Contents
Images
Upload your image
DSS Images Other Images
Related articles
UBVRI Light Curves of 44 Type Ia Supernovae
We present UBVRI photometry of 44 Type Ia supernovae (SNe Ia) observedfrom 1997 to 2001 as part of a continuing monitoring campaign at theFred Lawrence Whipple Observatory of the Harvard-Smithsonian Center forAstrophysics. The data set comprises 2190 observations and is thelargest homogeneously observed and reduced sample of SNe Ia to date,nearly doubling the number of well-observed, nearby SNe Ia withpublished multicolor CCD light curves. The large sample of U-bandphotometry is a unique addition, with important connections to SNe Iaobserved at high redshift. The decline rate of SN Ia U-band light curvescorrelates well with the decline rate in other bands, as does the U-Bcolor at maximum light. However, the U-band peak magnitudes show anincreased dispersion relative to other bands even after accounting forextinction and decline rate, amounting to an additional ~40% intrinsicscatter compared to the B band.
| Chemistry and Star Formation in the Host Galaxies of Type Ia Supernovae
We study the effect of environment on the properties of Type Iasupernovae by analyzing the integrated spectra of 57 local Type Iasupernova host galaxies. We deduce from the spectra the metallicity,current star formation rate, and star formation history of the host andcompare these to the supernova decline rates. Additionally, we comparethe host properties to the difference between the derived supernovadistance and the distance determined from the best-fit Hubble law. Fromthis we investigate possible uncorrected systematic effects inherent inthe calibration of Type Ia supernova luminosities using light-curvefitting techniques. Our results indicate a statistically insignificantcorrelation in the direction of higher metallicity spiral galaxieshosting fainter Type Ia supernovae. However, we present qualitativeevidence suggesting that progenitor age is more likely to be the sourceof variability in supernova peak luminosities than is metallicity. We donot find a correlation between the supernova decline rate and hostgalaxy absolute B magnitude, nor do we find evidence of a significantrelationship between decline rate and current host galaxy star formationrate. A tenuous correlation is observed between the supernova Hubbleresiduals and host galaxy metallicities. Further host galaxyobservations will be needed to refine the significance of this result.Finally, we characterize the environmental property distributions forType Ia supernova host galaxies through a comparison with two larger,more general galaxy distributions using Kolmogorov-Smirnov tests. Theresults show the host galaxy metallicity distribution to be similar tothe metallicity distributions of the galaxies of the NFGS and SDSS.Significant differences are observed between the SN Ia distributions ofabsolute B magnitude and star formation histories and the correspondingdistributions of galaxies in the NFGS and SDSS. Among these is an abruptupper limit observed in the distribution of star formation histories ofthe host galaxy sample, suggesting a Type Ia supernovae characteristicdelay time lower limit of approximately 2.0 Gyr. Other distributiondiscrepancies are investigated and the effects on the supernovaproperties are discussed.
