J/ApJS/106/27 J/ApJS/106/27 Spiral galaxies in pairs W C Keel Astrophys. J. Suppl. Ser. 106 27 1996 1996ApJS..106...27K VII/77 : Catalog of Pairs of Galaxies (CPG) (Karachentsev+ 1972) Galaxies, rotation galaxies: distances and redshifts galaxies: kinematics and dynamics galaxies: Seyfert galaxies: spiral Rotation curves have been obtained for 76 spiral galaxies in pairs, including a geometrically selected subset from the Karachentsev catalog and a set of Seyfert galaxies with close companions. Derived parameters of the rotation curves and the galaxies' light distributions are also presented. The rotation curves are classified broadly by shape, with special emphasis on kinematic disturbances and regions of solid-body behavior that may lead to bar development. Broadband images of the galaxies allow assessments of their degree of symmetry or disturbance. These velocity slices afford an empirical basis for evaluating the accuracy of radial velocity measures for spiral galaxies in pairs, and the dynamically important radial velocity differences. Specifically, the disagreement among several plausible ways of estimating the central velocity from these rotation data is used to estimate how closely any of these might approximate the nuclear or center-of-mass values. From seven indicators of central velocity, the internal scatter is delta_vv = 34 km/s. Of these, the velocity weighted by Halpha intensity along the slit shows a systematic offset of about 20 km/s with respect to the others for the Karachentsev pairs, in the sense that this measure is redshifted with respect to the other indicators. This is in the sense (but not of the total magnitude) required to account for statistical asymmetries in pair velocity differences. Individual scatter between the velocity indicators taken pairwise ranges from delta = 20 to 52 km/s. These results imply that emission-line data such as these cannot specify the center of mass or nuclear redshift at a level more accurate than this, even for arbitrarily precise velocity measurements, because it is not clear how the observed quantities relate to the desired measurement in a physical sense. No useful predictor of which galaxies have large or small scatter among velocity measures was found, except that the scatter is small for the class of "nonrotating" galaxies with small overall velocity amplitudes. Projected separation, separation normalized to disk scale length, and morphological disturbance do not correlate with velocity scatter.

CPG CPG (Cat. <VII/77>) name --- Name Other name --- n_CPG absorption --- PA Position angle deg HVcorr Correction to heliocentric velocity km/s Peak Adopted location along the slit from the continuum peak --- CPG CPG (Cat. <VII/77>) name --- Pixel Pixel number along the slit Pixel number along the slit, at a scale of 0.78 arcsecond/pixel. The slices are along the position angles indicated in the header records. Smaller pixel numbers are at the eastern end of the slit (that is, NNE for PA 10 degrees, SSE at PA 170). pix Vobs Weighted mean velocity in the relativistic convention km/s e_Vobs 2-sigma error derived from photon statistics km/s Halpha Total Halpha intensity Total H-alpha intensity in instrumental units (neglecting the broad-line component where it can be distinguished). --- Cont Continuum intensity --- Lines Number of emission lines measured --- Patricia Bauer CDS 1997Feb03AAS CD-ROM series, Volume 7, 1996 Lee Brotzman [ADS] 09-Oct-96 J_ApJS_106_27.xml