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

NGC 4500



Upload your image

DSS Images   Other Images

Related articles

The Second Byurakan Survey. General Catalogue
The Second Byurakan Survey (SBS) General Catalogue is presented. TheSBS, a continuation of the Markarian survey reaching fainter limitingmagnitudes, is the first survey which combines the search of galaxiesand QSOs. A total area of 991OS#square;degrees of the Northern sky wascovered with the use of three objective prisms in combination withSchott filters. The limited magnitude on the best plates reached B ~19.5.The General Catalogue consists of 3563 objects presented in two parts: aCatalogue of galaxies (1863 objects) and one of stellar objects (1700objects). The Catalogue of SBS AGN consists of 761 objects (155 SyG, 596QSOs, and 10 BLLac). Multi-wavelength data are presented for 1438 SBSobjects identified with X-ray, IRAS and FIRST sources.Spectrophotometric observations obtained over 26 years are available for3132 objects. Redshifts were measured for ~ 2100 extragalactic objects.Spectral classification is presented for ~ 2970 objects. The majority ofthe data is presented here for the first time. The Catalogue presentsnew large homogeneous deep representative complete samples of brightQSOs, AGNs, and faint UVX galaxies in the Northern sky. The SBS sampleis found to be complete at 70% for galaxies and ~ 85% for AGN/QSOs withB ≤ 17.5.

Spectroscopic study of blue compact galaxies. V. Oxygen abundance and the metallicity-luminosity relation
This is the fifth paper in a series studying the stellar components,star formation histories, star formation rates and metallicities of ablue compact galaxy (BCG) sample. Based on our high-quality ground-basedspectroscopic observations, we have determined the electrontemperatures, electron densities, nitrogen abundances and oxygenabundances for 72 star-forming BCGs in our sample, using differentoxygen abundance indicators. The oxygen abundance covers the range 7.15< 12 + log (O/H)< 9.0, and nitrogen is found to be mostly aproduct of secondary nucleosynthesis for 12 + log (O/H)>8.2 andapparently a product of primary nucleosynthesis for 12 + log (O/H)<8.2. To assess the possible systematic differences among differentoxygen abundance indicators, we have compared oxygen abundances of BCGsobtained with the Te method, R23 method, P method,N2 method and O3N2 method. The oxygen abundances derived from theTe method are systematically lower by 0.1-0.25 dex than thosederived from the strong line empirical abundance indicators, consistentwith previous studies based on region samples. We confirm the existenceof the metallicity-luminosity relation in BCGs over a large range ofabundances and luminosities. Our sample of galaxies shows that the slopeof the metallicity-luminosity relation for the luminous galaxies(~-0.05) is slightly shallower than that for the dwarf galaxies(~-0.17). An offset was found in the metallicity-luminosity relation ofthe local galaxies and that of the intermediate redshift galaxies. Itshows that the metallicity-luminosity relation for the emission linegalaxies at high redshift is displaced to lower abundances, higherluminosities, or both.

Spectroscopic study of blue compact galaxies. IV. Star formation rates and gas depletion timescales
This is the fourth paper in a series studying star formation rates,stellar components, metallicities, and star formation histories of ablue compact galaxy (BCG) sample. Using Hα, [O II]λ3727,infrared (IR), radio (1.4 GHz) luminosities and neutral hydrogen (H I)gas masses, we estimated star formation rates and gas depletiontimescales of 72 star-forming BCGs. The star formation rates of the BCGsin our sample span nearly four orders of magnitude, from approximately10-2 to 102 Mȯ yr-1,with a median star formation rate of about 3 Mȯyr-1. The typical gas depletion timescale of BCGs is aboutone billion years. Star formation could be sustained at the currentlevel only on a timescale significantly lower than the age of theuniverse before their neutral gas reservoir is completely depleted. Toassess the possible systematic differences among different starformation rate indicators, we compared the star formation rates derivedfrom Hα, [O II]λ3727, IR, and radio luminosities, andinvestigated the effects from underlying stellar absorption and dustextinction. We found that subtracting underlying stellar absorption isvery important to calculate both dust extinction and star formation rateof galaxies. Otherwise, the intrinsic extinction will be overestimated,the star formation rates derived from [O II]λ3727 and Hαwill be underestimated (if the underlying stellar absorption and theinternal extinction were not corrected from the observed luminosity) oroverestimated (if an overestimated internal extinction were used forextinction correction). After both the underlying stellar absorption andthe dust extinction were corrected, a remarkably good correlationemerges among Hα, [O II]λ3727, IR and radio star formationrate indicators. Finally, we find a good correlation between themeasured star formation rate and the absolute blue magnitude,metallicity, interstellar extinction of BCGs. Our results indicate thatfaint, low-mass BCGs have lower star formation rates.Star formation rates and gas depletion timescales of BCGs are availablein electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr( or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/425/417

