On physical conditions in the chromosphere above sunspot umbrae

Abstract

By means of an inversion of H and K Ca II line profiles the temperature and electron density in the chromosphere above the umbrae of two sunspots have been estimated. The temperature gradient 5 K km -1 exceeds the corresponding values in both quiet regions and plages. At a height of about 1500 km the umbra becomes hotter than the quiet region. At a temperature of about 10 000 K the temperature gradient increases sharply. The electron density at 1500 km is approximately the same as that in the quiet chromosphere at the same height.

A Three-Dimensional View of the Thermal Structure in a Super-Penumbral Canopy

“…As a result, inversions of chromospheric line spectra (e.g. Liu & Skumanich 1974;Teplitskaia et al 1978;Socas-Navarro et al 2000;Sheminova et al 2005;Pietarila et al 2007;Teplitskaya & Grigoryeva 2009;de la Cruz Rodríguez et al 2012;Martínez González et al 2012;Beck et al 2013b) are less common than their counterparts for photospheric spectra (e.g. Keller et al 1990;Ruiz Cobo & del Toro Iniesta 1992;Frutiger et al 2000;Socas-Navarro et al 2001;Bellot Rubio et al 2004;Carroll & Kopf 2008;Asensio Ramos et al 2008;Judge & Carlsson 2010;Beck 2011, and references therein).…”