Садржај
Слике
Уплоадјуј своје слике
DSS Images Other Images
Везани чланци
UBVR and Hubble Space Telescope Mid-Ultraviolet and Near-Infrared Surface Photometry and Radial Color Gradients of Late-Type, Irregular, and Peculiar Galaxies
We introduce a data set of 142 mostly late-type spiral, irregular, andpeculiar (interacting or merging) nearby galaxies observed in UBVR atthe Vatican Advanced Technology Telescope (VATT), and we present ananalysis of their radial color gradients. We confirm that nearbyelliptical and early- to mid-type spiral galaxies show either no or onlysmall color gradients, becoming slightly bluer with radius. In contrast,we find that late-type spiral, irregular, peculiar, and merging galaxiesbecome on average redder with increasing distance from the center. Thescatter in radial color gradient trends increases toward later Hubbletype. As a preliminary analysis of a larger data set obtained with theHubble Space Telescope (HST), we also analyze the color gradients of sixnearby galaxies observed with NICMOS in the near-IR (H) and with WFPC2in the mid-UV (F300W) and red (F814W). We discuss the possibleimplications of these results on galaxy formation and compare our nearbygalaxy color gradients to those at high redshift. We present examples ofimages and UBVR radial surface brightness and color profiles, as well asof the tables of measurements; the full atlas and tables are publishedin the electronic edition only.Based on observations made with the NASA/ESA Hubble Space Telescope,obtained at the Space Telescope Science Institute, which is operated bythe Association of Universities for Research in Astronomy, Inc., underNASA contract NAS 5-26555. These observations are associated withprograms 8645, 9124, and 9824.
| The Chandra view of NGC1800 and the X-ray scaling properties of dwarf starbursts
The superb spatial resolution of Chandra is utilized to study the X-raymorphology of the dwarf starburst galaxy NGC1800 embedded in a smallgroup of galaxies. Diffuse galactic emission is detected, extendingseveral kiloparsec above the galactic plane, with an overall morphologysimilar to the galactic winds seen in nearby X-ray-bright starburstgalaxies. This makes NGC1800 the most distant dwarf starburst with aclear detection of diffuse X-ray emission. The diffuse X-ray luminosityof 1.3 +/- 0.3 × 1038ergs-1 accounts for atleast 60 per cent of the total soft X-ray output of the galaxy. A hotgas temperature of kT= 0.25 keV and metallicity Z~ 0.05Zsolarare derived, the latter being consistent with results from opticalspectroscopy of the interstellar medium. Our failure to detect any hotgas associated with the embedding galaxy group translates into an upperlimit to the group X-ray luminosity of LX <1041ergs-1. There is no convincing evidence thatthe outflowing wind of NGC1800 is currently interacting with anyintragroup gas, and mechanical considerations indicate that the wind canescape the galaxy and its surrounding HI halo, eventually deliveringenergy and metals to the intragroup gas. Properties of NGC1800 arecompared to those of other dwarf starburst galaxies, and a firstdetailed discussion of the X-ray scaling properties of this populationof objects is given, set against the equivalent results obtained fornormal starburst galaxies. Results indicate that dwarf starbursts to alarge degree behave as down-scaled versions of normal starburstgalaxies.
| ROSAT All-Sky Survey observations of IRAS galaxies. I. Soft X-ray and far-infrared properties
The 120 000 X-ray sources detected in the RASS II processing of theROSAT All-Sky Survey are correlated with the 14 315 IRAS galaxiesselected from the IRAS Point Source Catalogue: 372 IRAS galaxies showX-ray emission within a distance of 100 arcsec from the infraredposition. By inspecting the structure of the X-ray emission in overlayson optical images we quantify the likelihood that the X-rays originatefrom the IRAS galaxy. For 197 objects the soft X-ray emission is verylikely associated with the IRAS galaxy. Their soft X-ray properties aredetermined and compared with their far-infrared emission. X-ray contourplots overlaid on Palomar Digitized Sky Survey images are given for eachof the 372 potential identifications. All images and tables displayedhere are also available in electronic form.
| 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.
| 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.
| Parameters of 2447 Southern Spiral Galaxies for Use in the Tully-Fisher Relation
I-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.
