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Astrophysics and Space Science, 2005
This article reviews how observations of dense molecular gas can help us understand the dynamics and evolution of ultra-compact H II (UCHII) regions. Particular attention is paid to the cometary objects, which it is argued are likely to be the dominant class.
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This article reviews how observations of dense molecular gas can help us understand the dynamics and evolution of ultra-compact H II (UCHII) regions. Particular attention is paid to the cometary objects, which it is argued are likely to be the dominant class.
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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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1987
By virtue of its spectrometers having simultaneous multichannel integration capability and relatively large input apertures, the International Ultraviolet Explorer satellite has been the first instrument capable of effective study of the ultraviolet spectra of the gas from extended H ii regions. This review will concentrate on discussing the results of
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By virtue of its spectrometers having simultaneous multichannel integration capability and relatively large input apertures, the International Ultraviolet Explorer satellite has been the first instrument capable of effective study of the ultraviolet spectra of the gas from extended H ii regions. This review will concentrate on discussing the results of
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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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Antibiotic resistance in the environment
Nature Reviews Microbiology, 2021D G Joakim Larsson, Carl-Fredrik Flach
exaly