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A study of the Type II-P supernova 2003gd in M74
We present photometric and spectroscopic data of the Type II-P supernova(SN II-P) 2003gd, which was discovered in M74 close to the end of itsplateau phase. SN 2003gd is the first Type II supernova (SN) to have adirectly confirmed red supergiant (RSG) progenitor. We compare SN 2003gdto SN 1999em, a similar SN II-P, and estimate an explosion date of 2003March 18. We determine a reddening towards the SN of E(B-V) = 0.14 +/-0.06, using three different methods. We also calculate three newdistances to M74 of 9.6 +/- 2.8, 7.7 +/- 1.7 and 9.6 +/- 2.2Mpc. Theformer was estimated using the standard candle method (SCM), for Type IIsupernovae (SNe II), and the latter two using the brightest supergiantsmethod (BSM). When combined with existing kinematic and BSM distanceestimates, we derive a mean value of 9.3 +/- 1.8Mpc. SN 2003gd was foundto have a lower tail luminosity compared with other normal Type II-Psupernovae (SNe II-P) bringing into question the nature of this SN. Wepresent a discussion concluding that this is a normal SN II-P, which isconsistent with the observed progenitor mass of8+4-2 Msolar.
| 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.
| Low-luminosity Type II supernovae: spectroscopic and photometric evolution
In this paper we present spectroscopic and photometric observations forfour core-collapsed supernovae (SNe), namely SNe 1994N, 1999br, 1999euand 2001dc. Together with SN 1997D, we show that they form a group ofexceptionally low-luminosity events. These SNe have narrow spectrallines (indicating low expansion velocities) and low luminosities atevery phase (significantly lower than those of typical core-collapsedsupernovae). The very-low luminosity during the 56Coradioactive decay tail indicates that the mass of 56Niejected during the explosion is much smaller (MNi~ 2-8× 10-3 Msolar) than the average(MNi~ 6-10 × 10-2 Msolar). Twosupernovae of this group (SN 1999br and SN 2001dc) were discovered veryclose to the explosion epoch, allowing us to determine the lengths oftheir plateaux (~100 d) as well as establishing the explosion epochs ofthe other, less completely observed SNe. It is likely that this group ofSNe represent the extreme low-luminosity tail of a single continuousdistribution of Type II plateau supernovae events. Their kinetic energyis also exceptionally low. Although an origin from low-mass progenitorshas also been proposed for low-luminosity core-collapsed SNe, recentwork provides evidence in favour of the high-mass progenitor scenario.The incidence of these low-luminosity SNe could be as high as 4-5 percent of all Type II SNe.
| The ISOPHOT 170 μm Serendipity Survey II. The catalog of optically identified galaxies%
The ISOPHOT Serendipity Sky Survey strip-scanning measurements covering≈15% of the far-infrared (FIR) sky at 170 μm were searched forcompact sources associated with optically identified galaxies. CompactSerendipity Survey sources with a high signal-to-noise ratio in at leasttwo ISOPHOT C200 detector pixels were selected that have a positionalassociation with a galaxy identification in the NED and/or Simbaddatabases and a galaxy counterpart visible on the Digitized Sky Surveyplates. A catalog with 170 μm fluxes for more than 1900 galaxies hasbeen established, 200 of which were measured several times. The faintest170 μm fluxes reach values just below 0.5 Jy, while the brightest,already somewhat extended galaxies have fluxes up to ≈600 Jy. For thevast majority of listed galaxies, the 170 μm fluxes were measured forthe first time. While most of the galaxies are spirals, about 70 of thesources are classified as ellipticals or lenticulars. This is the onlycurrently available large-scale galaxy catalog containing a sufficientnumber of sources with 170 μm fluxes to allow further statisticalstudies of various FIR properties.Based on observations with ISO, an ESA project with instruments fundedby ESA Member States (especially the PI countries: France, Germany, TheNetherlands and the UK) and with the participation of ISAS and NASA.Members of the Consortium on the ISOPHOT Serendipity Survey (CISS) areMPIA Heidelberg, ESA ISO SOC Villafranca, AIP Potsdam, IPAC Pasadena,Imperial College London.Full Table 4 and Table 6 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/422/39
| Peculiar, low-luminosity Type II supernovae: low-energy explosions in massive progenitors?
