Radio Recombination Line Emission from Ultracompact HII Regions

1990 ◽  
pp. 83-92 ◽  
Author(s):  
E. Churchwell ◽  
C. M. Walmsley ◽  
D. O. S. Wood ◽  
H. Steppe
Keyword(s):  
Line Emission ◽  
Hii Regions ◽  
Recombination Line ◽  
Radio Recombination Line ◽  
Ultracompact Hii

scholarly journals A Search for Recombination Line Emission from the Galactic Equator at 408 MHz

1976 ◽  
Vol 29 (5) ◽  
pp. 419 ◽  
Author(s):  
MJ Batty
Keyword(s):  
Surface Brightness ◽  
Thermal Emission ◽  
Line Emission ◽  
Hii Regions ◽  
Line Of Sight ◽  
Recombination Line ◽  
Upper Limits ◽  
Low Surface Brightness ◽  
Lower Limits ◽  
Galactic Longitude

A search for H 2520( recombination line emission was made by scanning the galactic equator region using the Molonglo radio telescope. Upper limits were established over the range of galactic longitude accessible to the instrument. For the region III ;S 40�, estimates of the background thermal continuum brightness temperature were used to derive lower limits of ~ 2000 K for the electron temperature of the gas along the line of sight. Lower limits for the electron density obtained by considering probable non-LTE effects suggest that the thermal emission over this range is due to low surface brightness HII regions. The observed H 2520( upper limit averaged over the range 270� ;S I ;S 320� just admits the line intensity calculated by Shaver (1975) for the cold cloud component of the general interstellar medium.

scholarly journals Classification of Supernova Remnants and HII Regions from their Recombination Line Emission

1972 ◽  
Vol 25 (5) ◽  
pp. 539 ◽  
Author(s):  
JR Dickel ◽  
DK Milne
Keyword(s):  
Electron Temperature ◽  
Supernova Remnants ◽  
Line Emission ◽  
Hii Regions ◽  
Radio Sources ◽  
Recombination Line ◽  
Line Frequency ◽  
Upper Limits ◽  
Galactic Radio

H109a, recombination line observations are used in an attempt to classify 46 galactic radio sources as either supernova remnants or HII regions. Long integrations at the H109a line frequency on two well-known supernova remnants (IC 443 and 3C 391) provide improved upper limits on the line emission from these objects. From these results the electron temperature in IC 443 is estimated to be in excess of 1�6 � 104 K.

scholarly journals Submillimetre Observations of UC HII Regions and Hot Molecular Cores

2000 ◽  
Vol 197 ◽  
pp. 113-124
Author(s):  
G. H. Macdonald ◽  
M. A. Thompson
Keyword(s):  
Star Formation ◽  
Line Emission ◽  
Hii Regions ◽  
High Mass ◽  
Mass Star ◽  
Molecular Line ◽  
Continuum Radiation ◽  
Ob Stars ◽  
Hot Gas ◽  
Ultracompact Hii

Recent submillimetre observations of continuum radiation from warm dust and molecular line emission from hot gas in regions of high mass star formation are reviewed. Such regions are characterised by ultracompact HII regions around young OB stars and associated hot molecular cores which appear to harbour high mass protostars at an earlier stage of evolution.

scholarly journals Hydrogen Radio Recombination Line Emission from M51 and NGC 628

2018 ◽  
Vol 130 (990) ◽  
pp. 084101 ◽  
Author(s):  
Matteo Luisi ◽  
L. D. Anderson ◽  
T. M. Bania ◽  
Dana S. Balser ◽  
Trey V. Wenger ◽  
...  
Keyword(s):  
Line Emission ◽  
Recombination Line ◽  
Radio Recombination Line

scholarly journals A survey of molecular line emission towards ultracompact Hii regions

1998 ◽  
Vol 133 (1) ◽  
pp. 29-49 ◽  
Author(s):  
J. Hatchell ◽  
M. A. Thompson ◽  
T. J. Millar ◽  
G. H. Macdonald
Keyword(s):  
Line Emission ◽  
Hii Regions ◽  
Molecular Line ◽  
Ultracompact Hii
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