| Reddening, Absorption, and Decline Rate Corrections for a Complete Sample of Type Ia Supernovae Leading to a Fully Corrected Hubble Diagram to v < 30,000 km s-1
Photometric (BVI) and redshift data corrected for streaming motions arecompiled for 111 ``Branch-normal,'' four 1991T-like, seven 1991bg-like,and two unusual supernovae of Type Ia (SNe Ia). Color excessesE(B-V)host of normal SNe Ia, due to the absorption of thehost galaxy, are derived by three independent methods, giving excellentagreement leading to the intrinsic colors at maximum of(B-V)00=-0.024+/-0.010 and (V-I)00=-0.265+/-0.016if normalized to a common decline rate of Δm15=1.1. Thestrong correlation between redshift absolute magnitudes (based on anarbitrary Hubble constant of H0=60 km s-1Mpc-1), corrected only for the extrinsic Galactic absorption,and the derived E(B-V)host color excesses leads to thewell-determined yet abnormal absorption-to-reddening ratios ofRBVI=3.65+/-0.16, 2.65+/-0.15, and 1.35+/-0.21.Comparison with the canonical Galactic values of 4.1, 3.1, and 1.8forces the conclusion that the law of interstellar absorption in thepath length to the SN in the host galaxy is different from the localGalactic law, a result consistent with earlier conclusions by others.Improved correlations of the fully corrected absolute magnitudes (on thesame arbitrary Hubble constant zero point) with host galaxymorphological type, decline rate, and intrinsic color are derived. Werecover the result that SNe Ia in E/S0 galaxies are ~0.3 mag fainterthan in spiral galaxies for possible reasons discussed in the text. Thenew decline rate corrections to absolute magnitudes are smaller thanthose by some authors for reasons explained in the text. The fourspectroscopically peculiar 1991T-type SNe are significantly overluminousas compared to Branch-normal SNe Ia. The overluminosity of the seven1999aa-like SNe is less pronounced. The seven 1991bg types in the sampleconstitute a separate class of SNe Ia, averaging in B 2 mag fainter thanthe normal Ia. New Hubble diagrams in B, V, and I are derived out to~30,000 km s-1 using the fully corrected magnitudes andvelocities, corrected for streaming motions. Nine solutions for theintercept magnitudes in these diagrams show extreme stability at the0.02 mag level using various subsamples of the data for both low andhigh extinctions in the sample, proving the validity of the correctionsfor host galaxy absorption. We shall use the same precepts for fullycorrecting SN magnitudes for the luminosity recalibration of SNe Ia inthe forthcoming final review of our Hubble Space Telescope Cepheid-SNexperiment for the Hubble constant.
| Multicolor Surface Photometry of Lenticular Galaxies. I. The Data
We present multicolor surface and aperture photometry in the B, V, R,and K' bands for a sample of 34 lenticular galaxies from the UppsalaGeneral Catalogue. From surface photometric analysis, we obtain radialprofiles of surface brightness, colors, ellipticity, position angle, andthe Fourier coefficients that describe the departure of isophotal shapesfrom a purely elliptical form; we find the presence of dust lanes,patches, and ringlike structure in several galaxies in the sample. Weobtain total integrated magnitudes and colors and find that these are ingood agreement with the values from the Third Reference Catalogue.Isophotal colors are correlated with each other, following the sequenceexpected for early-type galaxies. The color gradients in lenticulargalaxies are more negative than the corresponding gradients inelliptical galaxies. There is a good correlation between B-V and B-Rcolor gradients, and the mean gradients in the B-V, B-R, and V-K' colorsare -0.13+/-0.06, -0.18+/-0.06, and -0.25+/-0.11 mag dex-1 inradius, respectively.
| 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
| Cosmological Results from High-z Supernovae
The High-z Supernova Search Team has discovered and observed eight newsupernovae in the redshift interval z=0.3-1.2. These independentobservations, analyzed by similar but distinct methods, confirm theresults of Riess and Perlmutter and coworkers that supernova luminositydistances imply an accelerating universe. More importantly, they extendthe redshift range of consistently observed Type Ia supernovae (SNe Ia)to z~1, where the signature of cosmological effects has the oppositesign of some plausible systematic effects. Consequently, thesemeasurements not only provide another quantitative confirmation of theimportance of dark energy, but also constitute a powerful qualitativetest for the cosmological origin of cosmic acceleration. We find a ratefor SN Ia of(1.4+/-0.5)×10-4h3Mpc-3yr-1at a mean redshift of 0.5. We present distances and host extinctions for230 SN Ia. These place the following constraints on cosmologicalquantities: if the equation of state parameter of the dark energy isw=-1, then H0t0=0.96+/-0.04, andΩΛ-1.4ΩM=0.35+/-0.14. Includingthe