Home     Getting Started     To Survive in the Universe    
Inhabited Sky
    News@Sky     Astro Photo     The Collection     Forum     Blog New!     FAQ     Press     Login  

NGC 1620



Upload your image

DSS Images   Other Images

Related articles

Star Formation in Satellite Galaxies
We present narrowband observations of the Hα emission in a sampleof 31 satellites orbiting isolated giant spiral galaxies. The samplestudied spans the range -19 mag

The connection between shear and star formation in spiral galaxies
We present a sample of 33 galaxies for which we have calculated (i) theaverage rate of shear from published rotation curves, (ii) thefar-infrared luminosity from IRAS fluxes, and (iii) theKs-band luminosity from the Two Micron All Sky Survey(2MASS). We show that a correlation exists between the shear rate andthe ratio of the far-infrared to Ks-band luminosity. Thisratio is essentially a measure of the star formation rate per unit mass,or the specific star formation rate. From this correlation we show thata critical shear rate exists, above which star formation would turn offin the discs of spiral galaxies. Using the correlation between shearrate and spiral arm pitch angle, this shear rate corresponds to thelowest pitch angles typically measured in near-infrared images of spiralgalaxies.

On the Relation between Circular Velocity and Central Velocity Dispersion in High and Low Surface Brightness Galaxies
In order to investigate the correlation between the circular velocityVc and the central velocity dispersion of the spheroidalcomponent σc, we analyzed these quantities for a sampleof 40 high surface brightness (HSB) disk galaxies, eight giant lowsurface brightness (LSB) spiral galaxies, and 24 elliptical galaxiescharacterized by flat rotation curves. Galaxies have been selected tohave a velocity gradient <=2 km s-1 kpc-1 forR>=0.35R25. We used these data to better define theprevious Vc-σc correlation for spiralgalaxies (which turned out to be HSB) and elliptical galaxies,especially at the lower end of the σc values. We findthat the Vc-σc relation is described by alinear law out to velocity dispersions as low as σc~50km s-1, while in previous works a power law was adopted forgalaxies with σc>80 km s-1. Ellipticalgalaxies with Vc based on dynamical models or directlyderived from the H I rotation curves follow the same relation as the HSBgalaxies in the Vc-σc plane. On the otherhand, the LSB galaxies follow a different relation, since most of themshow either higher Vc or lower σc withrespect to the HSB galaxies. This argues against the relevance of baryoncollapse to the radial density profile of the dark matter halos of LSBgalaxies. Moreover, if the Vc-σc relation isequivalent to one between the mass of the dark matter halo and that ofthe supermassive black hole, then these results suggest that the LSBgalaxies host a supermassive black hole (SMBH) with a smaller masscompared to HSB galaxies with an equal dark matter halo. On the otherhand, if the fundamental correlation of SMBH mass is with the halocircular velocity, then LSB galaxies should have larger black holemasses for a given bulge dispersion. Elliptical galaxies withVc derived from H I data and LSB galaxies were not consideredin previous studies.Based on observations made with European Southern Observatory telescopesat the Paranal Observatory under programs 67.B-0283, 69.B-0573, and70.B-0171.

