Model of a sunspot chromosphere based on OSO 8 observations

Journal Article · Tue Jun 01 04:00:00 EDT 1982 · Astrophys. J., Suppl. Ser.; (United States)

DOI:https://doi.org/10.1086/190800· OSTI ID:5129659

Lites, B W; Skumanich, A

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.

• Research Organization: High Altitude Observatory, National Center for Atmospheric Research
• OSTI ID: 5129659
• Journal Information: Astrophys. J., Suppl. Ser.; (United States), Journal Name: Astrophys. J., Suppl. Ser.; (United States) Vol. 49:2; ISSN APJSA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALKALINE EARTH METALS
ATMOSPHERES
BALMER LINES
CALCIUM
CHROMOSPHERE
ELEMENTS
EMISSION SPECTRA
EMISSION SPECTROSCOPY
HYDROGEN
MAGNESIUM
MATHEMATICAL MODELS
METALS
NONMETALS
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR CORONA
SPECTRA
SPECTROSCOPY
SUNSPOTS
VISIBLE SPECTRA