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| Format: | Artículo científico |
| Langue: | en |
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Universidad Nacional Autónoma de México
2002
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| Accès en ligne: | https://www.redalyc.org/articulo.oa?id=57112082 |
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- Density bounding in the H II regions of galactic disks: evidence and consequences M. Relaño A. Cardwell A. Zurita J. E. Beckman M. Rozas Física, Astronomía y Matemáticas ISM: GENERAL GALAXIES: ISM GALAXIES: SPIRAL ISM: H II REGIONS We present four lines of evidence leading to the conclusion that a notable fraction of the ionizing photonemission from the stars within H II regions in the disks of normal galaxies escapes from the regions into thesurrounding galaxy and beyond. These are: (1) The surface brightness intensity distribution of the di use H emitted by a disk galaxy is well modeled by assuming that the Lyman continuum producing it leaks from theH II regions. (2) The relation of the central H surface brightness to total luminosity of an H II region departsfrom the predictions of uniform ionization bounded systems. (3) The H luminosity function of complete H IIregion populations shows a break whose parameters are explicable using the density bounding hypothesis, butnot via competing hypotheses. (4) The relation between the H internal velocity half{width and luminosityfor H II regions is naturally explained via density bounding. A fractally clumpy cloud structure, and a simplelaw relating the mass of the most luminous star in a young cluster to the mass of its placental gas cloud givemodel parameters which can account for the observations. We show how the fraction of the Lyc escaping fromleaky H II regions which nally completely escapes the galactic disks can ionize large volumes of the ultra{lowdensity intracluster gas around galaxies. 2002 artículo científico 0185-1101 https://www.redalyc.org/articulo.oa?id=57112082 en http://www.redalyc.org/revista.oa?id=571 Revista Mexicana de Astronomía y Astrofísica application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Astronomía y Astrofísica (México) Vol.12