Abstract
Intensity observations of sunspot umbrae and penumbrae in the visible and infrared are reviewed. The continuum intensity in the darkest part of the umbra and the average penumbral intensity are known with relatively high accuracy in large sunspots. With the aim of understanding conflicting observations of umbral dots it is suggested that the umbral core is nearly free of umbral dots, and that an umbral core only occurs in sunspots above a certain size.
The present status of semi-empirical models of the temperature stratification in umbrae and penumbrae is discussed and the need for extending the model calculations to more than one dimension is pointed out.
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Maltby, P. (1992). Continuum Observations and Empirical Models of the Thermal Structure of Sunspots. In: Thomas, J.H., Weiss, N.O. (eds) Sunspots: Theory and Observations. NATO ASI Series, vol 375. Springer, Dordrecht. https://doi.org/10.1007/978-94-011-2769-1_4
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DOI: https://doi.org/10.1007/978-94-011-2769-1_4
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