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Rings and Bent Chain Galaxies in the GEMS and GOODS Fields
Twenty-four galaxies with rings or partial rings were studied in theGEMS and GOODS fields out to z~1.4. Most resemble local collisional ringgalaxies in morphology, size, and clumpy star formation. Clump agesrange from 108 to 109 yr, and clump masses go upto several × 108 Msolar, based on colorevolution models. The clump ages are consistent with the expectedlifetimes of ring structures if they are formed by collisions. Fifteenother galaxies that resemble the arcs in partial ring galaxies but haveno evident disk emission were also studied. Their clumps have bluercolors at all redshifts compared to the clumps in the ring and partialring sample, and their clump ages are younger than in rings and partialrings by a factor of ~10. In most respects, they resemble chain galaxiesexcept for their curvature; we refer to them as ``bent chains.'' Severalrings are symmetric with centered nuclei and no obvious companions. Theycould be outer Lindblad resonance rings, although some have no obviousbars or spirals to drive them. If these symmetric cases are resonancerings, then they could be the precursors of modern resonance rings,which are only ~30% larger on average. This similarity in radiussuggests that the driving pattern speed has not slowed by more by ~30%during the last ~7 Gyr. Those without bars could be examples ofdissolved bars.
| Massive star formation in the central regions of spiral galaxies
Context: . The morphology of massive star formation in the centralregions of galaxies is an important tracer of the dynamical processesthat govern the evolution of disk, bulge, and nuclear activity. Aims. Wepresent optical imaging of the central regions of a sample of 73 spiralgalaxies in the Hα line and in optical broad bands, and deriveinformation on the morphology of massive star formation. Methods. Weobtained images with the William Herschel Telescope, mostly at a spatialresolution of below one second of arc. For most galaxies, no Hαimaging is available in the literature. We outline the observing anddata reduction procedures, list basic properties, and present the I-bandand continuum-subtracted Hα images. We classify the morphology ofthe nuclear and circumnuclear Hα emission and explore trends withhost galaxy parameters. Results. We confirm that late-type galaxies havea patchy circumnuclear appearance in Hα, and that nuclear ringsoccur primarily in spiral types Sa-Sbc. We identify a number ofpreviously unknown nuclear rings, and confirm that nuclear rings arepredominantly hosted by barred galaxies. Conclusions. Other than instimulating nuclear rings, bars do not influence the relative strengthof the nuclear Hα peak, nor the circumnuclear Hα morphology.Even considering that our selection criteria led to an over-abundance ofgalaxies with close massive companions, we do not find any significantinfluence of the presence or absence of a close companion on therelative strength of the nuclear Hα peak, nor on the Hαmorphology around the nucleus.
| A Hubble Space Telescope Study of Star Formation in the Inner Resonance Ring of NGC 3081
We present Hubble Space Telescope Wide Field Planetary Camera 2 imagesof the inner regions of NGC 3081, an absolute magnitudeMB=-20.0 early-type barred spiral having four well-definedresonance rings: a nuclear ring, an inner ring, an outer R1ring, and an outer R'2 pseudoring. Here we focuson a photometric study of the inner ring, a feature likely associatedwith an inner 4:1 resonance near the ends of the bar. The ring isnotable for its high contrast and sharp definition, which is due to asignificant degree of active star formation. The ring is also notablefor its significant intrinsic elongation and parallel alignment with thebar. These characteristics influence the way star-forming sites aredistributed around the ring. The ring is lined by numerous blue sources,many of which appear to be slightly diffuse compared with the stellarpoint-spread function. These blue sources are strongly concentratedwithin +/-60° of the bar axis and follow the Hα distributionwell. The blue sources are much larger than typical Galactic open orglobular clusters and may represent young massive clusters like the``populous clusters'' of the LMC and objects seen previously mainly inintermediate- to late-type spiral galaxies. We also present an analysisof the integrated light of the inner ring, to deduce information on itsstar formation history. A profile analysis is used to separate the ringfrom the background old disk starlight. High-resolution Fourier analysisis used to search for wavelength-dependent phase shifts along the ringto determine if star-forming sites stay in the ring as they age. Theresults give an intriguing picture of a galaxy in an advancedevolutionary state where periodic orbits are clearly manifested in themorphology.Based on observations with the NASA/ESA Hubble Space Telescope, obtainedat the Space Telescope Science Institute, which is operated by theAssociation of Universities for Research in Astronomy (AURA), Inc.,under NASA contract NAS 5-26555.
