Upload your image
DSS Images Other Images
Submit a new article
|Stellar abundance gradients in galactic discs - I. Method and spectral line gradients|
We describe the technique of absorption-line imaging of galaxy discsusing the Taurus Tunable Filter on the Anglo-Australian Telescope anddemonstrate its sensitivity to the behaviour of spectral featuresassociated with Mg and Fe. Radial profiles of Mg2 and Fe5270line strengths are presented for a sample of eight face-on spiralgalaxies spanning a range of Hubble types. Signatures of phenomenaincluding merger-induced star formation, HII rings and galactic bars arealso reported. This study demonstrates the capacity of tunable filtersto measure Mg and Fe line strengths across the face of spiral galaxies,which can ultimately reveal clues about the star formation history andchemical evolution.
|Sample of minor merger of galaxies: Optical CCD surface photometry and HII region properties|
We present the results of the B, V and I photometry of eleven southernminor mergers. The total apparent B magnitude, integrated B-V and V-Icolours were measured. We built B, V, and I equivalent profiles for eachgalaxy and decomposed them into bulge and disk components when possible.From Hα+N[II] images we have estimated the basic photometricparameters of the HII regions, such as position, size, B-V and V-Icolours, Hα+[NII] luminosity and EW(Hα+[NII]) equivalentwidth. Primary components have blue absolute magnitudes in the range -22< MB <-18, with a peak at MB = - 22. Themagnitudes of the secondary components are in the range -22
|Spiral galaxies observed in the near-infrared K band. I. Data analysis and structural parameters|
Deep surface photometry in the K band was obtained for 54 normal spiralgalaxies, with the aim of quantifying the percentage of faint bars andstudying the morphology of spiral arms. The sample was chosen to cover awider range of morphological types while inclination angles anddistances were limited to allow a detailed investigation of the internalstructure of their disks and future observations and studies of the diskkinematics. An additional constraint for a well defined subsample wasthat no bar structure was seen on images in the visual bands. Accuratesky projection parameters were determined from the K maps comparingseveral different methods. The surface brightness distribution wasdecomposed into axisymmetric components while bars and spiral structureswere analyzed using Fourier techniques.Bulges were best represented by a Sérsic r1/n law withan index in the typical range of 1-2. The central surface brightness ofthe exponential disk and bulge-to-disk ratio only showed weakcorrelation with Hubble type. Indications of a central point source werefound in many of the galaxies. An additional central, steep, exponentialdisk improved the fit for more than 80% of the galaxies suggesting thatmany of the bulges are oblate.Bars down to the detection level at a relative amplitude of 3% weredetected in 26 of 30 galaxies in a subsample classified as ordinary SAspirals. This would correspond to only 5% of all spiral galaxies beingnon-barred at this level. In several cases, bars are significantlyoffset compared to the starting points of the main spiral pattern whichindicates that bar and spiral have different pattern speeds. A smallfraction (10%) of the sample has complex central structuresconsisting of several sets of bars, arcs or spirals.A majority of the galaxies (60%) displays a two-armed, grand-designspiral pattern in their inner parts which often breaks up into multiplearms in their outer regions. Phase shifts between the inner and outerpatterns suggest in some cases that they belong to different spiralmodes. The pitch angles of the main two-armed symmetric spiral patternin the galaxies have a typical range of 5-30 °. The sample shows alack of strong, tight spirals which could indicate that such patternsare damped by non-linear, dynamical effects due to their high radialforce perturbations.Based on observations collected at the European Southern Observatory, LaSilla, Chile; programs: ESO 63.N-0343, 65.N-0287, 66.N-0257.Table 2 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (188.8.131.52) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/423/849Appendix A is only available in electronic form athttp://www.edpsciences.org
|A Catalog of H I-Selected Galaxies from the South Celestial Cap Region of Sky|
The first deep catalog of the H I Parkes All Sky Survey (HIPASS) ispresented, covering the south celestial cap (SCC) region. The SCC areais ~2400 deg2 and covers δ<-62°. The average rmsnoise for the survey is 13 mJy beam-1. Five hundredthirty-six galaxies have been cataloged according to their neutralhydrogen content, including 114 galaxies that have no previous catalogedoptical counterpart. This is the largest sample of galaxies from a blindH I survey to date. Most galaxies in optically unobscured regions of skyhave a visible optical counterpart; however, there is a small populationof low-velocity H I clouds without visible optical counterparts whoseorigins and significance are unclear. The rms accuracy of the HIPASSpositions is found to be 1.9′. The H I mass range of galaxiesdetected is from ~106 to ~1011 Msolar.There are a large number of late-type spiral galaxies in the SCC sample(66%), compared with 30% for optically selected galaxies from the sameregion in the NASA Extragalactic Database. The average ratio of H I massto B luminosity of the sample increases according to optical type, from1.8 Msolar/Lsolar for early types to 3.2Msolar/Lsolar for late-type galaxies. The HI-detected galaxies tend to follow the large-scale structure traced bygalaxies found in optical surveys. From the number of galaxies detectedin this region of sky, we predict the full HIPASS catalog will contain~5000 galaxies, to a peak flux density limit of ~39 mJy (3 σ),although this may be a conservative estimate as two large voids arepresent in the region. The H I mass function for this catalog ispresented in a subsequent paper.
