WIKISKY.ORG
 Home Getting Started To Survive in the Universe News@Sky Astro Photo The Collection Forum Blog New! FAQ Press Login

# NGC 615

Contents

### Images

DSS Images   Other Images

### Related articles

 HI content in galaxies in loose groupsGas deficiency in cluster spirals is well known and ram-pressurestripping is considered the main gas removal mechanism. In some compactgroups too gas deficiency is reported. However, gas deficiency in loosegroups is not yet well established. Lower dispersion of the membervelocities and the lower density of the intragroup medium in small loosegroups favour tidal stripping as the main gas removal process in them.Recent releases of data from the HI Parkes All-Sky Survey (HIPASS) andcatalogues of nearby loose groups with associated diffuse X-ray emissionhave allowed us to test this notion. In this paper, we address thefollowing questions: (i) do galaxies in groups with diffuse X-rayemission statistically have lower gas content compared to the ones ingroups without diffuse X-ray emission? (ii) does HI deficiency vary withthe X-ray luminosity, LX, of the loose group in a systematicway? We find that (i) galaxies in groups with diffuse X-ray emission, onaverage, are HI deficient, and have lost more gas compared to those ingroups without X-ray emission; the latter are found not to havesignificant HI deficiency; (ii) no systematic dependence of the HIdeficiency with LX is found. Ram-pressure-assisted tidalstripping and evaporation by thermal conduction are the two possiblemechanisms to account for this excess gas loss. New photometric and spectroscopic observations of the Seyfert galaxy Mrk 315We present new important results about the intermediate-type Seyfertgalaxy Mrk 315, recently observed through optical imaging andintegral-field spectroscopy. Broad-band images were used to study themorphology of the host galaxy, narrow-band Hα images to trace thestar-forming regions, and middle-band [OIII] images to evidence thedistribution of the highly ionized gas. Some extended emission regionswere isolated and their physical properties studied by means offlux-calibrated spectra. High-resolution spectroscopy was used toseparate different kinematic components in the velocity fields of gasand stars. Some peculiar features characterize this apparentlyundisturbed and moderately isolated active galaxy. Such features,already investigated by other authors, are re-analysed and discussed inthe light of these new observations. The most relevant results weobtained are: the multitiers structure of the disc; the presence of aquasi-ring of regions with star formation much higher than previousclaims; a secondary nucleus confirmed by a stellar componentkinematically decoupled by the main galaxy; a new hypothesis about thecontroversial nature of the long filament, initially described as hookshaped, and more likely made of two independent filaments caused byinteraction events between the main galaxy and two dwarf companions. Rotational Widths for Use in the Tully-Fisher Relation. I. Long-Slit Spectroscopic DataWe 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. The orientation parameters and rotation curves of 15 spiral galaxiesWe analyzed ionized gas motion and disk orientation parameters for 15spiral galaxies. Their velocity fields were measured with the Hαemission line by using the Fabry-Perot interferometer at the 6 mtelescope of SAO RAS. Special attention is paid to the problem ofestimating the position angle of the major axis (PA0) and theinclination (i) of a disk, which strongly affect the derived circularrotation velocity. We discuss and compare different methods of obtainingthese parameters from kinematic and photometric observations, takinginto account the presence of regular velocity (brightness) perturbationscaused by spiral density waves. It is shown that the commonly usedmethod of tilted rings may lead to systematic errors in the estimationof orientation parameters (and hence of circular velocity) being appliedto galaxies with an ordered spiral structure. Instead we recommend usingan assumption of constancy of i and PA0 along a radius, toestimate these parameters. For each galaxy of our sample we presentmonochromatic Hα- and continuum maps, velocity fields of ionizedgas, and the mean rotation curves in the frame of a model of purecircular gas motion. Significant deviations from circular motion withamplitudes of several tens of km s-1 (or higher) are found inalmost all galaxies. The character and possible nature of thenon-circular motion are briefly discussed.Based on observations collected with the 6 m telescope of the SpecialAstrophysical Observatory (SAO) of the Russian Academy of Sciences(RAS), operated under the financial support of the Science Department ofRussia (registration number 01-43).Section 4 and Figs. 6-19 are only avalaible in electronic form athttp://www.edpsciences.org The Rotation Curves of Dwarf Galaxies: A Problem for Cold Dark Matter?We address the issue of accuracy in recovering density profiles fromobservations of rotation curves of galaxies. We observe'' and analyzeour models