constraint of a flat universe, we findΩM=0.28+/-0.05, independent of any large-scalestructure measurements. Adopting a prior based on the Two Degree Field(2dF) Redshift Survey constraint on ΩM and assuming aflat universe, we find that the equation of state parameter of the darkenergy lies in the range -1.48-1, we obtain w<-0.73 at 95% confidence.These constraints are similar in precision and in value to recentresults reported using the WMAP satellite, also in combination with the2dF Redshift Survey.Based in part on observations 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 (AURA), Inc.,under NASA contract NAS 5-26555. This research is primarily associatedwith proposal GO-8177, but also uses and reports results from proposalsGO-7505, 7588, 8641, and 9118.Based in part on observations taken with the Canada-France-Hawaii Telescope, operated by the National Research Council of Canada, le Centre National de la Recherche Scientifique de France, and the University of Hawaii. CTIO: Based in part on observations taken at the Cerro Tololo Inter-American Observatory.Keck: Some of the data presented herein were obtained at the W. M. KeckObservatory, which is operated as a scientific partnership among theCalifornia Institute of Technology, the University of California, and theNational Aeronautics and Space Administration. The Observatory was madepossible by the generous financial support of the W. M. Keck Foundation.UH: Based in part on observations with the University of Hawaii 2.2 mtelescope at Mauna Kea Observatory, Institute for Astronomy, University ofHawaii. UKIRT: Based in part on observations with the United KingdomInfrared Telescope (UKIRT) operated by the Joint Astronomy Centre on behalfof the UK. Particle Physics and Astronomy Research Council. VLT: Based inpart on observations obtained at the European Southern Observatory,Paranal, Chile, under programs ESO 64.O-0391 and ESO 64.O-0404. WIYN: Based in part on observations taken at the WIYN Observatory, a joint facility of the University of Wisconsin-Madison, Indiana University, Yale University, and the National Optical Astronomy Observatories.
| Redshift-Distance Survey of Early-Type Galaxies: Spectroscopic Data
We present central velocity dispersions and Mg2 line indicesfor an all-sky sample of ~1178 elliptical and S0 galaxies, of which 984had no previous measures. This sample contains the largest set ofhomogeneous spectroscopic data for a uniform sample of ellipticalgalaxies in the nearby universe. These galaxies were observed as part ofthe ENEAR project, designed to study the peculiar motions and internalproperties of the local early-type galaxies. Using 523 repeatedobservations of 317 galaxies obtained during different runs, the dataare brought to a common zero point. These multiple observations, takenduring the many runs and different instrumental setups employed for thisproject, are used to derive statistical corrections to the data and arefound to be relatively small, typically <~5% of the velocitydispersion and 0.01 mag in the Mg2 line strength. Typicalerrors are about 8% in velocity dispersion and 0.01 mag inMg2, in good agreement with values published elsewhere.
| Redshift-Distance Survey of Early-Type Galaxies: Circular-Aperture Photometry
We present R-band CCD photometry for 1332 early-type galaxies, observedas part of the ENEAR survey of peculiar motions using early-typegalaxies in the nearby universe. Circular apertures are used to tracethe surface brightness profiles, which are then fitted by atwo-component bulge-disk model. From the fits, we obtain the structuralparameters required to estimate galaxy distances using theDn-σ and fundamental plane relations. We find thatabout 12% of the galaxies are well represented by a pure r1/4law, while 87% are best fitted by a two-component model. There are 356repeated observations of 257 galaxies obtained during different runsthat are used to derive statistical corrections and bring the data to acommon system. We also use these repeated observations to estimate ourinternal errors. The accuracy of our measurements are tested by thecomparison of 354 galaxies in common with other authors. Typical errorsin our measurements are 0.011 dex for logDn, 0.064 dex forlogre, 0.086 mag arcsec-2 for<μe>, and 0.09 for mRC,comparable to those estimated by other authors. The photometric datareported here represent one of the largest high-quality and uniformall-sky samples currently available for early-type galaxies in thenearby universe, especially suitable for peculiar motion studies.Based on observations at Cerro Tololo Inter-American Observatory (CTIO),National Optical Astronomy Observatory, which is operated by theAssociation of Universities for Research in Astronomy, Inc., undercooperative agreement with the National Science Foundation (NSF);European Southern Observatory (ESO); Fred Lawrence Whipple Observatory(FLWO); and the MDM Observatory on Kitt Peak.
