Upload your image
DSS Images Other Images
Submit a new article
|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.
|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.
|ISOCAM survey and dust models of 3CR radio galaxies and quasars|
We present a survey of all 3CR sources imaged with ISOCAM onboard theInfrared Space Observatory (ISO). The sample consists mostly ofradio-loud active galactic nuclei (AGN). For each source, we presentspatially integrated mid-infrared (MIR, 5-18 μm) fluxes measured fromnewly calibrated ISOCAM images. In total, we detected 68 objects of the3CR catalogue, at redshifts z ≤2.5, and obtained upper limits for 17objects. In addition, we detected 10 galaxies not listed in the 3CRcatalogue. The one with the highest redshift is 4C+72.26 at z = 3.53.ISOCAM data are combined with other photometric measurements toconstruct the spectral energy distribution (SED) from optical to radiowavelengths. The MIR emission may include synchrotron radiation of theAGN, stars of the host galaxy or dust. Extrapolation of radio corefluxes to the MIR show that the synchrotron contribution is in mostcases negligible. In order to describe dust emission we apply newradiative transfer models. In the models the dust is heated by a centralsource which emits photons up to energies of 1 keV. By varying threeparameters, luminosity, effective size and extinction, we obtain a fitto the SED for our objects. Our models contain also dust at large(several kpc) distances from the AGN. Such a cold dust component wasneglected in previous computations which therefore underestimated theAGN contribution to the far infrared (FIR). In 53 cases ( 75% ofour detected 3CR sources), the MIR emission can be attributed to dust.The hot dust component is mainly due to small grains and PAHs. Themodelling demonstrates that AGN heating suffices to explain the ISObroad band data, starburst activity is not necessary. In the models, atype 1 AGN is represented by a compact dust distribution, the dust istherefore very warm and emission of PAHs is weak because ofphoto-destruction. In AGNs of type 2, the dust is relatively colder butPAH bands are strong.Based on observations with ISO, an ESA project with instruments fundedby ESA Member States (especially the PI countries: France, Germany, TheNetherlands and the UK) with the participation of ISAS and NASA.Appendices A and B are only available in electronic form athttp://www.edpsciences.org
|The optical jet in 3C 31 on 15 arcsec scales|
Evidence has been found for optical emission from the northern radio jetof 3C 31, the radio source associated with NGC 383. The jet emerges fromthe dust disc and ring of emission at a radius of 5 arcsec, and within10.4 arcsec is measured to have a B-band flux of 2.1 μJy and anR-band flux of 2.3 μJy. The radio-to-optical spectral index of thisregion is 0.78. A second connected region, 11.8 arcsec along the jet inposition angle 340°, found to have similar optical colours andradio-to-optical spectral index may also be jet emission. We combine ournew data with recent radio and X-ray results to conclude that theemission of the jet is synchrotron from the radio to the X-ray.
|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.
|Near-Infrared Spectra of Type Ia Supernovae|
We report near-infrared (NIR) spectroscopic observations of 12``branch-normal'' Type Ia supernovae (SNe Ia) that cover the wavelengthregion from 0.8 to 2.5 μm. Our sample more than doubles the number ofSNe Ia with published NIR spectra within 3 weeks of maximum light. Theepochs of observation range from 13 days before maximum light to 18 daysafter maximum light. A detailed model for a Type Ia supernovae is usedto identify spectral features. The Doppler shifts of lines are measuredto obtain the velocity and thus the radial distribution of elements. TheNIR is an extremely useful tool to probe the chemical structure in thelayers of SNe Ia ejecta. This wavelength region is optimal for examiningcertain products of the SNe Ia explosion that may be blended or obscuredin other spectral regions. We identify spectral features from Mg II, CaII, Si II, Fe II, Co II, Ni II, and possibly Mn II. We find noindications for hydrogen, helium, or carbon in the spectra. The spectralfeatures reveal important clues about the physical characteristics ofSNe Ia. We use the features to derive upper limits for the amount ofunburned matter, to identify the transition regions from explosivecarbon to oxygen burning and from partial to complete silicon burning,and to estimate the level of mixing during and after the explosion.Elements synthesized in the outer layers during the explosion appear toremain in distinct layers. That provides strong evidence for thepresence of a detonation phase during the explosion as it occurs indelayed detonation or merger models. Mg II velocities are found toexceed 11,000-15,000 km s-1, depending on the individual SNeIa. That result suggests that burning during the explosion reaches theoutermost layers of the progenitor and limits the amount of unburnedmaterial to less than 10% of the mass of the progenitor. Small residualsof unburned material are predicted by delayed detonation models but areinconsistent with pure deflagration or merger models. Differences in thespectra of the individual SNe Ia demonstrate the variety of theseevents.
