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

NGC 4275



Upload your image

DSS Images   Other Images

Related articles

Dwarf and Normal Spiral Galaxies: are they Self-Similar?
The investigation presented here was focused on clarifying the existenceof dwarf spiral galaxies as a separate group from classical spirals.First, a list of spiral galaxies with small sizes was obtained.Information on colors, luminosities, morphologies and chemical contentwas searched for in the literature for these galaxies. Using thisinformation, it can be concluded that dwarf spirals are not likely to bethe tail of the distribution of classical galaxies. On the contrary,significant differences in some of the most important properties ofspiral galaxies, such as the metallicity gradient and the bar frecuency,were found. In any case, further and more accurate observations areneeded for a definitive answer.

A Face-on Tully-Fisher Relation
We construct the first ``face-on'' Tully-Fisher (TF) relation for 24galaxies with inclinations between 16° and 41°. The enablingmeasurements are integral-field echelle spectroscopy from the WIYN 3.5 mtelescope, which yield accurate kinematic estimates of disk inclinationto ~15°. Kinematic inclinations are of sufficient accuracy that ourmeasured TF scatter of 0.42 mag is comparable to other surveys evenwithout internal absorption corrections. Three of four galaxies withsignificant kinematic and photometric asymmetries also have the largestdeviations from our TF relation, suggesting that asymmetries make animportant contribution to TF scatter. By measuring inclinations below40°, we establish a direct path to linking this scatter to theunprojected structure of disks and making nondegenerate dynamical massdecompositions of spiral galaxies.

A new catalogue of ISM content of normal galaxies
We have compiled a catalogue of the gas content for a sample of 1916galaxies, considered to be a fair representation of ``normality''. Thedefinition of a ``normal'' galaxy adopted in this work implies that wehave purposely excluded from the catalogue galaxies having distortedmorphology (such as interaction bridges, tails or lopsidedness) and/orany signature of peculiar kinematics (such as polar rings,counterrotating disks or other decoupled components). In contrast, wehave included systems hosting active galactic nuclei (AGN) in thecatalogue. This catalogue revises previous compendia on the ISM contentof galaxies published by \citet{bregman} and \citet{casoli}, andcompiles data available in the literature from several small samples ofgalaxies. Masses for warm dust, atomic and molecular gas, as well asX-ray luminosities have been converted to a uniform distance scale takenfrom the Catalogue of Principal Galaxies (PGC). We have used twodifferent normalization factors to explore the variation of the gascontent along the Hubble sequence: the blue luminosity (LB)and the square of linear diameter (D225). Ourcatalogue significantly improves the statistics of previous referencecatalogues and can be used in future studies to define a template ISMcontent for ``normal'' galaxies along the Hubble sequence. The cataloguecan be accessed on-line and is also available at the Centre desDonnées Stellaires (CDS).The catalogue is available in electronic form athttp://dipastro.pd.astro.it/galletta/ismcat and at the CDS via anonymousftp to\ cdsarc.u-strasbg.fr ( or via\http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/405/5

The QDOT all-sky IRAS galaxy redshift survey
We describe the construction of the QDOT survey, which is publiclyavailable from an anonymous FTP account. The catalogue consists ofinfrared properties and redshifts of an all-sky sample of 2387 IRASgalaxies brighter than the IRAS PSC 60-μm completeness limit(S_60>0.6Jy), sparsely sampled at a rate of one-in-six. At |b|>10deg, after removing a small number of Galactic sources, the redshiftcompleteness is better than 98per cent (2086/2127). New redshifts for1401 IRAS sources were obtained to complete the catalogue; themeasurement and reduction of these are described, and the new redshiftstabulated here. We also tabulate all sources at |b|>10 deg with noredshift so far, and sources with conflicting alternative redshiftseither from our own work, or from published velocities. A list of 95ultraluminous galaxies (i.e. with L_60μm>10^12 L_solar) is alsoprovided. Of these, ~20per cent are AGN of some kind; the broad-lineobjects typically show strong Feii emission. Since the publication ofthe first QDOT papers, there have been several hundred velocity changes:some velocities are new, some QDOT velocities have been replaced by moreaccurate values, and some errors have been corrected. We also present anew analysis of the accuracy and linearity of IRAS 60-μm fluxes. Wefind that the flux uncertainties are well described by a combination of0.05-Jy fixed size uncertainty and 8per cent fractional uncertainty.This is not enough to cause the large Malmquist-type errors in the rateof evolution postulated by Fisher et al. We do, however, find marginalevidence for non-linearity in the PSC 60-μm flux scale, in the sensethat faint sources may have fluxes overestimated by about 5per centcompared with bright sources. We update some of the previous scientificanalyses to assess the changes. The main new results are as follows. (1)The luminosity function is very well determined overall but is uncertainby a factor of several at the very highest luminosities(L_60μm>5x10^12L_solar), as this is where the remainingunidentified objects are almost certainly concentrated. (2) Thebest-fitting rate of evolution is somewhat lower than our previousestimate; expressed as pure density evolution with density varying as(1+z)^p, we find p=5.6+/-2.3. Making a rough correction for the possible(but very uncertain) non-linearity of fluxes, we find p=4.5+/-2.3. (3)The dipole amplitude decreases a little, and the implied value of thedensity parameter, assuming that IRAS galaxies trace the mass, isΩ=0.9(+0.45, -0.25). (4) Finally, the estimate of density varianceon large scales changes negligibly, still indicating a significantdiscrepancy from the predictions of simple cold dark matter cosmogonies.

