PHOTOCHEMICAL HEATING OF DENSE MOLECULAR GAS

ABSTRACT Photochemical heating is analyzed with an emphasis on the heating generated by chemical reactions initiated by the products of photodissociation and photoionization. The immediate products are slowed down by collisions with the ambient gas and then heat the gas. In addition to this direct p...

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Bibliographic Details
Published in:The Astrophysical journal 2015-09, Vol.810 (2), p.125
Main Authors: Glassgold, A. E., Najita, J. R.
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
ATOMS
COLLISIONS
DE-EXCITATION
DISSOCIATION
EV RANGE
HEAT
HEATING
HYDROGEN
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
KINETIC ENERGY
molecular processes
MOLECULES
PHOTOCHEMISTRY
PHOTOIONIZATION
PHOTOLYSIS
protoplanetary disks
PROTOPLANETS
radiation mechanisms: thermal
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Summary:ABSTRACT Photochemical heating is analyzed with an emphasis on the heating generated by chemical reactions initiated by the products of photodissociation and photoionization. The immediate products are slowed down by collisions with the ambient gas and then heat the gas. In addition to this direct process, heating is also produced by the subsequent chemical reactions initiated by these products. Some of this chemical heating comes from the kinetic energy of the reaction products and the rest from collisional de-excitation of the product atoms and molecules. In considering dense gas dominated by molecular hydrogen, we find that the chemical heating is sometimes as large, if not much larger than, the direct heating. In very dense gas, the total photochemical heating approaches 10 eV per photodissociation (or photoionization), competitive with other ways of heating molecular gas.
ISSN:0004-637X
1538-4357
1538-4357
DOI:10.1088/0004-637X/810/2/125