Properties of isolated disk galaxies
We present a new sample of northern isolated galaxies, which are definedby the physical criterion that they were not affected by other galaxiesin their evolution during the last few Gyr. To find them we used thelogarithmic ratio, f, between inner and tidal forces acting upon thecandidate galaxy by a possible perturber. The analysis of thedistribution of the f-values for the galaxies in the Coma cluster leadus to adopt the criterion f ≤ -4.5 for isolated galaxies. Thecandidates were chosen from the CfA catalog of galaxies within thevolume defined by cz ≤5000 km s-1, galactic latitudehigher than 40o and declination ≥-2.5o. Theselection of the sample, based on redshift values (when available),magnitudes and sizes of the candidate galaxies and possible perturberspresent in the same field is discussed. The final list of selectedisolated galaxies includes 203 objects from the initial 1706. The listcontains only truly isolated galaxies in the sense defined, but it is byno means complete, since all the galaxies with possible companions underthe f-criterion but with unknown redshift were discarded. We alsoselected a sample of perturbed galaxies comprised of all the diskgalaxies from the initial list with companions (with known redshift)satisfying f ≥ -2 and \Delta(cz) ≤500 km s-1; a totalof 130 objects. The statistical comparison of both samples showssignificant differences in morphology, sizes, masses, luminosities andcolor indices. Confirming previous results, we found that late spiral,Sc-type galaxies are, in particular, more frequent among isolatedgalaxies, whereas Lenticular galaxies are more abundant among perturbedgalaxies. Isolated systems appear to be smaller, less luminous and bluerthan interacting objects. We also found that bars are twice as frequentamong perturbed galaxies compared to isolated galaxies, in particularfor early Spirals and Lenticulars. The perturbed galaxies have higherLFIR/LB and Mmol/LB ratios,but the atomic gas content is similar for the two samples. The analysisof the luminosity-size and mass-luminosity relations shows similartrends for both families, the main difference being the almost totalabsence of big, bright and massive galaxies among the family of isolatedsystems, together with the almost total absence of small, faint and lowmass galaxies among the perturbed systems. All these aspects indicatethat the evolution induced by interactions with neighbors would proceedfrom late, small, faint and low mass Spirals to earlier, bigger, moreluminous and more massive spiral and lenticular galaxies, producing atthe same time a larger fraction of barred galaxies but preserving thesame relations between global parameters. The properties we found forour sample of isolated galaxies appear similar to those of high redshiftgalaxies, suggesting that the present-day isolated galaxies could bequietly evolved, unused building blocks surviving in low densityenvironments.Tables \ref{t1} and \ref{t2} are only available in electronic form athttp://www.edpsciences.org

Starbursts in barred spiral galaxies. VI. HI observations and the K-band Tully-Fisher relation
This paper reports a study of the effect of a bar on the neutralhydrogen (HI) content of starburst and Seyfert galaxies. We also makecomparisons with a sample of ``normal'' galaxies and investigate howwell starburst and Seyfert galaxies follow the fundamental scalingTully-Fisher (TF) relation defined for normal galaxies. 111 Markarian(Mrk) IRAS galaxies were observed with the Nançay radiotelescope,and HI data were obtained for 80 galaxies, of which 64 are newdetections. We determined the (20 and 50%) linewidths, the maximumvelocity of rotation and total HI flux for each galaxy. Thesemeasurements are complemented by data from the literature to form asample of Mrk IRAS (74% starburst, 23% Seyfert and 3% unknown) galaxiescontaining 105 unbarred and 113 barred ones. Barred galaxies have lowertotal and bias-corrected HI masses than unbarred galaxies, and this istrue for both Mrk IRAS and normal galaxies. This robust result suggeststhat bars funnel the HI gas toward the center of the galaxy where itbecomes molecular before forming new stars. The Mrk IRAS galaxies havehigher bias-corrected HI masses than normal galaxies. They also showsignificant departures from the TF relation, both in the B and K bands.The most deviant points from the TF relation tend to have a strongfar-infrared luminosity and a low oxygen abundance. These resultssuggest that a fraction of our Mrk IRAS galaxies are still in theprocess of formation, and that their neutral HI gas, partly of externalorigin, has not yet reached a stationary state.Based on observations obtained at the large radiotelescope ofObservatoire de Nançay, operated by Observatoire de Paris.Tables 5 and 6 are only (and Table 4 also) available in electronic format the CDS via anonymous ftp to cdsarc.u-strasbg.fr ( orvia http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/416/515

