منابع مشابه
Near and Mid Infrared Observations of Ultracompact HII Regions
This review discusses nearand midinfrared observations of Ultracompact (UC) HII regions. The importance of ISO mid-IR fine-structure nebular lines is emphasised, since only a small fraction of UCHII regions are observed directly in the near-IR. The reliability of contemporary atmospheric models for such indirect diagnostics is discussed, whilst a revised spectral type-temperature calibration is...
متن کاملProspects for Redshifted 21-cm Observations of Quasar Hii Regions
The introduction of low-frequency radio arrays over the coming decade is expected to revolutionize the study of the reionization epoch. Observation of the contrast in redshifted 21cm emission between a large H II region and the surrounding neutral IGM will be the simplest and most easily interpreted signature. We assess the sensitivity of three generations of planned low-frequency arrays to qua...
متن کاملMid - and high - J CO observations towards ultracompact HII regions
Aims. A study of 12 ultracompact HII regions was conducted to probe the physical conditions and kinematics in the inner envelopes of the molecular clumps harboring them. Methods. The APEX telescope was used to observe the sources in the CO (4–3) and 13 CO (8–7) lines. Line intensities were modeled with the RATRAN radiative transfer code using power laws for the density and temperature to descri...
متن کاملRelic HII Regions and Radiative Feedback at High-Redshifts
UV radiation from early astrophysical sources could have a large impact on subsequent star formation in nearby protogalaxies, and in general on the progress of cosmological reionization. Theoretical arguments based on the absence of metals in the early Universe suggest that the first stars were likely massive, bright, yet short-lived, with lifetimes of a few million years. Here we study the rad...
متن کاملOn the structure of giant HII regions and HII galaxies
We review the structural properties of giant extragalactic HII regions and HII galaxies based on two dimensional hydrodynamic calculations, and propose an evolutionary sequence that accounts for their observed detailed structure. The model assumes a massive and young stellar cluster surrounded by a large collection of clouds. These are thus exposed to the most important star-formation feedback ...
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 1967
ISSN: 0035-8711,1365-2966
DOI: 10.1093/mnras/137.2.141