Determinations of S III, O IV and Nev abundances in planetary nebulae from infrared lines
Journal Article
·
· Astrophys. J.; (United States)
Airborne observations of the infrared forbidden lines (SIII) 18.71 ..mu..m, (Ne v) 24.28 ..mu..m, and (O IV) 25.87 ..mu..m have been made for 12 planetary nebulae. One or more of the lines were detected in seven of these nebulae, and ionic abundances were calculated. These results are insensitive to nebula temperatures, in contrast to the case for optical of UV lines. However, density eliminates from optical and UV forbidden lines were required to obtain abundances. The Ne v infrared line flux from NGC 7662 was combined with the 3426 A flux to obtain a Ne v electron temperature of 11,200/sup +2000//sub -/1100 K, which overlaps O III temperature measurements. Since the ionization potential of Ne IV is much greater than that of O II, T/sub e/ (Ne v) would be expected to be much greater than T/sub e/ (OIII). In fact, numerical models predict T/sub e/ (Ne v)roughly-equal(16-20) x 10/sup 3/ K. This discrepancy may indicate inaccuracies in currently available atomic parameters for Ne v.
- Research Organization:
- Center for Radiophysics and Space Research, Cornell University
- OSTI ID:
- 5471353
- Journal Information:
- Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 270:2; ISSN ASJOA
- Country of Publication:
- United States
- Language:
- English
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