Author(s): Robitaille P.-M.
Journal: Progress in Physics
ISSN 1555-5534
Volume: 3;
Start page: 93;
Date: 2011;
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Keywords: Stellar Opacity | Achilles' Heel | Gaseous Sun | Kirchhoff
ABSTRACT
The standard gaseous model of the Sun is grounded on the concept of local thermal equilibrium. Given this condition, Arthur Milne postulated that Kirchho’s law could be applied within the deep solar interior and that a blackbody spectrum could be generated in this region, based solely on equilibrium arguments. Varying internal solar opacity then ensured that a blackbody spectrum could be emitted at the photosphere. In this work, it is demonstrated that local thermal equilibrium and solar opacity arguments provide a weak framework to account for the production of the thermal spectrum. The problemsare numerous, including: 1) the validity of Kirchho’s formulation, 2) the soundness of local thermal equilibrium arguments, 3) the requirements for understanding the elemental composition of the Sun, and 4) the computation of solar opacities. The OPAL calculations and the Opacity Project will be briefly introduced. These represent modernapproaches to the thermal emission of stars. As a whole, this treatment emphasizes the dramatic steps undertaken to explain the origins of the continuous solar spectrum in the context of a gaseous Sun.
Journal: Progress in Physics
ISSN 1555-5534
Volume: 3;
Start page: 93;
Date: 2011;
VIEW PDF
DOWNLOAD PDF Original pageKeywords: Stellar Opacity | Achilles' Heel | Gaseous Sun | Kirchhoff
ABSTRACT
The standard gaseous model of the Sun is grounded on the concept of local thermal equilibrium. Given this condition, Arthur Milne postulated that Kirchho’s law could be applied within the deep solar interior and that a blackbody spectrum could be generated in this region, based solely on equilibrium arguments. Varying internal solar opacity then ensured that a blackbody spectrum could be emitted at the photosphere. In this work, it is demonstrated that local thermal equilibrium and solar opacity arguments provide a weak framework to account for the production of the thermal spectrum. The problemsare numerous, including: 1) the validity of Kirchho’s formulation, 2) the soundness of local thermal equilibrium arguments, 3) the requirements for understanding the elemental composition of the Sun, and 4) the computation of solar opacities. The OPAL calculations and the Opacity Project will be briefly introduced. These represent modernapproaches to the thermal emission of stars. As a whole, this treatment emphasizes the dramatic steps undertaken to explain the origins of the continuous solar spectrum in the context of a gaseous Sun.