| 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
| The far-infrared/radio correlation in the ISO era. The warm and cold far-infrared/radio correlations
We present the correlation between the far-infrared (FIR) and radioemissions from a composite sample of 72 nearby normal galaxies observedwith the ISOPHOT instrument on board the Infrared Space Observatory. Thegalaxies in the sample have measurements at three FIR wavelengths (60,100 and 170 mu m), which allowed a direct determination of the warm andcold FIR emission components. This is the first time that thecorrelation has been established for the total FIR luminosity, of whichmost is carried by the cold dust component predominantly emittinglongwards of the spectral coverage of IRAS. The slope of thiscorrelation is slightly non-linear (1.10+/- 0.03). Separate correlationsbetween the warm and cold FIR emission components and the radio emissionhave also been derived. The slope of the warm FIR/radio correlation wasfound to be linear (1.03 +/- 0.03). For the cold FIR/radio correlationwe found a slightly non-linear (1.13 +/- 0.04) slope. We qualitativelyinterpret the correlations in terms of star formation rate and find thatboth the FIR and radio emissions may be consistent with a non-lineardependence on star formation rate for galaxies not undergoing starburstactivity.Based on observations with the Infrared Space Observatory (ISO), an ESAproject with instruments funded by ESA member States (especially the PIcountries: France, Germany, The Netherlands, and the UK) and with theparticipation of ISAS and NASA.Table \ref{Tab2} and Appendices A and B are only available in electronicform at http://www.edpsciences.org
| Simulations of central structure in barred galaxies
We have studied the formation of complex central structures in barredgalaxies - nested bars, nuclear spirals and circumnuclear rings - bymaking N-body simulations, which include the gas component asinelastically colliding particles. Our models suggest that many of theobserved features in both the stellar and gas components can beexplained by the dynamical effect of two or more modes in the stellardisc. Especially, many morphological features in our simulationscorrespond to analytically studied orbit loops in double-barredpotentials. Interestingly, a fast-rotating secondary bar forms in apurely stellar disc in our simulations, which disagrees with someprevious studies where the presence of a dissipative component wasneeded.
| Analysis of the distribution of HII regions in external galaxies. IV. The new galaxy sample. Position and inclination angles
We have compiled a new sample of galaxies with published catalogs of HIIregion coordinates. This sample, together with the former catalog ofGarcía-Gómez & Athanassoula (\cite{gga1}), will formthe basis for subsequent studies of the spiral structure in discgalaxies. In this paper we address the problem of the deprojection ofthe galaxy images. For this purpose we use two deprojection methodsbased on the HII region distribution and compare the results with thevalues found in the literature using other deprojection methods. Takinginto account the results of all the methods, we propose optimum valuesfor the position and inclination angles of all the galaxies in oursample. Tables 2 and 3 are only available in electronic form athttp://www.edpsciences.org
| 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°.
| Nearby Optical Galaxies: Selection of the Sample and Identification of Groups
In this paper we describe the Nearby Optical Galaxy (NOG) sample, whichis a complete, distance-limited (cz<=6000 km s-1) andmagnitude-limited (B<=14) sample of ~7000 optical galaxies. Thesample covers 2/3 (8.27 sr) of the sky (|b|>20deg) andappears to have a good completeness in redshift (97%). We select thesample on the basis of homogenized corrected total blue magnitudes inorder to minimize systematic effects in galaxy sampling. We identify thegroups in this sample by means of both the hierarchical and thepercolation ``friends-of-friends'' methods. The resulting catalogs ofloose groups appear to be similar and are among the largest catalogs ofgroups currently available. Most of the NOG galaxies (~60%) are found tobe members of galaxy pairs (~580 pairs for a total of ~15% of objects)or groups with at least three members (~500 groups for a total of ~45%of objects). About 40% of galaxies are left ungrouped (field galaxies).We illustrate the main features of the NOG galaxy distribution. Comparedto previous optical and IRAS galaxy samples, the NOG provides a densersampling of the galaxy distribution in the nearby universe. Given itslarge sky coverage, the identification of groups, and its high-densitysampling, the NOG is suited to the analysis of the galaxy density fieldof the nearby universe, especially on small scales.
