Formation of H II Regions.
نویسندگان
چکیده
منابع مشابه
Formation of Mini-galaxies in Defunct Cosmological H Ii Regions
Using a large set of high resolution numerical simulations incorporating non-equilibrium molecular hydrogen chemistry and a constant source of external radiation, we study gas collapse in previously photo-ionized mini-galaxies with virial temperatures less than 104 K in the early universe (redshifts z = 10 − 20). We confirm that the mechanism of positive feedback of ionizing radiation on star f...
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RESUMEN Discutimos algunos resultados observacionales recientes sobre regiones H II ultracompactas. En particular, discutimos la emisión extendida de algunas regiones H II UC y el descubrimiento de una nueva clase, denominada regiones H II " hipercompactas ". Además, describimos la obtención de la estructura de densidad usando la técnica del análisis deí ındice espectral. ABSTRACT We discuss so...
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The nebular properties (electronic density, extinction , age, O/H abundances) of H ii regions found along the bars of the sample of barred spiral galaxies studied by Martin & Friedli (1997) are examined. From line ratio diagnostic diagrams, it is showed that regions located along the major axis of the bars have a normal photoionization spectrum, that is, line ratios reproductible from nebular c...
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We have discovered a number of very small isolated H ii regions 20-30 kpc from their nearest galaxy. The H ii regions appear as tiny emission line dots (ELdots) in narrow band images obtained by the NOAO Survey for Ionization in Neutral Gas Galaxies (SINGG). We have spectroscopic confirmation of 5 isolated H ii regions in 3 systems. The Hα luminosities of the H ii regions are equivalent to the ...
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The hypothesis that massive stars form by accretion can be investigated by simple analytical calculations that describe the effect that the formation of a massive star has on its own accretion flow.Within a simple accretion model that includes angular momentum, that of gas flow on ballistic trajectories around a star, the increasing ionization of a massive star growing by accretion produces a t...
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ژورنال
عنوان ژورنال: The Astronomical Journal
سال: 1962
ISSN: 0004-6256
DOI: 10.1086/108788