Infrared mergers and infrared quasi-stellar objects with galactic winds - II. NGC5514: two extranuclear starbursts with LINER properties and a supergiant bubble in the rupture phase
A study of the morphology, kinematics and ionization structure of theinfrared (IR) merger NGC5514 is presented. This study is based mainly onINTEGRAL two-dimensional (2D) spectroscopy (obtained at the 4.2-mWilliam Herschel Telescope, WHT), plus optical and near-IR images. Clearevidence of two extranuclear starbursts with young outflows (OFs) andlow-ionization nuclear emission region (LINER) activity are reported.One of these OFs has generated a supergiant bubble and the other isassociated with an extended complex of HII regions.In the galactic bubble it was found that: (i) the [SII], Hα,[NII], [OI] and [OIII] emission-line maps show a bubble with a distortedellipsoidal shape, with major and minor axes of ~6.5 kpc [13.6 arcsec;at position angle (PA) = 120°+/- 10°] and ~4.5 kpc (9.6 arcsec);(ii) these maps depict four main knots, a very strong one and threeothers more compact and located at the border; (iii) the centre of thebubble is located at ~4.1 kpc (8.5 arcsec) to the west of the mainnucleus; (iv) the WHT spectra show, in this area, two strong components:blue and red emission-line systems, probably associated with emissionfrom the near and far side of the external shell, for which the mean OFvelocities were measured as VOFblue= (-320 +/- 20)kms-1 and VOFred= (+265 +/- 25) kms-1(v) these two components depict LINER properties, probably associatedwith large-scale OF + shocks; (vi) at the east border, the kinematics ofthe ionized gas and the [SII] emission-line maps show an extendedejection of 4 kpc aligned with the PA of the major axis; (vii) threeother ejections were found, two of them perpendicular to the extendedone. Each ejection starts in one of the knots. These results suggestthat the bubble is in the rupture phase.For the complex of giant HII regions it was found that: (i) theHα, [NII] and [SII] emission-line maps show a compact strongemission area (peaking at ~810 pc ~1.7 arcsec, to the east of the secondnucleus) and faint extended emission with an elongated shape, and majorand minor axes of ~5.1 kpc (10.8 arcsec; at PA ~20°) and ~2.9 kpc(6.0 arcsec); (ii) inside this complex, the spectra show HII region andtransition LINER/HII characteristics; (iii) at the border of thisextended HII area the spectra have outflow components and LINERproperties.INTEGRAL 2D [NII], Hα, [SII] and [OIII] velocity fields (VFs) arepresented. These VF maps show results consistent with an expansion ofthe bubble, plus four ejections of ionized gas. The U, B, V, I, J, H andKS images show a pre-merger morphology, from which faintfilaments of emission emerge, centred on the bubble. The ionizationstructure and the physical conditions were analysed using the following2D emission-line ratio and width maps: [SII]/Hα, [NII]/Hα,[OI]/Hα, [OIII]/Hβ and FWHM-[NII]. In the region of thebubble, 100 per cent of the [NII]/Hα and [SII]/Hα ratiosshow very high values (>0.8) consistent with LINER processesassociated with high-velocity shocks. These new results support theprevious proposition that extreme nuclear and `extranuclear' starburstswith galactic winds + shocks play an important role in the evolution ofIR mergers/quasi-stellar objects.

The Properties of Satellite Galaxies in External Systems. II. Photometry and Colors
In this second paper dedicated to the study of satellite galaxies wepresent broadband photometry in the B, V, R, and I filters of 49satellite galaxies orbiting giant isolated spiral galaxies. Firstanalysis of the properties of these objects are presented by means ofcolor-color and color-magnitude diagrams for early- and late-typesatellites. Although we find differences in the slope of the V-I versusMv color magnitude diagram, as a whole, the relations are inagreement with the trends known to date for galaxies of similarmagnitudes in nearby clusters of galaxies. Comparison with the relationsfound for satellites in the Local Group allows us to sample better thebright end of the luminosity function of satellite galaxies and extendsfor brighter objects the validity of the color-magnitude relation foundfor dwarf galaxies in the Local Group. Most of the E/S0 galaxies in oursample show a negative color gradient with values similar to those knownfor early-type galaxies in other environments.

Ionized gas and stellar kinematics of seventeen nearby spiral galaxies
Ionized gas and stellar kinematics have been measured along the majoraxes of seventeen nearby spiral galaxies of intermediate to latemorphological type. We discuss the properties of each sample galaxy,distinguishing between those characterized by regular or peculiarkinematics. In most of the observed galaxies, ionized gas rotates morerapidly than stars and has a lower velocity dispersion, as is to beexpected if the gas is confined in the disc and supported by rotationwhile the stars are mostly supported by dynamical pressure. In a fewobjects, gas and stars show almost the same rotational velocity and lowvelocity dispersion, suggesting that their motion is dominated byrotation. Incorporating the spiral galaxies studied by Bertola et al.(\cite{Bertola1996}), Corsini et al. (\cite{Corsini1999},\cite{Corsini2003}) and Vega Beltrán et al. (\cite{Vega2001}) wehave compiled a sample of 50 S0/a-Scd galaxies, for which the major-axiskinematics of the ionized gas and stars have been obtained with the samespatial (≈1'') and spectral (≈50 km;s-1) resolution,and measured with the same analysis techniques. This allowed us toaddress the frequency of counter-rotation in spiral galaxies. It turnsout that less than 12% and less than 8% (at the 95% confidence level) ofthe sample galaxies host a counter-rotating gaseous and stellar disc,respectively. The comparison with S0 galaxies suggests that theretrograde acquisition of small amounts of external gas gives rise tocounter-rotating gaseous discs only in gas-poor S0s, while in gas-richspirals the newly acquired gas is swept away by the pre-existing gas.Counter-rotating gaseous and stellar discs in spirals are formed onlyfrom the retrograde acquisition of large amounts of gas exceeding thatof pre-existing gas, and subsequent star formation, respectively.Based on observations carried out at the European Southern Observatory,La Silla (Chile) (ESO 56.A-0684 and 57.A-0569).Tables 3 and 4 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr ( or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/424/447Full Fig. \ref{fig:kinematics} and Figs. \ref{fig:gascomparison} and\ref{fig:starcomparison} are only available in electronic form athttp://www.edpsciences.org

