Continuum and atomic hydrogen line emission from the IC5146 galactic complex
| dc.contributor.author | Irwin, Judith Ann | en_US |
| dc.date.accessioned | 2024-08-14T17:53:01Z | |
| dc.date.available | 2024-08-14T17:53:01Z | |
| dc.date.copyright | 1978 | en_US |
| dc.date.issued | 1978 | |
| dc.degree.department | Department of Physics | |
| dc.degree.department | Department of Physics and Astronomy | |
| dc.degree.level | Master of Science M.Sc. | en |
| dc.description.abstract | The synthesis interferometer at the Dominion Radio Astrophysical Observatory has been used to map a 2° field around the HII region, IC5146, in the continuum and atomic hydrogen line. Resolutions of 2:0 in right ascension and 2:1 in declination were obtained as well as 0.66 km•s⁻¹ in velocity for the HI line. The flux density of IC5146 is 1.95 ± 0.05 Jy. The excitation parameter and Lyman continuum luminosity indicate a spectral type of BOY for the exciting star. The continuum brightness distribution is consistent with an electron density distribution which falls off from the centre of the HII region in a Gaussian fashion. The average electron density and total HII mass are 26 cm⁻³ and 12.2 M⊙ respectively, for an electron temperature of 7000 °K. HI line emission extends over a range of 12 km•s⁻¹ in radial velocity. Two spin temperatures are inferred from the data. The mass of fine structure HI(≤ 28' in extent) is 230 ± 50 M⊙ for a spin temperature of 120 °K, and the mass of broad structure HI (>28' in extent) is 2410 ± 480 M⊙ for a spin temperature of 100 °K. IC5146 is on the near side of the neutral cloud and there is a deficit of HI at its position and velocity. Gas from the HII region is expanding on the near side at about 5 km•s⁻¹ with respect to the HI cloud. The ionization front on the far side is also still expanding into the neutral cloud at about 2 km•s⁻¹ and there is evidence for the existence of an expanding half-shell of HI on the far side. Hill and Hollenbach's (1978) model for the dissociation of H₂ with a total particle density of 350 cm⁻³, can account for the observed HI emission. The model implies that IC5146 is 2 x 10⁵ years old, much younger than the associated stellar cluster age of 3 x 10⁶ years. | en_US |
| dc.format.extent | 199 pages | |
| dc.identifier.uri | https://hdl.handle.net/1828/18283 | |
| dc.rights | Available to the World Wide Web | en_US |
| dc.title | Continuum and atomic hydrogen line emission from the IC5146 galactic complex | en_US |
| dc.type | Thesis | en_US |
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