| A new catalogue of ISM content of normal galaxies
We have compiled a catalogue of the gas content for a sample of 1916galaxies, considered to be a fair representation of ``normality''. Thedefinition of a ``normal'' galaxy adopted in this work implies that wehave purposely excluded from the catalogue galaxies having distortedmorphology (such as interaction bridges, tails or lopsidedness) and/orany signature of peculiar kinematics (such as polar rings,counterrotating disks or other decoupled components). In contrast, wehave included systems hosting active galactic nuclei (AGN) in thecatalogue. This catalogue revises previous compendia on the ISM contentof galaxies published by \citet{bregman} and \citet{casoli}, andcompiles data available in the literature from several small samples ofgalaxies. Masses for warm dust, atomic and molecular gas, as well asX-ray luminosities have been converted to a uniform distance scale takenfrom the Catalogue of Principal Galaxies (PGC). We have used twodifferent normalization factors to explore the variation of the gascontent along the Hubble sequence: the blue luminosity (LB)and the square of linear diameter (D225). Ourcatalogue significantly improves the statistics of previous referencecatalogues and can be used in future studies to define a template ISMcontent for ``normal'' galaxies along the Hubble sequence. The cataloguecan be accessed on-line and is also available at the Centre desDonnées Stellaires (CDS).The catalogue is available in electronic form athttp://dipastro.pd.astro.it/galletta/ismcat and at the CDS via anonymousftp to\ cdsarc.u-strasbg.fr (130.79.128.5) or via\http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/405/5
| Classifications of the Host Galaxies of Supernovae
Classifications on the DDO system are given for the host galaxies of 177supernovae (SNe) that have been discovered since 1997 during the courseof the Lick Observatory Supernova Search with the Katzman AutomaticImaging Telescope. Whereas SNe Ia occur in all galaxy types, it isfound, at a high level of statistical confidence, that SNe Ib, Ic, andII are strongly concentrated in late-type galaxies. However, attentionis drawn to a possible exception provided by SN 2001I. This SN IInoccurred in the E2 galaxy UGC 2836, which was not expected to harbor amassive young supernova progenitor.
| The UZC-SSRS2 Group Catalog
We apply a friends-of-friends algorithm to the combined Updated ZwickyCatalog and Southern Sky Redshift Survey to construct a catalog of 1168groups of galaxies; 411 of these groups have five or more members withinthe redshift survey. The group catalog covers 4.69 sr, and all groupsexceed the number density contrast threshold, δρ/ρ=80. Wedemonstrate that the groups catalog is homogeneous across the twounderlying redshift surveys; the catalog of groups and their membersthus provides a basis for other statistical studies of the large-scaledistribution of groups and their physical properties. The medianphysical properties of the groups are similar to those for groupsderived from independent surveys, including the ESO Key Programme andthe Las Campanas Redshift Survey. We include tables of groups and theirmembers.
| The Subluminous Type Ia Supernova 1998de in NGC 252
We present spectroscopic and extensive photometric observations ofsupernova (SN) 1998de in the S0 galaxy NGC 252, discovered during thecourse of the Lick Observatory Supernova Search. These data, which spana time period of 8 days before to 76 days after B-band maximum,unambiguously establish SN 1998de as a peculiar and subluminous Type Iasupernova (SN Ia) with strong similarities to SN 1991bg, the prototypeof these intrinsically dim SNe Ia. We find that SN 1998de, which hasΔm15(B)=1.95+/-0.09 mag, rises and declines much fasterthan normal SNe Ia and does not exhibit the usual plateau in the R band.In the I band it shows a short plateau phase or possibly a secondarymaximum, soon after the first maximum. We find that subluminous SNe Iawith the same value of Δm15(B) can have slightlydifferent light curves at longer wavelengths. The notable spectroscopicsimilarities between SN 1998de and SN 1991bg are the wide Ti II troughat 4100-4500 Å, the strong Ca II features, and the early onset ofthe nebular phase. We observe that spectroscopic deviations of SN 1998defrom SN 1991bg increase toward redder wavelengths. These deviationsinclude the absence of the conspicuous Na I D absorption found in SN1991bg at 5700 Å and the evolution of a region (6800-7600 Å)from featureless to feature-rich. Several lines of evidence suggest thatSN 1998de was a slightly more powerful explosion than SN 1991bg. Wediscuss the implications of our observations for progenitor models andthe explosion mechanism of peculiar, subluminous SNe Ia. The extensivephotometric data make SN 1998de a better template than SN 1991bg forcalibrating the low-luminosity end of the luminosity versus decline raterelationship.
