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|Classification of Spectra from the Infrared Space Observatory PHT-S Database|
We have classified over 1500 infrared spectra obtained with the PHT-Sspectrometer aboard the Infrared Space Observatory according to thesystem developed for the Short Wavelength Spectrometer (SWS) spectra byKraemer et al. The majority of these spectra contribute to subclassesthat are either underrepresented in the SWS spectral database or containsources that are too faint, such as M dwarfs, to have been observed byeither the SWS or the Infrared Astronomical Satellite Low ResolutionSpectrometer. There is strong overall agreement about the chemistry ofobjects observed with both instruments. Discrepancies can usually betraced to the different wavelength ranges and sensitivities of theinstruments. Finally, a large subset of the observations (~=250 spectra)exhibit a featureless, red continuum that is consistent with emissionfrom zodiacal dust and suggest directions for further analysis of thisserendipitous measurement of the zodiacal background.Based on observations with the Infrared Space Observatory (ISO), aEuropean Space Agency (ESA) project with instruments funded by ESAMember States (especially the Principle Investigator countries: France,Germany, Netherlands, and United Kingdom) and with the participation ofthe Institute of Space and Astronautical Science (ISAS) and the NationalAeronautics and Space Administration (NASA).
|Spectrophotometry of Star-forming Regions in H II Galaxies|
We present spectrophotometric observations of 111 H II galaxies selectedfrom various surveys. Apart from the integrated spectra, we presentemission-line fluxes and equivalent widths of different star-formingknots for 33 galaxies for which the spatial distribution of physicalproperties can be assessed. Most of the objects have been observedpreviously. We reobserved these galaxies with uniform instrumentation,and data reduction was performed with homogeneous methods. Our analysisof the quality of the data indicates that our observations reach goodsignal-to-noise ratio over the whole spectral range, allowing themeasurement of-and the inclusion of additional-low-intensity emissionlines.Based on observations collected at the European Southern Observatory,Chile, under an agreement between the Observatório Nacional,Brazil, and the ESO.
|Stellar populations in HII galaxies|
We analyse the stellar content of a large number of HII galaxies fromthe continua and absorption features of their spectra using populationsynthesis methods, in order to gain information about the star formationhistories of these objects.We find that all galaxies of our sample contain an old stellarpopulation (≥1 Gyr) that dominates the stellar mass, and in amajority of these we also found evidence for an intermediate-agepopulation ≥50 Myr apart from the presently bursting, ionizing younggeneration ≤107 yr.Appendix A is only available in electronic form athttp://www.edpsciences.org
|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.
|Star Formation in a Complete Spectroscopic Survey of Galaxies|
The 15R-North galaxy redshift survey is a uniform spectroscopic survey(S/N~10) covering the range 3650-7400 Å for 3149 galaxies withmedian redshift 0.05. The sample is 90% complete to R=15.4. The medianslit covering fraction is 24% of the galaxy, apparently sufficient tominimize the effects of aperture bias on the EW(Hα). Forty-ninepercent of the galaxies in the survey have one or more emission linesdetected at >=2 σ. In agreement with previous surveys, thefraction of absorption-line galaxies increases steeply with galaxyluminosity. We use Hβ, [O III], Hα, and [N II] todiscriminate between star-forming galaxies and AGNs. At least 20% of thegalaxies are star-forming, at least 17% have AGN-like emission, and 12%have unclassifiable emission. The unclassified 12% may include a``hybrid'' population of galaxies with both star formation and AGNactivity. The AGN fraction increases steeply with luminosity; thefraction of star-forming galaxies decreases. We use the EW(Hα+[NII]) to estimate the Scalo birthrate parameter, b, the ratio of thecurrent star formation rate to the time averaged star formation rate.The median birthrate parameter is inversely correlated with luminosityin agreement with the conclusions based on smaller samples (Kennicutt,Tamblyn, & Congdon). Because our survey is large, we identify 33vigorously star-forming galaxies with b>3. We confirm the conclusionof Jansen, Franx, & Fabricant that EW([O II]) must be used withcaution as a measure of current star formation. Finally, we examine theway galaxies of different spectroscopic type trace the large-scalegalaxy distribution. As expected the absorption-line fraction decreasesand the star-forming emission-line fraction increases as the galaxydensity decreases. The AGN fraction is insensitive to the surroundinggalaxy density; the unclassified fraction declines slowly as the densityincreases. For the star-forming galaxies, the EW(Hα) increasesvery slowly as the galaxy number density decreases. Whether a galaxyforms stars or not is strongly correlated with the surrounding galaxydensity averaged over a scale of a few Mpc. This dependence reflects, inlarge part, the morphology-density relation. However, for galaxiesforming stars, the stellar birthrate parameter is remarkably insensitiveto the galaxy density. This conclusion suggests that the triggering ofstar formation occurs on a smaller spatial scale.
