Persistent Link:
http://hdl.handle.net/10150/290002
Title:
The evolution of giant planets
Author:
Fortney, Jonathan J.
Issue Date:
2004
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
As a whole this dissertation aims to understand giant planets as an entire class of astronomical objects. Initially we investigate the mechanics and evolutionary effects of phase separation in the deep interiors of giant planets. We present the first models of Saturn and Jupiter to couple their evolution to both a radiative-atmosphere grid and to high-pressure phase diagrams of hydrogen with helium and other admixtures. We find that previously calculated hydrogen-helium phase diagrams in which Saturn's interior reaches a region of predicted helium immiscibility do not allow enough energy release to prolong Saturn's cooling to its known age and effective temperature. We explore modifications to published phase diagrams that would lead to greater energy release. Alternatively, we also explore the evolutionary effects of the phase separation of an icy component. We then expand our inhomogeneous evolutionary models to the evolution of hypothetical extrasolar giant planets (EGPs) in the 0.15 to 3.0 Jupiter mass range, incorporating helium phase separation using the hydrogen-helium phase diagram we have calibrated to Jupiter and Saturn. We show how phase separation increases the luminosity, effective temperature, and radii, and decreases the atmospheric helium mass fraction, for various giant planets as a function of age. We also show the effects of irradiation and dense cores. Next we turn to the atmosphere of the transiting EGP, HD209458b. Using a self-consistent atmosphere code, we construct a new model of the planet's atmosphere to investigate the disparity between the observed strength of the sodium absorption feature at 589 nm and the predictions of previous models. For the atmospheric temperature-pressure profile we derive, silicate and iron clouds reside at a pressure of several mbar in the planet's atmosphere. These clouds lead to increased absorption in bands directly adjacent to the sodium line core. Using a non-LTE sodium ionization model, we show that ionization leads to a slight weakening of the sodium feature. The sensitivity of our conclusions to the derived atmospheric temperature-pressure profile is discussed. We show how our investigation leads to a better understanding of how the planetary radius measurements should be compared to model radii.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Physics, Astronomy and Astrophysics.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Planetary Sciences
Degree Grantor:
University of Arizona
Advisor:
Hubbard, William B.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleThe evolution of giant planetsen_US
dc.creatorFortney, Jonathan J.en_US
dc.contributor.authorFortney, Jonathan J.en_US
dc.date.issued2004en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractAs a whole this dissertation aims to understand giant planets as an entire class of astronomical objects. Initially we investigate the mechanics and evolutionary effects of phase separation in the deep interiors of giant planets. We present the first models of Saturn and Jupiter to couple their evolution to both a radiative-atmosphere grid and to high-pressure phase diagrams of hydrogen with helium and other admixtures. We find that previously calculated hydrogen-helium phase diagrams in which Saturn's interior reaches a region of predicted helium immiscibility do not allow enough energy release to prolong Saturn's cooling to its known age and effective temperature. We explore modifications to published phase diagrams that would lead to greater energy release. Alternatively, we also explore the evolutionary effects of the phase separation of an icy component. We then expand our inhomogeneous evolutionary models to the evolution of hypothetical extrasolar giant planets (EGPs) in the 0.15 to 3.0 Jupiter mass range, incorporating helium phase separation using the hydrogen-helium phase diagram we have calibrated to Jupiter and Saturn. We show how phase separation increases the luminosity, effective temperature, and radii, and decreases the atmospheric helium mass fraction, for various giant planets as a function of age. We also show the effects of irradiation and dense cores. Next we turn to the atmosphere of the transiting EGP, HD209458b. Using a self-consistent atmosphere code, we construct a new model of the planet's atmosphere to investigate the disparity between the observed strength of the sodium absorption feature at 589 nm and the predictions of previous models. For the atmospheric temperature-pressure profile we derive, silicate and iron clouds reside at a pressure of several mbar in the planet's atmosphere. These clouds lead to increased absorption in bands directly adjacent to the sodium line core. Using a non-LTE sodium ionization model, we show that ionization leads to a slight weakening of the sodium feature. The sensitivity of our conclusions to the derived atmospheric temperature-pressure profile is discussed. We show how our investigation leads to a better understanding of how the planetary radius measurements should be compared to model radii.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectPhysics, Astronomy and Astrophysics.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplinePlanetary Sciencesen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorHubbard, William B.en_US
dc.identifier.proquest3119943en_US
dc.identifier.bibrecord.b45629493en_US
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