|Nuclear activity and stellar population of a sample of interacting galaxies|
In this paper we investigate the nuclear activity and stellar populationin a sample of 27 physical galaxy pairs. Equivalent widths of absorptionfeatures are used to characterise the nuclear stellar populationaccording to templates: most galaxies of the sample have important fluxcontributions from stars younger than 10(8) years. According toclassical diagnostic-diagrams the galaxies in our sample are eitherclassified as H II regions or have emission line ratios near thetransition zone between H II regions and LINERs. Based on the observedspectra, only 4 galaxies show LINER properties and 1 nucleus is aSeyfert 2. We found that the spectrum of a transition object (38% of thesample) can be described by a combination of an AGN with an H II region.As a result, 20 galaxies of the present sample may host a low-luminosityactive nucleus. Based on observations made at CASLEO and CTIO. ComplejoAstronómico El Leoncito (CASLEO) is operated under agreementbetween the Consejo Nacional de Investigaciones Cient\'\i ficas yTécnicas de la República Argentina and the NationalUniversities of La Plata, Córdoba and San Juan.
|Optical Spectroscopic Properties of a Sample of Interacting Galaxies|
We present spectroscopic observations of 83 galaxies from a sample of 49pairs of optically selected interacting galaxies, most of thempreviously unobserved. These pairs consist of a main galaxy (componentA) and a companion (component B) that has about half or less thediameter of component A. From our spectra we determine that 27 galaxiesform truly physical pairs and seven are apparent pairs, for theremaining pairs we could only extract the spectra of the A components.The spectra of the physical pairs were classified into four groupsaccording to the emission-line spectra observed in each component. Theseclassifications were made because the sample exhibits a very large rangeof spectral properties, ranging from well-evolved stellar populations(older than 200 Myr) to emission-line--dominated starburst systems (80Myr or younger). In general terms, these spectral types are wellcorrelated with the morphological types of the galaxies. However, wefind no evidence of correlation of the equivalent width of H alpha + [NII] emission lines with the degree of the interaction or with the blueabsolute magnitude of the components. From the data it is alsodetermined that the average EW(H alpha + [N II]) for the physical pairsis 37 A for the A components and 54 A for the B components. For thegalaxies that form apparent pairs we obtain EW(H alpha + [N II]) = 27 A,confirming that physical pairs have higher mean star formation ratesthan isolated galaxies. This enhancement of the star formation activityis more likely to take place in both galaxies, but the strength of theactivity seems to be higher in the B components. The mean observedvalues of EW(H alpha + [N II]) are comparable with those observed in asample of strongly interacting or merging galaxies. On the other hand,we do not find the excess of Seyfert-type nuclei previously reported instudies of similar samples of galaxies.
|Constraining the Ages of Supernova Progenitors. I. Supernovae and Spiral Arms|
We present the first results of a three-part study of supernova (SN)ages using positional age indicators in spiral galaxies. We havemeasured the positions of 90 Spectroscopically identified Type Ia andType II SNs (SNs Ia and SNs II) relative to spiral arms in their hostgalaxies, making a special effort to reduce inhomogeneity in the processof arm tracing for different galaxies. We find that SNs II are moretightly concentrated to the arms than SNs Ia, but both kinds of SNsoccur closer to arms than a random disk population. However, whencompared with the distribution of V and I light relative to the arms,the SNs Ia are no more tightly concentrated than the general stellarpopulation. This indicates that SNs Ia occur in a population old enoughto have diffused away from their formation regions.