The PDS versus Markarian starburst galaxies: comparing strong and weak IRAS emitter at 12 and 25 μm in the nearby Universe
The characteristics of the starburst galaxies from the Pico dos Diassurvey (PDS) are compared with those of the nearby ultraviolet (UV)bright Markarian starburst galaxies, having the same limit in redshift(vh < 7500 km s-1) and absolute B magnitude(MB < -18). An important difference is found: theMarkarian galaxies are generally undetected at 12 and 25 μm in IRAS.This is consistent with the UV excess shown by these galaxies andsuggests that the youngest star-forming regions dominating thesegalaxies are relatively free of dust.The far-infrared selection criteria for the PDS are shown to introduce astrong bias towards massive (luminous) and large size late-type spiralgalaxies. This is contrary to the Markarian galaxies, which are found tobe remarkably rich in smaller size early-type galaxies. These resultssuggest that only late-type spirals with a large and massive disc arestrong emitters at 12 and 25 μm in IRAS in the nearby Universe.The Markarian and PDS starburst galaxies are shown to share the sameenvironment. This rules out an explanation of the differences observedin terms of external parameters. These differences may be explained byassuming two different levels of evolution, the Markarian being lessevolved than the PDS galaxies. This interpretation is fully consistentwith the disc formation hypothesis proposed by Coziol et al. to explainthe special properties of the Markarian SBNG.

Spectroscopic study of blue compact galaxies. III. Empirical population synthesis
This is the third paper of a series dedicated to the study of the starformation rates, star formation histories, metallicities and dustcontents of a sample of blue compact galaxies (BCGs). We constrain thestellar contents of 73 blue compact galaxies by analyzing theircontinuum spectra and the equivalent widths of strong stellar absorptionfeatures using a technique of empirical population synthesis based on alibrary of observed star-cluster spectra. Our results indicate that bluecompact galaxies are typically age-composite stellar systems; inaddition to young stars, intermediate-age and old stars contributesignificantly to the 5870 Å continuum emission of most galaxies inour sample. The stellar populations of blue compact galaxies also span avariety of metallicities. The ongoing episodes of star formation startedtypically less than a billion years ago. Some galaxies may be undergoingtheir first global episode of star formation, while for most galaxies inour sample, older stars are found to contribute up to half the opticalemission. Our results suggest that BCGs are primarily old galaxies withdiscontinuous star formation histories. These results are consistentwith the results from deep imaging observations of the color-magnitudediagrams of a few nearby BCGs using HST and large ground-basedtelescopes. The good quality of our population synthesis fits of BCGspectra allow us to estimate the contamination of the Hβox{Hα }, Hβ , Hγ and Hdelta Balmer emission lines bystellar absorption. The absorption equivalent widths measured in thesynthetic spectra range from typically 1.5 Å for Hβox{Hα }, to 2-5 Å for Hβ , Hγ , and Hdelta . Theimplied accurate measurements of emission-line intensities will be usedin a later study to constrain the star formation rates and gas-phasechemical element abundances of blue compact galaxies.

The cold gas properties of Markarian galaxies
A sample of 61 Markarian galaxies detected in the CO line was compiled.Using available HI, element H2, optical and radio continuumdata, the analysis of the gas kinematics and the star formationproperties for this sample of galaxies was performed. The mainconclusion can be summarized as follows: (1) The HI and CO line widthsare well correlated. Interaction between galaxies has no influence onthe CO line broadening. A rapidly rotating nuclear disk in the galaxymight lead to the CO line broadening with less influence on the HI line.(2) The atomic and molecular gas surface densities are well correlatedwith the blue, FIR and radio continuum surface brightness; however, thecorrelation for molecular component is stronger.\ (3) In general, thegalaxies with UV-excess (Markarian galaxies) do not differ in their starformation properties from the non-UV galaxies.

