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Photodissociation Regions in Planetary Nebulae

Published online by Cambridge University Press:  07 August 2017

V. Escalante
Affiliation:
Instituto de Astronomía, UNAM, Ap. Postal 70-264, Mexico, DF 04510, México
A. Góngora-T
Affiliation:
Instituto de Física, UNAM, Ap. Postal 20-364, México, DF 01000, México

Abstract

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The photodissociation rate of H2 molecules by UV photons from PN central stars is generally several orders of magnitude larger than the rate produced by the average interstellar field (Sternberg 1988, Escalante et al. 1991). Thus, in neutral envelopes of PN's, H2 molecules are destroyed quickly, and a photodissociation region forms around ionization bounded nebulae. Observations of H2 in PN's reveal that not all the hydrogen is photodissociated, and it has been suggested that this is due to the existence of dense disks around the ionized region (Zuckerman and Gatley 1988).

Type
III. Highlights on the Nebulae
Copyright
Copyright © Kluwer 1993 

References

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