A number of supernovae, classified as Type II, show remarkably peculiarproperties such as an extremely low expansion velocity and anextraordinarily small amount of 56Ni in the ejecta. Wepresent a joint analysis of the available observations for two of thesepeculiar Type II supernovae, SN 1997D and SN 1999br, using acomprehensive semi-analytic method that can reproduce the light curveand the evolution of the line velocity and continuum temperature. Wefind that these events are underenergetic with respect to a typical TypeII supernova and that the inferred mass of the ejecta is relativelylarge. We discuss the possibility that these supernovae originate fromthe explosion of a massive progenitor in which the rate of early infallof stellar material on the collapsed core is large. Events of this typecould form a black hole remnant, giving rise to significant fallback andlate-time accretion.
| Core-collapse supernovae and evidence for black hole formation
A group of core-collapse supernovae show remarkably peculiar properties,such as an extremely low expansion velocity and an extraordinary smallamount of Nickel in the ejecta. They may originate from high massprogenitors undergoing a low energy explosion with the formation of ablack hole.
| Galaxy interactions - poor starburst triggers. III. A study of a complete sample of interacting galaxies
We report on a study of tidally triggered star formation in galaxiesbased on spectroscopic/photometric observations in the optical/near-IRof a magnitude limited sample of 59 systems of interacting and merginggalaxies and a comparison sample of 38 normal isolated galaxies. From astatistical point of view the sample gives us a unique opportunity totrace the effects of tidally induced star formation. In contrast toresults from previous investigations, our global UBV colours do notsupport a significant enhancement of starforming activity in theinteracting/merging galaxies. We also show that, contrary to previousclaims, there is no significantly increased scatter in the colours ofArp galaxies as compared to normal galaxies. We do find support formoderate (a factor of ~ 2-3) increase in star formation in the verycentres of the interacting galaxies of our sample, contributingmarginally to the total luminosity. The interacting and in particularthe merging galaxies are characterized by increased far infrared(hereafter FIR) luminosities and temperatures that weakly correlate withthe central activity. The LFIR/LB ratio however,is remarkably similar in the two samples, indicating that truestarbursts normally are not hiding in the central regions of the FIRluminous cases. The gas mass-to-luminosity ratio in optical-IR ispractically independent of luminosity, lending further support to thepaucity of true massive starburst galaxies triggered byinteractions/mergers. We estimate the frequency of such cases to be ofthe order of ~ 0.1% of the galaxies in an apparent magnitude limitedsample. Our conclusion is that interacting and merging galaxies, fromthe global star formation aspect, generally do not differ dramaticallyfrom scaled up versions of normal, isolated galaxies. No drastic changewith redshift is expected. One consequence is that galaxy formationprobably continued over a long period of time and did not peak at aspecific redshift. The effects of massive starbursts, like blowoutscaused by superwinds and cosmic reionization caused by starburstpopulations would also be less important than what is normally assumed.Based on observations collected at the European Southern Observatory, LaSilla, Chile.
| Environmental effects in galaxies. Molecular gas, star formation, and activity
In order to study whether there is any correlation between nuclearactivities, gas content, and the environment where galaxies reside, wehave obtained optical and millimetric spectra for a well-defined sampleof intermediate Hubble type spirals in dense environments and in thefield. We found that these spirals in dense environments have onaverage: less molecular gas per blue luminosity, a higher atomic gasfraction, lower current star formation rate, and the same star formationefficiency as field galaxies. Although none of these results stands outas a single strong diagnostic given their statistical significance,taken together they indicate a trend for diminished gas content andstar-formation activity in galaxies in high-density environments. Ourresults suggest that galaxies in dense environments have either (i)consumed their molecular gas via star formation in the past or (ii) thatdense environments leads to an inhibition of molecular gas from atomicphase. The similarities in star-formation efficiency of the denseenvironments and field galaxies suggest that the physical processescontroling the formation of stars from the molecular gas are localrather than global. We also found that star formation rate per blueluminosity increases linearly as the total amount of gas increases inLINERs. This result, based on a small sample, suggests that LINERs arepowered by star formation rather than an AGN. Based on observations atthe European Southern Observatory at the 15 m Swedish ESO Submillimetretelescope, SEST, and at the the 1.52 m telescope which is operated underthe ESO-ON agreement.
| Environmental effects in galaxies. The data{
We present optical and millimetric data for 47 intermediate Hubble typespiral galaxies located either in dense environments or in the field. Wecompare correlations between global parameters, such as far-infraredluminosity, blue luminosity, and total molecular gas content, with othersamples of galaxies, including normal galaxies, clusters andultraluminous infrared galaxies. We find that overall our sample is awell-defined subset of these other samples of galaxies. Based onobservations at the European Southern Observatory at the 15 m SwedishESO Submillimetre telescope, SEST, and at the the 1.52 m telescope whichis operated under the ESO-ON agreement. Appendix A is only available inelectronic form at http://www.edpsciences.org
| The fading of supernova 1997D
We present a new set of spectroscopic and photometric data extending theobservations of SN 1997D to over 400d after the explosion. Theseobservations confirm the peculiar properties of SN 1997D, such as thevery low abundance of 56Co (0.002Msolar) and thelow expansion velocity of the ejecta (~1000kms-1). We discussthe implications of these observations for the character of theprogenitor and the nature of the remnant, showing that a Crab-likepulsar or an accreting neutron star formed in the explosion of alow-mass progenitor should already have produced a detectable luminosityat this epoch, in contrast with photometric data. On the other hand, theexplosion of a high-mass progenitor with the formation of a black holeis consistent with the available observations. The consequences of thisconclusion regarding the nature of the explosion and the prospects ofdirectly identifying the black hole are also addressed.
| Homogenization of the Stellar Population along Late-Type Spiral Galaxies
We present a study of the broadband UBV color profiles for 257 Sbcbarred and nonbarred galaxies, using photoelectric aperture photometrydata from the literature. Using robust statistical methods, we haveestimated the color gradients of the galaxies, as well as the total andbulge mean colors. A comparative photometric study using CCD images wasdone. In our sample, the color gradients are negative (reddish inward)in approximately 59% of the objects, are almost null in 27%, and arepositive in 14%, considering only the face-on galaxies, which representapproximately 51% of the sample. The results do not change, essentially,when we include the edge-on galaxies. As a consequence of this study wehave also found that barred galaxies are overrepresented among theobjects having null or positive gradients, indicating that bars act as amechanism of homogenization of the stellar population. This effect ismore evident in the U-B color index, although it can also be detected inthe B-V color. A correlation between the total and bulge colors wasfound that is a consequence of an underlying correlation between thecolors of bulges and disks found by other authors. Moreover, the meantotal color is the same irrespective of the gradient regime, whilebulges are bluer in galaxies with null or positive gradients, whichindicates an increase of the star formation rate in the central regionsof these objects. We have also made a quantitative evaluation of theamount of extinction in the center of these galaxies. This was doneusing the Wide Field Planetary Camera 2 (WFPC2) and the Near InfraredCamera and Multi-Object Spectrometer (NICMOS) Hubble Space Telescope(HST) archival data, as well as CCD B, V, and I images. We show thatalthough the extinction in the V-band can reach values up to 2 mag inthe central region, it is unlikely that dust plays a fundamental role inglobal color gradients. We found no correlation between color and O/Habundance gradients. This result could suggest that the color gradientsare more sensitive to the age rather than to the metallicity of thestellar population. However, the absence of this correlation may becaused by dust extinction. We discuss this result by considering apicture in which bars are a relatively fast, recurrent phenomenon. Theseresults are not compatible with a pure classical monolithic scenario forbulge and disk formation. On the contrary, they favor a scenario inwhich both these components are evolving in a correlated process inwhich stellar bars play a crucial role. Based partly on observationsmade at the Pico dos Dias Observatory (PDO/LNA-CNPq), Brazil.
| 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.
| 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.
| Black Hole Emergence in Supernovae
If a black hole formed in a core-collapse supernova is accretingmaterial from the base of the envelope, the accretion luminosity couldbe observable in the supernova light curve. Here we continue the studyof matter fallback onto a black hole in the wake of a supernova andexamine realistic supernovae models that allow for an early emergence ofthe accretion luminosity. Such cases may provide a direct observationalidentification of the black hole formed in the aftermath of theexplosion. Our approach combines analytic estimates and fullyrelativistic, radiation-hydrodynamic numerical computations. We employ anumerical hydrodynamical scaling technique to accommodate the diverserange of dynamical timescales in a single simulation. We find that whilein typical Type II supernovae heating by radioactive decays dominatesthe late-time light curve, low-energy explosions of more massive starsshould provide an important exception where the accretion luminositywill emerge while it is still relatively large. Our main focus is on theonly current candidate for such an observation, the very unusual SN1997D. Owing to the low energy of the explosion and the very small(2×10-3 Msolar) inferred mass of56Co in the ejected envelope, we find that accretion shouldbecome the dominant source of its luminosity during the year 2000. Thetotal luminosity at emergence is expected to lie in the range0.5-3×1036 ergs s-1, potentially detectablewith the Hubble Space Telescope. We also discuss the more favorable caseof explosions that eject negligible amounts of radioactive isotopes andfind that the black hole is likely to emerge a few tens of days afterthe explosion, with a luminosity of ~1037 ergss-1.
| The nature of SN 1997D: low-mass progenitor and weak explosion
We analyzed the spectra and light curve of the peculiar type II-Psupernova 1997D to recover ejecta parameters. The optimal hydrodynamicalmodel of SN 1997D, which meets observational constraints at thephotospheric epoch, suggests a low explosion energy of about1050 erg, ejecta mass around 6 Msun, andpresupernova radius near 85 Rsun. We confirm the previousresult by Turatto et al. (\cite{tmy98}) that the ejecta contain a verylow amount of radioactive 56Ni (~ 0.002 Msun).Modelling the nebular spectrum supports the hydrodynamical model andpermits us to estimate the mass of freshly synthesized oxygen (0.02-0.07Msun). Combined with the basic results of stellar evolutiontheory the obtained parameters of SN 1997D imply that the progenitor wasa star from the 8-12 Msun mass range at the main sequence.The fact that at least some progenitors from this mass range give riseto core-collapse supernovae with a low kinetic energy (~ 1050erg) and low amount of radioactive 56Ni (~ 0.002Msun) has no precedent and imposes important constraints onthe explosion mechanism. We speculate that the galactic supernovae 1054and 1181 could be attributed to SN 1997D-like events. All the SN~1997Dspectra used in this paper were kindly provided by Massimo Turrato
| Will a Black Hole Soon Emerge from SN 1997D?
Observations combined with theoretical modeling of the light curve ofthe recently discovered supernova 1997D in NGC 1536 suggest that itmight host a black hole formed in the aftermath of the explosion. Weconsider some observable consequences of a black hole in SN 1997D andestimate the late-time accretion luminosity of the material that fallsback onto the hole. We find that this luminosity, decaying with acharacteristic power-law dependence on time, may emerge above theemission of the envelope in just a few years. Its detection would thusprovide unmistakable evidence for the presence of a black hole.
| The Peculiar Type II Supernova 1997D: A Case for a Very Low 56Ni Mass
SN 1997D in NGC 1536 is possibly the least luminous and energetic TypeII supernova discovered to date. The entire light curve is subluminous,never reaching MV=-14.65 . The radioactive tail follows the56 Co decay slope. In the case of a nearly complete trappingof the gamma -rays, the 56 Ni mass derived from the tailbrightness is extremely small, ~0.002 Msolar. At discovery, the spectrashowed a red continuum and line velocities on the order of 1000 km s^{-1} . The luminosity and the photospheric expansion velocity suggestthat the explosion occurred about 50 days before discovery and that aplateau probably followed. Model light curves and spectra of theexplosion of a 26 Msolar star successfully fitted the observations.Low-mass models are inconsistent with the observations. The radius ofthe progenitor, constrained by the prediscovery upper limits, isR0<~300 Rsolar. A low explosion energy of ~4x1050 ergs is then required in the modeling. The strong BaII lines in the photospheric spectra are reproduced with a solarabundance and low T_{{eff}} . A scenario in which the low 56Ni mass observed in SN 1997D is due to fallback of material onto thecollapsed remnant of the explosion of a 25-40 Msolar star appears to befavored over the case of the explosion of an 8-10 Msolar star with low56 Ni production.
| 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.
| Supernova 1997D in NGC 1536
IAUC 6537 available at Central Bureau for Astronomical Telegrams.
| Scaleheights of 486 southern spiral galaxies and some statistical correlation
Based on Peng's method (1988), we obtain scaleheights of 486 southernspiral galaxies, the images of which are taken from the Digitized SkySurvey at Xinglong Station of Beijing Astronomical Observatory. Thefitted spiral arms of 70 galaxies are compared with their images to gettheir optimum inclinations. The scaleheights of other 416 ones arelisted in Table A1 in Appendix. After compiling and analyzing the data,we find some statistical correlations. The most interesting results arethat a flatter galaxy is bluer and looks brighter, and galaxies becomeflatter along the Hubble sequence Sab -- Scd. Based on photographic dataof the National Geographic Society -- Palomar Observatory Sky Survey(NGS-POSS) obtained using the Oschin Telescope Palomar Mountain. TheNGS-POSS was funded by a grant from the National Geographic Society tothe California Institute of Technology. The plates were processed intothe present compressed digital form with their permission. The DigitizedSky Survey was produced at the Space Telescope Science Institute underUS Government grant NAG W-2166. Table A1 is available in electronic fromonly, via anonymous ftp 130.79.128.5 orhttp://cdsweb.u-strasbg.fr/Abstract.html
| CO and HI in a southern sample of interacting galaxies. I. The data
Using SEST, the Parkes antenna and the Australia Telescope CompactArray, we have made a survey of the ^12CO(1-0) and HI emission of anoptically-selected sample of ~60 southern interacting and merginggalaxies. In this paper we present the data and determine global massesof neutral gas (in molecular and atomic form) for the observed galaxies.We have detected HI in 26 systems and found that these galaxies haveless than 15% of their gas in molecular form. Figure 3 in its entirelyis only available in electronic form at CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| A catalog of far-ultraviolet point sources detected with the fast FAUST Telescope on ATLAS-1
We list the photometric measurements of point sources made by the FarUltraviolet Space Telescope (FAUST) when it flew on the ATLAS-1 spaceshuttle mission. The list contains 4698 Galactic and extragalacticobjects detected in 22 wide-field images of the sky. At the locationssurveyed, this catalog reaches a limiting magnitude approximately afactor of 10 fainter than the previous UV all-sky survey, TDl. Thecatalog limit is approximately 1 x 10-14 ergs A sq cm/s,although it is not complete to this level. We list for each object theposition, FUV flux, the error in flux, and where possible anidentification from catalogs of nearby stars and galaxies. Thesecatalogs include the Michigan HD (MHD) and HD, SAO, the HIPPARCOS InputCatalog, the Position and Proper Motion Catalog, the TD1 Catalog, theMcCook and Sion Catalog of white dwarfs, and the RC3 Catalog ofGalaxies. We identify 2239 FAUST sources with objects in the stellarcatalogs and 172 with galaxies in the RC3 catalog. We estimate thenumber of sources with incorrect identifications to be less than 2%.
| A Preliminary Classification Scheme for the Central Regions of Late-Type Galaxies
The large-scale prints in The Carnegie Atlas of Galaxies have been usedto formulate a classification scheme for the central regions oflate-type galaxies. Systems that exhibit small bright central bulges ordisks (type CB) are found to be of earlier Hubble type and of higherluminosity than galaxies that do not contain nuclei (type NN). Galaxiescontaining nuclear bars, or exhibiting central regions that are resolvedinto individual stars and knots, and galaxies with semistellar nuclei,are seen to have characteristics that are intermediate between those oftypes CB and NN. The presence or absence of a nucleus appears to be auseful criterion for distinguishing between spiral galaxies andmagellanic irregulars.
