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Publications of the Astronomical Society of the Pacific, 1974
This is a review of the current status of the study of H II regions in other galaxies, especially their spatial distribution and relation to galactic structure. An extensive table compiles all available data on the H-alpha surveys of galaxies.
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This is a review of the current status of the study of H II regions in other galaxies, especially their spatial distribution and relation to galactic structure. An extensive table compiles all available data on the H-alpha surveys of galaxies.
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1974
The study of HII regions is very old. In the 17th century Christiaan Huygens had already observed and described the Orion nebula. Our understanding of this and similar objects increased dramatically between 1925 and 1940 when quantum theory made it possible to interprete the emission line spectra quantitatively.
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The study of HII regions is very old. In the 17th century Christiaan Huygens had already observed and described the Orion nebula. Our understanding of this and similar objects increased dramatically between 1925 and 1940 when quantum theory made it possible to interprete the emission line spectra quantitatively.
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Publications of the Astronomical Society of the Pacific, 1986
Models of H II regions provide ionization corrections for abundance determinations and estimates of the ionizing star temperature Tasterisk and of the nebular ionization parameter U. In the absence of observed electron temperatures, models may be used to determine abundances; and a systematic procedure is described here.
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Models of H II regions provide ionization corrections for abundance determinations and estimates of the ionizing star temperature Tasterisk and of the nebular ionization parameter U. In the absence of observed electron temperatures, models may be used to determine abundances; and a systematic procedure is described here.
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Pressure and Density Gradients in H ii Regions
Astrophysics and Space Science, 2001Here we discuss the effects of large ambient pressures and decreasing density gradients on the observed properties of dusty UCH ii regions. Dust absorption can effectively reduce the size of the photoionized region, and density gradients can modify the spectral index of the emission.
José Franco +6 more
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Observations of High Velocities in H II Regions
Nature, 1970SEVERAL investigators using a variety of optical instruments have indicated that small components of the ionized matter in H II regions are in a highly turbulent state1–5. In particular, Shcheglov3, using a photographic, single etalon Fabry–Perot at Hα in a non-classical combination with a telescope, found small components with turbulence of up to 100 ...
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2008
A probable evolutionary sequence of H II regions based on six distinct types of observed objects is suggested. Two examples which may deviate from this idealized sequence, are discussed. Even though a sizemean density relation for H II regions can be used as a rough indication of whether a nebula is very young or evolved, it is argued that such a ...
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A probable evolutionary sequence of H II regions based on six distinct types of observed objects is suggested. Two examples which may deviate from this idealized sequence, are discussed. Even though a sizemean density relation for H II regions can be used as a rough indication of whether a nebula is very young or evolved, it is argued that such a ...
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1979
Symposia and several review papers have recently been devoted to H II Regions (see e.g. the Mittelberg Symposium on H II regions and Related Topics 1975; the I.A.U. Symposium no.75 on Star Formation 1977; Mezger 1978a, for a discussion of the properties of the interstellar matter; Brown et at.
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Symposia and several review papers have recently been devoted to H II Regions (see e.g. the Mittelberg Symposium on H II regions and Related Topics 1975; the I.A.U. Symposium no.75 on Star Formation 1977; Mezger 1978a, for a discussion of the properties of the interstellar matter; Brown et at.
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Grain Sizes in H I and H II Regions
Publications of the Astronomical Society of the Pacific, 1965Significant deviations in the shape of the reddening curves in directions toward and away from H il regions have been recently substantiated by the detailed investigations of Johnson and Borgman.1 These deviations can in part be seen in the changes of the ratio of total to selective scattering, R = Av/EB-v, which varies between about 3.1 for most H i ...
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The molecular basis for cellular function of intrinsically disordered protein regions
Nature Reviews Molecular Cell Biology, 2023Alex S Holehouse +2 more
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Photodissociation and X-Ray-Dominated Regions
Annual Review of Astronomy and Astrophysics, 2022Mark G Wolfire +2 more
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