Results 291 to 300 of about 1,094,944 (319)
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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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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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The H II regions of NGC 6822. I - an atlas of 157 H II regions
Publications of the Astronomical Society of the Pacific, 1988A CCD survey at Hα results in a catalog of 157 H II regions in the Local Group irregular galaxy NGC 6822. Most of them are newly detected, faint surface-brightness objects. Positions and maps are given, and identifications are correlated with those of previous studies.
Paul Hodge +2 more
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Galactic H II Region Abundances
1999A review of the chemical abundances of Galactic H II regions is presented. The C and O abundances derived from recombination lines are higher than those derived from forbidden lines; arguments in favor of the recombination abundances are given. The Galactic abundance gradients are discussed.
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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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The molecular basis for cellular function of intrinsically disordered protein regions
Nature Reviews Molecular Cell Biology, 2023Alex S Holehouse, Birthe B Kragelund
exaly
Lake and drained lake basin systems in lowland permafrost regions
Nature Reviews Earth & Environment, 2022Benjamin Jones +2 more
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