A New Database of Observed Spectral Energy Distributions of Nearby Starburst Galaxies from the Ultraviolet to the Far-Infrared
We present a database of UV-to-FIR data of 83 nearby starburst galaxies.The galaxies are selected based upon the availability of IUE data. Wehave recalibrated the IUE UV spectra for these galaxies by incorporatingthe most recent improvements. For 45 of these galaxies we useobservations by Storchi-Bergmann et al. and McQuade et al. for thespectra in the optical range. The NIR data are from new observationsobtained at the NASA/IRTF and the Mount Laguna Observatory, combinedwith the published results from observations at the Kitt Peak NationalObservatory. In addition, published calibrated ISO data are included toprovide mid-IR flux densities for some of the galaxies. Theoptical-to-IR data are matched as closely as possible to the IUE largeaperture. In conjunction with IRAS and ISO FIR flux densities, all thesedata form a set of observed spectral energy distributions (SEDs) of thenuclear regions of nearby starburst galaxies. The SEDs should be usefulin studying star formation and dust/gas attenuation in galaxies. We alsopresent the magnitudes in the standard BVRI and various HST/WFPC2bandpasses synthesized from the UV and optical wavelength ranges ofthese SEDs. For some of the galaxies, the HST/WFPC2 magnitudessynthesized from the SEDs are checked with those directly measured fromWFPC2 images to test the photometric errors of the optical data andtheir effective matching of apertures with the UV data. The implicationsof the new SEDs on the star formation rates and dust/gas attenuation arebriefly discussed.

Far-Infrared Census of Starburst-Seyfert Connection
Far-infrared flux densities are newly extracted from the IRAS databasefor the Revised Shapley-Ames and CfA complete samples of Seyfertgalaxies. These data are used to classify the Seyfert galaxies intothose where the far-infrared continuum emission is dominated by theactive galactic nucleus (AGN), circumnuclear starburst, or host galaxy.While AGN-dominant objects consist of comparable numbers of Seyfert 1and 2 galaxies, starburst- and host-dominant objects consistpreferentially of Seyfert 2 galaxies. Thus, in addition to the dustytorus, the circumnuclear starburst region and host galaxy are importantin hiding the broad-line region. Morphologically, starburst-dominantSeyfert galaxies are of later types and more strongly interacting thanAGN-dominant Seyfert galaxies. In a later type galaxy, the AGN centralengine has a lower Eddington luminosity, and the gaseous content ishigher. The gas is efficiently supplied to the starburst via agalaxy-galaxy interaction. Morphologies of host-dominant Seyfertgalaxies are of various types. Since starbursts in Seyfert galaxies areolder than those in classical starburst galaxies, we propose anevolution from starburst to starburst-dominant Seyfert to host-dominantSeyfert for a late-type galaxy. An evolution from AGN-dominant Seyfertto host-dominant Seyfert is proposed for an early-type galaxy. Thesesequences have durations of a few times 108 yr and occurrepeatedly within a galaxy during its evolution from a late type to anearly type.

Spectroscopic study of blue compact galaxies. II. Spectral analysis and correlations
This is the second paper in a series studying the star formation rates,stellar components, metallicities, and star formation histories andevolution of a sample of blue compact galaxies. We analyzed spectralproperties of 97 blue compact galaxies, obtained with the BeijingAstronomical Observatory (China) 2.16 m telescope, with spectral range3580 Å-7400 Å. We classify the spectra according to theiremission lines: 13 of the total 97 BCG sample are non-emission linegalaxies (non-ELGs); 10 have AGN-like emission (AGNs), and 74 of themare star-forming galaxies (SFGs). Emission line fluxes and equivalentwidths, continuum fluxes, the 4000 Å Balmer break index andequivalent widths of absorption lines are measured from the spectra. Weinvestigate the emission line trends in the integrated spectra of thestar-forming galaxies in our sample, and find that: 1) The equivalentwidths of emission lines are correlated with the galaxy absolute bluemagnitude MB; lower luminosity systems tend to have largerequivalent widths. 2) The equivalent width ratio [N II]6583/Hα isanti-correlated with equivalent width Hα; a relationship is giventhat can be used to remove the [N II] contribution from blendedHα+ [N II]6548, 6583. 3) The [O II], Hβ , Hγ andHα fluxes are correlated; those can be used as star formationtracers in the blue. 4) The metallicity indices show trends with galaxyabsolute magnitude and attenuation by dust, faint, low-mass BCGs havelower metallicity and color excess. Tables 1-4, and 6 are only availablein electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr( or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/396/503