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.

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 ( 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 ^12^CO(1-0) survey of spiral galaxies in the region of the Coma supercluster.
We present observations of the ^12^CO(J=1-0) line at 2.6mm of 65galaxies located in the Coma supercluster region: 33 actually belong tothe Coma supercluster while 32 are either foreground or backgroundobjects. These data have been obtained using the NRAO 12m telescope atKitt Peak (United States), and for four galaxies, using the IRAM 30mtelescope at Pico Veleta (Spain). Out of these 65 galaxies, 54 had neverbeen observed in the CO(1-0) line; 49 have been detected by us, of which37 are new detections. We give molecular gas masses deduced from the COline integrated intensities, and upper limits for the 16 undetectedobjects, computed with a Galactic conversion factorN(H_2_)=2.3x10^20^I(CO) and H_0_=75km/s/Mpc.

The UV properties of normal galaxies. III. Standard luminosity profiles and total magnitudes.
In the previous papers of this series we collected and reduced to thesame system all the available photometric data obtained in theultraviolet (UV) range for normal (i.e. non active) galaxies. Here weuse these data to derive standard UV luminosity profiles for threemorphological bins (E/S0; Sa/Sb; Sc/Sd) and extrapolated totalmagnitudes for almost 400 galaxies. We find that: 1) the UV growthcurves are well matched by the B-band revised standard luminosityprofiles, once a proper shift in the effective radius is applied, and 2)the UV light in early-type galaxies is more centrally concentrated thanthe visible light.

The UV properties of normal galaxies. II. The ``non-IUE'' data.
In the last decade several satellite and balloon borne experiments havecollected a large number of ultraviolet fluxes of normal galaxiesmeasured through apertures of various sizes and shapes. We havehomogenized this data set by deriving scale corrections with respect toIUE. In a forthcoming paper these data will be used to derive standardluminosity profiles and total magnitudes.

The extended 12 micron galaxy sample
We have selected an all-sky (absolute value of b greater than or equalto 25 deg) 12 micron flux-limited sample of 893 galaxies from the IRASFaint Source Catalog, Version 2 (FSC-2). We have obtained accurate totalfluxes in the IRAS wavebands by using the ADDSCAN procedure for allobjects with FSC-2 12 micron fluxes greater than 0.15 Jy and increasingflux densities from 12 to 60 microns, and defined the sample by imposinga survey limit of 0.22 Jy on the total 12 micron flux. Its completenessis verified, by means of the classical log N - log S andV/Vmax tests, down to 0.30 Jy, below which we have measuredthe incompleteness down to the survey limit, using the log N - log Splot, for our statistical analysis. We have obtained redshifts (mostlyfrom catalogs) for virtually all (98.4%) the galaxies in the sample.Using existing catalogs of active galaxies, we defined a subsample of118 objects consisting of 53 Seyfert 1s and quasars, 63 Seyfert 2s, andtwo blazars (approximately 13% of the full sample), which is the largestunbiased sample of Seyfert galaxies ever assembled. Since the 12 micronflux has been shown to be about one-fifth of the bolometric flux forSeyfert galaxies and quasars, the subsample of Seyferts (includingquasars and blazars) is complete not only to 0.30 Jy at 12 microns butalso with respect to a bolometric flux limit of approximately 2.0 x10-10 ergs/s/sq cm. The average value of V/Vmaxfor the full sample, corrected for incompleteness at low fluxes, is 0.51+/- 0.04, expected for a complete sample of uniformly distributedgalaxies, while the value for the Seyfert galaxy subsample is 0.46 +/-0.10. We have derived 12 microns and far-infrared luminosity functionsfor the AGNs, as well as for the entire sample. We extracted from oursample a complete subsample of 235 galaxies flux-limited (8.3 Jy) at 60microns. The 60 micron luminosity function computed for this subsampleis in satisfactory agreement with the ones derived from the brightgalaxy sample (BGS) and the deep high-galactic latitude sample, bothselected at 60 microns.