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 ( or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/422/39

Dark halo properties from rotation curves
We study a large set of high spatial resolution optical rotation curvesof galaxies with the goal of determining the model parameters for a discembedded within a cold dark matter (CDM) halo, which we model witheither a Navarro-Frenk-White (NFW) profile or pseudo-isothermal profile.We show that parameter degeneracies present in lower resolution data arelifted at these higher resolutions. 34 per cent of the galaxies do nothave a meaningful fit when using the NFW profile and 32 per cent whenusing the pseudo-isothermal profile, however only 14 per cent do nothave a meaningful fit in either model. In both models we findcorrelations between the disc baryon fraction fd and the spinparameter of the halo λ', between fd and the dark halomass M200, and between M200 and the concentrationparameter c. We show that the distribution of the concentrationparameter c, for a NFW halo, is in good agreement with CDM predictions;no significant galaxy population is found with very low values of c. Theoverall distribution of λ' is in good agreement with theoreticalpredictions from hierarchical tidal torque theory. The whole sample isalso well fitted by a pseudo-isothermal dark halo with a core, but thesize of the core is rather small (6 per cent of the virial radius orsmaller; for 70 per cent of the sample the core size is less than 2kpc). Thus we conclude that the profile of dark matter is steep(r-1 or steeper) down to this radius; large dark matter cores(and therefore very low dark matter central densities) seem to beexcluded. Low-surface-brightness galaxies tend to have higher values ofλ' for a given fd and lower values of c for a givenmass than high-surface-brightness galaxies. In an appendix we give someuseful formulae for pseudo-isothermal profile haloes and we discuss indetail the issue of parameter degeneracies.

The Nature of Peculiar Stellar Complexes
The nature of stellar complexes with peculiar populations andmorphologies is investigated. The existence in the LMC of complexes madeup of isolated stars, on the one hand, and consisting exclusively ofclusters, on the other hand, could be due to different turbulencepatterns in the initial gaseous medium. Arc-shaped stellar complexes areunlikely to be the result of star formation in a gaseous shell swept upby a central source of pressure, and instead probably reflect the shapeof a bow shock that develops when a sufficiently dense cloud is subjectto dynamical pressure. A peculiar arc-shaped complex in NGC 6946, whichcontains a young, massive cluster, may be the result of an obliqueinfall of a high-velocity cloud onto a region of the gaseous disk of theGalaxy with a strong, regular magnetic field; the properties of thiscomplex can be explained as the result of a collision of the resultingshocks. The arc-shaped complexes in the LMC were also probably producedby high-velocity clouds moving obliquely through the more tenuous gas ofthe LMC disk. A similar complex in NGC 300 may owe its origin to theeffect produced on a dense cloud by the shock from an extremely powerfulexternal explosion, whose stellar remnant may have survived as an X-raysource now located along the line of symmetry of the arc of the complex.The rareness of such structures can be explained by the narrow range ofconditions under which they can develop.