|On the local radio luminosity function of galaxies. II. Environmental dependences among late-type galaxies|
Using new extensive radio continuum surveys at 1.4 GHz (FIRST and NVSS),we derive the distribution of the radio/optical and radio/NIR luminosity(RLF) of late-type (Sa-Irr) galaxies (m_p<15.7) in 5 nearby clustersof galaxies: A262, Cancer, A1367, Coma and Virgo. With the aim ofdiscussing possible environmental dependences of the radio properties,we compare these results with those obtained for relatively isolatedobjects in the Coma supercluster. We find that the RLF of Cancer, A262and Virgo are consistent with that of isolated galaxies. Conversely weconfirm earlier claims that galaxies in A1367 and Coma have their radioemissivity enhanced by a factor ~ 5 with respect to isolated objects. Wediscuss this result in the framework of the dynamical pressure sufferedby galaxies in motion through the intra-cluster gas (ram-pressure). Wefind that the radio excess is statistically larger for galaxies in fasttransit motion. This is coherent with the idea that enhanced radiocontinuum activity is associated with magnetic field compression. TheX-ray luminosities and temperatures of Coma and A1367 imply that thesetwo clusters have significantly larger intracluster gas density than theremaining three studied ones, providing a clue for explaining the higherradio continuum luminosities of their galaxies. Multiple systems in theComa supercluster bridge (with projected separations smaller than 300kpc) have radio luminosities significantly larger than isolatedgalaxies. Table~1 is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (126.96.36.199) or viahttp://cdsweb.u-strasbg.fr/Abstract.html}
|An image database. II. Catalogue between δ=-30deg and δ=70deg.|
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
|A multifrequency radio continuum and IRAS faint source survey of markarian galaxies|
Results are presented from a multifrequency radio continumm survey ofMarkarian galaxies (MRKs) and are supplemented by IRAS infrared datafrom the Faint Source Survey. Radio data are presented for 899 MRKsobserved at nu = 4.755 GHz with the National Radio Astronomy Observatory(NRAO)-Green Bank 300 foot (91 m) telescope, including nearly 88% ofthose objects in Markarian lists VI-XIV. In addition, 1.415 GHzmeasurements of 258 MRKs, over 30% of the MRKs accessible from theNational Aeronomy and Ionosphere Center (NAIC)-Arecibo, are reported.Radio continuum observations of smaller numbers of MRKs were made at10.63 GHz and at 23.1 GHz and are also presented. Infrared data from theIRAS Faint Source Survey (Ver. 2) are presented for 944 MRKs, withreasonably secure identifications extracted from the NASA/IPACExtragalactic Database. MRKs exhibit the same canonical infraredcharacteristics as those reported for various other galaxy samples, thatis well-known enhancement of the 25 micrometer/60 micrometer color ratioamong Seyfert MRKs, and a clear tendency for MRKs with warmer 60micrometer/100 micrometer colors to also possess cooler 12 micrometer/25micrometer colors. In addition, non-Seyfert are found to obey thewell-documented infrared/radio luminosity correlation, with the tightestcorrelation seen for starburst MRKs.
