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|Atomic and Molecular Gas in Colliding Galaxy Systems. I. The Data|
We present H I and CO (1-0) interferometric observations of 10comparable-mass interacting systems obtained at the Very Large Array(VLA) and the Owens Valley Radio Observatory (OVRO) millimeter array.The primary intent of this study is to investigate the response of coldgas during the early stages of collision of massive disk galaxies. Thesample sources are selected based on their luminosity(MB<=-19), projected separation (5-40 kpc), andsingle-dish CO (1-0) content (SCO>=20 Jy kms-1). These selection criteria result in a sample thatprimarily consists of systems in the early stages of an interaction or amerger. Despite this sample selection, 50% of the systems show long H Itidal tails indicative of a tidal disruption in a prograde orbit. Inaddition, all (4/4) of the infrared luminous pairs (LIRGs) in the sampleshow long H I tails, suggesting that the presence of a long H I tail canbe a possible signature of enhanced star formation activity in acollision of gas-rich galaxies. More than half of the groups show adisplacement of H I peaks from the stellar disks. The CO (1-0)distribution is generally clumpy and widely distributed, unlike in mostIR-selected late stage mergers-in fact, CO peaks are displaced from thestellar nucleus in 20% (4/18) of the galaxies with robust CO detection.H I and CO (1-0) position-velocity diagrams (PVDs) and rotation curvesare also presented, and their comparison with the numerical simulationanalyzed in Paper I show evidence for radial inflow and wide occurrencesof nuclear molecular rings. These results are further quantified byexamining physical and structural parameters derived in comparison withisolated systems in the BIMA SONG sample in our forthcoming paper.
|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.
|UBVRI photometry of the Durham-AAT redshift survey|
Using the PDS microdensitometer at the Royal Greenwich Observatory, wehave acquired U, B, V, R and I surface photometry from UK Schmidtphotographic plates for all the galaxies with measured redshifts in theDurham-AAT redshift survey. By comparison with CCD photometry we showthat such precision photographic photometry of galaxies off IIIaemulsions is capable of an accuracy as good as a few hundredths of amagnitude. We discuss the color-related properties of these galaxies,and derive luminosity functions in each waveband. We show that, whendivided by color, the faint-end slope of the luminosity function of thebluer galaxies is significantly steeper than that for the redder ones.
|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.
|CCD galaxy photometry and the calibration of photographic surveys|
We present CCD UBVRI aperture photometry and total B-band magnitudes fora sample of 155 galaxies with B<~18 covering 14UK Schmidt fields. The data, taken on a variety of telescopes, have beenacquired in order to calibrate photographic photometry on these fields.Using these data, we discuss the calibration of photographic galaxysurveys at these magnitudes, and show that the accuracy of suchphotometry is potentially better than +/-0.05 mag. However, data fromboth the COSMOS and APM automatic plate measuring machines show strongsurface-brightness-dependent systematic errors, which primarily manifestthemselves as a much increased scatter (~+/-0.25 mag). The cause ofthese effects is almost certainly related to the limited dynamic rangeof the automated machines. They have the potential to introduce scaleerrors of up to ~0.1 mag per magnitude into the photographic magnitudes,and we discuss the implications of this for bright galaxynumber-magnitude counts. We show evidence for a scale error in the APMgalaxy survey magnitudes. Our revised APM magnitudes allow a standard,non-evolving cosmological model to fit the APM galaxy counts in therange 17<B<20, although this model continuesto overpredict the galaxy count at brighter magnitudes.
|Galaxy redshifts in an equatorial field in Virgo and the spatial distribution of local Lyman alpha clouds|
New redshifts are presented for 51 galaxies which lie in a narrow stripalong the celestial equator. The redshifts are derived from a mixture ofoptical and H I spectra; for the latter subset (37 galaxies) H I fluxesand line widths are also given. One of the two Ly-alpha clouds in theLocal Supercluster appears to be associated with a spiral galaxy,although the angular and physical separations (42 arcmin and 180 kpc)are large. The other nearby Ly-alpha cloud and the large H I cloudappear to be more isolated. None of the nine Ly-alpha clouds withvelocities between 5000-20,000 km/s are associated with any specificgalaxies, but most appear to fall within or near the large-scalestructures defined by the galaxies.
|Isolated Triplets of Galaxies - a Complete Summary of Radial Velocities and Reduced Data|
|A complete galaxy redshift sample. III - Methods and catalogue|
Redshifts and photometry are presented for 329 field galaxies selectedin five high-latitude fields to limiting isophotal B1 magnitudes ofabout 17. The essential spectroscopy was obtained at theAnglo-Australian Telescope. It is demonstrated that the photometricprecision is better than 0.10 mag and that the radial velocity errorsare mostly below 45 km/s. Some aspects of the galaxy distribution andspectral-line statistics are briefly discussed.
|Radial velocities and virial masses of some isolated triplets of galaxies|
Spectroscopic observations of isolated triple systems from the list ofKarachentseva et al. (1979), obtained using the UAGS spectrograph andUM-92 image tube (slit scale 8.6 arcsec/mm, reciprocal dispersion 100A/mm) on the 6-m telescope of the Special Astrophysical Observatory ofthe USSR Academy of Sciences during 1981-1982, are reported. Radialvelocities for 31 components belonging to 13 triplets and calculatedvirial masses and mass-luminosity ratios (f) for seven triplets arepresented in tables. The corrected values of f range from 0.2 to 82.4solar f.
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