| N-body simulations of resonance rings in galactic disks
We have studied the formation of rings in the disks of galaxies by usingtwo-dimensional N-body simulations where the gas component is modelledas dissipatively colliding test particles. Our results support thestandard hypothesis that ring formation occurs when gas is driven toresonances by the gravitational torque of a rotating stellar bar. Whenthe bar is absent, a weaker oval-shaped mode or a spiral mode can havethe same effect. Typical locations of the rings are as follows: theouter rings are usually near the outer Lindblad resonances, the innerrings near the inner 4/1-resonance and the nuclear rings near the innerLindblad resonances. However, we have also found a few exceptions tothese rules. We also have studied why a significant fraction of barredgalaxies lack one, two or all ring types. Our models suggest that theabsence of rings may be related to timescales of ring formation: theinner and nuclear rings usually form faster than the outer rings. Thelack of inner and nuclear rings can be related to the strength of thebar: in high amplitude cases, one or both of these ring types areabsent. Also, bars may rotate fast enough such that they lack the innerLindblad resonance and thus cannot form nuclear rings. The potentialouter ring region is often dominated by a slower spiral mode, which inprinciple could inhibit or delay ring formation. However, we found thatwhen both the bar mode and the slower spiral mode coexist in the outerdisk, there can be almost cyclic alternation between different outerring morphologies. In addition to the outer Lindblad resonance of thebar, certain resonances of the slower mode can also exist near the ringradius. The deceleration of the bar rotation rate and the correspondingchange in the resonance positions did not inhibit ring formation ordestroy an existing ring. The presence of more than one mode could alsoaffect the region of inner or nuclear rings. This can explain part ofthe case in which the ring is misaligned with respect to the main barcomponent.
| The ISOPHOT 170 μ m serendipity survey. I. Compact sources with galaxy associations
The first set of compact sources observed in the ISOPHOT 170 μmSerendipity Survey is presented. From the slew data with low(I100 μm <= 15 MJy/sr) cirrus background, 115well-observed sources with a high signal-to-noise ratio in all detectorpixels having a galaxy association were extracted. Of the galaxies withknown optical morphologies, the vast majority are classified as spirals,barred spirals, or irregulars. The 170 μm fluxes measured from theSerendipity slews have been put on an absolute flux level by usingcalibration sources observed additionally with the photometric mappingmode of ISOPHOT. For all but a few galaxies, the 170 μm fluxes aredetermined for the first time, which represents a significant increasein the number of galaxies with measured Far-Infrared (FIR) fluxes beyondthe IRAS 100 μm limit. The 170 μm fluxes cover the range 2 <~F170 μm la 100 Jy. Formulae for the integrated FIR fluxesF40-220μm and the total infrared fluxesF1-1000μm incorporating the new 170 μm fluxes areprovided. The large fraction of sources with a high F170μm / F100 μm flux ratio indicates that a cold(TDust la 20 K) dust component is present in many galaxies.The detection of such a cold dust component is crucial for thedetermination of the total dust mass in galaxies, and, in cases with alarge F170 μm / F100 μm flux ratio,increases the dust mass by a significant factor. The typical mass of thecoldest dust component is MDust = 107.5 +/- 0.5Msun , a factor 2-10 larger than that derived from IRASfluxes alone. As a consequence, the majority of the derived gas-to-dustratios are much closer to the canonical value of ~ 160 for the MilkyWay. By relaxing the selection criteria, it is expected that theSerendipity Survey will eventually lead to a catalog of 170 μm fluxesfor ~ 1000 galaxies. Based on observations with ISO, an ESA project withinstruments funded by ESA Member States (especially the PI countries:France, Germany, the Netherlands and the United Kingdom) and with theparticipation of ISAS and NASA. Members of the Consortium on the ISOPHOTSerendipity Survey (CISS) are MPIA Heidelberg, ESA ISO SOC Villafranca,AIP Potsdam, IPAC Pasadena, Imperial College London.
| L'histoire mouvementee des formes galactiques.
