The transfer of radio recombination line radiation through a cold gas. I - Hydrogen and helium lines in compact H II regions

1975 ◽  
Vol 200 ◽  
pp. 598 ◽  
Author(s):  
R. L. Brown ◽  
J. Gomez-Gonzalez
Keyword(s):  
H Ii Regions ◽  
Recombination Line ◽  
Line Radiation ◽  
Radio Recombination Line ◽  
Cold Gas

A hydrogen and helium radio recombination-line survey of galactic H II regions at 10 GHz

1979 ◽  
Vol 229 ◽  
pp. 524 ◽  
Author(s):  
S. M. Lichten ◽  
L. F. Rodriguez ◽  
E. J. Chaisson
Keyword(s):  
H Ii Regions ◽  
Recombination Line ◽  
Radio Recombination Line ◽  
Line Survey

scholarly journals Recent Radio Observations of Galactic H ii regions

1974 ◽  
Vol 60 ◽  
pp. 195-218
Author(s):  
E. Churchwell
Keyword(s):  
Energy Balance ◽  
Aperture Synthesis ◽  
Small Scale ◽  
H Ii Regions ◽  
Recombination Line ◽  
Radio Observations ◽  
Synthesis Techniques ◽  
Radio Recombination Line ◽  
Intermediate Size

The structure and physics of Hiiregions are reviewed. The discussion is principally based on the radio mapping of intermediate-size Hiiregions to measure the energy balance, the mapping of small-scale structure by aperture-synthesis techniques to define the ionization conditions, and determination of helium abundances from radio recombination-line observations of H and He in Hiiregions.

Radio recombination line observations towards Spitzer infrared bubbles with the TianMa radio telescope

2019 ◽  
Vol 489 (4) ◽  
pp. 4862-4874
Author(s):  
L G Hou ◽  
X Y Gao
Keyword(s):  
Radio Telescope ◽  
Detection Rate ◽  
Milky Way ◽  
Absorption Method ◽  
Recombination Line ◽  
Ionized Gas ◽  
Radio Recombination Line ◽  
Warm Ionized Medium

ABSTRACT Many of the Spitzer infrared bubbles identified by the Milky Way Project (MWP) are suggested to be $\rm{H \small {II}} $ regions in nature. More than 70 per cent of the ∼5000 known bubbles do not have radio recombination line (RRL) observations, hence have not been confirmed as $\rm{H \small {II}} $ regions. A systematic RRL survey should be helpful to identify the nature of the bubbles. With the Shanghai TianMa 65-m radio telescope, we searched for RRLs towards 216 selected Spitzer bubbles by simultaneously observing 19 RRLs in the C band (4–8 GHz). RRLs are detected in the directions of 75 of the 216 targets. 31 of the 75 RRL sources are classified as new detections, which are possibly from new $\rm{H \small {II}} $ regions or diffuse warm ionized medium; 36 of them are probably from the outskirts of nearby bright $\rm{H \small {II}} $ regions, rather than bubble-encircled ionized gas; and the detected RRLs towards 8 bubbles are identified from known $\rm{H \small {II}} $ regions. For 58 of the 75 RRL sources, we obtained their distances after resolving the kinematic distance ambiguity by combining the results of the H2CO absorption method, the $\rm{H \small {I}} $ emission/absorption method, and the $\rm{H \small {I}} $ self-absorption method. The low detection rate of new $\rm{H \small {II}} $ regions implies that a number of MWP bubbles in the DR1 catalogue are too faint if they are $\rm{H \small {II}} $ regions.

Recombination-line and continuum observations of compact H II regions at 10.5 GHz

1976 ◽  
Vol 81 ◽  
pp. 512 ◽  
Author(s):  
M. R. Viner ◽  
J. N. Clarke ◽  
V. A. Hughes
Keyword(s):  
H Ii Regions ◽  
Recombination Line
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