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Rotational Widths for Use in the Tully-Fisher Relation. I. Long-Slit Spectroscopic Data
We present new long-slit Hα spectroscopy for 403 noninteractingspiral galaxies, obtained at the Palomar Observatory 5 m Hale telescope,which is used to derive well-sampled optical rotation curves. Becausemany of the galaxies show optical emission features that aresignificantly extended along the spectrograph slit, a technique wasdevised to separate and subtract the night sky lines from the galaxyemission. We exploit a functional fit to the rotation curve to identifyits center of symmetry; this method minimizes the asymmetry in thefinal, folded rotation curve. We derive rotational widths using bothvelocity histograms and the Polyex model fit. The final rotational widthis measured at a radius containing 83% of the total light as derivedfrom I-band images. In addition to presenting the new data, we use alarge sample of 742 galaxies for which both optical long-slit and radioH I line spectroscopy are available to investigate the relation betweenthe H I content of the disks and the extent of their rotation curves.Our results show that the correlation between those quantities, which iswell established in the case of H I-poor galaxies in clusters, ispresent also in H I-normal objects: for a given optical size, starformation can be traced farther out in the disks of galaxies with largerH I mass.
| New H I observations for some edge-on spiral galaxies
We present new H I observations made at the Nancay radiotelescope for 53previously undetected galaxies. For each of the 47 detected objects wegive the heliocentric H I velocity, H I linewidths at 20 percent and 50percent of the maximum intensity, and the H I flux. These galaxies havebeen included in a sample built for the study of group membership.
| New H I observations for some edge-on spiral galaxies
We present new H I-observations made at the Nancay radiotelescope for 53previously undetected galaxies. For each of the 47 detected objects wegive the heliocentric H I-velocity, H I-linewidths at 20 percent and 50percent of the maximum intensity and the H I-flux. These galaxies havebeen included in a sample built for the study of group membership.
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