|Galaxy Properties at the North Galactic Pole. I. Photometric Properties on Large Spatial Scales|
A two-color study of the galaxies detected on POSS-I in a 289 squaredegree region centered on the North Galactic Pole is presented. We use avariety of mapping techniques to characterize the large-scale spatialdistribution of galaxies. The depth and sample size of this new surveyallows, for the first time, the isolation of large photometricsubsamples of galaxies in high- and low-density environments on thescale of superclusters. Our principal finding is a statisticallysignificant difference between the mean photometric properties of thesesubsamples in the sense that galaxies in the high-density Coma andfilament environments have redder colors and larger concentrationindices than galaxies drawn from low-density interfilament regions.These results are in accord with the known morphology-density relation.Thus, appropriately chosen photometric and morphological parameters, inconcert with a galaxy surface density map, can be used to selectstructures from the projected galaxy distribution which correspond toregions of high density. An illustration of this point is our discoveryof a concentration of blue galaxies identified in our maps near the coreof the Coma cluster. This feature is comprised of early-type galaxieswhich exhibit signs of current or recent star formation. These resultsare predicated on relations between morphological type and photometricparameters derived from APS scans of POSS-I. We therefore discuss theimage calibration procedures used to compile our catalog of physicallysignificant photometric parameters. We demonstrate the morphologicaltype dependence among quantities such as mean color and imageconcentration index, and the lack of such a dependence for mean surfacebrightness.
|Pairing properties of Markarian starburst Galaxies|
The environmental parameters of 516 non-Seyfert Markarian galaxies werestudied in a redshift-bounded sample, supplemented by new spectra andredshift measures for possible companions, in order to evaluate theiroccurrence in galaxy pairs, defined through quantitative criteria. Itwas found that one-third of these galaxies occur in pairs (while only 6to 10 percent of optically-selected galaxies are known to be paired). Acomparison of various optical and IR properties of paired and nonpairedMarkarian galaxies showed no differences in the shape of the optical,far-IR, or H-alpha luminosity functions. It was found, however, that theMarkarian component is brighter than the other galaxy in each pair by0.66 magnitude in the mean at B.
|KISO survey for ultraviolet-excess galaxies. XI|
Charts of UV-excess galaxies detected on multicolor plates with the KisoSchmidt telescope are presented. A total of 10 survey field areconsidered. In a 300-sq-deg sky area, 460 objects are cataloged to aphotographic magnitude of about 18.
|The Wasilewski sample of emission-line galaxies - Follow-up CCD imaging and spectroscopic and IRAS observations|
The results of an extensive imaging and spectroscopic follow-up of theobjective prism-selected emission line galaxy (ELG) sample of Wasilewski(1982) are presented. Fluxes at 12, 25, 60, and 100 microns were alsoobtained from the coadded IRAS survey data. ELGs found by objectiveprism surveys are found to be generally small and underluminous galaxieswhich usually have higher than average optical surface brightness. TheSeyfert detection rate in objective prism surveys is roughly 10 percentand the ratio of the space densities of Seyfert 2 to Seyfert 1 galaxiesis significantly larger than unity. Most of the galaxies selected byobjective prism surveys are star-forming, late-type spirals which oftenshow disturbed morphology. About 25 percent of the galaxies detected bythe surveys are faint, high-excitation metal-poor compact H II regions.
