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

1973 ◽  
Vol 26 (2) ◽  
pp. 267 ◽  
Author(s):  
JR Dickel ◽  
DK Milne
Keyword(s):  
Supernova Remnants ◽  
Supernova Remnant ◽  
Line Emission ◽  
Hii Regions ◽  
Recombination Line ◽  
Hii Region ◽  
Galactic Source ◽  
Source Number

The galactic source number designations G35'6-0'4 and G35�5-0�0 in Table 1 should be interchanged. Thus G35'6-0'4 is the supernova remnant and G35�5 -0�0 appears to be an HII region. The authors thank Dr. T Velusamy for calling this error to their attention.

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 Supernova Remnants in Giant HII Regions

1988 ◽  
Vol 101 ◽  
pp. 201-204
Author(s):  
You-Hua Chu ◽  
Robert C. Kennicutt
Keyword(s):  
Supernova Remnants ◽  
Detection Rate ◽  
Massive Stars ◽  
Line Emission ◽  
Hii Regions ◽  
Radio Continuum ◽  
Hii Region ◽  
The Core ◽  
Large Numbers ◽  
Optical Line

Giant HII regions contain large numbers of massive stars, and hence are expected to contain large numbers of SNRs. Until recently, however, only a few SNRs have been identified in extragalactic giant HII regions. Moreover, most of these SNRs are located at the outskirts of HII regions, instead of the core where most of the stars are located. The low detection rate and the outlying locations of the SNRs may be due to: 1) observational difficulties - the background HII regions are much more luminous than the SNRs in both optical line emission and radio continuum; 2) intrinsic invisibility of SNRs - stellar wind and SNRs may have created a supershell (Mac Low and McCray 1987), and the core of a giant HII region is filled with hot tenuous coronal gas; or 3) a genuine deficiency of supernovae and SNRs in the HII regions (Sramek and Weedman 1986).

Observations of the 1→0 Transition of CO Towards Southern HII Regions

1982 ◽  
Vol 4 (4) ◽  
pp. 434-440 ◽  
Author(s):  
J. B. Whiteoak ◽  
Robina E. Otrupcek ◽  
C. J. Rennie
Keyword(s):  
Radio Telescope ◽  
Molecular Cloud ◽  
Milky Way ◽  
Line Emission ◽  
Hii Regions ◽  
Hii Region ◽  
Giant Molecular Cloud ◽  
Molecular Lines ◽  
Csiro Division

The 4-m radio telescope of the CSIRO Division of Radiophysics at Epping is being used to survey the line emission associated with the 1→0 transition of CO (rest frequency 115.271 GHz) in the southern Milky Way. The programme includes mapping the CO distribution across giant molecular-cloud/HII-region complexes. As a first stage the emission has been observed towards bright southern HII regions. These results will not only serve as a basis for future extensive mapping but will also provide data which is directly comparable with observations of other molecular lines that have been made towards the HII regions.

Observations of Recombination-Line Emission in the Direction of Two Supernova Remnants

1973 ◽  
Vol 183 ◽  
pp. L143 ◽  
Author(s):  
Diego A. Cesarsky ◽  
Catherine J. Cesarskly
Keyword(s):  
Supernova Remnants ◽  
Line Emission ◽  
Recombination Line

A Second Compact Radio Component Detected in the LMC HII Region N159

1994 ◽  
Vol 11 (1) ◽  
pp. 68-73 ◽  
Author(s):  
M. R. Hunt ◽  
J. B. Whiteoak
Keyword(s):  
Line Emission ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Recombination Line ◽  
Hii Region ◽  
Infrared Wavelengths ◽  
5 Ghz ◽  
Compact Array

AbstractThe Australia Telescope Compact Array has been used for observations, with arcsecond resolution, of the HII region N159 in the Large Magellanic Cloud. Images at 5 GHz reveal a second compact continuum component which has no obvious counterpart at optical and infrared wavelengths. Observations of HI 10α recombination-line emission, and HI and H2CO absorption, suggest that the object is a compact HII region embedded in a dense obscuring cloud on the edge of N159.

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 Survey of OH Masers at 1665 and 1667 MHz. I. Galactic Longitudes 326° to 40°

1980 ◽  
Vol 33 (3) ◽  
pp. 639 ◽  
Author(s):  
JL Caswell ◽  
RF Haynes ◽  
WM Goss
Keyword(s):  
Supernova Remnants ◽  
Luminosity Function ◽  
Galactic Plane ◽  
Line Emission ◽  
Zeeman Splitting ◽  
State Transitions ◽  
Line Profiles ◽  
Polarization Data ◽  
Hii Region ◽  
Nonthermal Radio

The galactic plane between longitudes 3260 and 3400 has been searched for OH emiSSIOn and bsorption on the 1665 and 1667 MHz transitions. Forty main-line emission sources were detected (27 new ones, 13 previously known), and these constitute a sample complete to a weIl-defined lower intensity limit in this region of sky. Line profiles of all sources are shown and the statistics on variability and on the intensity ratios of the ground state transitions are summarized. The completeness of the sample encouraged us to make a first attempt to construct a luminosity function and to estimate the total number of such masers in our Galaxy. A study of the velocity structures showed these to be extremely varied, but none exceed a total range of 25 km s -1; combined velocity and polarization data are compatible with a Zeeman splitting origin for the circular polarization, and with this interpretation several sources yield an estimate for the line-of-sight magnetic field strength of a few mG. Preliminary investigations of the associations with other celestial objects indicate that many of the masers are loosely associated with HII region complexes, but in at least eight instances no HII regions have yet been detected; of these eight masers, two may be associated with supernova remnants and one with an unidentified nonthermal radio source.

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