|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 nuclear dust disks of five nearby 3CR elliptical galaxies|
We present broad- and narrow-band WFPC2 images of the nuclear dust disksand rings of five low-/z elliptical galaxies hosting 3C radio sources:NGC 383 (3C 31)/NGC 382, NGC 3862 (3C 264), NGC 4261 (3C 270), UGC 12064(3C 449), and NGC 7720 (3C 465)/NGC 7720A. We detect resolved lineemission in all the disks. In NGC 383, the line emission consists of a``bar'' and spectacular filamentary arms to the north and south while inNGC 7720 and UGC 12064, it is extended along the major axis of thedisks, suggesting a true physical association between the ionizedmaterial and the dust. The color maps clearly reveal that the disks ofNGC 383, NGC 4261, NGC 7720, and possibly NGC 3862 are inclined. Thedisk of NGC 383 is the most disturbed and filamentary and appears toconsist of an ``inner'' (/~0.5 kpc) and ``outer'' (/~2.5 kpc) disk. Wesuggest that the colors of the unresolved nuclei of NGC 383 and NGC 3862may be partially accounted for by optical synchrotron emission (and mayin fact dominate in NGC 3862) while in NGC 4261, the nuclear emission iscompletely dominated by line emission. The disk colors are generallyredder than predicted by a simple ``sandwich'' model, suggesting thatthe disks cannot be simply treated as thin uniform sheets of dust. Wehave begun exploring radiative transfer models with varying dustcomposition, temperature, and distribution and preliminary results arevery promising.
|A Chandra observation of the X-ray environment and jet of 3C 31|
We have used a deep Chandra observation of the central regions of thetwin-jet Fanaroff-Riley class I (FRI) radio galaxy 3C 31 to resolve thethermal X-ray emission in the central few kpc of the host galaxy, NGC383, where the jets are thought to be decelerating rapidly. This allowsus to make high-precision measurements of the density, temperature andpressure distributions in this region, and to show that the X-rayemitting gas in the centre of the galaxy has a cooling time of only5×107yr. In a companion paper, these measurements areused to place constraints on models of the jet dynamics. A previouslyunknown one-sided X-ray jet in 3C 31, extending up to 8arcsec from thenucleus, is detected and resolved. Its structure and steep X-rayspectrum are similar to those of X-ray jets known in other FRI sources,and we attribute the radiation to synchrotron emission from ahigh-energy population of electrons. In situ particle acceleration isrequired in the region of the jet where bulk deceleration is takingplace. We also present X-ray spectra and luminosities of the galaxies inthe Arp 331 chain of which NGC 383 is a member. The spectrum and spatialproperties of the nearby bright X-ray source 1E 0104+3153 are used toargue that the soft X-ray emission is mostly due to a foreground groupof galaxies rather than to the background broad absorption-line quasar.
|Herbig-Haro Jets from Orbiting Sources|
The origin of the wiggles detected in the trajectory of Herbig-Haro (HH)jets, microjets, and radio continuum jets from young stellar objects isinvestigated. We propose that the orbital motion of a binary stellarsystem is the cause of these outflow morphologies. The analyticaltrajectories of a ballistic jet ejected by a source moving along acircular orbit have been derived, and their validity has been checkedthrough a comparison with three-dimensional gasdynamic simulations. Wepropose a simple method to calculate the mass of the outflow source andthe orbital parameters using observational measurements (i.e., theopening angle of the wiggling jet pattern, the separation betweensuccessive wiggles, the jet velocity, and the orientation of the outflowwith respect to the plane of the sky), and we apply it to the DG Taumicrojet, HH 47, and the Serpens radio continuum jet. For these threeobjects we obtain orbital parameters and masses that are reasonable forpre-main-sequence binaries. From this result we conclude that theobserved wiggles (of these three outflows) can indeed be interpreted interms of a model of an outflow ejected from a source with an orbitalmotion.
