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

NGC 7156



Upload your image

DSS Images   Other Images

Related articles

The AMIGA sample of isolated galaxies. II. Morphological refinement
We present a refinement of the optical morphologies for galaxies in theCatalog of Isolated Galaxies that forms the basis of the AMIGA (Analysisof the interstellar Medium of Isolated GAlaxies) project. Uniformreclassification using the digitized POSS II data benefited from thehigh resolution and dynamic range of that sky survey. Comparison withindependent classifications made for an SDSS overlap sample of more than200 galaxies confirms the reliability of the early vs. late-typediscrimination and the accuracy of spiral subtypes within Δ T =1-2. CCD images taken at the Observatorio de Sierra Nevada were alsoused to solve ambiguities in early versus late-type classifications. Aconsiderable number of galaxies in the catalog (n = 193) are flagged forthe presence of nearby companions or signs of distortion likely due tointeraction. This most isolated sample of galaxies in the local Universeis dominated by two populations: 1) 82% are spirals (Sa-Sd) with thebulk being luminous systems with small bulges (63% between types Sb-Sc)and 2) a significant population of early-type E-S0 galaxies (14%). Mostof the types later than Sd are low luminosity galaxies concentrated inthe local supercluster where isolation is difficult to evaluate. Thelate-type spiral majority of the sample spans a luminosity rangeMB-corr = -18 to -22 mag. Few of the E/S0 population are moreluminous than -21.0 marking the absence of the often-sought superL* merger (e.g. fossil elliptical) population. The rarity ofhigh luminosity systems results in a fainter derived M* forthis population compared to the spiral optical luminosity function(OLF). The E-S0 population is from 0.2 to 0.6 mag fainter depending onhow the sample is defined. This marks the AMIGA sample as unique amongsamples that compare early and late-type OLFs separately. In othersamples, which always involve galaxies in higher density environments,M^*_E/S0 is almost always 0.3-0.5 mag brighter than M^*_S, presumablyreflecting a stronger correlation between M* andenvironmental density for early-type galaxies.

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

Revised positions for CIG galaxies
We present revised positions for the 1051 galaxies belonging to theKarachentseva Catalog of Isolated Galaxies (CIG). New positions werecalculated by applying SExtractor to the Digitized Sky Survey CIG fieldswith a spatial resolution of 1 arcsper 2. We visually checked theresults and for 118 galaxies had to recompute the assigned positions dueto complex morphologies (e.g. distorted isophotes, undefined nuclei,knotty galaxies) or the presence of bright stars. We found differencesbetween older and newer positions of up to 38 arcsec with a mean valueof 2 arcsper 96 relative to SIMBAD and up to 38 arcsec and 2 arcsper 42respectively relative to UZC. Based on star positions from the APMcatalog we determined that the DSS astrometry of five CIG fields has amean offset in (alpha , delta ) of (-0 arcsper 90, 0 arcsper 93) with adispersion of 0 arcsper 4. These results have been confirmed using the2MASS All-Sky Catalog of Point Sources. The intrinsic errors of ourmethod combined with the astrometric ones are of the order of 0 arcsper5.Full Table 1 is 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/411/391

12CO(1-0) observation of isolated late-type galaxies
We present 12CO(J=1-0) line observations of 99 galaxiesobtained with the SEST 15 m, the Kitt Peak 12 m and the IRAM 30 mtelescopes. The target galaxies were selected from the catalogue ofisolated galaxies of Karachentseva (\cite{Karachentseva73}). These dataare thus representative of the CO properties of isolated late-typegalaxies. All objects were observed in their central position, thosewith large angular sizes were mapped. These new measurements are used toestimate the molecular gas mass of the target galaxies. The moleculargas is on average ~ 18% of the atomic gas mass.Tables 1 and 2 are also 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/411/381Based on observations made with the 12-m National Radio AstronomicalObservatory, Kitt Peak, Arizona, with the Swedish-ESO Submillimetretelescope SEST, La Silla, Chile, with the IRAM 30 m radiotelescope, PicoVeleta, Granada, Spain.

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.