Not Available
| The Southern Sky Redshift Survey
We report redshifts, magnitudes, and morphological classifications for5369 galaxies with m_B <= 15.5 and for 57 galaxies fainter than thislimit, in two regions covering a total of 1.70 sr in the southerncelestial hemisphere. The galaxy catalog is drawn primarily from thelist of nonstellar objects identified in the Hubble Space TelescopeGuide Star Catalog (GSC). The galaxies have positions accurate to ~1"and magnitudes with an rms scatter of ~0.3 mag. We compute magnitudes(m_SSRS2) from the relation between instrumental GSC magnitudes and thephotometry by Lauberts & Valentijn. From a comparison with CCDphotometry, we find that our system is homogeneous across the sky andcorresponds to magnitudes measured at the isophotal level ~26 magarcsec^-2. The precision of the radial velocities is ~40 km s^-1, andthe redshift survey is more than 99% complete to the m_SSRS2 = 15.5 maglimit. This sample is in the direction opposite that of the CfA2; incombination the two surveys provide an important database for studies ofthe properties of galaxies and their large-scale distribution in thenearby universe. Based on observations obtained at Cerro TololoInter-American Observatory, National Optical Astronomy Observatories,operated by the Association of Universities for Research in Astronomy,Inc., under cooperative agreement with the National Science Foundation;Complejo Astronomico El Leoncito, operated under agreement between theConsejo Nacional de Investigaciones Científicas de laRepública Argentina and the National Universities of La Plata,Córdoba, and San Juan; the European Southern Observatory, LaSilla, Chile, partially under the bilateral ESO-ObservatórioNacional agreement; Fred Lawrence Whipple Observatory;Laboratório Nacional de Astrofísica, Brazil; and the SouthAfrican Astronomical Observatory.
| NGC 3081 - Surface photometry and kinematics of a classic resonance ring barred galaxy
This paper presents a detailed photometric and kinematic study of thewell-known Seyfert 2 galaxy NGC 3081, one of the best examples of aresonance ring barred galaxy in the sky. Improved optical imagescompared to previous studies reveal that NGC 3081 is a classic R1R'2galaxy, a type that shows a distinctive outer ring/pseudoring pattern atlarge radii that can be linked to orbit families at the outer Lindbladresonance (OLR). Together with an exceptionally strong inner ring and ablue nuclear ring, NGC 3081 has the rare distinction of having all fourof the main types of resonance rings that have been predicted bytest-particle models of barred spirals. NIR imaging of NGC 3081 revealsclear old rings connected to the inner ring and the R1 outer ring.Objective comparison of the B- and H-band positions of the inner ringindicates no significant difference in shape, major-axis position angle,or major-axis radius between the two passbands, in spite of thedifferent stellar populations each band emphasizes. Imaging Fabry-Perotinterferometry provides an intriguing picture of star formation in thegalaxy and of the dynamics of the system. H-alpha emission is strong inthe inner ring and is confined to a bounded elliptical annulus ofdiffuse emission whose ellipticity increases from the inner edge to theouter edge. A few H II regions are connected to the strong R1-type outerring, particularly just off the major axis of the inner ring where'dimples', typical of the R1 morphology, are found.
| The Distribution and Properties of H II Regions in Early-to-Intermediate Hubble Type Ringed Galaxies
This paper presents a study of the H II regions in 32 ringed andpseudo-ringed galaxies having Hubble types in the range S0 + to Sc. Theobjective is to illustrate the distributions of H II regions in classicexamples of ringed galaxies and to relate the observed properties toresonance theory. The sample is selected from the Catalog of SouthernRinged Galaxies and includes examples covering a range of ring andgalaxy morphological properties. We find that the distribution ofHα luminosity around inner rings is sensitive to the intrinsicshape of the rings. Extremely oval inner rings show a greaterconcentration of H II regions near the intrinsic ring major axiscompared to more circular rings. Nuclear rings are present in several ofthe sample galaxies and show a range of morphological properties, from adouble nuclear ring in NGC 1317 to an irregular feature in NGC 1433. Wefind also that in galaxies in which an R_1_ outer ring is prominent inthe continuum image, the H II regions follow an R^'^_2_ morphology. Inseveral cases, the observed distribution of H II regions stronglysupports the idea that the rings are linked to specific orbitalresonances with the bar. H II region luminosity functions have beenderived for all of the sample galaxies. The functions can be representedby power laws whose exponents are very similar to those found fornonringed galaxies. In a few cases, a luminous nuclear ring produces asecondary peak in the luminosity function. One galaxy shows a break inthe luminosity function similar to that observed in other galaxies byKennicutt, Edgar, & Hodge. The most unusual Hα distribution inthe sample was found in the large outer-ringed galaxy NGC 1291. Theprimary bar, lens, and secondary bar regions of this SO/a galaxy arefilled with a wispy pattern of ionized gas filaments very reminiscent ofwhat is seen in the bulge of M31.
