Carbon Recombination Lines Research Articles

Carbon recombination line observations of the sharpless 140 region

Carbon recombination-line emission has been detected at two frequencies from a dark cloud contiguous with the small H II region Sharpless 140. The observations show the dark cloud to be of unusually low temperature and to have a markedly inhomogeneous density distribution, with localized region of high density surrounding one or more embedded stars. The carbon is probably ionized by photons from both the exciting star of S140 and the embedded stars. The dark cloud and S140 apparently represent two stages of star formation which have occurred over a period of at least 500,000 years in adjacent regions of the same dark cloud.

Radio recombination line observations of the C II region NGC 2023

The reflection nebula NGC 2023 has been observed at four frequencies in a study of its carbon recombination line emission. The observations show the recombination line region to be about 2 pc in diameter, with an average electron density of about 0.2 per cu cm and electron temperature of about 20 K. The electron density increases exponentially near the B1.5 star HD 37903, the illuminating star of NGC 2023. The most reasonable interpretation of the observational results is that the carbon emission lines arise in a cold C II region surrounding HD 37903. The coexistence of the C II region with a region of enhanced CO emission suggests that the CO in NGC 2023 may be excited by electron collisions.

Microwave Spectroscopic Mapping of Gaseous Nebulae. III. - Gen, Helium, and Carbon in Orion a I

view Abstract Citations (11) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Microwave Spectroscopic Mapping of Gaseous Nebulae. III. - Gen, Helium, and Carbon in Orion a I Chaisson, E. J. Abstract Recombination lines of hydrogen and helium have been detected at five locations distributed throughout the interior portion of Ori A. The average values of 9200 K for the temperature and of 0.10 for the relative ionized helium abundance are essentially constant throughout the region mapped. Carbon recombination lines that are thought to originate in a partially ionized region have also been mapped at five locations. Carbon-line emission is found to be most intense near the dark dust lane toward the northeast. Subject headings: abundances, nebular - nebulae - Orion Nebula - radio lines Publication: The Astrophysical Journal Pub Date: December 1973 DOI: 10.1086/152518 Bibcode: 1973ApJ...186..545C full text sources ADS | Related Materials (3) Part 1: 1973ApJ...182..767C Part 2: 1973ApJ...183..479L Part 4: 1973ApJ...186..555C

Microwave Observations of a Partially Ionized Interstellar Cloud

High resolution spectroscopy has enabled detection of recombination lines of excited hydrogen, carbon and elements of intermediate mass from a cool cloud in the direction of W3.

Detection of Interstellar Recombination Lines from Emitters of Intermediate Mass

view Abstract Citations (34) References (6) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Detection of Interstellar Recombination Lines from Emitters of Intermediate Mass Chaisson, E. J. ; Black, J. H. ; Dupree, A. K. ; Cesarsky, D. A. Abstract The 18-cm microwave spectra of Orion B and W3A show evidence of an emission feature to the high- frequency side of the carbon recombination line. Observations at different frequencies establish that this feature results from electronic recombination. In addition, theoretical considerations, results of 21- cm observations, and computer-simulated spectra suggest that the new feature originates in a predominantly neutral hydrogen region and can be explained by a superposition of recombination lines from any or all of the following elements: 24Mg, 28Si, 325, and 56Fe. Publication: The Astrophysical Journal Pub Date: May 1972 DOI: 10.1086/180932 Bibcode: 1972ApJ...173L.131C full text sources ADS |

Radiofrequency Recombination Lines as Diagnostics of the Cool Interstellar Medium

Quantitative details are given of a new diagnostic technique for the carbon and hydrogen (H I) recombination lines. Theoretical results are presented for conditions expected in H I clouds, and are compared with available observations for Orion A and NGC 2024.

Discussion following Mezger's Report

The Discussion has been rearranged into five sections: 1. Density Concentrations, Cocoon Stars, and OH Sources; 2. The Carbon Recombination Line; 3. The He/H Abundance; 4. Various Shorter Comments; 5. A New Mechanism for Star Formation. A part of the Discussion which related to Spiegel's Report has been transferred to Chapter 13. A short exchange on Hi shells around Hii regions has been deleted and added to Chapter 5. A short part on the dust cloud in Orion at the end of Section 4 has been transferred from Tuesday, September 16.