Catalogue of HI maps of galaxies. I.
A catalogue is presented of galaxies having large-scale observations inthe HI line. This catalogue collects from the literature the informationthat characterizes the observations in the 21-cm line and the way thatthese data were presented by means of maps, graphics and tables, forshowing the distribution and kinematics of the gas. It containsfurthermore a measure of the HI extension that is detected at the levelof the maximum sensitivity reached in the observations. This catalogueis intended as a guide for references on the HI maps published in theliterature from 1953 to 1995 and is the basis for the analysis of thedata presented in Paper II. The catalogue is only available inelectronic form at the CDS via anonymous ftp orhttp://cdsweb.u-strasbg.fr/Abstract.html

Kinematics of the local universe. VII. New 21-cm line measurements of 2112 galaxies
This paper presents 2112 new 21-cm neutral hydrogen line measurementscarried out with the meridian transit Nan\c cay radiotelescope. Amongthese data we give also 213 new radial velocities which complement thoselisted in three previous papers of this series. These new measurements,together with the HI data collected in LEDA, put to 6 700 the number ofgalaxies with 21-cm line width, radial velocity, and apparent diameterin the so-called KLUN sample. Figure 5 and Appendices A and B forcorresponding comments are available in electronic form at thehttp://www.edpsciences.com

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.

Lopsided Spiral Galaxies and a Limit on the Galaxy Accretion Rate
We present a measurement of lopsidedness for the stellar disks of 60field spiral galaxies in terms of the azimuthal m = 1 Fourier amplitude,A1, of the stellar light. We confirm the previous result (Rix &Zaritsky) that ~30% of field spiral galaxies in a magnitude-limitedsample exhibit significant lopsidedness ( >= 0.2) atlarge radii (R > 1.5 disk scalelengths). We conjecture that thislopsidedness is caused by tidal interactions and calculate an upperlimit on the accretion rate of small galaxies. We exploit thecorrelation between lopsidedness and photometric measures of recent starformation (Zaritsky) to obtain two independent estimates of the lifetimeof these m = 1 distortions. First, we show that lopsided galaxies havean excess of blue luminosity relative to that of symmetric galaxies withthe same H I linewidth, which we attribute to a recent star formationepisode that was triggered by an interaction between the galaxy and acompanion. We use stellar population models (Bruzual & Charlot) toestimate the time since that interaction. Second, we use the N-bodysimulation of an infalling satellite by Walker, Mihos, & Hernquistto estimate how fast tidally induced m = 1 distortions are erasedthrough phase mixing. Both approaches indicate that the observations areconsistent with a hypothesized tidal interaction that occurred about 1Gyr ago for galaxies that are lopsided at the 20% level. By combiningthis lifetime estimate for lopsidedness, the observed frequency of suchdistortions, and a correction to the survey volume that depends on theincrease in luminosity during an interaction, we derive an upper limiton the current companion accretion rate of field spiral galaxies (forcompanion masses ~10% parent galaxy mass) that lies in the range0.07--0.25 Gyr-1. The principal uncertainty in this limit arises fromambiguities in the interpretation of the correlation betweenlopsidedness and MB.

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.

Nonaxisymmetric Structures in the Stellar Disks of Galaxies
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ...447...82R&db_key=AST

Thickness determination of three dimensional spiral galaxy
CCD images of some spiral galaxies were obtained with a 1 m telescope inYunnan Observatory. After processing and measuring the images with acomputer, we obtained the morphological parameters, thickness, andrelative errors of seven spiral galaxies (NGC2608, NGC2713, NGC2776,NGC3631, NGC5669, NGC5985 and NGC7156) by fitting their spiral arms withlogarithmic spirals. This method is the only one to be generallyapplicable for measuring the thickness of most spiral galaxies.

The far-infrared properties of the CfA galaxy sample. I - The catalog
IRAS flux densities are presented for all galaxies in the Center forAstrophysics magnitude-limited sample (mB not greater than 14.5)detected in the IRAS Faint Source Survey (FSS), a total of 1544galaxies. The detection rate in the FSS is slightly larger than in thePSC for the long-wavelength 60- and 100-micron bands, but improves by afactor of about 3 or more for the short wavelength 12- and 25-micronbands. This optically selected sample consists of galaxies which are, onaverage, much less IR-active than galaxies in IR-selected samples. Itpossesses accurate and complete redshift, morphological, and magnitudeinformation, along with observations at other wavelengths.

