H(0) =50 km/s per Mpc. It is found that (1) the two-point function is zeta(r)equal to about (r0/r) exp 1.76, with r(0) equal to about 7 Mpc (forOmega 0 = 1), and (2) higher order correlation functions are detected upto the sixth order and are found to fit the hierarchical expression.
| The universal galaxy rotation curve
The correlation between the shape of the rotation curves and theluminosity is considered, and it is found that for a given luminositythe rotation curves within the optical radius are a universal function.This result implies strong systematic variations of the amplitude andthe profile of the circular velocity with luminosity. Faint galaxieshave low velocities and steep velocity gradients and bright galaxieshave high velocities and shallow velocity gradients. Because luminousdisks are self-similar, the observed progression of the shape ofrotation curves with luminosity suggests that the dark-to-visibleinterplay varies with luminosity.
|
Enviar un nuevo artículo
Enlaces relacionados
- - No se han encontrado enlaces -
En viar un nuevo enlace
Miembro de los siguientes grupos:
|
Datos observacionales y astrométricos
Catálogos y designaciones:
|