The Properties of Satellite Galaxies in External Systems. I. Morphology and Structural Parameters
We present the first results of an ongoing project to study themorphological, kinematical, dynamical, and chemical properties ofsatellite galaxies of external giant spiral galaxies. The sample ofobjects has been selected from the catalog by Zaritsky et al. The paperanalyzes the morphology and structural parameters of a subsample of 60such objects. The satellites span a great variety of morphologies andsurface brightness profiles. About two-thirds of the sample are spiralsand irregulars, the remaining third being early-types. Some casesshowing interaction between pairs of satellites are presented andbriefly discussed.

Beyond the Bulge: A Fundamental Relation between Supermassive Black Holes and Dark Matter Halos
The possibility that the masses MBH of supermassive blackholes (SBHs) correlate with the total gravitational mass of their hostgalaxy, or the mass MDM of the dark matter halo in which theypresumably formed, is investigated using a sample of 16 spiral and 20elliptical galaxies. The bulge velocity dispersion σc,typically defined within an aperture of size R<~0.5 kpc, is found tocorrelate tightly with the galaxy's circular velocity vc, thelatter measured at distances from the Galactic center at which therotation curve is flat, R~20-80 kpc. By using the well-knownMBH-σc relation for SBHs and a prescriptionto relate vc to the mass of the dark matter haloMDM in a standard ΛCDM cosmology, the correlationbetween σc and vc is equivalent to onebetween MBH and MDM. Such a correlation is foundto be nonlinear, with the ratio MBH/MDM decreasingfrom 2×10-4 for MDM~1014Msolar to 10-5 for MDM~1012Msolar. Preliminary evidence suggests that halos of masssmaller than ~5×1011 Msolar are increasinglyless efficient at forming SBHs-perhaps even unable to form them.

Penetrating the Dust: The Duality of Spiral Structure
Not Available

Arc-Shaped and Spheroidal Stellar Complexes
Complexes of young clusters and high-luminosity stars in the shape ofregular, circular arcs have been found in a number of galaxies, firstand foremost the LMC, NGC 6946, and M83. These shapes are found even instrongly inclined galaxies, suggesting that the observed arcs areprojections of partial spherical shells. Obviously, these stellar shellsmust have formed from gaseous shells swept up by some source of centralpressure and become gravitationally unstable. The power of this sourcecorresponds to several dozen supernova explosions; however, its natureremains unclear. A central cluster providing a source of O stars andsupernovae is usually absent. The presence of multiple arcs locatedclose to each other can be explained by the fall of a swarm of fragmentsor by the progenitor stars originating in a single peculiar starcluster, implying the existence of stellar objects capable of givingrise to explosions with energies an order of magnitude higher than thoseof individual supernovae. The same objects may be responsible forgamma-ray bursts. It may be that only the most massive clusters withfrequent or especially powerful supernova explosions are capable ofproducing HI supershells. Otherwise, it is impossible to explain why nosupershells have been found around numerous clusters that should becapable of producing them according to current theories. The presence ofstar clusters in shell-like structures provides extremely importantinformation about the physical conditions in and the ages of the initialgaseous shells, making stellar arcs the best available laboratory forstudies of triggered star formation.

Homogenization of the Stellar Population along Late-Type Spiral Galaxies
We present a study of the broadband UBV color profiles for 257 Sbcbarred and nonbarred galaxies, using photoelectric aperture photometrydata from the literature. Using robust statistical methods, we haveestimated the color gradients of the galaxies, as well as the total andbulge mean colors. A comparative photometric study using CCD images wasdone. In our sample, the color gradients are negative (reddish inward)in approximately 59% of the objects, are almost null in 27%, and arepositive in 14%, considering only the face-on galaxies, which representapproximately 51% of the sample. The results do not change, essentially,when we include the edge-on galaxies. As a consequence of this study wehave also found that barred galaxies are overrepresented among theobjects having null or positive gradients, indicating that bars act as amechanism of homogenization of the stellar population. This effect ismore evident in the U-B color index, although it can also be detected inthe B-V color. A correlation between the total and bulge colors wasfound that is a consequence of an underlying correlation between thecolors of bulges and disks found by other authors. Moreover, the meantotal color is the same irrespective of the gradient regime, whilebulges are bluer in galaxies with null or positive gradients, whichindicates an increase of the star formation rate in the central regionsof these objects. We have also made a quantitative evaluation of theamount of extinction in the center of these galaxies. This was doneusing the Wide Field Planetary Camera 2 (WFPC2) and the Near InfraredCamera and Multi-Object Spectrometer (NICMOS) Hubble Space Telescope(HST) archival data, as well as CCD B, V, and I images. We show thatalthough the extinction in the V-band can reach values up to 2 mag inthe central region, it is unlikely that dust plays a fundamental role inglobal color gradients. We found no correlation between color and O/Habundance gradients. This result could suggest that the color gradientsare more sensitive to the age rather than to the metallicity of thestellar population. However, the absence of this correlation may becaused by dust extinction. We discuss this result by considering apicture in which bars are a relatively fast, recurrent phenomenon. Theseresults are not compatible with a pure classical monolithic scenario forbulge and disk formation. On the contrary, they favor a scenario inwhich both these components are evolving in a correlated process inwhich stellar bars play a crucial role. Based partly on observationsmade at the Pico dos Dias Observatory (PDO/LNA-CNPq), Brazil.

