Contents
Images
Upload your image
DSS Images Other Images
Related articles
A wide-field HI study of the NGC 1566 group
We report on neutral hydrogen observations of a ~ 5.5 × 5.5deg2 field around the NGC 1566 galaxy group with themultibeam narrow-band system on the 64-m Parkes Telescope. We detected13 HI sources in the field, including two galaxies not previously knownto be members of the group, bringing the total number of confirmedgalaxies in this group to 26. Each of the HI galaxies can be associatedwith an optically catalogued galaxy. No `intergalactic HI clouds' werefound to an HI mass limit of ~3.5 ×108Msolar. We have estimated the expected HIcontent of the late-type galaxies in this group and find that the totaldetected HI is consistent with our expectations. However, while noglobal HI deficiency is inferred for this group, two galaxies exhibitindividual HI deficiencies. Further observations are needed to determinethe gas removal mechanisms in these galaxies.
| Nebular abundances of nearby southern dwarf galaxies
The results of optical spectroscopy of H II regions in a sample ofsouthern dwarf irregulars consisting of five dwarf galaxies in theCentaurus A group, four dwarfs in the Sculptor group, and eightadditional dwarf galaxies are presented. Oxygen abundances are derivedusing the direct method where [O III]lambda 4363 is detected;otherwise, abundances are derived with the bright-line method using theMcGaugh and the Pilyugin calibrations. ESO358-G060 has the lowest oxygenabundance (12+log(O/H) = 7.32) in the sample, which is comparable to thevalue for the second most metal-poor galaxy known (SBS 0335-052). Inall, new oxygen abundances are reported for nine dwarf galaxies; updatedvalues are presented for the remaining galaxies. Derived oxygenabundances are in the range from 3% to 26% of the solar value. Oxygenabundances for dwarfs in the southern sample are consistent with themetallicity-luminosity relationship defined by a control sample of dwarfirregulars with [O III]lambda 4363 abundances and well-measureddistances. However, NGC 5264 appears to have an (upper branch) oxygenabundance approximately two to three times higher than other dwarfs atsimilar luminosities. Nitrogen-to-oxygen and neon-to-oxygen abundanceratios are also reported; in particular, IC 1613 and IC 5152 showelevated nitrogen-to-oxygen ratios for their oxygen abundances.
| The Dwarf Galaxy Population of the Dorado Group Down to MV~-11
We present V and I CCD photometry of suspected low surface brightnessdwarf galaxies detected in a survey covering ~2.4 deg2 aroundthe central region of the Dorado group of galaxies. The low surfacebrightness galaxies were chosen based on their sizes and magnitudes atthe limiting isophote of 26 Vμ. The selected galaxies have magnitudesbrighter than V~20 (MV~-11 for an assumed distance to thegroup of 17.2 Mpc), with central surface brightnessesμ0>22.5 V mag arcsec-2, scale lengths h>2", anddiameters >=14" at the limiting isophote. Using these criteria, weidentified 69 dwarf galaxy candidates. Four of them are large very lowsurface brightness galaxies that were detected on a smoothed image,after masking high surface brightness objects. Monte Carlo simulationsperformed to estimate completeness, photometric uncertainties and toevaluate our ability to detect extended low surface brightness galaxiesshow that the completeness fraction is, on average, >80% for dwarfgalaxies with -17=14"). The V-I colors of the dwarfcandidates vary from -0.3 to 2.3 with a peak on V-I=0.98, suggesting arange of different stellar populations in these galaxies. The projectedsurface density of the dwarf galaxies shows a concentration toward thegroup center similar in extent to that found around five X-ray groupsand the elliptical galaxy NGC 1132 studied by Mulchaey & Zabludoff,suggesting that the dwarf galaxies in Dorado are probably physicallyassociated with the overall potential well of the group. Based on thedata collected at the Cerro Tololo Inter-American Observatory (CTIO) andLas Campanas Observatory, Chile.
| FAUST observations in the Fourth Galactic Quadrant*
We analyse UV observations with FAUST of four sky fields in the generaldirection of the Fourth Galactic Quadrant, in which we detect 777 UVsources. This is ~50 per cent more than detected originally by Bowyer etal. We discuss the source detection process and the identification of UVsources with optical counterparts. For the first time in this project weuse ground-based objective-prism information for two of the fields, toselect the best-matching optical objects with which to identify the UVsources. Using this, and correlations with existing catalogues, wepresent reliable identifications for ~75 per cent of the sources. Mostof the remaining sources have assigned optical counterparts but, lackingadditional information, we offer only plausible identifications. Wediscuss the types of objects found, and compare the observed populationwith predictions of our UV Galaxy model.
