Astron. Astrophys. 364, L101-L104 (2000)

Letter to the Editor

Successful spectral synthesis of Zeeman-split molecular bands in sunspot spectra

S.V. Berdyugina ¹, C. Frutiger ², S.K. Solanki ³ and W. Livingstone <sup>4

1</sup> University of Oulu, Astronomy Division, P.O. Box 3000, 90014 Finland
² ETHZ, Institut für Astronomie, Scheuchzerstrasse 7, 8092 Zürich, Switzerland
³ Max-Planck-Institut für Aeronomie, Max-Planck-Strasse 2, 37191 Katlenburg-Lindau, Germany
⁴ National Solar Observatory, AURA, P.O. Box 26732, Tucson, AZ 85726, USA

Received 26 October 2000 / Accepted 20 November 2000

Abstract

We present the first spectral synthesis of Zeeman-split Stokes profiles of the MgH - green system and TiO -system. The calculations involve different regimes of the molecular Zeeman effect, up to the complete Paschen-Back effect for individual lines. The synthetic spectra are compared with observations of Stokes I and V in sunspot umbrae. We find that although the Stokes I spectra are reasonably reproduced, some lines are obviously still missing from the employed line lists. The Stokes V spectra turn out to be much cleaner since the missing lines do not appear to be Zeeman-split. We thus provide the first good fit to Zeeman-split molecular lines, including profiles with unconventional Stokes V shapes, determined by the Paschen-Back effect.

Key words: Sun: magnetic fields Sun: sunspots line: formation polarization molecular processes

Send offprint requests to: S.V.Berdyugina (sveta@ukko.oulu.fi)

© European Southern Observatory (ESO) 2000

Online publication: January 29, 2001

helpdesk.link@springer.de