Variable HII Regions
نویسندگان
چکیده
منابع مشابه
Anomalous emission from HII regions
Spinning dust appears to be the best explanation for the anomalous emission that has been observed at ∼ 10 − 60 GHz. One of the best examples of spinning dust comes from a HII region in the Perseus molecular cloud. Observations of other HII regions also show tentative evidence for excess emission at frequencies ∼ 30 GHz, although at lower emissivity levels. A new detection of excess emission at...
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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 ...
متن کاملNarrowband CCD Photometry of Giant HII Regions
We have obtained accurate CCD narrow band Hβ and Hα photometry of Giant HII Regions in M 33, NGC 6822 and M 101. Comparison with previous determinations of emission line fluxes show large discrepancies; their probable origins are discussed. Combining our new photometric data with global velocity dispersion (σ) derived from emission line widths we have reviewed the L(Hβ)) − σ relation. A reanaly...
متن کاملHydrodynamics of Cometary Compact Hii Regions
We present numerical radiation-hydrodynamic simulations of cometary H II regions for a number of champagne flow and bowshock models. For the champagne flow models we study smooth density distributions with both steep and shallow gradients. We also consider cases where the ionizing star has a strong stellar wind, and cases in which the star additionally has a proper motion within the ambient den...
متن کاملWater Masers Toward Ultracompact HII Regions
We present a survey in the 6 16 − 5 23 rotational H 2 O transition toward 33 galactic ultracompact HII regions. Maser emission is detected toward 18 of these sources; two are new detections. High quality spectra are provided for all 18 sources. We discuss the detection rate of this survey and the correlation of various maser properties with other physical parameters. In addition, we report wide...
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ژورنال
عنوان ژورنال: International Astronomical Union Colloquium
سال: 1989
ISSN: 0252-9211
DOI: 10.1017/s0252921100023526