Forum Springer Astron. Astrophys.
Forum Whats New Search Orders

Astron. Astrophys. 348, L37-L40 (1999)

Next Section Table of Contents

Letter to the Editor

Infrared lines as probes of solar magnetic features

XV. Evershed flow in cool, weak penumbral fields

I. Rüedi 1, S.K. Solanki 1 and C.U. Keller 2

1 ETH-Zentrum, Institute of Astronomy, CH-8092 Zürich, Switzerland
2 National Solar Observatory, NOAO *, P.O. Box 26732, Tucson, AZ 85726, USA

Received 2 July 1999 / Accepted 14 July 1999


Observations of Ti [FORMULA] lines at 2.2 µm show that the Evershed flow takes place in cool, almost horizontal channels with a low magnetic field strength ([FORMULA] G) that does not appear to change significantly across the penumbra. This property might allow an outward directed siphon flow to exist along such cool flux tubes.

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

* Operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.

Send offprint requests to: I. Rüedi

This article contains no SIMBAD objects.


Next Section Table of Contents

© European Southern Observatory (ESO) 1999

Online publication: July 26, 1999