Does the physical state of a mantle indicate the stage of evolution of a star?
| Autor: | Anne B. Underhill |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Physics
Convection Photosphere Turbulence Astronomy Line of force Astrophysics::Cosmology and Extragalactic Astrophysics Magnetic flux Mantle (geology) Physics::Geophysics Magnetic field Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics Chromosphere Astrophysics::Galaxy Astrophysics |
| Zdroj: | Cool Stars, Stellar Systems, and the Sun ISBN: 9783540129073 |
| DOI: | 10.1007/3-540-12907-3_208 |
| Popis: | The physical state of the mantle of a star (its chromosphere, corona, and wind) is chiefly determined by the amount of nonradiative heat and momentum deposited in the mantle. Because the presence of magnetic lines of force buffeted by turbulent or convective elements in the photosphere seems to be a dominating factor for determining how much energy and momentum are deposited in the mantle, the question of the title can be rephrased to ask can the presence of magnetic fields in the mantle of a star and the presence of rotationally or convectively driven turbulence in the photosphere be related uniquely to any particular stage of evolution of a star. The answer to this question is important because many of the spectroscopic features which have been empirically selected as criteria for spectral type are products of the physical state of the mantle of the star rather than of its photosphere. The standard theory relates properties of the photosphere to the stage of evolution of a model star, not properties of the mantle. It is conditions in the envelope of the star that cause strands of magnetic flux to be created and expelled from the photosphere. The strands then expand, grow, and decay in the mantle of the star. Until the generation of the needed magnetic flux can be related uniquely and unambiguously to the age of the star, one cannot use the spectroscopic phenomena generated in the mantle as an unambiguous key to the stage of evolution of the star. |
| Databáze: | OpenAIRE |
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