| HI observations of nearby galaxies . I. The first list of the Karachentsev catalog
We present HI observations of the galaxies in the first list of theKarachentsev catalog of previously unknown nearby dwarf galaxies(Karachentseva & Karachentsev 1998). This survey covers all knownnearby galaxy groups within the Local Volume (i.e. within 10 Mpc) andtheir environment, that is about 25% of the total sky. A total of 257galaxies have been observed with a detection rate of 60%. We searched afrequency band corresponding to heliocentric radial velocities from -470km s-1 to ~ +4000 km s-1. Non-detections areeither due to limited coverage in radial velocity, confusion with LocalHI (mainly in the velocity range -140 km s-1 to +20 kms-1), or lack of sensitivity for very weak emission. 25% ofthe detected galaxies are located within the Local Volume. Thosegalaxies are dwarf galaxies judged by their optical linear diameter (1.4+/- 0.2 kpc on the average), their mean total HI mass (4.6107 Msun), and their observed linewidths (39 kms-1).
| HI observations of southern LSB dwarf galaxies from the Karachentsev catalogue
In this paper, we report on HI observations of newly detected nearbydwarf galaxies from the first part of the Karachentsev catalogue whichcontains low surface brightness galaxies spotted on the POSS II. Weperformed HI observations of 220 galaxies using the 100-m radiotelescope at Effelsberg, the Nancay radio telescope, and the AustraliaTelescope Compact Array. We discuss global parameters of the wholesample and the observations of the southern sample in more detail.Global parameters of the observed galaxies are as expected from thesample of nearby galaxies (Kraan-Korteweg and Tammann 1979). Theincrease of the number of known galaxies in the Local Volume (i.e.within a distance of 10 Mpc) could be as high as 20% for the whole sky.
| An automated search for nearby low-surface-brightness galaxies - I. The catalogue
We have developed an automatic technique to search forlow-surface-brightness (LSB) galaxies in the local Universe (v <=5000 km s^-1) using the automated plate measuring (APM) scan data of UKSchmidt photographic plates. We optimized our technique and selectioncriteria by surveying the known LSB galaxies in the Fornax cluster.Plate-to-plate magnitude calibrations were carried out using independentCCD sequences. The galaxies we detected are brighter than 20 B mag, havescalesizes greater than 3 arcsec and a central surface brightnessfainter than 22.5 mag arcsec^-2. In total 2435 LSB galaxies weredetected over a total area of 2187 deg^2. The survey covers the Fornaxcluster, NGC 1400, Sculptor and Dorado groups and the field between. Wedetect on average 32 LSB galaxies per 5.8 deg x 5.8 deg field. We haveestimated the background (v>5000 km s^-1) contamination in threeways: by numerical modelling, using a limited redshift sample andcomparing our Fornax data with those of Ferguson. The results indicate acontamination of about 19 galaxies per field.
| A list of new nearby dwarf galaxy candidates
To increase completeness of the distance limited sample of nearbygalaxies from the \cite[Kraan-Korteweg & Tammann (1979)]{Kra79}catalogue we undertook a search for small companions of larger knowngalaxies which have corrected radial velocities within 500 km/s. Basedprimarily on the POSS-II and ESO/SERC films we found 260 nearby dwarfgalaxy candidates with angular diameters aga0 .5 arcmin. More than 50%of the objects were revealed for the first time. As we suppose, asignificant part of them (about 30%) may really belong to the LocalVolume sample. Tables 1 and 2 also available in electronic form at CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via\breakftp://cdsweb.u-strasbg.fr/Abstract.html
| 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.
| A catalog of southern groups of galaxies
A catalog of groups of galaxies identified in the southern Galactic capis presented. This catalog was constructed utilizing the group-findingalgorithm developed by Huchra and Geller (1982) to analyze galaxysamples with well-defined selection criteria and complete velocityinformation.
| Southern Galaxy Catalogue.
Not Available
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
Catalogs and designations:
|
