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Title: Model of a sunspot chromosphere based on OSO 8 observations

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;more » (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.« less

Authors:
;
Publication Date:
Research Org.:
High Altitude Observatory, National Center for Atmospheric Research
OSTI Identifier:
5129659
Resource Type:
Journal Article
Journal Name:
Astrophys. J., Suppl. Ser.; (United States)
Additional Journal Information:
Journal Volume: 49:2
Country of Publication:
United States
Language:
English
Subject:
71 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; 640104* - Astrophysics & Cosmology- Solar Phenomena

Citation Formats

Lites, B W, and Skumanich, A. Model of a sunspot chromosphere based on OSO 8 observations. United States: N. p., 1982. Web. doi:10.1086/190800.
Lites, B W, & Skumanich, A. Model of a sunspot chromosphere based on OSO 8 observations. United States. doi:10.1086/190800.
Lites, B W, and Skumanich, A. Tue . "Model of a sunspot chromosphere based on OSO 8 observations". United States. doi:10.1086/190800.
@article{osti_5129659,
title = {Model of a sunspot chromosphere based on OSO 8 observations},
author = {Lites, B W and Skumanich, A},
abstractNote = {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.},
doi = {10.1086/190800},
journal = {Astrophys. J., Suppl. Ser.; (United States)},
number = ,
volume = 49:2,
place = {United States},
year = {1982},
month = {6}
}