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.

Near infrared observations of galaxies in the Coma supercluster and in the Cancer cluster. II
New near infrared observations of 110 galaxies in the Coma/A1367supercluster region, and 40 galaxies in the Cancer cluster arepresented. These observations are part of an ongoing investigation ofthe properties of normal galaxies and of their near-IR emission, whichaims at obtaining homogeneous, multifrequency data for a large sample ofgalaxies in different density environments. The addition of theseobservations to the sample presented in Gavazzi and Trinchieri (1989)raises the number of Coma/A1367 galaxies with near-IR data to 275. Themeasurements, together with data published by Bothun et al. (1985), givea sample of 45 spirals in the Cancer cluster.

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.

Ultraviolet observations and star-formation rate in galaxies
The present 149 galaxies, essentially of spiral and irregular types wereobserved at about 2000 A in a survey using a balloon-borne imagingtelescope. Total ultraviolet fluxes in an about 125-A wide bandpass havebeen obtained by comparison with field stars. On average, the m(2000)-Bcolor gets redder from late to early morphological types. For a giventype, this color exhibits a large scatter which increases from late toearly types. As expected, the galaxies show a relation between them(2000)-B and B-V colors. After a correction for dust extinction basedon the neutral hydrogen content of each galaxy, the observed fluxes areused to obtain quantitative estimates of the current star formation rate(SFR). A good correlation is found between the SFR and the total gascontent. A weak correlation observed between the SFR per unit area andthe average gas surface density might be compatible with the existenceof a power-law relation of exponent 1, between birthrate and gasdensity. The SFR per unit gas mass shows both a significant dispersionand a decrease toward later types. Implications in terms of starformation history are discussed.

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.

A catalog of hierarchical subclustering in the Turner-Gott groups
Information on the substructure, to four levels of hierarchy, ispresented for the 103 groups listed by Turner and Gott (TG) in theircatalog of groups of galaxies. All galaxies brighter than Mpg= 14.0 in the region delta is 0 deg or greater and b(II) is 40 deg orgreater that have been assigned group memberships by TG are included.Also listed is the local environmental information for each of thegalaxies, giving the surface density enhancement beta in the galaxy'sneighborhood, calculated at 15 levels in the range beta = 4.6 to 10,000.

Accurate Optical Positions of Arakelian Galaxies
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1981AJ.....86..820K&db_key=AST

Galaxies of high surface brightness
Two lists are presented which contain 621 galaxies whose surfacebrightness, as derived from their apparent magnitudes, is at least 22.0magnitudes from an area of 1 sq arcsec. The lists were compiled in anattempt to verify observationally a possible correlation between surfacebrightness and nuclear activity. Four percent of all the galaxies in anarea of 4.5 sr at declinations higher than -3 deg and galactic latitudesgreater than 20 deg are listed, including 30 Markarian, 29 Zwicky, and 7blue Haro galaxies. A morphological study of 130 of the galaxiesindicates that about half are elliptical or lenticular, 50 are compactor peculiar, and that there is an excess of elliptical and lenticularobjects in comparison with a random sample. Notes on the morphologicaltypes and colors of the galaxies are provided along with identificationcharts.

Submit a new article

Related links

  • - No Links Found -
Submit a new link

Member of following groups:

Observation and Astrometry data

Constellation:Coma Berenices
Right ascension:12h19m52.60s
Aparent dimensions:0.851′ × 0.776′

Catalogs and designations:
Proper Names   (Edit)
NGC 2000.0NGC 4275

→ Request more catalogs and designations from VizieR