in much the same way as observers do the real galaxies. Ourmodels include stellar disks, disks with bars, and small bulges. We findthat the tilted-ring model analysis produces an underestimate of thecentral rotational velocity. In some cases the galaxy halo densityprofile seems to have a flat core, while in reality it does not. Weidentify three effects that explain the systematic biases: inclination,small bulge, and bar. Inclination effects are due to the finitethickness of the disk, bar, or bulge. Admixture of a nonrotating bulgecomponent reduces the rotational velocity. A small (200-500 pc) bulgemay be overlooked, leading to systematic bias even on relatively large(~1 kpc) distances. In the case of a disk with a bar, the underestimateof the circular velocity is larger because of a combination ofnoncircular motions and random velocities. The effect of the bar dependson the angle that the bar makes with the line of sight. Signatures ofbars can be difficult to detect in the surface brightness profiles ofthe model galaxies. The variations of inclination angle and isophoteposition angle with radius are more reliable indicators of bar presencethan the surface brightness profiles. The systematic biases in thecentral ~1 kpc of galaxies are not large. Each effect separately givestypically a few km s-1 error, but the effects add up. In somecases the error in circular velocity was a factor of 2, but typically weget about a 20% effect. The result is the false inference that thedensity profile of the halo flattens in the central parts. Ourobservations of real galaxies show that for a large fraction of galaxiesthe velocity of gas rotation (as measured by emission lines) is veryclose to the rotation of the stellar component (as measured byabsorption lines). This implies that the systematic effects discussed inthis paper are also applicable both for the stars and emission-line gas. Ionized gas and stellar kinematics of seventeen nearby spiral galaxiesIonized 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 Chemically Distinct Nucleus and Structure of the S0 Galaxy NGC 80The giant lenticular galaxy NGC 80, which is the brightest member of arich group, possesses a central evolutionarily-distinct region: thestars in the nucleus and in a circumnuclear ring of radius 5″t7″ have a mean age of only 7 Gyr, whereas the stellar populationof the bulge is older than 10 Gyr. The nucleus of NGC 80 is alsochemically distinct: it is a factor of 2 2.5 richer in metals than itsimmediate neighborhood and is characterized by a high magnesium-to-ironabundance ratio [Mg/Fe]≈+0.3. The global stellar disk of NGC 80 has atwo-tiered structure: its outer part has an exponential scale length of11 kpc and normal surface density, while the inner disk, which is alsoexponential and axisymmetric, is more compact and brighter. Although thetwo-tiered structure and the chemically distinct nucleus obviously havea common origin and owe their existence to some catastrophicrestructuring of the protogalactic gaseous disk, the origin of thisremains unclear, since the galaxy lacks any manifestations of perturbedmorphology or triaxiality. A new catalogue of ISM content of normal galaxiesWe have compiled a catalogue of the gas content for a sample of 1916galaxies, considered to be a fair representation of normality''. Thedefinition of a normal'' galaxy adopted in this work implies that wehave purposely excluded from the catalogue galaxies having distortedmorphology (such as interaction bridges, tails or lopsidedness) and/orany signature of peculiar kinematics (such as polar rings,counterrotating disks or other decoupled components). In contrast, wehave included systems hosting active galactic nuclei (AGN) in thecatalogue. This catalogue revises previous compendia on the ISM contentof galaxies published by \citet{bregman} and \citet{casoli}, andcompiles data available in the literature from several small samples ofgalaxies. Masses for warm dust, atomic and molecular gas, as well asX-ray luminosities have been converted to a uniform distance scale takenfrom the Catalogue of Principal Galaxies (PGC). We have used twodifferent normalization factors to explore the variation of the gascontent along the Hubble sequence: the blue luminosity (LB)and the square of linear diameter (D225). Ourcatalogue significantly improves the statistics of previous referencecatalogues and can be used in future studies to define a template ISMcontent for normal'' galaxies along the Hubble sequence. The cataloguecan be accessed on-line and is also available at the Centre desDonnées Stellaires (CDS).The catalogue is available in electronic form athttp://dipastro.pd.astro.it/galletta/ismcat and at the CDS via anonymousftp to\ cdsarc.u-strasbg.fr (130.79.128.5) or via\http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/405/5 The H I Line Width/Linear Diameter Relationship as an Independent Test of the Hubble ConstantThe relationship between corrected H I line widths and linear diameters(LW/LD) for spiral galaxies is used as an independent check on the valueof the Hubble constant. After calibrating the