Spectroscopic study of blue compact galaxies. I. The spectra
Blue compact galaxies are compact objects that are dominated by intensestar formation. Most of them have dramatically different propertiescompared to the Milky Way and many other nearby galaxies. Using theIRAS, H I data, and optical spectra, we wanted to measure the currentstar formation rates, stellar components, metallicities, and starformation histories and evolution of a large blue compact galaxy sample.We anticipate that our study will be useful as a benchmark for studiesof emission line galaxies at high redshift. In the first paper of thisseries, we describe the selection, spectroscopic observation, datareduction and calibration, and spectrophotometric accuracy of a sampleof 97 luminous blue compact galaxies. We present a spectrophotometricatlas of rest-frame spectra, as well as tables of the recessionvelocities and the signal-to-noise ratios. The recession velocities ofthese galaxies are measured with an accuracy of delta V< 67 kms-1. The average signal-to-noise ratio of sample spectra is ~51. The spectral line strengths, equivalent widths and continuum fluxesare also measured for the same galaxies and will be analyzed in the nextpaper of this series. The atlas and tables of measurements will be madeavailable electronically. Table 3 and Fig. 4 are only available inelectronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr( or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/389/845

Photometric studies of starburst galaxies
We present the results of a detailed morphological analysis of a sampleof Markarian starburst galaxies. CCD surface photometry of thosegalaxies was carried out based on observations made in U BV RI and H?.The morphology of the sample objects was studied using isophotalcontours and colour images. The radial variations of the surfacebrightness, ellipticity, position angle and the colour profiles wereconstructed using ellipse fitting techniques. We find that the starformation activity is not confined to the central region alone, but italso occurs at various other locations like the ends of bars, alongcircum-nuclear rings or even globally in a few cases. The luminosityprofiles show an exponential nature in the outer region. Strongisophotal twisting is observed in almost all the S0 galaxies in oursample. In a few cases, this is accompanied by boxiness, indicating astrong interaction or merger. Blue light is more centrally concentratedas compared to red light in early type galaxies while the reverse holdsfor spirals. The scale lengths in B and R are comparable. Compositemodels were constructed and ages between 106 and 107 years and burststrength between 1% to 5% were able to explain the observed colours.

Accurate optical positions for 2978 objects from the Second Byurakan Survey (SBS) with the Digitized Sky Survey
Optical positions of 2978 objects listed in the Second Byurakan Survey(SBS) were obtained using the Digitized Sky Survey (DSS), and are givenwith an rms uncertainty ~ 1 arcsec in each coordinate. Tables 1 and 2are only available in electronic form at the CDS via anonymous ftp130.79.128.5 or via http://cdsweb.u-strasbg.fr/Abstract.html

Stellar population synthesis for blue compact galaxies.
Not Available

Arcsecond Positions of UGC Galaxies
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.

Dust Absorption and the Ultraviolet Luminosity Density at Z~3 as Calibrated by Local Starburst Galaxies
We refine a technique to measure the absorption-corrected ultraviolet(UV) luminosity of starburst galaxies using rest-frame UV quantitiesalone and apply it to Lyman-limit U dropouts at z~3 found in the HubbleDeep Field (HDF). The method is based on an observed correlation betweenthe ratio of far-infrared (FIR) to UV fluxes with spectral slope beta (aUV color). A simple fit to this relation allows the UV flux absorbed bydust and reprocessed to the FIR to be calculated, and hence thedust-free UV luminosity to be determined. International UltravioletExplorer spectra and Infrared Astronomical Satellite fluxes of localstarbursts are used to calibrate the F_FIR/F_1600 versus beta relationin terms of A_1600 (the dust absorption at 1600 Å) and thetransformation from broadband photometric color to beta. Bothcalibrations are almost completely independent of theoreticalstellar-population models. We show that the recent marginal andnondetections of HDF U dropouts at radio and submillimeter wavelengthsare consistent with their assumed starburst nature and our calculatedA_1600. This is also true of recent observations of the ratio of opticalemission-line flux to UV flux density in the brightest U dropouts. Thislatter ratio turns out not to be a good indicator of dust extinction. InU dropouts, absolute magnitude M_1600,0 correlates with beta: brightergalaxies are redder, as is observed to be the case for local starburstgalaxies. This suggests that a mass-metallicity relationship is alreadyin place at z~3. The absorption-corrected UV luminosity function of Udropouts extends up to M_1600,0~-24 AB mag, corresponding to a starformation rate ~200 M_solar yr^-1 (H_0=50 km s^-1 Mpc^-3 and q_0=0.5 areassumed throughout). The absorption-corrected UV luminosity density atz~3 is rho_1600,0>=1.4x10^27 ergs^-1 Hz^-1 Mpc^-1. It is still alower limit since completeness corrections have not been done andbecause only galaxies with A_1600<~3.6 mag are blue enough in the UVto be selected as U dropouts. The luminosity-weighted meandust-absorption factor of our sample is 5.4+/-0.9 at 1600 Å.

