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Ýlgili Makaleler
A Search for Radio Emission from Type Ia Supernovae
We present and discuss the radio observations of 27 Type Ia supernovae(SNe Ia), observed over two decades with the Very Large Array. No SN Iahas been detected so far in the radio, implying a very low density forany possible circumstellar material established by the progenitor, orprogenitor system, before explosion. We derive 2 σ upper limits toa steady mass-loss rate for individual SN systems as low as~3×10-8 Msolar yr-1, which arguesstrongly against white dwarf accretion via a stellar wind from a massivebinary companion in the symbiotic star, an example of the``single-degenerate'' scenario. However, a white dwarf accreting from arelatively low mass companion via a sufficiently high efficiency(>60%-80%) Roche lobe overflow is still consistent with our limits.The ``double-degenerate'' merger scenario also cannot be excluded.
| Mid-Infrared Spectral Diagnostics of Nuclear and Extranuclear Regions in Nearby Galaxies
Mid-infrared diagnostics are presented for a large portion of theSpitzer Infrared Nearby Galaxies Survey (SINGS) sample plus archivaldata from ISO and Spitzer. The SINGS data set includes low- andhigh-resolution spectral maps and broadband imaging in the infrared forover 160 nuclear and extranuclear regions within 75 nearby galaxiesspanning a wide range of morphologies, metallicities, luminosities, andstar formation rates. Our main result is that these mid-infrareddiagnostics effectively constrain a target's dominant power source. Thecombination of a high-ionization line index and PAH strength serves asan efficient discriminant between AGNs and star-forming nuclei,confirming progress made with ISO spectroscopy on starbursting andultraluminous infrared galaxies. The sensitivity of Spitzer allows us toprobe fainter nuclear and star-forming regions within galaxy disks. Wefind that both star-forming nuclei and extranuclear regions stand apartfrom nuclei that are powered by Seyfert or LINER activity. In fact, weidentify areas within four diagnostic diagrams containing >90%Seyfert/LINER nuclei or >90% H II regions/H II nuclei. We also findthat, compared to starbursting nuclei, extranuclear regions typicallyseparate even further from AGNs, especially for low-metallicityextranuclear environments. In addition, instead of the traditionalmid-infrared approach to differentiating between AGNs and star-formingsources that utilizes relatively weak high-ionization lines, we showthat strong low-ionization cooling lines of X-ray-dominated regions like[Si II] 34.82 μm can alternatively be used as excellentdiscriminants. Finally, the typical target in this sample showsrelatively modest interstellar electron density (~400 cm-3)and obscuration (AV~1.0 mag for a foreground screen),consistent with a lack of dense clumps of highly obscured gas and dustresiding in the emitting regions.
| Using Line Profiles to Test the Fraternity of Type Ia Supernovae at High and Low Redshifts
Using archival data of low-redshift (z<0.01 Center for Astrophysicsand SUSPECT databases) Type Ia supernovae (SNe Ia) and recentobservations of high-redshift (0.161.7] SNe Ia, which are also subluminous. Inaddition, we give the first direct evidence in two high-z SN Ia spectraof a double-absorption feature in Ca II λ3945, an event alsoobserved, although infrequently, in low-redshift SN Ia spectra (6 out of22 SNe Ia in our local sample). Moreover, echoing the recent studies ofDessart & Hillier in the context of Type II supernovae (SNe II), wesee similar P Cygni line profiles in our large sample of SN Ia spectra.First, the magnitude of the velocity location at maximum profileabsorption may underestimate that at the continuum photosphere, asobserved, for example, in the optically thinner line S II λ5640.Second, we report for the first time the unambiguous and systematicintrinsic blueshift of peak emission of optical P Cygni line profiles inSN Ia spectra, by as much as 8000 km s-1. All the high-z SNeIa analyzed in this paper were discovered and followed up by the ESSENCEcollaboration and are now publicly available.Based in part on observations obtained at the Cerro TololoInter-American Observatory, which is operated by the Association ofUniversities for Research in Astronomy (AURA), Inc., under cooperativeagreement with the National Science Foundation (NSF); the EuropeanSouthern Observatory, Chile (ESO program 170.A-0519) the GeminiObservatory, which is operated by AURA under a cooperative agreementwith the NSF on behalf of the Gemini partnership (the NSF [UnitedStates], the Particle Physics and Astronomy Research Council [UnitedKingdom], the National Research Council [Canada], CONICYT [Chile], theAustralian Research Council [Australia], CNPq [Brazil], and CONICET[Argentina]) (programs GN-2002B-Q-14, GN-2003B-Q-11, and GS-2003B-Q-11)the Magellan Telescopes at Las Campanas Observatory; the MMTObservatory, a joint facility of the Smithsonian Institution and theUniversity of Arizona; and the F. L. Whipple Observatory, which isoperated by the Smithsonian Astrophysical Observatory. Some of the datapresented herein were obtained at the W. M. Keck Observatory, which isoperated as a scientific partnership among the California Institute ofTechnology, the University of California, and the National Aeronauticsand Space Administration. The Observatory was made possible by thegenerous financial support of the W. M. Keck Foundation.
| Low-Luminosity Active Galaxies and Their Central Black Holes
Central black hole masses for 117 spiral galaxies representingmorphological stages S0/a through Sc and taken from the largespectroscopic survey of Ho et al. are derived using Ks-banddata from the Two Micron All Sky Survey. Black hole masses are foundusing a calibrated black hole-Ks bulge luminosity relation,while bulge luminosities are measured by means of a two-dimensionalbulge-disk decomposition routine. The black hole masses are correlatedagainst a variety of parameters representing properties of the nucleusand host galaxy. Nuclear properties such as line width (FWHM [N II]), aswell as emission-line ratios (e.g., [O III]/Hβ, [O I]/Hα, [NII]/Hα, and [S II]/Hα), show a very high degree ofcorrelation with black hole mass. The excellent correlation with linewidth supports the view that the emission-line gas is in virialequilibrium with either the black hole or bulge potential. The very goodemission-line ratio correlations may indicate a change in ionizingcontinuum shape with black hole mass in the sense that more massiveblack holes generate harder spectra. Apart from theinclination-corrected rotational velocity, no excellent correlations arefound between black hole mass and host galaxy properties. Significantdifferences are found between the distributions of black hole masses inearly-, mid-, and late-type spiral galaxies (subsamples A, B, and C) inthe sense that early-type galaxies have preferentially larger centralblack holes, consistent with observations that Seyfert galaxies arefound preferentially in early-type systems. The line width distributionsshow a marked difference among subsamples A, B, and C in the sense thatearlier type galaxies have larger line widths. There are also cleardifferences in line ratios between subsamples A+B and C that likely arerelated to the level of ionization in the gas. Finally, aKs-band Simien & de Vaucouleurs diagram shows excellentagreement with the original B-band relation, although there is a largedispersion at a given morphological stage.
| A radio census of nuclear activity in nearby galaxies
In order to determine the incidence of black hole accretion-drivennuclear activity in nearby galaxies, as manifested by their radioemission, we have carried out a high-resolution Multi-ElementRadio-Linked Interferometer Network (MERLIN) survey of LINERs andcomposite LINER/Hii galaxies from a complete magnitude-limited sample ofbright nearby galaxies (Palomar sample) with unknown arcsecond-scaleradio properties. There are fifteen radio detections, of which three arenew subarcsecond-scale radio core detections, all being candidate AGN.The detected galaxies supplement the already known low-luminosity AGN -low-luminosity Seyferts, LINERs and composite LINER/Hii galaxies - inthe Palomar sample. Combining all radio-detected Seyferts, LINERs andcomposite LINER/Hii galaxies (LTS sources), we obtain an overall radiodetection rate of 54% (22% of all bright nearby galaxies) and weestimate that at least ~50% (~20% of all bright nearby galaxies) aretrue AGN. The radio powers of the LTS galaxies allow the construction ofa local radio luminosity function. By comparing the luminosity functionwith those of selected moderate-redshift AGN, selected from the 2dF/NVSSsurvey, we find that LTS sources naturally extend the RLF of powerfulAGN down to powers of about 10 times that of Sgr A*.
| Ultraluminous X-Ray Sources in Nearby Galaxies from ROSAT High Resolution Imager Observations I. Data Analysis
X-ray observations have revealed in other galaxies a class ofextranuclear X-ray point sources with X-ray luminosities of1039-1041 ergs s-1, exceeding theEddington luminosity for stellar mass X-ray binaries. Theseultraluminous X-ray sources (ULXs) may be powered by intermediate-massblack holes of a few thousand Msolar or stellar mass blackholes with special radiation processes. In this paper, we present asurvey of ULXs in 313 nearby galaxies withD25>1' within 40 Mpc with 467 ROSAT HighResolution Imager (HRI) archival observations. The HRI observations arereduced with uniform procedures, refined by simulations that help definethe point source detection algorithm employed in this survey. A sampleof 562 extragalactic X-ray point sources withLX=1038-1043 ergs s-1 isextracted from 173 survey galaxies, including 106 ULX candidates withinthe D25 isophotes of 63 galaxies and 110 ULX candidatesbetween 1D25 and 2D25 of 64 galaxies, from which aclean sample of 109 ULXs is constructed to minimize the contaminationfrom foreground or background objects. The strong connection betweenULXs and star formation is confirmed based on the striking preference ofULXs to occur in late-type galaxies, especially in star-forming regionssuch as spiral arms. ULXs are variable on timescales over days to yearsand exhibit a variety of long term variability patterns. Theidentifications of ULXs in the clean sample show some ULXs identified assupernovae (remnants), H II regions/nebulae, or young massive stars instar-forming regions, and a few other ULXs identified as old globularclusters. In a subsequent paper, the statistic properties of the surveywill be studied to calculate the occurrence frequencies and luminosityfunctions for ULXs in different types of galaxies to shed light on thenature of these enigmatic sources.
| Infrared Spectral Energy Distributions of Nearby Galaxies
The Spitzer Infrared Nearby Galaxies Survey (SINGS) is carrying out acomprehensive multiwavelength survey on a sample of 75 nearby galaxies.The 1-850 μm spectral energy distributions (SEDs) are presented usingbroadband imaging data from Spitzer, 2MASS, ISO, IRAS, and SCUBA. Theinfrared colors derived from the globally integrated Spitzer data aregenerally consistent with the previous generation of models that weredeveloped using global data for normal star-forming galaxies, althoughsignificant deviations are observed. Spitzer's excellent sensitivity andresolution also allow a detailed investigation of the infrared SEDs forvarious locations within the three large, nearby galaxies NGC 3031(M81), NGC 5194 (M51), and NGC 7331. A wide variety of spectral shapesis found within each galaxy, especially for NGC 3031, the closest of thethree targets and thus the galaxy for which the smallest spatial scalescan be explored. Strong correlations exist between the local starformation rate and the infrared colors fν(70μm)/fν(160 μm) and fν(24μm)/fν(160 μm), suggesting that the 24 and 70 μmemission are useful tracers of the local star formation activity level.Preliminary evidence indicates that variations in the 24 μm emission,and not variations in the emission from polycyclic aromatic hydrocarbonsat 8 μm, drive the variations in the fν(8.0μm)/fν(24 μm) colors within NGC 3031, NGC 5194, andNGC 7331. If the galaxy-to-galaxy variations in SEDs seen in our sampleare representative of the range present at high redshift, thenextrapolations of total infrared luminosities and star formation ratesfrom the observed 24 μm flux will be uncertain at the factor of 5level (total range). The corresponding uncertainties using theredshifted 8.0 μm flux (e.g., observed 24 μm flux for a z=2source) are factors of 10-20. Considerable caution should be used wheninterpreting such extrapolated infrared luminosities.
| 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.
| The Westerbork HI survey of spiral and irregular galaxies. III. HI observations of early-type disk galaxies
We present Hi observations of 68 early-type disk galaxies from the WHISPsurvey. They have morphological types between S0 and Sab and absoluteB-band magnitudes between -14 and -22. These galaxies form the massive,high surface-brightness extreme of the disk galaxy population, few ofwhich have been imaged in Hi before. The Hi properties of the galaxiesin our sample span a large range; the average values of MHI/LB and DH I/D25 are comparableto the ones found in later-type spirals, but the dispersions around themean are larger. No significant differences are found between the S0/S0aand the Sa/Sab galaxies. Our early-type disk galaxies follow the same Himass-diameter relation as later-type spiral galaxies, but theireffective Hi surface densities are slightly lower than those found inlater-type systems. In some galaxies, distinct rings of Hi emissioncoincide with regions of enhanced star formation, even though theaverage gas densities are far below the threshold of star formationderived by Kennicutt (1989, ApJ, 344, 685). Apparently, additionalmechanisms, as yet unknown, regulate star formation at low surfacedensities. Many of the galaxies in our sample have lopsided gasmorphologies; in most cases this can be linked to recent or ongoinginteractions or merger events. Asymmetries are rare in quiescentgalaxies. Kinematic lopsidedness is rare, both in interacting andisolated systems. In the appendix, we present an atlas of the Hiobservations: for all galaxies we show Hi surface density maps, globalprofiles, velocity fields and radial surface density profiles.
| Supernova 2002bo: inadequacy of the single parameter description
We present optical/near-infrared photometry and spectra of the type IaSN 2002bo spanning epochs from -13 d before maximum B-band light to +102d after. The pre-maximum optical coverage is particularly complete. Theextinction deduced from the observed colour evolution and frominterstellar Na I D absorption is quite high, namely E(B-V) = 0.43 +/-0.10. On the other hand, model matches to the observed spectra point toa lower reddening [E(B-V) ~ 0.30]. In some respects, SN 2002bo behavesas a typical `Branch normal' type Ia supernova (SN Ia) at optical andinfrared wavelengths. We find a B-band risetime of 17.9 +/- 0.5 d, aΔm15(B) of 1.13 +/- 0.05, and a dereddenedMB=-19.41 +/- 0.42. However, comparison with other type Iasupernovae having similar Δm15(B) values indicates thatin other respects SN 2002bo is unusual. While the optical spectra of SN2002bo are very similar to those of SN 1984A [Δm15(B) =1.19], lower velocities and a generally more structured appearance arefound in SNe 1990N, 1994D and 1998bu. For supernovae havingΔm15(B) > 1.2, we confirm the variation of withΔm15(B). However, for supernovae such as SN 2002bo,with lower values of Δm15(B) the relation breaks down.Moreover, the evolution of for SN 2002bo is strikingly different fromthat shown by other type Ia supernovae. The velocities of SN 2002bo and1984A derived from S II 5640 Å, Si II 6355 Å and Ca II H andK lines are either much higher and/or evolve differently from those seenin other normal SNe Ia events. Thus, while SN 2002bo and SN 1984A appearto be highly similar, they exhibit behaviour which is distinctlydifferent from other SNe Ia having similar Δm15(B)values. We suggest that the unusually low temperature, the presence ofhigh-velocity intermediate-mass elements and the low abundance of carbonat early times indicates that burning to Si penetrated to much higherlayers than in more normal type Ia supernovae. This may be indicative ofa delayed detonation explosion.
| Optical and near-infrared photometry of supernovae in galaxies of the local Universe
In this paper I briefly present and discuss photometric results forthree SNe exploded in nearby galaxies: SN 1999el, SN 2000E and SN2002cv. All data were acquired at optical and infrared bands withdedicated telescopes that allowed us to obtain well sampled and accuratelight curves spanning a wide wavelength range. The fundamental role ofinfrared wavelengths in studying SNe is emphasized.
| Optical and Infrared Photometry of the Type Ia Supernovae 1991T, 1991bg, 1999ek, 2001bt, 2001cn, 2001cz, and 2002bo
We present optical and/or infrared photometry of the Type Ia supernovaeSN 1991T, SN 1991bg, SN 1999ek, SN 2001bt, SN 2001cn, SN 2001cz, and SN2002bo. All but one of these supernovae have decline rate parameters,Δm15(B), close to the median value of 1.1 for the wholeclass of Type Ia supernovae. The addition of these supernovae to therelationship between the near-infrared absolute magnitudes andΔm15(B) strengthens the previous relationships we havefound in that the maximum light absolute magnitudes are essentiallyindependent of the decline rate parameter. (SN 1991bg, the prototype ofthe subclass of fast-declining Type Ia supernovae, is a special case.)The dispersion in the Hubble diagram in JHK is only ~0.15 mag. Thenear-infrared properties of Type Ia supernovae continue to be excellentmeasures of the luminosity distances to the supernova host galaxiesbecause of the need for only small corrections from the epoch ofobservation to maximum light, low dispersion in absolute magnitudes atmaximum light, and the minimal reddening effects in the near-infrared.
| 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
| Properties of isolated disk galaxies
We present a new sample of northern isolated galaxies, which are definedby the physical criterion that they were not affected by other galaxiesin their evolution during the last few Gyr. To find them we used thelogarithmic ratio, f, between inner and tidal forces acting upon thecandidate galaxy by a possible perturber. The analysis of thedistribution of the f-values for the galaxies in the Coma cluster leadus to adopt the criterion f ≤ -4.5 for isolated galaxies. Thecandidates were chosen from the CfA catalog of galaxies within thevolume defined by cz ≤5000 km s-1, galactic latitudehigher than 40o and declination ≥-2.5o. Theselection of the sample, based on redshift values (when available),magnitudes and sizes of the candidate galaxies and possible perturberspresent in the same field is discussed. The final list of selectedisolated galaxies includes 203 objects from the initial 1706. The listcontains only truly isolated galaxies in the sense defined, but it is byno means complete, since all the galaxies with possible companions underthe f-criterion but with unknown redshift were discarded. We alsoselected a sample of perturbed galaxies comprised of all the diskgalaxies from the initial list with companions (with known redshift)satisfying f ≥ -2 and \Delta(cz) ≤500 km s-1; a totalof 130 objects. The statistical comparison of both samples showssignificant differences in morphology, sizes, masses, luminosities andcolor indices. Confirming previous results, we found that late spiral,Sc-type galaxies are, in particular, more frequent among isolatedgalaxies, whereas Lenticular galaxies are more abundant among perturbedgalaxies. Isolated systems appear to be smaller, less luminous and bluerthan interacting objects. We also found that bars are twice as frequentamong perturbed galaxies compared to isolated galaxies, in particularfor early Spirals and Lenticulars. The perturbed galaxies have higherLFIR/LB and Mmol/LB ratios,but the atomic gas content is similar for the two samples. The analysisof the luminosity-size and mass-luminosity relations shows similartrends for both families, the main difference being the almost totalabsence of big, bright and massive galaxies among the family of isolatedsystems, together with the almost total absence of small, faint and lowmass galaxies among the perturbed systems. All these aspects indicatethat the evolution induced by interactions with neighbors would proceedfrom late, small, faint and low mass Spirals to earlier, bigger, moreluminous and more massive spiral and lenticular galaxies, producing atthe same time a larger fraction of barred galaxies but preserving thesame relations between global parameters. The properties we found forour sample of isolated galaxies appear similar to those of high redshiftgalaxies, suggesting that the present-day isolated galaxies could bequietly evolved, unused building blocks surviving in low densityenvironments.Tables \ref{t1} and \ref{t2} are only available in electronic form athttp://www.edpsciences.org
| Classifications of the Host Galaxies of Supernovae, Set II
Classifications on the DDO system are given for an additional 231 hostgalaxies of supernovae that have been discovered during the course ofthe Lick Observatory Supernova Search with the Katzman Automatic ImagingTelescope (KAIT). This brings the total number of hosts of supernovae(SNe) discovered (or independently rediscovered) by KAIT, which have sofar been classified on a homogeneous system, to 408. The probabilitythat SNe Ia and SNe II have a different distribution of host-galaxyHubble types is found to be 99.7%. A significant difference is alsofound between the distributions of the host galaxies of SNe Ia and ofSNe Ibc (defined here to include SNe Ib, Ib/c, and Ic). However, nosignificant difference is detected between the frequency distributionsof the host galaxies of SNe II and SNe IIn. This suggests that SNe IInare generally not SNe Ia embedded in circumstellar material that aremasquerading as SNe II. Furthermore, no significant difference is foundbetween the distribution of the Hubble types of the hosts of SNe Ibc andof SNe II. Additionally, SNe II-P and SNe II-L are found to occur amongsimilar stellar populations. The ratio of the number of SNe Ia-pec tonormal SNe Ia appears to be higher in early-type galaxies than it is ingalaxies of later morphological types. This suggests that the ancestorsof SNe Ia-pec may differ systematically in age or composition from theprogenitors of normal SNe Ia. Unexpectedly, five SNe of Types Ib/c, II,and IIn (all of which are thought to have massive progenitors) are foundin host galaxies that are nominally classified as types E and S0.However, in each case the galaxy classification is uncertain, or newlyinspected images show evidence suggesting a later classification. Amongthese five objects, NGC 3720, the host galaxy of SN 2002at, wasapparently misidentified in the Carnegie Atlas of Galaxies.
| SINGS: The SIRTF Nearby Galaxies Survey
The SIRTF Nearby Galaxy Survey is a comprehensive infrared imaging andspectroscopic survey of 75 nearby galaxies. Its primary goal is tocharacterize the infrared emission of galaxies and their principalinfrared-emitting components, across a broad range of galaxy propertiesand star formation environments. SINGS will provide new insights intothe physical processes connecting star formation to the interstellarmedium properties of galaxies and provide a vital foundation forunderstanding infrared observations of the distant universe andultraluminous and active galaxies. The galaxy sample and observingstrategy have been designed to maximize the scientific and archivalvalue of the data set for the SIRTF user community at large. The SIRTFimages and spectra will be supplemented by a comprehensivemultiwavelength library of ancillary and complementary observations,including radio continuum, H I, CO, submillimeter, BVRIJHK, Hα,Paα, ultraviolet, and X-ray data. This paper describes the mainastrophysical issues to be addressed by SINGS, the galaxy sample and theobserving strategy, and the SIRTF and other ancillary data products.
| The PDS versus Markarian starburst galaxies: comparing strong and weak IRAS emitter at 12 and 25 μm in the nearby Universe
The characteristics of the starburst galaxies from the Pico dos Diassurvey (PDS) are compared with those of the nearby ultraviolet (UV)bright Markarian starburst galaxies, having the same limit in redshift(vh < 7500 km s-1) and absolute B magnitude(MB < -18). An important difference is found: theMarkarian galaxies are generally undetected at 12 and 25 μm in IRAS.This is consistent with the UV excess shown by these galaxies andsuggests that the youngest star-forming regions dominating thesegalaxies are relatively free of dust.The far-infrared selection criteria for the PDS are shown to introduce astrong bias towards massive (luminous) and large size late-type spiralgalaxies. This is contrary to the Markarian galaxies, which are found tobe remarkably rich in smaller size early-type galaxies. These resultssuggest that only late-type spirals with a large and massive disc arestrong emitters at 12 and 25 μm in IRAS in the nearby Universe.The Markarian and PDS starburst galaxies are shown to share the sameenvironment. This rules out an explanation of the differences observedin terms of external parameters. These differences may be explained byassuming two different levels of evolution, the Markarian being lessevolved than the PDS galaxies. This interpretation is fully consistentwith the disc formation hypothesis proposed by Coziol et al. to explainthe special properties of the Markarian SBNG.
| Companions of Bright Barred Shapley-Ames Galaxies
Companion galaxy environment for a subset of 78 bright and nearby barredgalaxies from the Shapley-Ames Catalog is presented. Among the spiralbarred galaxies, there are Seyfert galaxies, galaxies with circumnuclearstructures, galaxies not associated with any large-scale galaxy cloudstructure, galaxies with peculiar disk morphology (crooked arms), andgalaxies with normal disk morphology; the list includes all Hubbletypes. The companion galaxy list includes the number of companiongalaxies within 20 diameters, their Hubble type, and projectedseparation distance. In addition, the companion environment was searchedfor four known active spiral galaxies, three of them are Seyfertgalaxies, namely, NGC 1068, NGC 1097, and NGC 5548, and one is astarburst galaxy, M82. Among the results obtained, it is noted that theonly spiral barred galaxy classified as Seyfert 1 in our list has nocompanions within a projected distance of 20 diameters; six out of 10Seyfert 2 bar galaxies have no companions within 10 diameters, six outof 10 Seyfert 2 galaxies have one or more companions at projectedseparation distances between 10 and 20 diameters; six out of 12 galaxieswith circumnuclear structures have two or more companions within 20diameters.
| Photometry of SN 2002bo with template image subtraction
VRI photometry of the type Ia supernova 2002bo is presented. This SNexploded in a dusty region of the host galaxy NGC 3190, thus,subtraction of a template frame was necessary to obtain reliablephotometry. We used a template frame of NGC 3190 taken during the courseof our galaxy imaging project, fortunately, just a few days before SN2002bo was discovered. The aim of this project is to collect templateframes of nearby galaxies that are potential hosts of bright SNe.Subtraction of pre-SN images helped us to exclude the background lightcontamination of the host galaxy. The maximum occurred at JD 2,452,346,with maximal V bright ness of 13.58m. MLCS analysis led toT0(B) = JD 2,452,346.1 ± 0.8 (fiducial B-maximum),E(B-V),= 0.24m ± 0.02m, μ0=32.46±0.06$,Δ=-0.14±0.04. E(B-V)=0.24m(2) indicates a significantextinction in the host galaxy as the galactic reddening is negligibletoward NGC 3190. The accepted value of Δ indicates that SN 2002bowas a slightly overluminous SN by about 0.14m relative to fiducial SNtype Ia. The distance turned out to be 31.0±3 Mpc. In addition,the heavily obscured SN 2002cv was also detected on the I frame taken onJD 2,452,434 (June 8, 2002), and a variable star is found in the field,very close to the host galaxy.
| The Type Ia Supernova 2001V in NGC 3987
CCD photometry is presented of the type Ia SN 2001V occurred in theedge-on spiral galaxy NGC 3987. The observations made throughJohnson-Cousins BVRI filters were collected from Feb. 24 (t = - 8 days,with respect to B-maximum), up to May 5 (t = +62 days). The light curvesare analyzed with the revised Multi-Colour Light Curve Shape (MLCS)method (\cite{riess2}) by fitting template vectors to the observed lightcurves simultaneously. The reddening of SN 2001V is estimated to beE(B-V)=0.05 mag, while the galactic component is E(B-V) = 0.02 mag(Schlegel et al. \cite{sfd}), suggesting that part of the reddening maybe due to the ISM in the host galaxy. The Delta parameter in MLCSconverged to -0.47 mag, indicating that this SN was overluminousrelative to the majority of Type Ia SNe. The inferred distance to itshost galaxy, NGC 3987, is 74.5 +/- 5 Mpc, which is in good agreementwith recently determined kinematic distances, based on radial velocitycorrected for Virgo-infall and Hubble constant H0 = 65 kms-1Mpc-1. Based on observations obtained atGerman-Spanish Astronomical Centre, Calar Alto, operated by theMax-Planck-Institute for Astronomy, Heidelberg, jointly with the SpanishNational Commission for Astronomy.
| CCD Observations of a Nova and Two Supernovae in External Galaxies
Not Available
| Supernova 2002cv in NGC 3190
IAUC 7911 available at Central Bureau for Astronomical Telegrams.
| Supernova 2002cv in NGC 3190
IAUC 7903 available at Central Bureau for Astronomical Telegrams.
| Supernova 2002cv in NGC 3190
IAUC 7901 available at Central Bureau for Astronomical Telegrams.
| Supernova 2002cv in NGC 3190
IAUC 7901 available at Central Bureau for Astronomical Telegrams.
| Supernova 2002bo in NGC 3190
IAUC 7863 available at Central Bureau for Astronomical Telegrams.
| Supernova 2002bo in NGC 3190
IAUC 7851 available at Central Bureau for Astronomical Telegrams.
| Supernova 2002bo in NGC 3190
IAUC 7849 available at Central Bureau for Astronomical Telegrams.
| Supernova 2002bo in NGC 3190
IAUC 7848 available at Central Bureau for Astronomical Telegrams.
| Supernova 2002bo in NGC 3190
IAUC 7848 available at Central Bureau for Astronomical Telegrams.
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