|The Catalog of Southern Ringed Galaxies|
The Catalog of Southern Ringed Galaxies (CSRG) is a comprehensivecompilation of diameters, axis ratios, relative bar position angles, andmorphologies of inner and outer rings, pseudorings, and lenses in 3692galaxies south of declination -17 deg. The purpose of the catalog is toevaluate the idea that these ring phenomena are related to orbitalresonances with a bar or oval in galaxy potentials. The catalog is basedon visual inspection of most of the 606 fields of the Science ResearchCouncil (SRC) IIIa-J southern sky survey, with the ESO-B, ESO-R, andPalomar Sky surveys used as auxiliaries when needed for overexposed coreregions. The catalog is most complete for SRC fields 1-303 (mostly southof declination -42 deg). In addition to ringed galaxies, a list of 859mostly nonringed galaxies intended for comparison with other catalogs isprovided. Other findings from the CSRG that are not based on statisticsare the identification of intrinsic bar/ring misalignment; bars whichunderfill inner rings; dimpling of R'1pseudorings; pointy, rectangular, or hexagonal inner or outer ringshapes; a peculiar polar-ring-related system; and other extreme examplesof spiral structure and ring morphology.
|Multiwavelength Energy Distributions and Bolometric Luminosities of the 12 Micron Galaxy Sample|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ...453..616S&db_key=AST
|Distribution of supernovae relative to spiral arms and H II regions|
We have studied the association of supernovae in spiral galaxies withsites of recent stars formation -- sprial arms and H II regions. It isshown that supernovae (SNe) of Types Ia, Ib, and II exhibitconcentration to spiral arms and their distributions over the distanceto the nearest spiral arm do not differ significantly. This result isconfirmed by a Kolmogorov-Smirnov test comparison with the distancedistributions, expected if SNe are distributed randomly inside the modelgalaxy. SNe of types Ib and II show a strong concentration towards H IIregions, while distribution of SNe Ia can be explained by chancesuperposition. All studied distributions of SNe Ib and II show strikingsimilarity, which suggests that their progenitors are massive stars withsimilar ages and initial masses. The association of SNe Ia with spiralarms suggests that their progenitors in spiral galaxies are likely to beintermediate mass stars.
|A catalog of recent supernovae|
A listing is given of all supernovae discovered between 1 Jan 1989 and 1Apr 1993. The data show no evidence for a significant dependence of thediscovery probability of supernovae on parent galaxy inclination to theline of sight. If no inclination corrections need to be applied then thesupernova rates in spirals are only about half as large as previouslybelieved. The mean linear separation of supernovae of Type II (SNe II)from the center of their parent galaxy increases with increasingdistance (Shaw effect). The Shaw effect appears less evident, or absent,for (more luminous) supernovae of Type Ia. The data are consistent with,but do not prove, the hypothesis that (presumably reddended) SNe II aremore likely to be discovered in the red than in the blue. Due tointensive surveillance, most bright SNe Ia tend to be found beforemaximum, whereas the majority of faint SNe Ia are discovered aftermaximum light.
