H I line studies of galaxies. II. The 21-cm-width as an extragalactic distance indicator.
Abstract
From a sample of 864 galaxies having homogeneous 21-cm and optical data in RC 2, corrections are made to the 21-cm line widths measured at three levels (10 percent, 40 percent, 50 percent) for turbulent motions. It is shown that these corrections are far from negligible. The corrected half-widths are, independently of the level, statistically equal to the amplitude VM of the rotation curve. The choice of zero points is seen as having no effect on the linearity of the scale of distances derived from H I line profile widths. For this reason, the tests of the linearity of different distance scales derived from different indicators (including the 21-cm moduli here) which have been reported elsewhere are in no way affected by the remaining uncertainties in the zero point.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- February 1983
- Bibcode:
- 1983A&A...118....4B
- Keywords:
-
- Astronomical Spectroscopy;
- Distance Measuring Equipment;
- Galaxies;
- H Lines;
- Spectral Line Width;
- Centimeter Waves;
- Error Analysis;
- Galactic Structure;
- Red Shift;
- Velocity Distribution;
- Astrophysics