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).

Photometric studies of some starburst galaxies
We present the results of a detailed morphological analysis of tenstarburst galaxies selected from the Markarian catalog of uv-excessobjects. CCD surface photometry of these galaxies was carried out basedon observations made in B, V (Johnson) and R, I (Kron-Cousins) bandpasses. We present the radial variations of surface brightness,ellipticity, position angle and the colour indices for each galaxyobtained using ellipse fitting isophotal analysis. The residual imagesconstructed for extracting the fine structure are also presented. Avariety of morphological types are found to host the starburstphenomenon. The star formation activity is not confined to the nuclearregion alone, but it also occurs at various locations in the galaxy andis seen as clumpy regions. The colour index and the residual images areused for deriving information about the sites of enhanced star formationactivity and the triggers of the starburst. The luminosity profiles showan exponential behaviour in the outer region. The disk scale lengths andthe half-light radii are derived. The contribution of the burstcomponent has been estimated and the colours of the burst component arepresented. Strong isophotal twisting is detected in all the S0 and Egalaxies: Mrk 1002, Mrk 1308 and Mrk 14, in the sample. This isaccompanied by boxiness in some cases, suggesting that a merger isresponsible for the starburst activity in these galaxies. In case ofisolated spirals, a bar or a central oval distortion appear to be thelikely trigger for the starburst.

Starbursts in barred spiral galaxies. V. Morphological analysis of bars
We have measured the bar lengths and widths of 125 barred galaxiesobserved with CCDs. The dependence of bar strength (identified with baraxis ratio) on morphological type, nuclear activity, central and mid-barsurface brightness is investigated. The properties of the bars are bestexplained if the sample is divided into early- (< SBbc) and late-typegalaxies, and into active (starburst, Seyfert or LINER) and normalgalaxies. We find that galaxies with very long bars are mostly activeand that normal late-type galaxies have a distinct behavior from thethree other groups of galaxies. We confirm earlier findings that activelate-type galaxies tend to have both stronger and longer bars thannormal ones. An important result of this paper is that early-typegalaxies do not share this behavior: they all tend to have strong bars,whether they are active or not. We also find correlations between barstrength and relative surface brightness in the middle and at the edgeof the bar, which are not followed by normal late-type galaxies. Theseresults are interpreted in the light of recent numerical simulations andparadigms about galaxy evolution. They suggest that normal late-typegalaxies represent the first stage of galaxy evolution, and that bars inearly- and late-type galaxies do not have the same properties becausethey have a different origin. Based on observations obtained at the 2meter telescope of Observatoire du Pic du Midi, operated by INSU (CNRS)

The Supernova Rate in Starburst Galaxies
We conducted an optical CCD search for supernovae in a sample of 142bright [m(B) <= 16 mag], nearby (z<=0.03) starburst galaxies overthe period 1988 December to 1991 June, to a limiting R-band magnitude of18. Five supernovae were found, in all cases outside the host galaxy'snucleus. We determine supernova rates (in supernova units or SNU) in theextranuclear regions to be 0.7 h^2 SNU for Type Ia, 0.7 h^2 SNU for TypeIb/c, and ~0.6 h^2 SNU for Type II, with large uncertainties but upperlimits of 2.2 h^2, 2.5 h^2, and 1.7 h^2 SNU, respectively. These ratesare similar to those measured in ``normal'' galaxies. We found noevidence for a supernova-induced brightening in any galactic nucleusand, with a few reasonable assumptions, can place upper limits of 9 h^2,12 h^2, and 7 h^2 SNU on the rates of unobscured supernovae Types Ia,Ib/c, and II, respectively, inside the nuclei.

