Aluminum-hydride formation in the relaxation zones following shock waves in the atmosphere of long-period variable stars

dc.contributor.author Pierce, James
dc.contributor.department Physics and Astronomy
dc.date 2018-08-17T03:03:34.000
dc.date.accessioned 2020-07-02T05:56:35Z
dc.date.available 2020-07-02T05:56:35Z
dc.date.copyright Tue Jan 01 00:00:00 UTC 1980
dc.date.issued 1980
dc.description.abstract <p>The phase variations of AlH emission lines in LPV spectra were investigated using a model of the post-shock relaxation zone. Conditions at the shock were linked to position in the atmosphere and phase by a global, isothermal shock model. In the relaxation zone model, 78 species were considered, including e('-), H, H('+), H('-), H(,2), H(,2)('+), He, He('+), He('++), M, M('+), and M('++), where M is one of 23 metals. The model was applied at densities (LESSTHEQ) 10('-10.5), where the shocks were estimated to be optically thin, and molecular species were assumed to play a negligible role in determining the thermodynamic state of the gas. Calculations were performed for a 1.2 M(,(CIRCLE)) star, with P = 332('d), R = 225 R(,(CIRCLE)), and Q = 0.108 (fundamental mode pulsation).;At densities -12.5) of the atmosphere, relaxation occurs fast enough that the temperature profile of a given mass shell approaches the isothermal case.;The temperature of the atmosphere increases with radius.;The observed variations in AlH emission with phase are not caused solely by variations in the AlH formation rate, which decreases rapidly with decreasing density. Instead, the emergence and increased prominence of the emission lines toward minimum light are caused by the increasing transparency of the rising shock. Following minimum light, the declining formation rate diminishes the AlH emission lines, preventing their detection in the upper shock; this is consistent with the absence of the lines around maximum light.;Origin of these emission lines behind the rising lower shock causes a blue-shift in their velocities, which has been observed. Any AlH absorption features which are detected should be red-shifted.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/rtd/6802/
dc.identifier.articleid 7801
dc.identifier.contextkey 6293426
dc.identifier.doi https://doi.org/10.31274/rtd-180813-11116
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/6802
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/79610
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/rtd/6802/r_8028631.pdf|||Sat Jan 15 01:29:10 UTC 2022
dc.subject.disciplines Astrophysics and Astronomy
dc.subject.keywords Physics
dc.subject.keywords Astrophysics
dc.subject.keywords Astronomy
dc.title Aluminum-hydride formation in the relaxation zones following shock waves in the atmosphere of long-period variable stars
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication 4a05cd4d-8749-4cff-96b1-32eca381d930
thesis.degree.level dissertation
thesis.degree.name Doctor of Philosophy
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