| The Catalog of Southern Ringed Galaxies
The Catalog of Southern Ringed Galaxies (CSRG) is a comprehensivecompilation of diameters, axis ratios, relative bar position angles, andmorphologies of inner and outer rings, pseudorings, and lenses in 3692galaxies south of declination -17 deg. The purpose of the catalog is toevaluate the idea that these ring phenomena are related to orbitalresonances with a bar or oval in galaxy potentials. The catalog is basedon visual inspection of most of the 606 fields of the Science ResearchCouncil (SRC) IIIa-J southern sky survey, with the ESO-B, ESO-R, andPalomar Sky surveys used as auxiliaries when needed for overexposed coreregions. The catalog is most complete for SRC fields 1-303 (mostly southof declination -42 deg). In addition to ringed galaxies, a list of 859mostly nonringed galaxies intended for comparison with other catalogs isprovided. Other findings from the CSRG that are not based on statisticsare the identification of intrinsic bar/ring misalignment; bars whichunderfill inner rings; dimpling of R'1pseudorings; pointy, rectangular, or hexagonal inner or outer ringshapes; a peculiar polar-ring-related system; and other extreme examplesof spiral structure and ring morphology.
| Pattern speed domains in ringed disk galaxies from observational and simulational databases
New test-particle simulations have been carried out to learn more aboutthe secular evolution and morphology of the gaseous and stellardistributions in barred galaxies. We verify the previous results of M.P. Schwarz that gas clouds will tend to collect into ring-like patternsnear major orbit resonances, owing to gravity torques. However, weimprove on these results in several ways. Firstly, we use more gasclouds (10000 vs 2000) than Schwarz and track individual clouds todetermine when they collide, rather than using a collision box as didSchwarz. Secondly, besides Schwarz's isochrone rotation curve, we alsouse a flat rotation curve. Thirdly, we consider more bar pattern speedsand strengths than did Schwarz. Finally, unlike Schwarz and othersimulators, we have a large database of images and color index maps ofnearly 140 ringed galaxies that can be compared to the simulations toevaluate their significance. We confirm the two types of outer Lindbladresonance rings that Schwarz discovered, but find that their existenceis not due so much to the initial density distribution of gas clouds asto pattern speed and the time interval since the bar potential wasimposed. The simulations and the images lead us to suggest that we candivide barred galaxies according to the resonances which the bar patternspeed and rotation curve allow in the disk. We illustrate specificgalaxies that we believe belong to fast, medium, and slow bar patternspeed 'domains' and match them to particular simulation frames. We alsodiscuss alternative hypotheses in which the pattern speed is such thatall resonances are present but the gas has been depleted or wasdistributed differently in various galaxies to produce the threeclassification domains.
| Metric characteristics of nuclear rings and related features in spiral galaxies
The metric properties of nuclear rings, pseudorings, spirals, and barsare discussed in the context of resonance theory and are used to gaugethe range of sizes for such features. The nuclear rings and pseudoringsof strongly barred SB and SAB galaxies have a wide range in lineardiameter; the mean diameter is about 1.1 kpc for a sample of 20 objects.We suggest that there are clear analogs of the nuclear rings of stronglybarred spirals in both weakly barred (SAB) and nonbarred (SA) spirals.The size ratios of nuclear rings with respect to outer rings andpseudorings, as well as morphological characteristics, are bestexplained if outer rings and pseudorings are linked to the outerLindblad resonance, and nuclear rings, pseudorings, and spirals arelinked to the inner Lindblad resonance. Nuclear bars are oftenassociated with nuclear rings and spirals, but also can existindependently of such features. We present a list of 13 double-barredgalaxies and discuss the significance of the phase angle of the nuclearbar with respect to the primary bar.
| Southern Sky Redshift Survey - The catalog
The catalog of radial velocities for galaxies which comprise thediameter-limited sample of the Southern Sky Redshift Survey ispresented. It consolidates the data of observations carried out at theLas Campanas Observatory, Observatorio Nacional, and South AfricanAstronomical Observatory. The criteria used for the sample selection aredescribed, as well as the observational procedures and the techniqueutilized to obtain the final radial velocities. The intercomparisonbetween radial velocity measurements from different telescopes indicatesthat the final data base is fairly homogeneous with a typical error ofabout 40 km/s. The sample is at present 90 percent complete, and themissing galaxies are predominantly objects with very low surfacebrightness for which it is very difficult to obtain optical redshifts.
| IRAS Faint Source Catalogue, version 2.0.
Not Available
| A catalog of southern groups of galaxies
A catalog of groups of galaxies identified in the southern Galactic capis presented. This catalog was constructed utilizing the group-findingalgorithm developed by Huchra and Geller (1982) to analyze galaxysamples with well-defined selection criteria and complete velocityinformation.
| A catalogue of Seyfert galaxies.
Not Available
| Southern Galaxy Catalogue.
Not Available
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