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The UZC-SSRS2 Group Catalog
We apply a friends-of-friends algorithm to the combined Updated ZwickyCatalog and Southern Sky Redshift Survey to construct a catalog of 1168groups of galaxies; 411 of these groups have five or more members withinthe redshift survey. The group catalog covers 4.69 sr, and all groupsexceed the number density contrast threshold, δρ/ρ=80. Wedemonstrate that the groups catalog is homogeneous across the twounderlying redshift surveys; the catalog of groups and their membersthus provides a basis for other statistical studies of the large-scaledistribution of groups and their physical properties. The medianphysical properties of the groups are similar to those for groupsderived from independent surveys, including the ESO Key Programme andthe Las Campanas Redshift Survey. We include tables of groups and theirmembers.
| Galaxy coordinates. II. Accurate equatorial coordinates for 17298 galaxies
Using images of the Digitized Sky Survey we measured coodinates for17298 galaxies having poorly defined coordinates. As a control, wemeasured with the same method 1522 galaxies having accurate coordinates.The comparison with our own measurements shows that the accuracy of themethod is about 6 arcsec on each axis (RA and DEC).
| Evidence for a 3 X 10^8 M_ȯ Black Hole in NGC 7052 from Hubble Space Telescope Observations of the Nuclear Gas Disk
We present a Hubble Space Telescope (HST) study of the nuclear region ofthe E4 radio galaxy NGC 7052, which has a nuclear disk of dust and gas.The Second Wide Field and Planetary Camera (WFPC2) was used to obtain B,V, and I broadband images and an Hα + [N II] narrowband image. Theimages yield the stellar surface brightness profile, the optical depthof the dust, and the flux distribution of the ionized gas. The FaintObject Spectrograph was used to obtain Hα + [N II] spectra at sixdifferent positions along the major axis, using a 0.26" diametercircular aperture. The emission lines yield the rotation curve of theionized gas and the radial profile of its velocity dispersion. Theobserved rotation velocity at r = 0.2" from the nucleus is V = 155 +/-17 km s^-1. The Gaussian dispersion of the emission lines increases fromsigma ~ 70 km s^-1 at r = 1" to sigma ~ 400 km s^-1 on the nucleus. Tointerpret the gas kinematics, we construct axisymmetric models in whichthe gas and dust reside in a disk in the equatorial plane of the stellarbody and are viewed at an inclination of 70 deg. It is assumed that thegas moves on circular orbits, with an intrinsic velocity dispersion dueto turbulence (or otherwise nongravitational motion). The latter isrequired to fit the observed increase in the line widths toward thenucleus and must reach a value in excess of 500 km s^-1 in the central0.1". The circular velocity is calculated from the combinedgravitational potential of the stars and a possible nuclear black hole.Models without a black hole predict a rotation curve that is shallowerthan observed (V_pred = 92 km s^-1 at r = 0.2") and are ruled out atgreater than 99% confidence. Models with a black hole of massM_a=3.3^+2.3_-1.3x10^8 M_ȯ provide an acceptable fit. Thebest-fitting model with a black hole adequately reproduces the observedemission-line shapes on the nucleus, which have a narrower peak andbroader wings than a Gaussian. NGC 7052 can be added to the list ofactive galaxies for which HST spectra of a nuclear gas disk provideevidence for the presence of a central black hole. The black hole massesinferred for M87, M84, NGC 6251, NGC 4261, and NGC 7052 span a range ofa factor of 10, with NGC 7052 falling on the low end. By contrast, theluminosities of these galaxies are identical to within ~25%. Anyrelation between black hole mass and luminosity, as suggested byindependent arguments, must therefore have a scatter of at least afactor of 10.
| Scaleheights of 486 southern spiral galaxies and some statistical correlation
Based on Peng's method (1988), we obtain scaleheights of 486 southernspiral galaxies, the images of which are taken from the Digitized SkySurvey at Xinglong Station of Beijing Astronomical Observatory. Thefitted spiral arms of 70 galaxies are compared with their images to gettheir optimum inclinations. The scaleheights of other 416 ones arelisted in Table A1 in Appendix. After compiling and analyzing the data,we find some statistical correlations. The most interesting results arethat a flatter galaxy is bluer and looks brighter, and galaxies becomeflatter along the Hubble sequence Sab -- Scd. Based on photographic dataof the National Geographic Society -- Palomar Observatory Sky Survey(NGS-POSS) obtained using the Oschin Telescope Palomar Mountain. TheNGS-POSS was funded by a grant from the National Geographic Society tothe California Institute of Technology. The plates were processed intothe present compressed digital form with their permission. The DigitizedSky Survey was produced at the Space Telescope Science Institute underUS Government grant NAG W-2166. Table A1 is available in electronic fromonly, via anonymous ftp 130.79.128.5 orhttp://cdsweb.u-strasbg.fr/Abstract.html
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