Uncertainties in 21 centimeter redshifts. I - Data
High-precision data on the 21-cm redshifts, profile widths, and shapesfor 625 galaxies are presented. Each galaxy is listed in across-identification and morphology table. High-resolution spectra arealso given for each galaxy. Internal redshift consistency is roughly 1km/s for galaxies for which the S/N is above 15. No systematic effectshave been found which might influence the observed redshift quantizationat 72.5 km/s or its submultiples.

H I survey of face-on galaxies - The frequency of distortions in H I disks
The full results of an H I survey of face-on galaxies are presented andit is shown that narrow H I profiles are rare in normal spiral galaxies.This is due in part to the wider-than-expected range of the integraldispersion and in part to the frequent occurrence of large-scaledistortions in the H I disk. These factors reduce the number of galaxieswith half-power widths less than 30 km/s to about 24 percent of thosethat would occur if galaxies generally had quiescent, coplanar H Idisks. Two useful subsets may be drawn from this study of 212 face-ongalaxies with axial ratios greater than 0.87. Fifty-two spirals of allmorphological types have half-power widths smaller than 100 km/s and maybe used for studies that benefit from a small velocity spread and anenhanced beam-filling factor. About 40 galaxies have velocity widthsmuch larger than expected and are of interest in studies of dynamicallypeculiar systems.

The Malmquist bias and the value of H0 from the Tully-Fisher relation
A large sample (n = 395) of spiral (Sab to Sd type) galaxies havingcorrected apparent magnitudes B-zero-sub-T and 21-cm line data (HI linewidths and radial velocities) is used to investigate in a new way theinfluence of the Malmquist bias on the determination of theextragalactic distance scale and the Hubble constant derived from theapplication of the B-band Tully-Fisher relation. This effect is clearlyidentified by using relative kinematic distances derived from aclassical local velocity field model and the concept of normalizedrelative kinematic distance. It results in an unbiased estimate of theHubble constant H0 which appears quite insensitive to the parameters(mean velocity of Virgo and infall velocity of the Local Group towardVirgo) adapted for the local velocity field model. A similar effect isfound from a sample of galaxies (n = 72) which are 'sosies' of 14primary galaxies. It is suggested that the presently derived H0represents the global value of the Hubble constant.

CCD surface photometry of field Galaxies. II - Bulge/disk decompositions
Major- and minor-axis profiles given previously for 105 galaxies of allmorphological types are decomposed into bulge and disk components. Inaddition, three model-independent parameters which measure the meansurface brightness, scale radius, and degree of light concentration arederived. The best correlations are found between Hubble type,concentration, bulge/disk ratio, and mean surface brightness.Correlations between the individual bulge and disk parameters generallyshow large scatter. The properties of S0 galaxies are inconsistent withtheir having been formed from spiral galaxies via gas depletion; theirproperties are intermediate between those of ellipticals and spirals.Most elliptical galaxies probably do not form by the merging of diskgalaxies. The difficulty of distinguishing between elliptical and S0galaxies in some cases is emphasized.

Supplement to the detailed bibliography on the surface photometry of galaxies
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985A&AS...60..517P&db_key=AST

CCD surface photometry of field galaxies. I - Observations
Images of 105 galaxies selected from a larger complete sample ofintrinsically luminous galaxies have been obtained for the purpose ofcomputing surface brightness profiles. The intensity profiles along themajor and minor axes are computed by a method in which ellipticalcontours whose position angle and ellipticity are allowed to vary withradius are fitted to the true isophotes of a galaxy. The resultingprofiles and ellipse parameters are listed for each object. An extensivecomparison of the present photometry with that of other workers is madeto assess the reliability of the data. For most objects, additionalphotometric information is given, including an isophotal radius andmagnitude within a limiting isophote of 24.0 mag/sq arcsec, anapproximate total magnitude, the effective radius containing one-halfthe total light, and the mean surface brightness inside this radius. Afull analysis of the data is deferred to a second paper where theprofiles will be decomposed into bulge and disk components.

