Astronomy and Astrophysics – Astrophysics
Scientific paper
Feb 1988
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1988a%26a...191..278p&link_type=abstract
Astronomy and Astrophysics (ISSN 0004-6361), vol. 191, no. 2, Feb. 1988, p. 278-282. CNPq-supported research.
Astronomy and Astrophysics
Astrophysics
11
Atomic Collisions, Helium, Planetary Nebulae, Abundance, Line Spectra, Photoionization
Scientific paper
The collisional enhancement of the strongest optical lines of He I from the metastable level 2 3S is investigated on the basis of 700-1040-nm spectra of the PN NGC 7027, obtained using the Carelec spectrograph and a CCD detector on the 1.93-m telescope at the Observatoire de Haute-Provence during 1986. The collisional amplifications of the He I lines are presented in tables and compared with the values predicted by recombination theory. It is concluded that some of the collision strengths determined by Berrington et al. (1985) are overestimated, and that the enhancement of the 4471-A reference line is less than 15 percent in NGC 7027. It is inferred that recently determined nebular He I abundances are not overestimated by more than 5 percent. The fact that the observed strength of the 1.083-micron collisional line is significantly lower than predicted is tentatively attributed to selective absorption by dust.
Baluteau Jean-Paul
Gruenwald Ruth B.
Pequignot Daniel
No associations
LandOfFree
The collisional excitation of helium in nebulae does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The collisional excitation of helium in nebulae, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The collisional excitation of helium in nebulae will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1224485