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Astron. Astrophys. 349, L37-L40 (1999)

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Letter to the Editor

Vertical mass flux in a sunspot penumbra

R. Schlichenmaier and W. Schmidt

Kiepenheuer-Institut für Sonnenphysik, Schöneckstrasse 6, D-79104 Freiburg, Germany (schliche,wolfgang@kis.uni-freiburg.de)

Received 26 July 1999 / Accepted 12 August 1999

Abstract

We present the first direct measurement of vertical motion in the deepest atmospheric layers of a penumbra, obtained at hitherto unreached spatial resolution. Isolated hot upflows in the inner penumbra feed the horizontal Evershed flow that is observed in the mid and outer penumbra. We discover cool downflows which surround the hot upflows in the inner penumbra. At the outer edge of the penumbra, the Evershed flow terminates in a ring of downflow channels. The upflows transport a sufficient amount of energy to account for the observed brightness of the penumbra. These measurements have therefore significant implications for understanding the mass balance and the energy transport in a sunspot penumbra.

Key words: Sun: photosphere – Sun: sunspots – Sun: magnetic fields

Send offprint requests to: R. Schlichenmaier

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© European Southern Observatory (ESO) 1999

Online publication: September 2, 1999
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