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J/ApJS/106/27           Spiral galaxies in pairs                (Keel, 1996)
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Rotation curves and velocity measures for spiral galaxies in pairs
     Keel W.C.
    <Astrophys. J. Suppl. Ser. 106, 27 (1996)>
    =1996ApJS..106...27K
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ADC_Keywrods: Galaxies, rotation
Keywords: galaxies: distances and redshifts -
          galaxies: kinematics and dynamics - galaxies: Seyfert -
          galaxies: spiral

Abstract:
    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.

File Summary:
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  FileName      Lrecl  Records   Explanations
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ReadMe             80        .   This file
table2a            38       52   Galaxy pair parameters
table2b            45     3250   Velocity curves for galaxy pairs
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See also:
     VII/77 : Catalog of Pairs of Galaxies (CPG) (Karachentsev+ 1972)

Byte-by-byte Description of file: table2a
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   Bytes Format Units   Label     Explanations
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   1-  8  A8    ---     CPG       CPG (Cat. <VII/77>) name
  10- 18  A9    ---     Name      Other name
  20- 22  A3    ---   n_CPG       [abs] absorption
  24- 26  I3    deg     PA        Position angle
  28- 32  F5.1  km/s    HVcorr    Correction to heliocentric velocity
  34- 38  F5.1  ---     Peak      Adopted location along the slit from the
                                   continuum peak
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Byte-by-byte Description of file: table2b
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   Bytes Format Units   Label     Explanations
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   1-  8  A8    ---     CPG       CPG (Cat. <VII/77>) name
  10- 12  I3    pix     Pixel    *Pixel number along the slit
  14- 20  F7.1  km/s    Vobs      Weighted mean velocity in the relativistic
                                      convention
  22- 27  F6.1  km/s  e_Vobs      2-sigma error derived from photon statistics
  29- 36  F8.1  ---     Halpha   *Total Halpha intensity
  38- 43  F6.1  ---     Cont      Continuum intensity
      45  I1    ---     Lines     Number of emission lines measured
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Note on Pixel:
  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).
Note on Halpha:
  Total H-alpha intensity in instrumental units (neglecting the
  broad-line component where it can be distinguished).
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Origin: AAS CD-ROM series, Volume 7, 1996           Lee Brotzman [ADS] 09-Oct-96
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(End)                                          Patricia Bauer [CDS]  03-Feb-1997