Recombination Lines 158a and 198ß in Nine Southern Nebulae

Abstract

SummaryRecombination lines H 158", He 158", and H 198,8 (near ,\ 18 em) have been observed in the HI! regions Orion Nebula, RCW 38 and 49, "I Carinae I, RCW 57, PKS1617-5OI in Norma, NGC6334 and 63571, and Omega Nebula. Physical parameters such as ratio of line to continuum temperatures TdT c, line halfwidths, median radial velocities, and intensity ratios 1(198,8)/1(158,,) and 1(He)/1(H) are given. A lack of agreement in the measured radial velocities of the H 198,8 and H 158" lines in three nebulae is discussed.

Models of Radio Recombination Line Sources

“…The northernmost nebula, M17, has been studied most intensely, whilst observations of the other four sources, all made with the Parkes radiotelescope, have produced far less data. Used in the analysis were the line data summarized by Hjellming and Gordon (1971), together with measurements by McGee and Gardner (1968), McGee et al (1969), Gardner et al (1970aGardner et al ( , 1970b, Simpson (1970), Wilson et al (1970), Pedlar and Davies (1972), Waltman and Johnston (1973), Batty (1974), , Huchtmeier (1974) and McGee et al (1975).…”