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|Kinematics of the local universe . XII. 21-cm line measurements of 586 galaxies with the new Nançay receiver|
This paper presents 586 new 21-cm neutral hydrogen line measurementscarried out with the FORT receiver of the meridian transit Nançayradiotelescope in the period July 2000-March 2003. This observationalprogramme is part of a larger project aiming at collecting an exhaustiveand magnitude-complete HI extragalactic catalogue for Tully-Fisherapplications. It is associated with the building of the MIGALEspectroscopic archive and database.Tables 2, 3 and HI-profiles and corresponding comments are onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (188.8.131.52) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/430/373, or directly atour web site http://klun.obs-nancay.fr
|The gas content of peculiar galaxies: Strongly interacting systems|
A study of the gas content in 1038 interacting galaxies, essentiallyselected from Arp, Arp & Madore, Vorontsov-Velyaminov catalogues andsome of the published literature, is presented here. The data on theinterstellar medium have been extracted from a number of sources in theliterature and compared with a sample of 1916 normal galaxies. The meanvalues for each of the different ISM tracers (FIR, 21 cm, CO lines,X-ray) have been estimated by means of survival analysis techniques, inorder to take into account the presence of upper limits. From the datait appears that interacting galaxies have a higher gas content thannormal ones. Galaxies classified as ellipticals have both a dust and gascontent one order of magnitude higher than normal. Spirals have in mostpart a normal dust and HI content but an higher molecular gas mass. TheX-ray luminosity also appears higher than that of normal galaxies ofsame morphological type, both including or excluding AGNs. We consideredthe alternative possibilities that the molecular gas excess may derivefrom the existence of tidal torques which produce gas infall from thesurrounding regions or from a different metallicity which affects the Xconversion factor between the observed CO line luminosity and the H_2calculated mass. According to our tests, it appears that interactinggalaxies possess a higher molecular mass than normal galaxies but with asimilar star formation efficiency.Table 1 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (184.108.40.206) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/422/941
|Formalism and quality of a proper motion link with extragalactic objects for astrometric satellite missions|
The accuracy of the link of the proper motion system of astrometricsatellite missions like AMEX and GAIA is discussed. Monte-Carlo methodswere used to simulate catalogues of positions and proper motions ofquasars and galaxies to test the link. The main conclusion is, thatfuture satellite missions like GAIA may be ``self-calibrated'' by theirmeasurements of QSOs, while additional measurements from radio stars orHST-data are needed to calibrate the less deep reaching astrometricsatellite missions of AMEX type.
|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.
|Spectroscopic Observations of Merging Galaxies|
In this paper we describe the spectroscopic and infrared properties of asample of 25 merging galaxy pairs, selected from the catalog of Arp& Madore, and we compare them with those observed in a similarsample of interacting galaxies (Donzelli & Pastoriza). It is notedthat mergers as well as interacting systems comprise a wide range ofspectral types, going from those corresponding to well-evolved stellarpopulations (older than 200 Myr) to those that show clear signatures ofH II regions with stellar populations younger than 8 Myr. However,merger galaxies show on average more excited spectra than interactingpairs, which could be attributed to lower gas metallicity. From theemission lines we also found that merging systems show on average higher(about a factor of 2) star formation rates than interacting galaxies.Classical diagnostic diagrams show that only three of 50 of the galaxies(6%) present some form of nuclear activity: two Seyfert galaxies and oneLINER. However, through a detailed analysis of the pure emission-linespectra, we conclude that this fraction may raise up to 23% of themergers if we consider that some galaxies host a low-luminosity activenucleus surrounded by strong star-forming regions. This latterassumption is also supported by the infrared colors of the galaxies.Regarding to the total infrared luminosities, the merging galaxies showon average an IR luminosity, log(Lir)=10.7, lower than thatof interacting systems, log(Lir)=10.9. We find that onlythree mergers of the sample (12%) can be classified as luminous infraredgalaxies, while this fraction increases to 24% in the interactingsample. Based on observations made at CASLEO. ComplejoAstronómico El Leoncito is operated under agreement between theConsejo Nacional de Investigaciones Científicas y Técnicasde la República Argentina and the National Universities of LaPlata, Córdoba and San Juan.
|Galaxy coordinates. II. Accurate equatorial coordinates for 17298 galaxies|
Using images of the Digitized Sky Survey we measured coodinates for17298 galaxies having poorly defined coordinates. As a control, wemeasured with the same method 1522 galaxies having accurate coordinates.The comparison with our own measurements shows that the accuracy of themethod is about 6 arcsec on each axis (RA and DEC).
|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.