The Pico DOS Dias Survey Starburst Galaxies
We discuss the nature of the galaxies found in the Pico dos Dias Survey(PDS) for young stellar objects. The PDS galaxies were selected from theIRAS Point Source catalog. They have flux density of moderate or highquality at 12, 25, and 60 μm and spectral indices in the ranges -3.00<= alpha(25, 12) <= + 0.35 and -2.50 <= alpha(60, 25) <=+0.85. These criteria allowed the detection of 382 galaxies, which are amixture of starburst and Seyfert galaxies. Most of the PDS Seyfertgalaxies are included in the catalog of warm IRAS sources by de Grijp etal. The remaining galaxies constitute a homogeneous sample of luminous[log F (L_B/L_ȯ) = 9.9 +/- 0.4] starburst galaxies, 67% of whichwere not recognized as such before. The starburst nature of the PDSgalaxies is established by comparing their L_IR/L_B ratios and IRAScolors with a sample of emission-line galaxies from the literaturealready classified as starburst galaxies. The starburst galaxies show anexcess of FIR luminosity, and their IRAS colors are significantlydifferent from those of Seyfert galaxies-99% of the starburst galaxiesin our sample have a spectral index alpha(60, 25) < -1.9. As opposedto Seyfert galaxies, very few PDS starbursts are detected in X-rays. Inthe infrared, the starburst galaxies form a continuous sequence withnormal galaxies. But they generally can be distinguished from normalgalaxies by their spectral index alpha(60, 25) > -2.5. This colorcutoff also marks a change in the dominant morphologies of the galaxies:the normal IRAS galaxies are preferentially late-type spirals (Sb andlater), while the starbursts are more numerous among early-type spirals(earlier than Sbc). This preference of starbursts for early-type spiralsis not new, but a trait of the massive starburst nucleus galaxies(Coziol et al.). As in other starburst nucleus galaxy samples, the PDSstarbursts show no preference for barred galaxies. No difference isfound between the starbursts detected in the FIR and those detected onthe basis of UV excess. The PDS starburst galaxies represent the FIRluminous branch of the UV-bright starburst nucleus galaxies, with meanFIR luminosity log (L_IR/L_ȯ) = 10.3 +/- 0.5 and redshifts smallerthan 0.1. They form a complete sample limited in flux in the FIR at 2 x10^-10 ergs cm^-2 s^-1.

Kinematics of the local universe. VII. New 21-cm line measurements of 2112 galaxies
This paper presents 2112 new 21-cm neutral hydrogen line measurementscarried out with the meridian transit Nan\c cay radiotelescope. Amongthese data we give also 213 new radial velocities which complement thoselisted in three previous papers of this series. These new measurements,together with the HI data collected in LEDA, put to 6 700 the number ofgalaxies with 21-cm line width, radial velocity, and apparent diameterin the so-called KLUN sample. Figure 5 and Appendices A and B forcorresponding comments are available in electronic form at thehttp://www.edpsciences.com

Starbursts in barred spiral galaxies. III. Definition of a homogeneous sample of starburst nucleus galaxies
This paper presents optical long-slit spectroscopic observations of 105barred Markarian IRAS galaxies. These observations are used to determinethe spectral type (starburst or Seyfert) of emission-line regions in thenucleus and along the bar of the galaxies, in order to define ahomogeneous sample of Starburst Nucleus Galaxies (SBNGs). Our selectioncriteria (ultraviolet excess, far infrared emission and barredmorphology) have been very efficient for selecting star-forminggalaxies, since our sample of 221 emission-line regions includes 82%nuclear or extranuclear starbursts. The contamination by Seyferts is low(9%). The remaining galaxies (9%) are objects with ambiguousclassification (Hii or LINER). The dust content and Hα luminosityincrease towards the nuclei of the galaxies. No significant variation ofthe electron density is found between nuclear and bar Hii regions.However, the mean Hα luminosity and electron density in the barare higher than in typical disk Hii regions. We investigate differentmechanisms for explaining the excess of nitrogen emission observed inour starburst nuclei. There is no evidence for the presence of a weakhidden active galactic nucleus in our starburst galaxies. The cause ofthis excess is probably a selective enrichment of nitrogen in the nucleiof the galaxies, following a succession of short and intense bursts ofstar formation. Our sample of SBNGs, located at a mean redshift of ~0.015, has moderate Hα ( ~ 10(41) erg s(-1) ) and far infrared ( ~10(10) Lsun) luminosities. The types are distributed equallyamong early- and late-type giant spirals with a slight preference forSbc/Sc types because of their barred morphology. The majority (62%) ofSBNGs are isolated with no sign of gravitational interaction. In termsof distance, luminosity and level of interaction, SBNGs are intermediatebetween Hii galaxies and luminous infrared galaxies. Based onobservations obtained at the 1.93 meter telescope of Observatoire deHaute-Provence operated by INSU (CNRS). Tables 1, 3, 4, 5 and 6 are onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr ( or viahttp://cdsweb.u-strasbg.fr/Abstract.html

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.