Photometric Properties of Bars in Galaxies
We have used surface photometry data for 100 barred galaxies todetermine the UBVRIJHK surface brightnesses and color indices for thebars. Two peaks are observed in the distribution of the average bar Bbrightnesses: at 21.0m2 and 22.2m2, characteristic of late-andearly-type galaxies, respectively. The average surface-brightnessdifference between the bar and the galaxy (within the 25.0m2 isophote)increases from 1.1m2 for SB0 galaxies to 2.3m2 for SBc-IBm galaxies. In(U-B)0-(B-V)0, (B-V 0-(V-R 0, and (B-V)0-(V-I)0 two-color diagrams, forall morphological types, the bars are shifted leftward from normal colorsequence for galaxies. This deviation is more pronounced for the outerthan for the inner regions of the bars. Using evolutionary models, weshow that this deviation is due to the scarcity of intermediate-age [(19)×109 yrs] stars in bars. Possible origins for this anomalouscomposition of the stellar population are discussed.

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.

A Dynamical Study of Galaxies in the Hickson Compact Groups
To investigate dynamical properties of spiral galaxies in the Hicksoncompact groups (HCGs), we present rotation curves of 30 galaxies in 20HCGs. We found as follows: (1) There is no significant relation betweendynamical peculiarity and morphological peculiarity in HCG spiralgalaxies. (2) There is no significant relation between the dynamicalproperties and the frequency distribution of nuclear activities in HCGspiral galaxies. (3) There are no significant correlations between thedynamical properties of HCG spiral galaxies and any group properties(i.e., size, velocity dispersion, galaxy number density, and crossingtime). (4) Asymmetric and peculiar rotation curves are more frequentlyseen in the HCG spiral galaxies than in field spiral galaxies or incluster ones. However, this tendency is more obviously seen in late-typeHCG spiral galaxies. These results suggest that the dynamical propertiesof HCG spiral galaxies do not strongly correlate with the morphology,the nuclear activity, and the group properties. Our results also suggestthat more frequent galaxy collisions occur in the HCGs than in the fieldand in the clusters.

Box- and peanut-shaped bulges. I. Statistics
We present a classification for bulges of a complete sample of ~ 1350edge-on disk galaxies derived from the RC3 (Third Reference Catalogue ofBright Galaxies, de Vaucouleurs et al. \cite{rc3}). A visualclassification of the bulges using the Digitized Sky Survey (DSS) inthree types of b/p bulges or as an elliptical type is presented andsupported by CCD images. NIR observations reveal that dust extinctiondoes almost not influence the shape of bulges. There is no substantialdifference between the shape of bulges in the optical and in the NIR.Our analysis reveals that 45% of all bulges are box- and peanut-shaped(b/p). The frequency of b/p bulges for all morphological types from S0to Sd is > 40%. In particular, this is for the first time that such alarge frequency of b/p bulges is reported for galaxies as late as Sd.The fraction of the observed b/p bulges is large enough to explain theb/p bulges by bars. Partly based on observations collected at ESO/LaSilla (Chile), DSAZ/Calar Alto (Spain), and Lowell Observatory/Flagstaff(AZ/U.S.A.). Tables 6 and 7 are only available in electronic form at CDSvia anonymous ftp to cdsarc.u-strasbg.fr ( or viahttp://cdsweb.u-strasbg.fr/Abstract.html

Arcsecond Positions of UGC Galaxies
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.