|Redshift-Distance Survey of Early-Type Galaxies. I. The ENEARc Cluster Sample|
This paper presents data on the ENEARc subsample of the larger ENEARsurvey of nearby early-type galaxies. The ENEARc galaxies belong toclusters and were specifically chosen to be used for the construction ofa Dn-σ template. The ENEARc sample includes newmeasurements of spectroscopic and photometric parameters (redshift,velocity dispersion, line index Mg2, and the angular diameterdn), as well as data from the literature. New spectroscopicdata are given for 229 cluster early-type galaxies, and new photometryis presented for 348 objects. Repeat and overlap observations withexternal data sets are used to construct a final merged catalogconsisting of 640 early-type galaxies in 28 clusters. Objectivecriteria, based on catalogs of groups of galaxies derived from completeredshift surveys of the nearby universe, are used to assign galaxies toclusters. In a companion paper, these data are used to construct thetemplate Dn-σ distance relation for early-typegalaxies, which has been used to estimate galaxy distances and derivepeculiar velocities for the ENEAR all-sky sample. Based on observationsat Complejo Astronomico El Leoncito, operated under agreement betweenthe Consejo Nacional de Investigaciones Científicas de laRepública Argentina and the National Universities of La Plata,Córdoba, and San Juan; Cerro Tololo Inter-American Observatory,National Optical Astronomical Observatory, which is operated by theAssociation of Universities for Research in Astronomy, Inc., undercooperative agreement with the National Science Foundation; the EuropeanSouthern Observatory (ESO), partially under the ESO-ON agreement; theFred Lawrence Whipple Observatory; the Observatório do Pico dosDias, operated by the Laboratório Nacional de Astrofísicaand the MDM Observatory at Kitt Peak.
|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.
|Supernova 2000dk in NGC 382|
IAUC 7509 available at Central Bureau for Astronomical Telegrams.
|Supernova 2000dl in UGC 1191|
IAUC 7494 available at Central Bureau for Astronomical Telegrams.
|Supernova 2000dk in NGC 382|
IAUC 7493 available at Central Bureau for Astronomical Telegrams.
|Nuclear Gas and Dust Disks in Nearby 3CR Elliptical Galaxies|
Using WFPC2 V, R, I, and Hα+[N II] images, we examine themorphologies, environments, colors, and line emission of dust and gasdisks located in the cores of seven low-redshift elliptical galaxieshosting 3C radio sources: NGC 383 (3C 31)/NGC 382, NGC 547 (3C 40), NGC3862 (3C 264), NGC 4261 (3C 270), NGC 5532 (3C 296), NGC 7720 (3C465)/NGC 7720A, and UGC 12064 (3C 449). The color maps are generallyconsistent with absorption by dust in flattened configurations viewed atintermediate inclinations. In most cases the disks are nonuniform incontinuum light and are surrounded by arcs, filaments, and diffuseabsorbing clumps, suggesting that the dust in the cores of thesegalaxies is not dynamically settled. Extended, clumpy or smoothHα+[N II] line emission is detected in all four cases (NGC 383,NGC 3862, UGC 12064, and NGC 7720) for which narrowband images areavailable. Line emission is found at projected locations from the nucleito the edges of the disks. The major axes of the disks and their hostsare preferentially aligned, with the degree of alignment uncorrelatedwith disk size. As projected on the sky, all the disks are moreflattened than their host galaxies. Three of the hosts have boxyisophotes, and the remainder are normal in shape. The two boxiestgalaxies, NGC 4261 and NGC 5532, show significant displacements betweentheir nuclear and isophotal centers. The mass of the disk in NGC 4261 isestimated using radiative transfer calculations. Scattering into theline of sight is included in the approximation that the dust isisotropically illuminated by surrounding stars. The observed colors andsurface brightness are shown to be matched by a thin layer of dust thatlies in front of three-quarters (eastern edge) to one-quarter (westernedge) of the starlight. When a Galactic opacity curve is used, the massdetermined is an order of magnitude larger than that found assuming thedust lies in a foreground screen. The opacity falls more steeply towardthe infrared than do those of Galactic and Magellanic Cloud grains,suggesting that the dust is not unprocessed material from a merger witha spiral or irregular galaxy. Based on observations made with theNASA/ESA Hubble Space Telescope, which is operated by AURA, Inc., underNASA contract NAS5-26555.