CO in blue compact and star burst galaxies
(12) CO(J=1->0) observations of 34 blue compact and star burstgalaxies are presented. Although these galaxies are experiencingvigorous star formation at the current epoch, CO has been detected inonly five of them. The five detections reported in this paper are all ingalaxies with relatively red colours, (B-V)0>0.4. The newobservations, when combined with previously published data on CO inBCGs, indicate that CO luminosity decreases with absolute luminosity ofBCGs. Since the absolute luminosity of a galaxy is correlated with itsmetallicity, these results confirm that low metallicity BCGs have lowabundances of CO gas. We also show that the star formation ratedetermined from the H_β\ luminosity is lower than that determinedfrom the far infrared luminosity.

Probing nuclear starburst activity in a sample of nearby spiral galaxies
As part of a systematic study of the UV properties of galaxies in theIUE library, we present in this paper an analysis of nuclear stellarpopulations in spiral galaxies with radial velocity <= 5000 km/s. Inthis sample of 60 galaxies the IUE aperture probes a mean 1.0 kpc x 2.1kpc area. Prior to any comparison of galaxy spectra in the range coveredby IUE (1200-3200 AA), we have formed subsets according to the absolutemagnitude and morphological type of the studied galaxies. In a secondstep, and within each subset, we have co-added the spectra, and hencethe objects into groups of similar spectral properties in the UV, alsotaking into account their spectral properties in thevisible/near-infrared ranges. As a result, high signal-to-noise ratiotemplates have been obtained, and information on spectral features cannow be extracted and interpreted. We distinguish 4 groups for Sa, 8 forSb, and 4 for Sc galaxies. We have carried out population synthesesusing as base elements: ion {H}{ii} regions, integrated star clusters,and far-UV weak elliptical galaxies as representative of bulge stellarpopulation. The variety of UV spectral types found in the centralregions of spiral galaxies can be readily explained by differentmixtures of bulge, circumnuclear burst and disc populations. Acrossdifferent morphological types, similar templates can also be found. Thisis due to compensation effects of bulge contribution with the disc andcircumnuclear burst ones. Flux fractions derived from the populationsynthesis have been converted into mass contributions and inferenceshave been made on the star-formation histories. In the central kpc ofthe galaxies with strong UV flux, we find that the mass stored in theyoung components (t<500 Myr) is typically \approx10^7 M_odot. Weconfirm that such star-formation enhancements occur preferentially inbarred spirals. Internal reddening in the templates has been studied andinferences have been made on the corresponding reddening laws. We findcases where an SMC-like law applies and others where a faint lambda2200AA absorption feature occurs resembling the reddening law of the LMC.The interest of the IUE data set resides in its rather large entranceaperture which samples a large portion of nearby galaxies, and istherefore quite suitable for the interpretation of large redshiftgalaxies. Based upon data collected with the International UltravioletExplorer (IUE) Satellite, supported by NASA, SERC and ESA.

A correlation between CO linewidth and starburst age in barred spiral galaxies.
New CO(1->0) and CO(2->1) profiles complemented by data from theliterature are used to obtain CO linewidths for 29 barred spiralgalaxies with young nuclear starbursts. The ages of the starbursts wereestimated from optical spectroscopy and recent evolutionary synthesismodels. The CO linewidths and the starburst ages are correlated:galaxies with young (4-6Myr) starbursts display narrow (<~100km/s) COline while those with older starbursts show broader CO lines. We discussseveral scenarios of the gas dynamics during the nuclear starbursts'evolution to interpret the correlation.

An image database. II. Catalogue between δ=-30deg and δ=70deg.
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.

A CO survey of galaxies with the SEST and the 20-m Onsala telescope.
A large survey of galaxies in the J=1-0 CO line, performed during1985-1988 using the 15-m SEST and the 20-m millimetre wave telescope ofOnsala Space Observatory, is presented. The HPBW of the telescopes are44" and 33" at 115GHz, respectively. The central positions of 168galaxies were observed and 101 of these were detected in the CO line.More than 20% of these are new detections. Maps of some of the galaxiesare also presented.

Submit a new article

Related links

  • - No Links Found -
Submit a new link

Member of following groups:

Observation and Astrometry data

Constellation:Ursa Major
Right ascension:12h31m22.00s
Aparent dimensions:1.549′ × 1.072′

Catalogs and designations:
Proper Names   (Edit)
NGC 2000.0NGC 4500

→ Request more catalogs and designations from VizieR