|The extended 12 micron galaxy sample|
We have selected an all-sky (absolute value of b greater than or equalto 25 deg) 12 micron flux-limited sample of 893 galaxies from the IRASFaint Source Catalog, Version 2 (FSC-2). We have obtained accurate totalfluxes in the IRAS wavebands by using the ADDSCAN procedure for allobjects with FSC-2 12 micron fluxes greater than 0.15 Jy and increasingflux densities from 12 to 60 microns, and defined the sample by imposinga survey limit of 0.22 Jy on the total 12 micron flux. Its completenessis verified, by means of the classical log N - log S andV/Vmax tests, down to 0.30 Jy, below which we have measuredthe incompleteness down to the survey limit, using the log N - log Splot, for our statistical analysis. We have obtained redshifts (mostlyfrom catalogs) for virtually all (98.4%) the galaxies in the sample.Using existing catalogs of active galaxies, we defined a subsample of118 objects consisting of 53 Seyfert 1s and quasars, 63 Seyfert 2s, andtwo blazars (approximately 13% of the full sample), which is the largestunbiased sample of Seyfert galaxies ever assembled. Since the 12 micronflux has been shown to be about one-fifth of the bolometric flux forSeyfert galaxies and quasars, the subsample of Seyferts (includingquasars and blazars) is complete not only to 0.30 Jy at 12 microns butalso with respect to a bolometric flux limit of approximately 2.0 x10-10 ergs/s/sq cm. The average value of V/Vmaxfor the full sample, corrected for incompleteness at low fluxes, is 0.51+/- 0.04, expected for a complete sample of uniformly distributedgalaxies, while the value for the Seyfert galaxy subsample is 0.46 +/-0.10. We have derived 12 microns and far-infrared luminosity functionsfor the AGNs, as well as for the entire sample. We extracted from oursample a complete subsample of 235 galaxies flux-limited (8.3 Jy) at 60microns. The 60 micron luminosity function computed for this subsampleis in satisfactory agreement with the ones derived from the brightgalaxy sample (BGS) and the deep high-galactic latitude sample, bothselected at 60 microns.
|Supernova 1992ao in NGC 7637|
IAUC 5573 available at Central Bureau for Astronomical Telegrams.
|Southern Sky Redshift Survey - The catalog|
The catalog of radial velocities for galaxies which comprise thediameter-limited sample of the Southern Sky Redshift Survey ispresented. It consolidates the data of observations carried out at theLas Campanas Observatory, Observatorio Nacional, and South AfricanAstronomical Observatory. The criteria used for the sample selection aredescribed, as well as the observational procedures and the techniqueutilized to obtain the final radial velocities. The intercomparisonbetween radial velocity measurements from different telescopes indicatesthat the final data base is fairly homogeneous with a typical error ofabout 40 km/s. The sample is at present 90 percent complete, and themissing galaxies are predominantly objects with very low surfacebrightness for which it is very difficult to obtain optical redshifts.
|The 12 micron galaxy sample. I - Luminosity functions and a new complete active galaxy sample|
An all-sky 12 micron flux-limited sample of active galaxies was selectedfrom the IRAS Point Source Catalog. Most of the sample galaxies are inexisting catalogs, and 99 percent have measured redshifts. The 12-micronand the far-infrared luminosity functions of active and normal galaxiesare derived using IRAS co-added data. A total of 22 percent of thesample galaxies harbor active nuclei. The sample consists almost equallyof Seyfert 1, Seyfert 2, and LINER nuclei. The derived luminosityfuctions for Seyfert 1 and Seyfert 2 galaxies are indistinguishable fromthose of the optically selected CfA sample. Thus, 12 micron selection isthe most efficient available technique for finding complete activegalaxy samples.
|Simulated aperture-photometry on CCD-frames for 67 southern galaxies in B and R|
As part of a large project to calibrate all the Schmidt plates of theESO Quick blue and the red survey, CCD-photometry in B and R has beenobtained for galaxies on 67 different survey fields. On these framessynthetic-aperture photometry is applied in order to present the data ina way which makes the comparison with photographic photometry easy.
|Southern Galaxy Catalogue.|
|Spectroscopic measures of galaxies, their companions, and peculiar galaxies in the southern hemisphere|
Examples of apparent association of galaxies and also of single peculiargalaxies have been drawn from the Catalogue of Southern PeculiarGalaxies and Associations (Arp and Madore, in preparation).Spectroscopic measures are reported for 75 central or peculiar galaxiesand for 97 companion galaxies. Objects are identified by position andillustrated by photographic prints from the UK Schmidt (SRC) survey.Absorption and emission characteristics are tabulated for each spectrum,and heliocentric redshifts are given. The redshifts are calculated to beon the Reference Catalog II system (de Vaucouleurs et al. 1976) towithin plus or minus 50 km/s. The average redshift is repeatable towithin plus or minus 50 km/s. Differential redshifts of objects observedsimultaneously or sequentially can be considerably more accurate.
Submit a new link
Member of following groups:
Observation and Astrometry data
Catalogs and designations: