Year: 1971
Type: article
Abstract: The neutral hydrogen survey of M33 taken with an angular resolution of |${14}^{\prime}\,\times\,{18}^{\prime}$| arc and a velocity resolution of 8.4 km s –1 has been analysed and compared with optical data. Comparison with the distribution of H II regions shows that they are more centrally concentrated than the neutral hydrogen; in the outer areas of M33 there is a significant amount of neutral hydrogen but no recorded H II regions. An investigation of the mean velocities of groups of H II regions showed close agreement with neutral hydrogen velocities obtained from the position of the ridge-lines in constant velocity maps. The neutral hydrogen mass of M33 was found to be |$1.35\,\times\,{10}^{9}\,{M}_{\odot}$| . An investigation was made of the distribution of the M/L ratio along the major axis of M33; the mean value of M/L is 4.9 uncorrected for internal absorption. Other derived parameters are given in Tables I–IV. The nature of the strong distortion found in the neutral hydrogen density and velocity distributions was investigated. It is interpreted in terms of a tilt in the neutral hydrogen plane of M33 similar to that already known in the Milky Way.
Authors: G. de Jager, R. D. Davies
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2066918052