|Spectrophotometry of Nearby Field Galaxies: The Data|
We have obtained integrated and nuclear spectra as well as U, B, Rsurface photometry for a representative sample of 196 nearby galaxies.These galaxies span the entire Hubble sequence in morphological type, aswell as a wide range of luminosities (MB=-14 to -22). Here wepresent the spectrophotometry for these galaxies. The selection of thesample and the U, B, R surface photometry is described in a companionpaper. Our goals for the project include measuring the current starformation rates and metallicities of these galaxies, and elucidatingtheir star formation histories, as a function of luminosity andmorphology. We thereby extend the work of Kennicutt to lower luminositysystems. We anticipate that our study will be useful as a benchmark forstudies of galaxies at high redshift. We describe the observing, datareduction, and calibration techniques and demonstrate that ourspectrophotometry agrees well with that of Kennicutt. The spectra spanthe range 3550-7250 Å at a resolution (FWHM) of ~6 Å andhave an overall relative spectrophotometric accuracy of ~+/-6%. Wepresent a spectrophotometric atlas of integrated and nuclear rest-framespectra as well as tables of equivalent widths and synthetic colors. Theatlas and tables of measurements will be made available electronically.We study the correlations of galaxy properties determined from thespectra and images. Our findings include: (1) galaxies of a givenmorphological class display a wide range of continuum shapes andemission-line strengths if a broad range of luminosities are considered,(2) emission-line strengths tend to increase and continua tend to getbluer as the luminosity decreases, and (3) the scatter on the generalcorrelation between nuclear and integrated Hα emission-linestrengths is large.
|Surface Photometry of Nearby Field Galaxies: The Data|
We have obtained integrated spectra and multifilter photometry for arepresentative sample of ~200 nearby galaxies. These galaxies span theentire Hubble sequence in morphological type, as well as a wide range ofluminosities (MB=-14 to -22) and colors (B-R=0.4-1.8). Herewe describe the sample selection criteria and the U, B, R surfacephotometry for these galaxies. The spectrophotometric results will bepresented in a companion paper. Our goals for the project includemeasuring the current star formation rates and metallicity of thesegalaxies, and elucidating their star formation histories, as a functionof luminosity and morphology. We thereby extend the work of Kennicutt tolower luminosity systems. We anticipate that our study will be useful asa benchmark for studies of galaxies at high redshift. We discuss theobserving, data reduction, and calibration techniques and show that ourphotometry agrees well with previous work in those cases in whichearlier data are available. We present an atlas of images, radialsurface brightness profiles, and color profiles as well as tables ofderived parameters. The atlas and tables of measurements will be madeavailable electronically. We study the correlations of galaxy propertiesdetermined from the galaxy images. Our findings include the following:(1) colors determined within the effective radius correlate better withmorphological type than with MB and (2) 50% of thelow-luminosity galaxies are bluest in their centers.
|Stellar population of ellipticals in different environments: near-infrared spectroscopic observations|
Near-infrared spectra of 50 elliptical galaxies in the Pisces, Abell2199 and 2634 clusters, and in the general field, have been obtained.The strength of the CO (2.3-mu m) absorption feature in these galaxiesis used to explore the presence of an intermediate-age population (e.g.asymptotic giant branch stars) in ellipticals in different environments.We find that the strongest evidence for such a population comes fromellipticals in groups of a few members, which we interpret as the resultof recent minor merging of these galaxies with later-type galaxies.Field galaxies from very isolated environments, on the other hand, showno evidence for young or intermediate-age stars as revealed by Hβand CO absorptions, and appear to form a very uniform, old populationwith very little scatter in metallicity and star formation history.
|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.
|X-ray study of the NGC 383 group of galaxies and the source 1E 0104+3153|
We present results from an analysis of the X-ray properties of the NGC383 galaxy group based on ROSAT PSPC and HRI data. X-ray emission can betraced out to ~ 1 h50(-1) Mpc, the estimated virial radius ofthe system. We determine a total mass of 6 10(13) h50(-1)Msun for the group inside this radius with a gas massfraction of 21%. The intragroup gas temperature of 1.5 keV is bothconsistent with the galaxy velocity dispersion and the X-ray luminosity- temperature relation of groups and clusters suggesting that the groupis fairly relaxed. This is also indicated by the almost sphericallysymmetric appearance of the group's X-ray halo. The X-ray properties ofthe radio galaxy NGC 383 (3C 31) which is located near the center of thegroup are discussed. Its spectrum is best described by a two-componentmodel, consisting of emission from a low-temperature Raymond-Smithplasma, and a hard tail. The emission from NGC 383 is not resolved bythe ROSAT HRI. The possible interaction of the radio jets of 3C 31 withthe IGM is studied. A spatial, spectral and temporal analysis of theEinstein source 1E0104+3153 located within the field of view isperformed, one goal being the identification of the optical counterpart(with both, a high-redshift BAL quasar and a nearby elliptical galaxy,member of a small group, located within the Einstein X-ray errorcircle). We find evidence that the IGM of the small group contributessignificantly to the X-ray emission of 1E0104, which can be described bya Raymond-Smith model of kT =~ 2 keV and a soft X-ray luminosity of L_x=~ 3 10(43) erg/s.
