2004/10/20 by M. Relaño, M. Relano, J. E. Beckman +3 · 3 citations
Chemistry · Physics and Astronomy · #Galaxies: Formation, Evolution, Phenomena #Spectroscopy and Laser Applications #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1051/0004-6361:20040483
19 pages, 10 figures,accepted for publication in A&A
arxiv created 2004/10/20 · openalex publication_date 2005/02/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We present an analysis of the integrated Hα emission line profiles for the H ii region population of the spiral galaxies NGC 1530, NGC 6951 and NGC 3359. We show that ~70% of the line profiles show two or three Gaussian components. The relations between the luminosity () and non-thermal line width () for the H ii regions of the three galaxies are studied and compared with the relation found taken all the H ii regions of the three galaxies as a single distribution. In all of these distributions we find a lower envelope in log . A clearer envelope in is found when only those H ii regions with are considered, where is a canonical estimate of the sound speed in the interestellar medium. The linear fit for the envelope is where the Hα luminosity of the region is taken directly from a photometric H ii region catalogue. When the Hα luminosity used instead is that fraction of the H ii region luminosity, corresponding to the principal velocity component, i.e. to the turbulent non-expanding contribution, the linear fit is , i.e. unchanged but slightly tighter. The masses of the H ii regions on the envelope using the virial theorem and the mass estimates from the Hα luminosity are comparable, which offers evidence that the H ii regions on the envelope are virialized systems, while the remaining regions, the majority, are not in virial equilibrium.