目录
图像
上传图像
DSS Images Other Images
相关文章
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 (130.79.128.5) or via\http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/405/5
| 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.
| 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.
| UGC galaxies stronger than 25 mJy at 4.85 GHz
UGC galaxies in the declination band +5 to +75 deg were identified byposition coincidence with radio sources stronger than 25 mJy on theGreen Bank 4.85 GHz sky maps. Candidate identifications were confirmedor rejected with the aid of published aperture-synthesis maps and new4.86 GHz VLA maps having 15 or 18 arcsec resolution, resulting in asample of 347 nearby radio galaxies plus five new quasar-galaxy pairs.The radio energy sources in UGC galaxies were classified as 'starbursts'or 'monsters' on the basis of their infrared-radio flux ratios, infraredspectral indices, and radio morphologies. The rms scatter in thelogarithmic infrared-radio ratio q is not more than 0.16 for starburstgalaxies selected at 4.85 GHz. Radio spectral indices were obtained fornearly all of the UGC galaxies, and S0 galaxies account for adisproportionate share of the compact flat-spectrum (alpha less than0.5) radio sources. The extended radio jets and lobes produced bymonsters are preferentially, but not exclusively, aligned within about30 deg of the optical minor axes of their host galaxies. The tendencytoward minor-axis ejection appears to be independent of radio-sourcesize and is strongest for elliptical galaxies.
| On the relationship between radio emission and optical properties in early-type galaxies
To study the origin of radio activity in early-type galaxies, thepossible dependence of their radio emission on basic optical parameters,such as the absolute magnitude, the central velocity dispersion sigma,and the mean surface brightness mu is explored. A sample of 743 E and SOgalaxies is used which is based on three independent radio surveys ofoptically selected galaxies with virtually complete information onmagnitudes, morphological types, redshift distances, diameters, andradio fluxes. For both E and SO galaxies, only the absolute magnitudeappears to be directly related to the radio activity, while sigma and mudo not. Also, a significant dependence of the apparent flattening onradio power is confirmed for E galaxies. Some relevant implications ofthese results are discussed.
| IRAS spectra planetary nebulae. III
Measurements of the IRAS spectra of planetary nebulae are presented. Thespectra cover the wavelength 7.5 to 23 microns. The lines observed aremainly from ions of neon and sulfur. The abundance of these two elementsis determined and compared to results found in other astronomicalobjects. It is also found that the Ne(4+) ion, when present, is formedin a region whose density is an order of magnitude higher than theregion whose density is an order of magnitude higher than the regionwhere most of the line emission originates. IUE measurements of theNe(3+) line of many of the nebulae are presented.
| A search for environmental effects on the optical properties of galaxies in groups
Environmental density-related modifications of basic optical properties(luminosities, sizes, axial ratios, and colors) of galaxies belonging toGeller and Huchra's (1983) groups have been investigated. Remarkably, itis found that the broad maxima of the distributions of luminosities anddiameters of spirals and the whole corresponding distributions oflenticulars tend to move to lower values as one goes to groups of highcompactness, whereas the luminosity-diameter relationship of spiralstends to become flatter. No color and axial ratio differences betweengalaxies of high- and low-compactness groups have been detected.
| Planetary nebulae - IUE results
The results of IUE observations of planetary nebulae are listed anddiscussed. With regard to the nebulae themselves, advances inunderstanding the density and temperature profiles across the nebula,the nebular continuum, the ionization structure, the chemicalcomposition, and the nebular dust are presented. With regard to thecentral stars, the mass loss phenomenon from fast winds, thedetermination of the temperature of the nuclei and the consequentimprovement of the star's HR diagram, and the chemical composition ofthe stellar surface layers are considered.
| 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.
| Profiles and intensity ratios of the C IV lambda 1548, 1550 emission lines in planetary nebulae
The C IV resonance doublet at lambda 1548, 1550 is an importantdiagnostic tool in the study of planetary nebulae. The predictedtheoretical intensity ratio of 2:1 is, however, rarely observed in thehigh dispersion IUE spectrograms. Values of 0.8-2.0 are observed for asampling of 11 planetary nebulae of various excitation classes and forthree proto-planetary nebulae. A diversity of line profiles is observed.In addition to the C IV doublet, weak subsidiary lines are seen. Thespacing between these pseudo-lines happens to correspond to theseparation of the C IV lines but are believed to be due to hot pixelsand do not conform to the radial velocity displacement of the C IVlines.
| Radial velocities of galaxies detected in the Arecibo 2380 MHz survey
The Loiano telescope's image tube spectrograph was used to obtain thepreviously unknown radial velocities of 50 galaxies detected during theArecibo 2380 MHz survey of bright galaxies, leading to the determinationof 224 radio-detected galaxy redshifts north of 15 deg. Both a 100km/sec typical standard error and minus 60 plus or minus 20 km/secsystematic zero error are derived for the velocities presented, on thebasis of comparisons with other redshift sources made on a furthersample of 35 galaxies.
|
提交文章
相关链接
提交链接
下列团体成员
|
观测天体数据
目录:
|
