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Date and Time of the Query: 2019-06-25 T15:05:06 PDT
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For refcode 1997AJ....113..950F:
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Copyright by American Astronomical Society. Reproduced by permission
1997AJ....113..950F KINEMATIC PROFILES OF S0 GALAXIES DAVID FISHER Kapteyn Astronomical Institute, University of Groningen. Postbus 800,9700 AV Groningen, The Netherlands Electronic mail: fish@astro.rug.nl Received 1996 May 15; revised 1996 September 5 ABSTRACT Stellar rotation curves, velocity dispersion profiles, and line-of-sight velocity distributions (LOSVD) as derived from absorption lines are presented for the major axes of 18 S0 and two elliptical galaxies. Ionized gas rotation curves and dispersions were measured from the [O III] 5007 A emission line in the 9 S0 galaxies displaying this feature. Minor-axis results are given for 14 of the S0 galaxies and one of the ellipticals. A wide range of behaviors are observed in the rotation and velocity dispersion profiles. These variations could be the result of the superposition of stars and gas belonging to the disks and bulges as well as the possible influences of bars, nuclear disks, and warps. Deviations from a Gaussian LOSVD are found along the major axes of all the galaxies in our sample. As parametrized by the Gauss-Hermite series of orthogonal functions, asymmetric deviations are always found in the inner regions of the S0 galaxies such that the prograde wing of the LOSVD is steeper than the retrograde wing. This is similar to the behavior observed in elliptical galaxies. However, at larger radii these asymmetries can change their sign. We find that in 9 of the 18 S0 galaxies a high-speed tail to the LOSVD develops along the major axis beyond the central regions. In 3 of these 9 objects the LOSVD asymmetries display a second change of sign with radius such that a low- speed tail is again present and persists to our last measured values. No correlations were found between the sizes of the stellar velocity dispersion gradients and either central velocity dispersion, absolute magnitude, disk-to-bulge ratio, Mg_2_ or Fe line strength gradients. For the objects in our sample with edge-on orientations a comparison between the minor-axis `bulge' velocity dispersion gradients and those found in elliptical galaxies indicates that the S0 bulges display, on average, logarithmic gradients approximately 4 times steeper than those found in normal luminous ellipticals. A number of galaxies show particularly interesting features. For the LINER S0 galaxy NGC 3998 we find that the velocity dispersion profiles of both the stars and gas rise sharply towards the center reaching nuclear values of {sigma} ~ 320 km s^-1^. Nuclear disks of rapidly rotating gas are found in NGC 4350 and NGC 4762. A nuclear stellar disk is apparent in the edge-on galaxy NGC 4111 and an extended disk of counterrotating gas is observed in the barred S0 NGC 3941.
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