The I-Band Tully-Fisher Relation for SC Galaxies: 21 Centimeter H I Line Data
A compilation of 21 cm line spectral parameters specifically designedfor application of the Tully-Fisher (TF) distance method is presentedfor 1201 spiral galaxies, primarily field Sc galaxies, for which opticalI-band photometric imaging is also available. New H I line spectra havebeen obtained for 881 galaxies. For an additional 320 galaxies, spectraavailable in a digital archive have been reexamined to allow applicationof a single algorithm for the derivation of the TF velocity widthparameter. A velocity width algorithm is used that provides a robustmeasurement of rotational velocity and permits an estimate of the erroron that width taking into account the effects of instrumental broadeningand signal-to-noise. The digital data are used to establish regressionrelations between measurements of velocity widths using other commonprescriptions so that comparable widths can be derived throughconversion of values published in the literature. The uniform H I linewidths presented here provide the rotational velocity measurement to beused in deriving peculiar velocities via the TF method.

The I-Band Tully-Fisher Relation for SC Galaxies: Optical Imaging Data
Properties derived from the analysis of photometric I-band imagingobservations are presented for 1727 inclined spiral galaxies, mostly oftypes Sbc and Sc. The reduction, parameter extraction, and errorestimation procedures are discussed in detail. The asymptotic behaviorof the magnitude curve of growth and the radial variation in ellipticityand position angle are used in combination with the linearity of thesurface brightness falloff to fit the disk portion of the profile. TotalI-band magnitudes are calculated by extrapolating the detected surfacebrightness profile to a radius of eight disk scale lengths. Errors inthe magnitudes, typically ~0.04 mag, are dominated by uncertainties inthe sky subtraction and disk-fitting procedures. Comparison is made withthe similar imaging database of Mathewson, Ford, & Buchhorn, both aspresented originally by those authors and after reanalyzing theirdigital reduction files using identical disk-fitting procedures. Directcomparison is made of profile details for 292 galaxies observed incommon. Although some differences occur, good agreement is found,proving that the two data sets can be used in combination with onlyminor accommodation of those differences. The compilation of opticalproperties presented here is optimized for use in applications of theTully-Fisher relation as a secondary distance indicator in studies ofthe local peculiar velocity field.

Triggered star formation in the LMC4/Constellation III region of the Large Magellanic Cloud
The origin of a regular, 600-pc-long arc of young stars and clusters inthe Constellation III region of the Large Magellanic Cloud isconsidered. The circular form of this arc suggests that the pre-stellargas was uniformly swept up by a central source of pressure. In thecentre of the arc are six ~30-Myr-old A-type supergiant stars and aCepheid variable of similar age, which may be related to the source ofthis pressure. We calculate the expansion of a bubble around a clusterof this age, and show that it could have triggered the formation of thearc at the right time and place. Surrounding the central old stars andextending well outside the young arc is the LMC4 superbubble and giantHI shell. We show how this superbubble and shell could have formed bythe continued expansion of the 15-Myr-old cavity, following starformation in the arc and the associated new pressures. The age sequenceproposed here was not evident in the recent observations by Olsen et al.and Braun et al. because the first generation stars in the centre of theLMC superbubble are relatively faint and scarce compared to the moresubstantial population of stars less than 15 Myr old that formedthroughout the region in a second generation. These considerations leadto an examination of the origin of the LMC4/Constellation III region andother large rings in the LMC and other galaxies. Their size andcircularity could be the result of low galactic shear and a thick disc,with several generations of star formation in their interiors now toofaint to be seen.

Giant Shells and Stellar Arcs as Relics of Gamma-Ray Burst Explosions
Gamma-ray burst (GRB) explosions are powerful and frequent enough tomake kiloparsec-size shells and holes in the interstellar media ofspiral and irregular galaxies. The observations of such remnants aresummarized. Several observed shells contain no obvious central starclusters and could be GRB remnants, but sufficiently old clusters, whichcould have formed these shells by supernovae and winds, might be hard todetect.

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.

