High-Resolution, High Signal-to-Noise, Global H I Spectra of Southern, Extreme Late-Type Spiral Galaxies

• Published in: The Astronomical journal Vol. 116; no. 3; pp. 1169 - 1185
• Main Authors: Matthews, L. D, van Driel, W, Gallagher III, J. S
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.09.1998
• ISSN: 1538-3881; 0004-6256; 1538-3881
• DOI: 10.1086/300492

We have used the Nanay decimetric radio telescope to obtain high-resolution, high SNR, global H I spectra of 30 southern, extreme late-type spiral galaxies with Vh 3000 km/s. For all of the galaxies we measure new precise radial velocities and H I velocity widths. Optical imaging and photometry of these galaxies was recently published by Matthews and Gallagher. In Appendix B we present new H I spectra for four additional late-type galaxies. The H I spectra of the extreme late-type spirals have velocity widths characteristic of true, rotationally supported disk galaxies, and most are double-peaked. Nonetheless, the morphologies of the H I profiles are diverse, indicating that disk galaxies with similar H I contents and optical luminosities can have very different H I distributions and/or velocity fields. H I profile type and Hubble type are generally well-correlated for our sample. Seventy-seven percent of our H I profiles show at least some degree of asymmetry; in many cases the stellar disk of these galaxies is also asymmetric. Several of our spectra have an additional H I peak near the systemic velocity, perhaps indicating a gas enhancement in the central regions of the galaxy disk. (Author)