|Scenic Vistas: The Pisces Group|
|Old Stellar Populations. VI. Absorption-Line Spectra of Galaxy Nuclei and Globular Clusters|
We present absorption-line strengths on the Lick/IDS line-strengthsystem of 381 galaxies and 38 globular clusters in the 4000-6400Angstroms region. All galaxies were observed at Lick Observatory between1972 and 1984 with the Cassegrain Image Dissector Scanner spectrograph,which makes this study one of the largest homogeneous collections ofgalaxy spectral line data to date. We also present a catalog of nuclearvelocity dispersions used to correct the absorption-line strengths ontothe stellar Lick/IDS system. Extensive discussion of both random andsystematic errors of the Lick/IDS system is provided. Indices are seento fall into three families: alpha -element-like indices (including CN,Mg, Na D, and TiO2) that correlate positively with velocity dispersion;Fe-like indices (including Ca, the G band, TiO1, and all Fe indices)that correlate only weakly with velocity dispersion and the alphaindices; and H beta that anticorrelates with both velocity dispersionand the alpha indices. C24668 seems to be intermediate between the alphaand Fe groups. These groupings probably represent different elementabundance families with different nucleosynthesis histories.
|Groups of galaxies. III. Some empirical characteristics.|
|The Universality of the Fundamental Plane of E and S0 Galaxies: Spectroscopic Data|
We present central velocity dispersion measurements for 325 early-typegalaxies in eight clusters and groups of galaxies, including newobservations for 212 galaxies. The clusters and groups are the A262,A1367, Coma (A1656), A2634, Cancer, and Pegasus Clusters and the NGC 383and NGC 507 Groups. The new measurements were derived frommedium-dispersion spectra that cover 600 Å centered on the Mg I btriplet at lambda ~ 5175 Å. Velocity dispersions were measuredusing the Tonry & Davis cross-correlation method, with a typicalaccuracy of 6%. A detailed comparison with other data sources is made.
|The Universality of the Fundamental Plane of E and S0 Galaxies: Sample Definition and I-Band Photometric Data|
As part of a project to compare the fundamental plane and Tully-Fisherdistance scales, we present here I-band CCD photometry for 636early-type galaxies in eight clusters and groups of galaxies. These arethe A262, A1367, Coma (A1656), A2634, Cancer and Pegasus Clusters, andthe NGC 383 and NGC 507 Groups. Sample selection, cluster properties,and cluster membership assignment criteria are discussed. We presentphotometric parameters that are used in the fundamental plane relation,the effective radius r_e, and the effective surface brightness mu_e, asderived from a r^1/4 fit to the observed radial photometric profile ofeach galaxy. A comparison with similar data found in the literature forthe Coma Cluster shows that large systematic uncertainties can beintroduced in the measurement of r_e and mu_e by the particular methodused to derive those parameters. However, the particular combination ofthese two parameters that enters in the fundamental plane relation is aquantity that can be measured with high accuracy.
|A catalogue of Mg_2 indices of galaxies and globular clusters|
We present a catalogue of published absorption-line Mg_2 indices ofgalaxies and globular clusters. The catalogue is maintained up-to-datein the HYPERCAT database. The measurements are listed together with thereferences to the articles where the data were published. A codeddescription of the observations is provided. The catalogue gathers 3541measurements for 1491 objects (galaxies or globular clusters) from 55datasets. Compiled raw data for 1060 galaxies are zero-point correctedand transformed to a homogeneous system. Tables 1, 3, and 4 areavailable in electronic form only at the CDS, Strasbourg, via anonymousftp 184.108.40.206. Table 2 is available both in text and electronic form.
Submit a new link
Member of following groups:
Observation and Astrometry data
Catalogs and designations: