Contents
Images
Upload your image
DSS Images Other Images
Related articles
Near-Infrared and Star-forming Properties of Local Luminous Infrared Galaxies
We use Hubble Space Telescope (HST) NICMOS continuum and Paαobservations to study the near-infrared and star formation properties ofa representative sample of 30 local (d~35-75 Mpc) luminous infraredgalaxies (LIRGs, infrared [8-1000 μm] luminosities oflogLIR=11-11.9 Lsolar). The data provide spatialresolutions of 25-50 pc and cover the central ~3.3-7.1 kpc regions ofthese galaxies. About half of the LIRGs show compact (~1-2 kpc)Paα emission with a high surface brightness in the form of nuclearemission, rings, and minispirals. The rest of the sample show Paαemission along the disk and the spiral arms extending over scales of 3-7kpc and larger. About half of the sample contains H II regions withHα luminosities significantly higher than those observed in normalgalaxies. There is a linear empirical relationship between the mid-IR 24μm and hydrogen recombination (extinction-corrected Paα)luminosity for these LIRGs, and the H II regions in the central part ofM51. This relation holds over more than four decades in luminosity,suggesting that the mid-IR emission is a good tracer of the starformation rate (SFR). Analogous to the widely used relation between theSFR and total IR luminosity of R. Kennicutt, we derive an empiricalcalibration of the SFR in terms of the monochromatic 24 μm luminositythat can be used for luminous, dusty galaxies.
| An IRAS High Resolution Image Restoration (HIRES) Atlas of All Interacting Galaxies in the IRAS Revised Bright Galaxy Sample
The importance of far-infrared observations for our understanding ofextreme activity in interacting and merging galaxies has beenillustrated by many studies. Even though two decades have passed sinceits launch, the most complete all-sky survey to date from which far-IRselected galaxy samples can be chosen is still that of the InfraredAstronomical Satellite (IRAS). However, the spatial resolution of theIRAS all-sky survey is insufficient to resolve the emission fromindividual galaxies in most interacting galaxy pairs, and hence previousstudies of their far-IR properties have had to concentrate either onglobal system properties or on the properties of very widely separatedand weakly interacting pairs. Using the HIRES image reconstructiontechnique, it is possible to achieve a spatial resolution ranging from30" to 1.5m (depending on wavelength and detector coverage), whichis a fourfold improvement over the normal resolution of IRAS. This issufficient to resolve the far-IR emission from the individual galaxiesin many interacting systems detected by IRAS, which is very importantfor meaningful comparisons with single, isolated galaxies. We presenthigh-resolution 12, 25, 60, and 100 μm images of 106 interactinggalaxy systems contained in the IRAS Revised Bright Galaxy Sample (RBGS,Sanders et al.), a complete sample of all galaxies having a 60 μmflux density greater than 5.24 Jy. These systems were selected to haveat least two distinguishable galaxies separated by less than threeaverage galactic diameters, and thus we have excluded very widelyseparated systems and very advanced mergers. Additionally, some systemshave been included that are more than three galactic diameters apart,yet have separations less than 4' and are thus likely to suffer fromconfusion in the RBGS. The new complete survey has the same propertiesas the prototype survey of Surace et al. We find no increased tendencyfor infrared-bright galaxies to be associated with other infrared-brightgalaxies among the widely separated pairs studied here. We find smallenhancements in far-IR activity in multiple galaxy systems relative toRBGS noninteracting galaxies with the same blue luminosity distribution.We also find no differences in infrared activity (as measured byinfrared color and luminosity) between late- and early-type spiralgalaxies.
| The IRAS Revised Bright Galaxy Sample
IRAS flux densities, redshifts, and infrared luminosities are reportedfor all sources identified in the IRAS Revised Bright Galaxy Sample(RBGS), a complete flux-limited survey of all extragalactic objects withtotal 60 μm flux density greater than 5.24 Jy, covering the entiresky surveyed by IRAS at Galactic latitudes |b|>5°. The RBGS includes629 objects, with median and mean sample redshifts of 0.0082 and 0.0126,respectively, and a maximum redshift of 0.0876. The RBGS supersedes theprevious two-part IRAS Bright Galaxy Samples(BGS1+BGS2), which were compiled before the final(Pass 3) calibration of the IRAS Level 1 Archive in 1990 May. The RBGSalso makes use of more accurate and consistent automated methods tomeasure the flux of objects with extended emission. The RBGS contains 39objects that were not present in the BGS1+BGS2,and 28 objects from the BGS1+BGS2 have beendropped from RBGS because their revised 60 μm flux densities are notgreater than 5.24 Jy. Comparison of revised flux measurements forsources in both surveys shows that most flux differences are in therange ~5%-25%, although some faint sources at 12 and 25 μm differ byas much as a factor of 2. Basic properties of the RBGS sources aresummarized, including estimated total infrared luminosities, as well asupdates to cross identifications with sources from optical galaxycatalogs established using the NASA/IPAC Extragalactic Database. Inaddition, an atlas of images from the Digitized Sky Survey with overlaysof the IRAS position uncertainty ellipse and annotated scale bars isprovided for ease in visualizing the optical morphology in context withthe angular and metric size of each object. The revised bolometricinfrared luminosity function, φ(Lir), forinfrared-bright galaxies in the local universe remains best fit by adouble power law, φ(L)~Lα, withα=-0.6(+/-0.1) and α=-2.2(+/-0.1) below and above the``characteristic'' infrared luminosityL*ir~1010.5Lsolar,respectively. A companion paper provides IRAS High Resolution (HIRES)processing of over 100 RBGS sources where improved spatial resolutionoften provides better IRAS source positions or allows for deconvolutionof close galaxy pairs.
| The infrared supernova rate in starburst galaxies
We report the results of our ongoing search for extincted supernovae(SNe) at near-infrared wavelengths. We have monitored at 2.2 mu m asample of 46 Luminous Infrared Galaxies and detected 4 SNe. The numberof detections is still small but sufficient to provide the firstestimate of supernova rate at near-infrared wavelengths. We measure a SNrate of SNNIR_r=7.6+/- 3.8 SNu which is an order of magnitudelarger than observed in quiescent galaxies. On the other hand, theobserved near-infrared rate is still a factor 3-10 smaller than thatestimated from the far-infrared luminosity of the galaxies. Amongvarious possibilities, the most likely scenario is that dust extinctionis so high (AV>30) to obscure most SNe even in thenear-IR.The role of type Ia SNe is also discussed within this context. We derivethe type Ia SN rate as a function of the stellar mass of the galaxy andfind a sharp increase toward galaxies with higher activity of starformation. This suggests that a significant fraction of type Ia SNe areassociated with young stellar populations.Finally, as a by-product, we give the average K-band light curve ofcore-collapse SNe based on all the existing data, and review therelation between SN rate and far-infrared luminosity.Based on observations collected at the European Southern Observatory,Chile (proposal 66.B-0417), at the Italian Telescopio Nazionale Galileo(TNG) operated on the island of La Palma by the Centro Galileo Galileiof the INAF (Istituto Nazionale di Astrofisica), and at the StewardObservatory 61'' telescope.
| Star Formation Rates in Interacting Starburst Galaxies
By narrowband imaging in Hα and in the adjacent red stellarcontinuum we have studied the rate and distribution of star formation in43 systems of luminous and ultraluminous IR galaxies currentlyundergoing interaction and merging. These galaxies are amongst the mostluminous at 60 μm and range in distance from ~50 up to 100 Mpc. Herewe present the Hα and the adjacent red-continuum narrowbandimages, and we compare the star formation rates derived from Hαwith those estimated from the IR luminosity. We find clear evidence forsubstantial extinction and obscuration of star-forming regions in theoptical. Without correction for reddening in the host galaxy orcorrection for [N II] contamination, the star formation rates derivedfor Hα are typically 0.5-1.0 dex lower than those estimated fromthe IR flux, and the scatter in the correlation is very large. However,an unexpected result is that when spectroscopic data are used toeliminate objects dominated by an active nucleus, to determine thegalaxian extinction, and to correct the Hα flux for both reddeningand for the contamination by the [N II] emission, a remarkably goodcorrelation emerges between the star formation rates estimated from theHα flux and those derived from the FIR continuum. In addition, astrong correlation is found between the extinction in the line-emittingregion, AHα, and the rate of star formation. Ourresults invalidate the use of Hα imaging as a reliable indicatorof star formation in starburst galaxies unless spectroscopic data arealso available. This has important implications for the determination ofstar formation rates in high-redshift galaxies. Finally, we find nocorrelation between the measured star formation rates, and theinteraction class, suggesting that the enhanced star formation ratestriggered by the interaction continue throughout the whole of themerging sequence.
| Southern Isolated Galaxy Triplets
Seventy-six isolated triple systems of galaxies with declinatiosnδ<-3° were selected using ESO/SERC and POSS-I sky surveydata. The equatorial coordinates, configuration types, angular sizes,component angular separations, component morphological types, totalmagnitudes, and other parameters are reported for each triplet.Radial-velocity estimates are available for all components in 33 of the76 triplets. The median values of the main dynamicalparametersradial-velocity dispersion, mean harmonic radius,absolute magnitudes of member galaxies, and mass-to-luminosityratiosare similar to those obtained earlier for 83 isolatedtriple systems with δ>-3°.
| Total magnitude, radius, colour indices, colour gradients and photometric type of galaxies
We present a catalogue of aperture photometry of galaxies, in UBVRI,assembled from three different origins: (i) an update of the catalogueof Buta et al. (1995) (ii) published photometric profiles and (iii)aperture photometry performed on CCD images. We explored different setsof growth curves to fit these data: (i) The Sersic law, (ii) The net ofgrowth curves used for the preparation of the RC3 and (iii) A linearinterpolation between the de Vaucouleurs (r(1/4) ) and exponential laws.Finally we adopted the latter solution. Fitting these growth curves, wederive (1) the total magnitude, (2) the effective radius, (3) the colourindices and (4) gradients and (5) the photometric type of 5169 galaxies.The photometric type is defined to statistically match the revisedmorphologic type and parametrizes the shape of the growth curve. It iscoded from -9, for very concentrated galaxies, to +10, for diffusegalaxies. Based in part on observations collected at the Haute-ProvenceObservatory.
| Mid-Infrared Continuum of Starburst Nuclei: Contribution from Hot Large Grains within H II Regions?
The IRAS 12 and 25 mu m fluxes are compared with the Br gamma flux in asample of starburst nuclei. Good correlations are found between them.The subsequent analysis indicates the presence of two components in themid-infrared continuum: the nonthermal emission from "small grains"(<=100 A) which are heated transiently by nonionizing photons outsidethe H II regions and the thermal emission from "large grains" which areheated to ~140 K by ionizing, nonionizing, and Ly alpha photons insidethe H II regions. The small grains emitting at 12 mu m are depleted by~20% with respect to cirrus clouds in our Galaxy. The ratio of amountsof large grains to gas in the H II regions is comparable to the standardinterstellar value. The emission from hot large grains appears to bemore enhanced over the emission from small grains in starburst nucleiwith higher excitations.
| The IRAS Bright Galaxy Survey - Part II: Extension to Southern Declinations (delta ~< -30), and Low Galactic Latitudes (f<|b|
Complete IRAS Observations and redshifts are reported for all sourcesidentified in the IRAS Bright Galaxy Survey-Part II (hereafter referredto as BGS_2_). Source positions, radial velocities, optical magnitudes,and total flux densities, peak flux densities, and spatial extents at12, 25, and 100 ,microns are reported for 288 sources having 60 micronflux densities > 5.24 Jy, the completeness limit of the originalBright Galaxy Survey [Soifer et al., AJ, 98,766(1989)], hereafterreferred to as BGS_1_. These new data represent the extension of theIRAS Bright Galaxy Survey to southern declinations,δ<~-30^deg^, and low Galactic latitudes,5^deg^<|b|<30^deg^. Although the sky coverage of the BGS_2_ (~19935 deg^2^) is 37% larger than the sky coverage of the BGS_1_, thenumber of sources is 8% smaller due primarily to large scale structurein the local distribution of galaxies. Otherwise, the sources in theBGS_2_ show similar relationships between number counts and flux densityas observed for the 313 sources in the BGS_1_. The BGS_2_ along with theearlier BGS, represents the best sample currently available for definingthe infrared properties of galaxies in the local (z <~ 0.1) Universe.
| Spectroscopic studies of emission line galaxies.
Not Available
| 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.
| Spectroscopic observations of Arp-Madore interacting galaxies. I - Pairs of comparably sized galaxies
Nuclear spectra of 129 galaxies from a sample of 71 pairs of interactingdoubles of comparably sized galaxies have been analyzed on the basis ofIRAS observations. Data obtained include radial velocities, relativeemission-line intensity measurements, and optical classifications. It isconfirmed that a large number of these objects are indeed showing H IIregion type spectra. It is suggested that a low LINER detection ratecould be due to the IR criteria which favor a strong H II region typeactivity and make it difficult to detect low-level LINER activity whichmay be present. The excess of Seyfert-type nuclei was not found, and thereason remains unclear. A high-frequency of one-sided enhancedstar-formation activity, suggested by the far-infrared study of the samesample of galaxies, also was not found. The enhancement of thestar-formation activity more likely to take place in both galaxies, butthe strength and/or time-scale and phase of the activity in each of thetwo galaxies of the pair may differ substantially.
| IRAS LRS spectroscopy of galaxies
The study presents IRAS LRS data for 350 galaxies with pointlike IRASsources having either S(12) or S(25) not less than 1.5 Jy. Techniquesare presented which form the mean of an ensemble of LRS spectra, ll ofwhich are only of low signal-to-noise ratio, by quantitative evaluationof the significance of the individual spectra for each object ratherthan mere acceptance of the 'average spectrum' present in the completeLRS data base. Average LRS spectra for groups of galaxies with distinctoptical nuclear properties are formed. Average LRS spectra for severalcategories of objects are presented and interpreted. H II regiongalaxies show the polycyclic aromatic hydrocarbon spectrum of bands inemissions; type 2 Seyferts present a broad emission feature parking near16 microns; LINERs and galaxies without optical emission lines have LRSspectra that decline with wavelength, whereas type 1 Seyferts and WRgalaxies have red spectra suggestive of nonthermal emission processes.
| Infrared properties of interacting IRAS galaxies
This paper presents near-infrared photometry and coadded IRAS data for asample of 19 interacting and merging galaxy systems selected by IRASflux and morphological criteria. The far-infrared activity LFIR/LB riseswith interaction strength. There are also changes in the far-infraredcolors: log(f12/f25) is lower and log(f60/f100) higher for stronginteractions. This behavior can be understood in the context oftwo-component models of the far-infrared emission as an increase in thecontribution of active star formation to the infrared activity. Thenear-infrared colors of the galaxies are studied, and the use of K-Lcolor excesses to search for far-infrared emission is justified. Thedistribution of infrared activity in binary galaxies is analyzed withthe help of K-L color excesses and confirmed using IRAS data. Contraryto some earlier studies, it is found that enhanced activity in bothcomponents of an interacting system is frequent. The implications ofthis behavior for the conditions necessary to trigger starbursts arediscussed. The occurrence of a significant number of systems withinfrared activity in both galaxies suggests that disturbances of thegaseous component leading to starbursts may be less sensitive to therelative orientation of the interacting galaxies than disturbances ofthe stellar component leading to prominent tidal tails.
| Imaging of the ionized gas and stars in emission line galaxies
Broad-band and narrow-band (mainly H-alpha and forbidden O III)observations of 11 galaxies with differing types of nuclear activity,obtained using a CCD imaging system on the 1.5-m Danish telescope at ESOduring December 1983 and August 1984, are reported. The data arepresented in tables and isophote maps and characterized in detail. Nineof the galaxies are shown to have diffuse ionized nebulosity extendingbeyond the spiral arms; the size of the nebulosity increases with thegalactic optical and UV luminosity but does not depend on the level ofnuclear activity or the radio loudness. It is inferred that extendedcloud structures may result from intergalactic tidal interactions, andthat in each galaxy the ionization mechanisms in the narrow-line regionand the nebulosity are the same.
| Southern Galaxy Catalogue.
Not Available
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
Catalogs and designations:
|