| Integrated photoelectric magnitudes and color indices of bright galaxies in the Johnson UBV system
The photoelectric total magnitudes and color indices published in theThird Reference Catalogue of Bright Galaxies (RC3) are based on ananalysis of approximately equals 26,000 B, 25,000 B-V, and 17,000 U-Bmultiaperture measurements available up to mid 1987 from nearly 350sources. This paper provides the full details of the analysis andestimates of internal and external errors in the parameters. Thederivation of the parameters is based on techniques described by theVaucouleurs & Corwin (1977) whereby photoelectric multiaperture dataare fitted by mean Hubble-type-dependent curves which describe theintegral of the B-band flux and the typical B-V and U-B integrated colorgradients. A sophisticated analysis of the residuals of thesemeasurements from the curves was made to allow for the random andsystematic errors that effect such data. The result is a homogeneous setof total magnitudes BTA total colors(B-V)T and (U-B)T, and effective colors(B-V)e and (U-B)e for more than 3000 brightgalaxies in RC3.
| A study of a complete sample of interacting galaxies. II. Images, colour distributions and spectra.
We present broadband images, two-colour maps and spectra of a magnitudelimited sample of interacting and merging galaxies.
| Galaxy properties in different environments. 1: The sample
This paper presents two galaxy samples, respectively in a high and in alow local density environments, that were generated from the SouthernSky Redshift Survey (SSRS) catalog using objective criteria. Apreliminary comparison of physical properties in these two samplesreveals that galaxies in high-density environments tend to be under ahigher starbursting activity, have a deficiency of the neutral hydrogencontent, present a higher fractional Seyfert population and a higherfraction of barred spirals as well. The present samples are intended tobe used in future spectroscopic observations for more detailedinvestigation.
| The distribution of dust in Sb's and Sc's - K-band infrared imaging of a diameter limited sample of 37 galaxies.
We present deep infrared K-band surface photometry for adiameter-limited sample of normal Sb and Sc galaxies. In addition,surface brightness, optical and optical-infrared colors andisophote-shapes have been obtained from the ESO-LV B and R photographicimages of these galaxies. For each galaxy we present global photometricparameters, as well as individual radial surface brightness and colorprofiles. Our analysis includes the fitting of ellipses in the threebands, bulge-disk decompositions, and the derivation of growth curves inelliptical apertures. The main conclusion of the paper is that thesegalaxies exhibit very large color gradients - B and K scale lengthratios vary between 1.2 and 2.0 and increase with axis ratio. The largemagnitude of these gradients suggest that they are not due to stellarpopulation differences, but are primarily due to extinction by dust inthe B-band. We also find that the range of central surface brightnessesin the K-band is considerably larger than in B, showing that the stellarproperties are better studied in K. A more detailed evaluation of theresults, specifically with regard to the spatial distribution of boththe dust and the stars in Sb and Sc galaxies, will be presented in anaccompanying paper (Peletier et al. 1994, Paper II).
| Ultraviolet observations of galaxies with the FAUST experiment
We have used the set of point sources detected by the Far UltravioletSpace Telescope (FAUST) instrument to identify galaxies and study thetotal galaxy flux in a 250 A wide band peaking at 1650 A. A sample of144 galaxies has been obtained after cross-reference with the RC3catalog, elimination of objects confused with stars and variouscorrections for the photometry. The UV-B color dispersion is found toincrease while the galaxies get redder from late to early types. Theirregular galaxies appear on average redder and the Sbc galaxies bluerthan indicated by the spectral energy distributions currently used forthe calculations of K-corrections. Various arguments lead us to make theassumption of a constant dust extinction within each galaxy. The UV fluxper unit area decreases on average from late to early type spirals. Wefind a weak correlation between the UV and far infra-red emission whilethe infra-red to UV flux ratio gets lower when galaxies get bluer (asmeasured by the UV to B flux ratio). The UV flux per unit areacorrelates with the HI gas surface density and the total gas surfacedensity when this quantity is available. The correlation with themolecular gas alone is weak. In the Virgo cluster, the UV flux per unitarea does not decrease in direct proportion to the HI deficiency. Galaxycounts per square degree and per magnitude interval have been obtainedat high-galactic latitudes. Combined with data at fainter magnitudes,they show a variation as a function of magnitude with a near-euclideanslope over a range of 8 magnitudes.
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