| The Montreal Blue Galaxy survey. 2: Second list of UV-bright candidates
We present and discuss the second list of the Montreal Blue Galaxysurvey. Following the inspection of 71 plates, we found 237 newcandidates with B less than 15.5. 73 percent of them are also detectedby Infrared Astronomy Satellite (IRAS). Spectrophotometry was carriedout, at medium resolution, for a subset of 40 objects leading to theidentification of three new AGNs and producing 13 new radial velocities.Spectral classification of our candidates confirms our previous findingthat the majority of our candidates are starburst nucleus galaxiessimilar to the objects studied by Balzano in 1983. Our survey is biasedagainst the high excitation starburst H II galaxies and the LINERgalaxies. Metallicities of our galaxies are found to be from log(O/H)=8.4 to 9.0, which suggests galaxies in advanced stages of chemicalevolution.
| Properties of the Magellanic type spirals. 2: The frequency of companion galaxies
A survey of the largest (log D25 greater than 1.3) Magellanicspiral galaxies in the RC3 catalog was performed using the Palomar andUK Schmidt Sky Surveys. An attempt was made to classify arm strengthsand a search for nearby neighbor galaxies was conducted. In astatistical analysis of the data gathered in this survey it wasdetermined that among 75 galaxies with well classified asymmetric arms,only four were found to have no nearby neighbor within a separation of 5log D25. The classification of these four systems asMagellanic type galaxies is highly questionable (Corwin, (1989)). In nocase was a bright, dominant arm classified in a system in which a clearneighbor galaxy was absent. The frequency distribution of apparentseparations, which is strongly peaked at small separations, suggeststhat the observed galaxy pairs are not due to chance optical alignments,but are in fact the result of physical associations. Hence, scenariosinvoking the formation of offset bars and/or dominant spiral armsthrough some tidal interaction mechanism might be attractive, since acommon trait among the Magellanic spirals appears to be the presence ofa physical neighbor.
| A southern sky survey of the peculiar velocities of 1355 spiral galaxies
The paper presents data from photometric and spectroscopic observationsof 1355 southern spiral galaxies and uses them to determine theirdistances and peculiar velocities via the Tully-Fisher (TF) relation.I-band CCD surface photometry was carried out using the 1-m and 3.9-mtelescopes at Siding Spring Observatory. H-alpha rotation curves for 965galaxies and 551 H I profiles are presented. The physical parameters,photometric and velocity data, distances, and peculiar velocities of thegalaxies are presented in tabular form. The mean distance, systemicvelocity, and average peculiar velocity of 24 clusters in the sample aregiven. TF diagrams are presented for each cluster.
| Groups of galaxies within 80 Mpc. II - The catalogue of groups and group members
This paper gives a catalog of the groups and associations obtained bymeans of a revised hierarchical algorithm applied to a sample of 4143galaxies with diameters larger than 100 arcsec and redshifts smallerthan 6000 km/s. The 264 groups of galaxies obtained in this way (andwhich contain at least three sample galaxies) are listed, with the looseassociations surrounding them and the individual members of eachaggregate as well; moreover, the location of every entity among 13regions corresponding roughly to superclusters is specified. Finally,1729 galaxies belong to the groups, and 466 to the associations, i.e.,the total fraction of galaxies within the various aggregates amounts to53 percent.
| 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.
| Additional members of the Local Group of galaxies and quantized redshifts within the two nearest groups
Published observational data on galaxies of redshift z less than about1000 km/s are compiled in extensive tables and diagrams and analyzed,searching for additional Local Group members among fainterhigher-redshift galaxies. A concentration toward the center of the LocalGroup and a concentration associated with NGC 55, NGC 300, and NGC 253are identified in the south Galactic hemisphere and characterized indetail. The galaxies near the centers of the concentrations are found toobey a quantization interval of Delta-cz0 = 72.4 km/s, as for the LocalGroup (Tifft, 1977); the accuracy of this finding is shown to be towithin + or - 8.2 km/s (for galaxies with redshifts known to + or - 8km/s) and to within 3-4 km/s (for a subset of galaxies with moreaccurately measured redshifts).
| Latel-type galaxies - Star formation rates
A simple method for determining star formation rates (SFRs) in externalgalaxies is presented which is based on surface photometry in one coloronly. The intensity distributions of 59 late-type spiral and irregulargalaxies were divided into two components each, one containing the lightof the smoothly distributed old disk population, the other containingthe light of the clumped extreme Population I. This makes it possible todetermine the ratios of the 'present' SFRs (for stars with ages lessthan 50 million yr) to the average SFRs. Among other results, this ratiois found to be higher in asymmetric galaxies than in symmetric ones.
| Southern Galaxy Catalogue.
Not Available
|
Додај нови чланак
Линкови у сродству са темом
Додај нови линк
Чланови следећих група \:
|
Посматрања и Астрометриски подаци
Каталог и designations:
|
