HI LINEWIDTHS, ROTATION VELOCITIES AND THE TULLY-FISHER RELATION

摘要: We determine the rotation velocities of 108 spiral and irregular galaxies (XV-Sample) from first-order curves position-velocity maps, based on short 21-cm observations with Westerbork Synthesis Radio Telescope (WSRT). To test usual random motion corrections, we compare global HI linewidths velocities, obtained kinematical fits to two-dimensional velocity fields for a sample 28 (RC-Sample), find that most frequently used correction formulae (Tully & Fouque 1985) are not very satisfactory. The parameter (the random-motion corrected linewidth: W?), derived these may be statistically equal two times true velocity, but in individual cases differences can large. analyse, both RC- XV-Samples, dependence slope of, scatter Tully-Fisher relation definition parameters- For RC-Sample, reduced considerably when instead H I linewidths. No such reduction is seen XV-Sample. conclude seems related use information: accurate inclination.