Neutral hydrogen in isolated galaxies. IV - Results for the Arecibo sample
A standard sample for the comparison of the H I content of galaxies invarious intergalactic environments is presently defined by means ofobservations of 324 isolated galaxies lying in the declination rangeaccessible to the Arecibo 305-m telescope. Both mapping and single pointspectra are used to compute the integral properties of these galaxies.Neutral hydrogen was detected in 288 of the 324 galaxies surveyed, andit is noted that the optical diameter of a spiral disk is bettercorrelated with the hydrogen mass than the morphological type. When usedto define a measure of H I content, the isolated galaxy sample canpredict 'normalcy' with an accuracy that carries a standard error ofabout 0.20 in the log of the H I mass, if a dependence on disk size, aswell as type, is taken into account.

H I line studies of galaxies. III - Distance moduli of 822 disk galaxies
The distance scale established on the basis of a distance moduli catalog(for 822 galaxies) that was derived from 21-cm line widths via theB-band Tully-Fisher relation is compared with several independent scaleshaving a common zero point, that are based on the indicators forluminosity index, redshift, ring diameters, brightest superassociations,and effective diameters. These are in excellent systematic agreement,and confirm the linearity of the H I scale in the 24-35 modulusinterval, but indicate a small systematic zero point difference of about0.2 mag, which must be added to the H I moduli to place them on the same'short' distance scale defined by the others.

A 21 centimeter line survey of a complete sample of interacting and isolated galaxies
The paper presents 21 cm line observations of a complete sample ofinteracting and isolated galaxies made with the National Radio AstronomyObservatory 91 and 43 m telescopes and the Arecibo 3035 m telescope. The21 cm line data are combined with a homogeneous set of optical data onangular diameters, axial ratios, magnitudes, and colors, and integralproperties are calculated for the galaxies in both samples. In thispaper, the sample selection procedures, the method of observation, thedata reduction, and the observational errors are described. Thedetection percentages are presented for both samples.

A survey of galaxy redshifts. IV - The data
The complete list of the best available radial velocities for the 2401galaxies in the merged Zwicky-Nilson catalog brighter than 14.5mz and with b (II) above +40 deg or below -30 deg ispresented. Almost 60 percent of the redshifts are from the CfA surveyand are accurate to typically 35 km/s.

Inner ring structures in galaxies as distance indicators. III - Distances to 453 spiral and lenticular galaxies
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1983ApJS...51..149B&db_key=AST

Velocity calibration of the Las Campanas redshift survey
The Center for Astrophysics redshift survey is being extended bySchectman et al. (1983) to the south galactic cap. Their initial resultsprovide independent estimates of both emission Ve velocities and theabsorption line Vc velocities, such that (Ve-Vc) = 54 + or - 13 km/s. HI line observations of 40 of the sample are presented here, to provide asecure velocity scale calibration. The Vc velocities are found to have a32 + or - 9 km/s zero-point error.

Redshifts for 115 galaxies near the equator
New redshifts for 115 bright galaxies located near the celestial equatorare reported. The spectra were observed with a blue-sensitivephoton-counting Reticon on the 100-in. DuPont telescope, and theredshifts were derived using the data-analysis system developed for theCfA Redshift Survey. Comparisons with other measured redshifts suggestthat these data are similar in quality to the redshifts measured at Mt.Hopkins for the CfA Redshift Survey; the velocity zero point is good to10 or 15 km/s, with a typical error of 35 km/s for the individualmeasurements.

101 spiral galaxies - Neutral hydrogen distribution
The neutral hydrogen properties of spiral galaxies have been measured atthe Arecibo Observatory using a 21 cm spectral line system. One hundredand thirty galaxies were observed, and 101 have been detected androughly mapped in H I. The data are used to derive the total mass ofneutral hydrogen gas, the gravitational mass, and a Gaussian hydrogendiameter for some galaxies. A large scatter in H I diameters within eachHubble type is reported and Sc galaxies appear to have smaller H Idiameters than Sb galaxies. Sb galaxies also show a strong tendency tohave asymmetric H I distributions. The H I profile is measured with thewidth at 50% the peak flux, and comparisons are made with the Green Bankmethod.

An H i Study of Scd Galaxies
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975ApJ...198..527S&db_key=AST

Submit a new article

Related links

  • - No Links Found -
Submit a new link

Member of following groups:

Observation and Astrometry data

Right ascension:21h54m33.60s
Aparent dimensions:1.445′ × 1.23′

Catalogs and designations:
Proper Names   (Edit)
NGC 2000.0NGC 7156

→ Request more catalogs and designations from VizieR