Radio Recombination Line Observations of Partially Ionized Gas in Galactic H II Regions

1995 ◽  
Vol 448 ◽  
pp. 727 ◽  
Author(s):  
Joseph S. Onello ◽  
J. A. Phillips
Keyword(s):  
H Ii Regions ◽  
Recombination Line ◽  
Ionized Gas ◽  
Radio Recombination Line ◽  
Partially Ionized

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.

High-resolution spectroscopy of partially ionized gas around H II regions

1991 ◽  
Vol 383 ◽  
pp. 693 ◽  
Author(s):  
Joseph S. Onello ◽  
J. A. Phillips ◽  
Yervant Terzian
Keyword(s):  
High Resolution ◽  
High Resolution Spectroscopy ◽  
H Ii Regions ◽  
Ionized Gas ◽  
Partially Ionized

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

A bipolar outflow of ionized gas in K3-50A: H76 alpha radio recombination line and continuum observations of K3-50

1994 ◽  
Vol 428 ◽  
pp. 670 ◽  
Author(s):  
C. G. Depree ◽  
W. M. Goss ◽  
Patrick Palmer ◽  
Robert H. Rubin
Keyword(s):  
Recombination Line ◽  
Ionized Gas ◽  
Bipolar Outflow ◽  
Radio Recombination Line

scholarly journals Radio continuum and radio recombination line observations of the Galactic center lobe

2013 ◽  
Vol 9 (S303) ◽  
pp. 129-131
Author(s):  
Halca Nagoshi ◽  
Kenta Fujisawa ◽  
Yuzo Kubose
Keyword(s):  
Electron Temperature ◽  
Galactic Center ◽  
Thermal Emission ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Recombination Line ◽  
Ionized Gas ◽  
Radio Recombination Line ◽  
Spatial Coverage ◽  
The Continuum

AbstractRadio continuum (cont) and radio recombination line (RRL) observations with the Yamaguchi 32-m radio telescope toward the lower part of the Galactic center lobe (GCL) in the Galactic center region are presented. While two ridges of the GCL were seen in both continuum and RRL images, the spatial coverage of the ridges of the continuum and RRL is not coincident. We distinguish the continuum emission of the GCL into thermal and non-thermal emission by assuming an electron temperature of the ionized gas of 4370 K, estimated based on the line width (14.1 km s−1). The thermal emission was found to be located inside and surrounded by the non-thermal emission.

scholarly journals Radio studies of the distribution of ionized gas

1979 ◽  
Vol 84 ◽  
pp. 73-79
Author(s):  
Felix J. Lockman
Keyword(s):  
Rotation Curve ◽  
Galactic Plane ◽  
Kinematic Model ◽  
Systematic Errors ◽  
Recombination Line ◽  
Ionized Gas ◽  
Quantitative Studies ◽  
Radio Recombination Line ◽  
Radio Studies ◽  
Kinematic Analyses

Although radio recombination line and continuum observations are very useful for investigating galactic structure, it is well to remember their limitations. First, they only provide measurements of coordinates and velocities; a kinematic model is needed to derive the distance and thus the actual location of every nebula. In some directions, particularly all longitudes from ℓ=0°, kinematic distance estimates are prone to systematic errors arising from velocity crowding or uncertainties in the rotation curve, and are of little use in quantitative studies. I will only discuss the distribution of radio nebulae in the inner ∼100° of the galactic plane, since in this area kinematic analyses can give reasonable results and, in any case, here we must rely on radio observations for most of our information.

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