| Late Light Curves of Type Ia Supernovae
We extend earlier efforts to determine whether the late (t>=60 days)light curves of Type Ia SNe are better explained by the escape ofpositrons from the ejecta or by the complete deposition of positronkinetic energy in a trapping magnetic field. We refine our selection ofIa SNe, using those that have extensive BVRI photometry 35 days or moreafter maximum light. Assuming that all SNe within a givenΔm15(B) range form a distinct subclass, we fit acombined light curve for all class members with a variety of models. Weimprove our previous calculations of energy deposition rates byincluding the transport of the Comptonized electrons. Their nonlocal andtime-dependent energy deposition produces a correction of as much as0.10 mag for Chandrasekhar-mass models and 0.18 mag forsub-Chandrasekhar-mass models. We produce bolometric corrections,derived from measured spectra, to B, V, R, and I light curves after day50. Comparisons of the resulting bolometric light curves with simulatedenergy deposition rates demonstrate that the energy deposition from thephotons and positrons created in 56Co-->56Fedecays are consistent with the observations if positron escape isassumed. This implies that there is no evidence of additional sources ofenergy deposition or of a shift of emission into unobserved wavelengthranges between days 60 and 900. The V band is shown to be an accurateindicator of total emission in the 3500-9700 Å range, with aconstant fraction (~25%) appearing in the V band after day 50. Thissuggests that the V band scales with the bolometric luminosity and thatthe deposited energy is instantaneously recycled into optical emissionduring this epoch. We see significant evolution of the colors of SNe Iabetween days 50 and 170. We suggest that this may be due to thetransition from spectra dominated by emission lines from the radioactivenucleus, 56Co, to those from the stable daughter nucleus,56Fe.
| The Progenitors of Subluminous Type Ia Supernovae
We find that spectroscopically peculiar subluminous Type Ia supernovae(SNe Ia) come from an old population. Of the 16 subluminous SNe Iaknown, 10 are found in E/S0 galaxies, and the remainder are found inearly-type spiral galaxies. The probability that this is a chanceoccurrence is only 0.2%. The finding that subluminous SNe Ia areassociated with an older stellar population indicates that for asufficiently large look-back time (already accessible in currenthigh-redshift searches) they will not be found. Due to a scarcity in oldpopulations, hydrogen and helium main-sequence stars and He red giantstars that undergo Roche lobe overflow are unlikely to be theprogenitors of subluminous SNe Ia. Earlier findings that overluminousSNe Ia [Δm15(B)<~0.95] come from a young progenitorpopulation are confirmed. The fact that subluminous SNe Ia andoverluminous SNe Ia come from different progenitor populations and alsohave different properties is a prediction of the CO white dwarf mergerprogenitor scenario.
| A High Intrinsic Peculiarity Rate among Type IA Supernovae
We have compiled a sample of 45 Type Ia supernovae (SNe Ia) discoveredby the Lick Observatory Supernova Search (LOSS) and the BeijingAstronomical Observatory Supernova Survey (BAOSS), and determined therate of spectroscopically peculiar SNe Ia (i.e., SN 1986G-like, SN1991bg-like, and SN 1991T-like objects) and the luminosity function ofSNe Ia. Because of the nature of the two surveys (distance-limited withsmall baselines and deep limiting magnitudes), nearly all SNe Ia havebeen discovered in the sample galaxies of LOSS and BAOSS; thus, theobserved peculiarity rate and luminosity function of SNe Ia areintrinsic. We find that 36%+/-9% of nearby SNe Ia are peculiar;specifically, the luminosity function of SNe Ia consists of 20% SN1991T-like, 64% normal, and 16% SN 1991bg-like objects. We have comparedour results to those found by earlier studies, and to those found athigh redshift. The apparent dearth of SN 1991T-like objects at highredshift may be due to extinction, and especially to the difficulty ofrecognizing them from spectra obtained past maximum brightness or fromspectra with low signal-to-noise ratios. Implications of the highpeculiarity rate for the progenitor systems of SNe Ia are also brieflydiscussed.