A catalogue of spatially resolved kinematics of galaxies: Bibliography
We present a catalogue of galaxies for which spatially resolved data ontheir internal kinematics have been published; there is no a priorirestriction regarding their morphological type. The catalogue lists thereferences to the articles where the data are published, as well as acoded description of these data: observed emission or absorption lines,velocity or velocity dispersion, radial profile or 2D field, positionangle. Tables 1, 2, and 3 are proposed in electronic form only, and areavailable from the CDS, via anonymous ftp to cdsarc.u-strasbg.fr (to130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

Collision-Induced Star Formation in Ring Galaxies
Not Available

Homogeneous Velocity-Distance Data for Peculiar Velocity Analysis. III. The Mark III Catalog of Galaxy Peculiar Velocities
This is the third in a series of papers in which we assemble and analyzea homogeneous catalog of peculiar velocity data. In Papers I and II, wedescribed the Tully-Fisher (TF) redshift-distance samples thatconstitute the bulk of the catalog and our methodology for obtainingmutually consistent TF calibrations for these samples. In this paper, wesupply further technical details of the treatment of the data andpresent a subset of the catalog in tabular form. The full catalog, knownas the Mark III Catalog of Galaxy Peculiar Velocities, is available inaccessible on-line databases, as described herein. The electroniccatalog incorporates not only the TF samples discussed in Papers I andII but also elliptical galaxy Dn- sigma samples originally presentedelsewhere. The relative zero pointing of the elliptical and spiral datasets is discussed here. The basic elements of the Mark III Catalog arethe observables for each object (redshift, magnitude, velocity width,etc.) and inferred distances derived from the TF or Dn- sigma relations.Distances obtained from both the forward and inverse TF relations aretabulated for the spirals. Malmquist bias--corrected distances arecomputed for each catalog object using density fields obtained from theIRAS 1.2 Jy redshift survey. Distances for both individual objects andgroups are provided. A variety of auxiliary data, including distancesand local densities predicted from the IRAS redshift surveyreconstruction method, are tabulated as well. We study the distributionsof TF residuals for three of our samples and conclude that they are wellapproximated as Gaussian. However, for the Mathewson et al. sample wedemonstrate a significant decrease in TF scatter with increasingvelocity width. We test for, but find no evidence of, a correlationbetween TF residuals and galaxy morphology. Finally, we derivetransformations that map the apparent magnitude and velocity width datafor each spiral sample onto a common system. This permits theapplication of analysis methods that assume that a unique TF relationdescribes the entire sample.

More Satellites of Spiral Galaxies
We present a revised and expanded catalog of satellite galaxies of a setof isolated spiral galaxies similar in luminosity to the Milky Way. Thissample of 115 satellites, 69 of which were discovered in our multifiberredshift survey, is used to probe the results obtained from the originalsample further (Zaritsky et al.). The satellites are, by definition, atprojected separations <~500 kpc, have absolute recessional velocitydifferences with respect to the parent spiral of less than 500 km s-1,and are at least 2.2 mag fainter than their associated primary galaxy. Akey characteristic of this survey is the strict isolation of thesesystems, which simplifies any dynamical analysis. We find no evidencefor a decrease in the velocity dispersion of the satellite system as afunction of radius out to galactocentric radii of 400 kpc, whichsuggests that the halo extends well beyond 200 kpc. Furthermore, the newsample affirms our previous conclusions (Zaritsky et al.) that (1) thevelocity difference between a satellite and its primary is not stronglycorrelated with the rotation speed of the primary, (2) the system ofsatellites has a slight net rotation (34 +/- 14 km s-1) in the samesense as the primary's disk, and (3) that the halo mass of an ~L* spiralgalaxy is in excess of 2 x 1012 Mȯ.

Optical Rotation Curves and Linewidths for Tully-Fisher Applications
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....114.2402C&db_key=AST

Three-color surface photometry of late-type galaxies: NGC 1620, 7292, and 7743
Not Available

Submit a new article

Related links

  • - No Links Found -
Submit a new link

Member of following groups:

Observation and Astrometry data

Right ascension:04h36m37.20s
Aparent dimensions:3.631′ × 1.047′

Catalogs and designations:
Proper Names   (Edit)
NGC 2000.0NGC 1620

→ Request more catalogs and designations from VizieR