Tully-Fisher (TF) relationin both the B and I bands, the B-band relation is used for galaxies ofmorphological/luminosity types Sc I, Sc I.2, Sc I.3, Sab, Sb, Sb I-II,and Sb II to derive the LW/LD relation. We find that for this sample thescatter in the LW/LD is smallest with a Hubble constant of 90-95 kms-1 Mpc-1. Lower values of the Hubble constantproduce a separation in the LW/LD relation that is a function ofmorphological type. Since a Hubble constant of 90-95 is significantlylarger than the final Key Project value of 72 km s-1Mpc-1, a comparison of TF, surface brightness fluctuation(SBF), and fundamental plane (FP) is made. This comparison indicatesthat the Key Project TF distances to 21 clusters may be too large. For asample of 11 clusters, the Key Project TF distances provide anunweighted mean Hubble constant of 77 km s-1Mpc-1, while a combination of the FP, SBF, and our TFdistances for the same 11 clusters gives H0=91 kms-1 Mpc-1. A more subtle result in our data is amorphological dichotomy in the Hubble constant. The data suggest that ScI galaxies follow a Hubble constant of 90-95 while Sb galaxies follow aHubble constant closer to 75 km s-1 Mpc-1.Possible explanations for this result are considered, but it is shownthat this Sb/Sc I Hubble flow discrepancy is also present in the VirgoCluster and is consistent with previous investigations that indicatethat some galaxies carry a component of age-related intrinsic redshift. Bar Galaxies and Their EnvironmentsThe 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. Complex Formation History of the Lenticular Galaxies with Stellar Counterrotation: NGC 4138 and NGC 4550Two lenticular galaxies with counterrotating stellar components in theirdisks have been studied with the Multi-Pupil Fiber Spectrograph of the 6m telescope (at the Special Astrophysical Observatory). In NGC 4138 thenucleus is certainly chemically distinct, with the central concentrationof magnesium enhancement marginally exceeding that of iron. The ionizedgas within R=4" of the nucleus rotates circularly in an inclined ring,perhaps a kind of a circumnuclear polar ring surrounding a compactstellar minibar. NGC 4550 exhibits complex extended structures in itscenter that can be identified by enhanced levels of magnesium and ironindices; the stellar population of the unresolved nucleus is youngerthan that of the circumnuclear region. We conclude that although NGC4550 does not possess a chemically distinct nucleus in the ordinarysense of the term, there are nevertheless clear signatures of asecondary star formation burst confined perhaps to the counterrotatingstellar gaseous disk. We argue that the inclination of thecounterrotating disk differs from that of the main stellar disk,implying that the two disks are not coplanar. Both galaxies seem to havepossessed bars, either actually present or already dissolved. Partlybased on observations collected with the 6 m telescope (BTA) at theSpecial Astrophysical Observatory of the Russian Academy of Sciences. Chemically distinct nuclei and circumnuclear rings in lenticular galaxies NGC 4429 and NGC 7013The central regions of the regular lenticular galaxies NGC 4429 and NGC7013 have been studied with the Multi-Pupil Field (Fiber) Spectrograph(MPFS) of the 6 m telescope of the Special Astrophysical Observatory RAS(Nizhnij Arkhyz, Russia) in two spectral ranges, the blue one includingthe strong absorption lines Mg I and Fe I and the red one including theemission lines Hα and [N II]lambda 6583. We confirm the presenceof the chemically distinct nucleus in NGC 7013 reported earlier. Besidesthis unresolved (in the magnesium index) structure, we have found a ringof younger stellar populations than those in the nucleus and in thebulge; the radius of this ring is about 6\arcsec (400 pc). A similarring, distinguished by high magnesium- and iron-index values andbordered by Hα emission at its inner edge, with a radius of6\arcsec (500 pc), is found in NGC 4429. We try to relate the ringedstructure of the chemically decoupled cores in these galaxies with past,now dissolved, large-scale bars whose remnants are now seen in NGC 4429and NGC 7013 as lenses between the bulges and global disks. An analysisof the gas and star kinematics in the centers of the galaxies hasrevealed the presence of an inclined circumnuclear disk in NGC 7013 andthe existence of minibar in NGC 4429. Based on observations collectedwith the 6 m telescope of the Special Astrophysical Observatory (SAO) ofthe Russian Academy of Sciences (RAS) which is operated under thefinancial support of Science Department of Russia (registration number01-43) and on data from the HST and ING Archives. Structure and Kinematics of NGC 615 and Its Nuclear Star Formation HistoryThe results of a complex photometric and spectral investigation of theregular Sb galaxy NGC 615 are presented. The observations were made withthe 6 m, 1 m, and 0.6 m telescopes of the Special AstrophysicalObservatory RAS (Nizhnij Arkhyz, Russia) and the 1.5 m ESO telescope (LaSilla, Chile). The analysis of the radial brightness profiles revealsthe existence of at least two