| 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.
| 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.
| 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).
| SGR 1900+14
IAUC 7005 available at Central Bureau for Astronomical Telegrams.
| Supernova 1998de in NGC 252
IAUC 6980 available at Central Bureau for Astronomical Telegrams.
| Supernova 1998de in NGC 252
IAUC 6977 available at Central Bureau for Astronomical Telegrams.
| Groups of galaxies. III. Some empirical characteristics.
Not Available
| Star Formation in UGC 491, a Gas-Rich S0 Galaxy
S0 galaxies form an important transition between elliptical and spiralgalaxies. It is therefore important to understand the extent of starformation in these systems and its relation to the gas content. We havestudied one gas-rich S0 galaxy UGC 491. Optical CCD images were obtainedin B, R, and continuum-subtracted H-alpha-N II. The neutral hydrogencontent was mapped with the VLA in the C-array (a 15 aresec beam) with avelocity resolution of 21 km/s. IRAF was used to perform ellipticalisophotal fitting and surface photometry. The total integrated magnitudefor B is 13.7 mag, and for R it is 12.2 mag. A comparison of the radialprofiles of (B-R) and H-alpha flux with the H I surface density and thepredicted critical gas density (Kennicutt 1989) provides insight intothe star formation properties of this gas-rich S0. We derive the starformation rate from the H-alpha flux and compare this with that forother types of spiral galaxies. We conclude that many gas-rich S0galaxies could be classified as anemic spirals with low surfacebrightness spiral structure and/or isolated regions of star formation.
| General study of group membership. II - Determination of nearby groups
We present a whole sky catalog of nearby groups of galaxies taken fromthe Lyon-Meudon Extragalactic Database. From the 78,000 objects in thedatabase, we extracted a sample of 6392 galaxies, complete up to thelimiting apparent magnitude B0 = 14.0. Moreover, in order to considersolely the galaxies of the local universe, all the selected galaxieshave a known recession velocity smaller than 5500 km/s. Two methods wereused in group construction: a Huchra-Geller (1982) derived percolationmethod and a Tully (1980) derived hierarchical method. Each method gaveus one catalog. These were then compared and synthesized to obtain asingle catalog containing the most reliable groups. There are 485 groupsof a least three members in the final catalog.
| The far-infrared properties of the CfA galaxy sample. I - The catalog
IRAS flux densities are presented for all galaxies in the Center forAstrophysics magnitude-limited sample (mB not greater than 14.5)detected in the IRAS Faint Source Survey (FSS), a total of 1544galaxies. The detection rate in the FSS is slightly larger than in thePSC for the long-wavelength 60- and 100-micron bands, but improves by afactor of about 3 or more for the short wavelength 12- and 25-micronbands. This optically selected sample consists of galaxies which are, onaverage, much less IR-active than galaxies in IR-selected samples. Itpossesses accurate and complete redshift, morphological, and magnitudeinformation, along with observations at other wavelengths.
| The neutral hydrogen content of early type disk galaxies
This paper presents the results of a sensitive 21-cm survey of massiveearly type galaxies made with the Arecibo radio telescope. Of the 81galaxies observed, the detections comprise 48 percent of the S0s, 73percent of the S0a's, and 96 percent of the Sa's. The values of thehybrid, distance-independent H I surface densities of the S0 galaxies inthe sample ranged continuously from amounts comparable to the mostgas-rich Sa galaxies to low estimated upper limts of the H I content.CCD images of most of the gas-rich S0s revealed either faint spiralfeatures or patchy structure in the disks. While no firm correlationbetween H I content and environmental density is apparent for thegalaxies in the sample, two-sample statistics suggest a differencebetween the highest and the lowest density bins. Early-type diskgalaxies within low density environments tend to have higher gas surfacedensities than those within high-density environments.
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
Catalogs and designations:
|
