|Author||Lites, B. W. ♦ Skumanich, A.|
|Source||United States Department of Energy Office of Scientific and Technical Information|
|Subject Keyword||CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS ♦ CALCIUM ♦ EMISSION SPECTRA ♦ VISIBLE SPECTRA ♦ CHROMOSPHERE ♦ BALMER LINES ♦ EMISSION SPECTROSCOPY ♦ MATHEMATICAL MODELS ♦ HYDROGEN ♦ MAGNESIUM ♦ SUNSPOTS ♦ SOLAR CORONA ♦ ALKALINE EARTH METALS ♦ ATMOSPHERES ♦ ELEMENTS ♦ METALS ♦ NONMETALS ♦ SOLAR ACTIVITY ♦ SOLAR ATMOSPHERE ♦ SPECTRA ♦ SPECTROSCOPY ♦ Astrophysics & Cosmology- Solar Phenomena|
|Abstract||OSO 8 observations of the profiles of the resonance lines of H I, Mg II, and Ca II obtained with the Laboratorie de Physique Stellaire et Planetaire de Centre National de la Recherche Scientifique (LPSP-CNRS) spectrometer (by A.S.) and of C IV obtained with the University of Colorado (CU) spectrometer (by B.W.L.) for a large quiet sunspot (1975 November 16--17) are analyzed along with near-simultaneous ground-based Stokes measurements obtained in a collaborative arrangement with L. L. House and T. Baur (HAO-NCAR) to yield an umbral chromosphere and transition region model. Features of this model include: (1) a chromosphere that is effectively thin in the important chromsopheric resonance lines of H I and Mg II and saturated in Ca II; (2) an upper chromospheric structure similar to quiet-Sun models; (3) penetration of the sunspot photospheric ''cooling wave'' to higher altitudes in the sunspot chromosphere than in quiet-Sun models, i.e., a more extended temperature minimum region in the sunspot atomphere; (4) a lower pressure corona above the sunspot umbra than above a typical quiet region; (5) very low nonthermal broadening in the umbral chromosphere; (6) a moderately strong downdraft; (7) chromospheric radiative loss rates not significantly different from their corresponding quiet-Sun values; (8) a temperature gradient in the transitons region near 10/sup 5/ Kapprox.0.1 times the corresponding quiet-Sun value. The Balmer continuum radiation from the photospheric areas outside the sunspot umbra controls the hydrogen ionization, and hence the electron density, in the chromosphere above the umbra.|
|Learning Resource Type||Article|
|Publisher Place||United States|
|Organization||High Altitude Observatory, National Center for Atmospheric Research|
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