decoupled exponential components; theparameters of the outer component are typical for the global disks of Sbgalaxies, and the inner component seen in the radius range 9"-30"(1.0-3.5 kpc) is distinguished by compactness and high surfacebrightness. A combination of two-dimensional velocity fields for starsand ionized gas in the central part of the galaxy and of the long-slitvelocity profiles along the major axis up to the optical border of NGC615 provides some interesting findings. In the very center, R<3" (0.3kpc), stars and gas rotate together, and the dynamical and photometricmajor axes are turned with respect to the global line of nodes; weconclude that an inclined circumnuclear disk is detected. In the bulge,R=3"-6" (0.35-0.75 kpc), the stellar velocity dispersion is more than100 km s-1, the stars rotate twice as slowly as the ionizedgas, and a counterrotating gaseous component is observed. In the innerexponential component the stars rotate together with the ionized gas,and the stellar velocity dispersion drops to about 50 km s-1.As the photometric major axis of this component is turned with respectto the line of nodes, we call it an oval inner disk.'' The mean age ofthe stellar populations in the nucleus and in the inner disk beyond itsH II regions is 5 Gyr, while the bulge is much older. Both thechemically decoupled nucleus of NGC 615 and the inner disk probablyformed the bulk of their more luminous stars in a secondary burst ofstar formation, perhaps provoked by the close passage of another galaxysome gigayears ago. Based on observations collected with the 6 m, 1 m,and 0.6 m telescopes of the Special Astrophysical Observatory (SAO) ofthe Russian Academy of Sciences (RAS) and with the 1.52 m ESO telescopeat La Silla. HI observations of nearby galaxies. IV. More dwarf galaxies in the southern skyIn this paper we present HI observations of nearby galaxies from twomore lists of the Karachentsev catalog of candidates for nearby dwarfgalaxies in the southern sky. Observations north of declination -31degrwere performed with the 100-m radio telescope at Effelsberg. Data formore southern galaxies were taken from HIPASS(www.atnf.csiro.au/research/multibeam). This sample is a supplement tothe list of 94 southern dwarf galaxy candidates (1998, A&AS, 127,409) located in the same declination range around the known Local Volumegalaxies (i.e. galaxies within 10 Mpc, LV hereafter). We observed 17galaxies not observed in the previous sample; and all 67 candidate dwarfgalaxies from the SERC EJ sky survey (Karachentsev et al.\cite{Karachentsev00) and 81 objects from a supplementary list ofcandidate dwarf galaxies (Karachentseva & Karachentsev\cite{Karachentseva00}). This yields a total of 165 (=17 + 67 + 81)galaxies. Overall we have a detection rate of 48%. The sample ofdetected galaxies has the following median parameters: radial velocityVLG= 1127 km s-1, HI line width W50 =59 km s-1, absolute blue magnitude MBT0= -14.4 mag, linear diameter A0 = 4.0 kpc, hydrogenmass-to-luminosity ratio 1.6 Msun/Lsun. The sampleof known galaxies within the Local Volume increased from 179 in 1979(Kraan-Korteweg & Tammann \cite{KraanKorteweg79}) to 387 now. Thiscorresponds to an increase in total luminosity of 22%. The known HI massin the LV increased by 25%; the relative HI contentMHI/LB increased from 0.21 to 0.26 for the wholevolume. However we still might have missed half of the dwarf galaxies inthe Local Volume. Table 1 is also, and Table 2 only, available inelectronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(139.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/377/801 Nearby Optical Galaxies: Selection of the Sample and Identification of GroupsIn 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. Box- and peanut-shaped bulges. I. StatisticsWe 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 Chemically decoupled nucleus and the structure of the nuclear region in the spiral galaxy NGC 488The regular Sb-type galaxy NGC 488 was observed at the 6-meter telescopewith the Multi-Pupil Field Spectrograph and found to have a chemicallydecoupled nucleus. Stellar population in the nucleus is twice richer inmetals than that of the central bulge. An analysis of the isophotalshapes in the central part of the galaxy based on the images obtainedwith broad-band filters allowed us to identify two isolated stellarcomponents in NGC 488: one in the radial range between 1 and 2 arcsecand another in the R 4-7 arcsec interval. The coincidence of photometricand dynamical major axes proves that both components are compactcircumnuclear disks tilted with respect to the plane of the globalgalactic disk. The stellar disk at the very center of the galaxy, whichends at R = 2 arcsec, has a gaseous extension up to R = 4 arcsec. Inboth stellar disks, a low-contrast spiral pattern can be distinguished. Flat rotation curves of galaxies are left in the past.Not Available The Southern Sky Redshift SurveyWe 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. Total magnitude, radius, colour indices, colour gradients and photometric type of galaxiesWe 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: BibliographyWe 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 Search for chemically decoupled galactic nuclei with the Multi-Pupil Field Spectrograph of the 6 M telescope.Not Available An Einstein X-Ray Survey of Optically Selected Galaxies. I. DataWe present the results of a complete Einstein imaging proportionalcounter X-ray survey of optically selected galaxies from theShapley-Ames Catalog, the Uppsala General Catalogue, and the EuropeanSouthern Observatory Catalog. Well-defined optical criteria are used toselect the galaxies, and X-ray fluxes are measured at the opticallydefined positions. The result is a comprehensive list of X-ray detectionand upper limit measurements for 1018 galaxies. Of these, 827 haveeither independent distance estimates or radial velocities. Associatedoptical, redshift, and distance data have been assembled for thesegalaxies, and their distances come from a combination of directlypredicted distances and those predicted from the Faber-Burstein GreatAttractor/Virgocentric infall model. The accuracy of the X-ray fluxeshas been checked in three different ways; all are consistent with thederived X-ray fluxes being of <=0.1 dex accuracy. In particular,there is agreement with previously published X-ray fluxes for galaxiesin common with a 1991 study by Roberts et al. and a 1992 study byFabbiano et al. The data presented here will be used in further studiesto characterize the X-ray output of galaxies of various morphologicaltypes and thus to enable the determination of the major sourcescontributing to the X-ray emission from galaxies. Molecular Gas, Morphology, and Seyfert Galaxy ActivityWe 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. Decoupled nuclei and nuclear polar rings in regular spiral galaxies. NGC 2841.The Sb galaxy NGC 2841 was observed at the 6 m telescope of SAO RAS withthe Multi-Pupil Field Spectrograph and at the 1 m telescope of SAO RASwith the long-slit spectrograph. An unresolved nucleus of NGC 2841 isshown to be chemically decoupled both in magnesium and in iron withabundance break estimates of 0.36dex for Mg and 0.6dex for Fe; anabundance gradient in the bulge is seen only in the magnesium index andis typical for early-type disk galaxies. The rotation axis of thenuclear ionized gas in NGC 2841 is perpendicular to that of the centralstellar population; an existence of a bulge stellar component withdecoupled rotation momentum in the radius range 5"-12" is suspected. Apossible scenario for the origin of the unusual central structure in NGC2841 is proposed. Parameters of 2447 Southern Spiral Galaxies for Use in the Tully-Fisher RelationI-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. Bias Properties of Extragalactic Distance Indicators. VI. Luminosity Functions of M31 and M101 Look-alikes Listed in the RSA2: H0 TherefromGalaxies whose morphologies are similar to M 101 (Sc I) and M3 1 (Sb I-II) are listed in two tables. The selection is made by inspecting directimages of Shapley-Ames galaxies in the recent Carnegie Atlas ofGalaxies. Absolute magnitudes, calculated from redshifts, give meanvalues of Integrated photoelectric magnitudes and color indices of bright galaxies in the Johnson UBV systemThe photoelectric total magnitudes and color indices published in theThird Reference Catalogue of Bright Galaxies (RC3) are based on ananalysis of approximately equals 26,000 B, 25,000 B-V, and 17,000 U-Bmultiaperture measurements available up to mid 1987 from nearly 350sources. This paper provides the full details of the analysis andestimates of internal and external errors in the parameters. Thederivation of the parameters is based on techniques described by theVaucouleurs & Corwin (1977) whereby photoelectric multiaperture dataare fitted by mean Hubble-type-dependent curves which describe theintegral of the B-band flux and the typical B-V and U-B integrated colorgradients. A sophisticated analysis of the residuals of thesemeasurements from the curves was made to allow for the random andsystematic errors that effect such data. The result is a homogeneous setof total magnitudes BTA total colors(B-V)T and (U-B)T, and effective colors(B-V)e and (U-B)e for more than 3000 brightgalaxies in RC3. Photometrically distinct nuclei in elliptical and early-type disks galaxies.Not Available H0 found by comparing linear diameters of M31 with similar field galaxiesThe method of finding a stringent upper limit to H by comparing theknown linear size of M101 with similar field galaxies and requiring thatM101 not be the largest in a distance-limited sample is extended here toSab and Sb galaxies using M31 as the calibrator. In agreement with theearlier result using M101, the upper limit using M31 is H less than 85km/s/Mpc. Because M31 is the nearest Sb spiral, the most probable actualvalue of H is found by equating the known linear diameter of M31 withthe mean of a distance-limited sample of similar galaxies. Data on 60RSA galaxies that are similar to M31 give the most probable value as H =45 +/- 12 km/s/Mpc by this method.
Submit a new article

• - No Links Found -