|Candidates for a southern extension of the Karachentsev catalogue of isolated pairs of galaxies.|
|Spectroscopic Observations of ARP / Madore Interacting Galaxies - Part Two - Galaxies with Tails Loops of Material or Debris|
We present spectroscopic observations of 103 galaxies from a sample ofinteracting galaxies with tails, loops of material or debris. Radialvelocities, relative emission-line intensity measurements and opticalclassifications are presented. Three new Seyfert candidates areidentified. The frequency of Seyfert-type nuclei in our sample of`strongly' interacting galaxies (3.9 per cent; 4/103) is notsignificantly different from that of the interacting doubles ofcomparably sized galaxies (3.1 per cent; 4/129), which are presumably atan earlier stage of interaction than the galaxies observed in thepresent-study. However, the lack of a suitable control sample for ourinteracting samples prevents us from confirming whether interactions andmergers enhance Seyfert nuclear activity compared to that of non-interacting galaxies. A large fraction of the galaxies in our sampleshow strong H II region type emission lines, which indicate ongoingenhanced star formation activity. Since the systems are at a relativelyearly stage of the merger process and are near the peak of theirstarburst activities, the interstellar gas in the disc must be collectedin the nuclear region on time-scales less than about a few X 10^8^-10^9^yr. Strong H II region type emission lines superimposed on a strongstellar Balmer absorption spectrum are seen in many of the systems inour sample, suggesting a possible recurrent starburst or propagation ofstar-forming regions within the galaxy. High-resolution imaging studiesare required for further analysis of the sample.
|Heavy-element abundances and massive star formation|
The observational consequences that arise for the heavy-elementabundances in normal spiral galaxies from variations in the IMF areinvestigated. The most recent calculations of supernova nucleosynthesisare used to calculate the oxygen yield for a given IMF. Assuminginstantaneous recycling of oxygen, the resultant oxygen abundance iscalculated. A comparison of the predicted and observed oxygen abundancesin the Milky Way shows that the overall abundance is well explained bythe IMF determined in the solar neighborhood. It is shown that theoxygen abundance is very sensitive to the underlying IMF; some of themodifed IMFs proposed for the Milky Way and starburst galaxies result inan oxygen abundance an order of magnitude larger than solar. It isconcluded that truncation of the IMF in starburst regions results in anoxygen abundance in conflict with the available observations, unlessvery large mass loss has occurred.
|The Galaxy activity-interaction connection. II - Radio observations|
VLA results are presented for southern interacting galaxies at 6 and 20cm, with a view to the detection and classification of the nature ofradio emission in a set of advanced-interaction disk galaxies. Maps ofradio emission are given for the 42 interacting systems in the sample,as well as 10 control systems, and radio properties are compared withoptical and IR properties; the radio in all of the present interactinggalaxies are attributable to properties associated with a burst of starformation due to galaxy interaction.
|The galaxy activity-interaction connection. I - Optical observations|
As part of an investigation into the triggering of nuclear radioemission in interacting galaxies, new multicolor, broadband data arepresented from a subset of Arp-Madore Catalog galaxies selected on thebasis of their optical morphology - systems with loops and/or tails. TheCTIO 4 m is used to obtain images in B, V, R, and I for the purpose ofperforming synthetic aperture photometry. Isophotal ellipse fitting tothe more regular objects in the sample is also performed to quantifytheir isophotal deviation from purely elliptical morphologies. Colorindex maps for the galaxies are constructed, and the opticalmorphologies, broadband colors, and detailed photometric properties aswell as the IRAS fluxes for the galaxies are discussed. These data areused to obtain a rough measure of the level of activity present in thesesystems.
|Southern Galaxy Catalogue.|
|Shock-induced star formation in IC2153 - A colliding pair of galaxies|
Direct photographic, photometric and spectroscopic observations of theinteracting galaxy-pair IC2153 = ESO 364-IG 22 are reported. Theobservations were performed with the ESO 3.6-m, 1.5 m and 1-m telescopesat La Silla, Chile. The mean radial velocity of the system is 2630 km/s( = or 30 km/s), corresponding to a distance of 35 Mpc. The system isaobut nine kpc across, and its UBV colors are consistent with thosefound in irregular galaxies. The absolute magnitude of the system is-18.4 mag. Spectral tracings of the main components show an early-typeabsorption spectrum and an emission spectrum. Spectra in theintermediate region of the pair have pure emission-line characteristics.Evidence of shock-heating in the galactic H-II regions, and it isestimated that about 7 percent of the light in H-beta originates fromshock-heating and that the remainder arises from photoionization by hotstars. From a stellar population model, it is found that the UBV Johnsoncolors in the pair represent a burst of star formation with an age of150 million years.
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