|Neutral hydrogen in starburst galaxies|
A survey of neutral-hydrogen 21 cm emission from a sample of starburstgalaxies was conducted in order to derive their global properties. Ofthe 72 galaxies surveyed, H I was detected in 47. Average mass-to-lightratios log (MH/Lpg) = -0.7 + or - 0.4 and log (MT/Lpg) = 0.5 + or - 0.4.The masses and luminosities span the range 10 to the 10th-12th solarmasses and 10 to the 9th-11th solar luminosities, typical of normal latespirals. The starburst activity, as measured by the luminosity of theH-alpha line, correlates roughly with the mass of atomic hydrogen, thetotal mass, and the total photographic luminosity of the host galaxy. Itis suggested that the occurrence of a nuclear starburst and the strengthof such an event probably do not depend strongly on the large-scaleproperties of the galaxy.
|A catalog of Markarian galaxies|
A catalog of Markarian galaxies is presented which tabulates redshifts,spectral and morphological classifications, magnitudes, infrared andradio flux densities, and over 600 references to available datapublished before January 1, 1986. Redshifts are now available for 1228objects with strong ultraviolet continua, and follow-up spectroscopicand photometric observations of Markarian galaxies have providedclassifications of 115 Seyfert 1, 43 Seyfert 2, and 137 starburst and HII-type galaxies. After a description of the Markarian survey and thecurrent catalog, a summary of the general results obtained from the datais presented. A preliminary study of the infrared properties ofMarkarian galaxies as measured by IRAS reveals a number of interestingresults, including the existence of a sample of elliptical andlenticular galaxies with appreciable infrared emission.
|Markarian galaxies and voids in the galaxy distribution|
In the course of identifying Markarian galaxies that fall within thepurported Bootes void, Balzano and Weedman (1982) went one step furtherand claimed that Markarian galaxies display a homogeneous spacedistribution. If true, this would be a remarkable discovery in view ofthe alternating void-supercluster-void structure which all otherordinary galaxies seem to follow. Furthermore, it would imply thatMarkarian galaxies should fill all other previously discovered voids. Totest the latter hypothesis, a search was made for Markarian galaxies inthe fields of three previously published redshift surveys, each of whichshows at least one void. While 43 Markarian galaxies were identified,all fall in regions heavily populated by ordinary galaxies, and nonefall in the voids. On the basis of nearest neighbor separations, thepossibility that Markarian galaxies fill the voids can be rejected withgreat confidence. Because Markarian galaxies are closely associated withordinary galaxies, it is likely that there are more, as yetunidentified, normal galaxies which are near neighbors of the 12Markarian galaxies identified in the Bootes region by Balzano andWeedman.
|The dynamics of rich clusters of galaxies. I - The Coma cluster|
Self-consistent analytical dynamical models are used to study theendpoint of cluster formation, concentrating on the Coma cluster.Particular attention is paid to the effects of anisotropy in thevelocity dispersion and variations in the energy-distribution functionon the cluster structure, the effect on the core structure of a massivecentral object, the dynamical consequences of morphological segregation,cosmological infall and the edge of a cluster, the distribution of darkmatter in a cluster, and the implications of X-ray observations for thedistribution of gravitating material in a cluster. Radial velocity datais displayed, and new and repeated redshifts are reported for a numberof galaxies in the central regions of the cluster. Cluster membership isdetermined and a velocity-dispersion profile is derived. A compositesurface-density profile is derived, and amazing examples are shown ofmodels with virtually identical surface-density profiles but otherwisecompletely different internal dynamics.
|Radio survey of Markarian galaxies at 6 and 11 CM|
One hundred and fifty-one objects from Markarian's lists 6 and 7 wereobserved at 6 cm with a 3 sigma detection limit of about 30 mJy. EightMarkarian objects were detected, six of which were also observed at 11cm. Forty-five others were negative at this wavelength. Two of thedetections, numbers 533 and 668, are Seyfert galaxies; additionally, UB1was detected at 6 cm and NGC 7715 and III Zw 2 were found at 11 cm.
|Spectroscopy of outlying faint galaxies in the region of the Coma cluster.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973ApJ...181...15T&db_key=AST
|Nota preliminar sobre galaxias azules con lineas de emision.|
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