Zeeman-split opposite-polarity OH lines in sunspot spectra: Resolution of a puzzle

¹ Astronomy Division, PO Box 3000, 90014 University of Oulu, Finland
² Max-Planck-Institut für Aeronomie, 37191 Katlenburg-Lindau, Germany

Corresponding author: S. V. Berdyugina, Sveta.Berdyugina@oulu.fi

Received: 7 September 2001
Accepted: 10 October 2001

Abstract

We present the first synthetic Zeeman-split Stokes I and V profiles of OH lines. They explain the puzzling observations reported by Harvey ([CITE]) of two pairs of lines from the infrared (2, 0) band with Stokes V profiles exhibiting opposite polarities. Our new perturbation calculations of the Zeeman effect in diatomic molecules, which allow states of any multiplicity to be treated, resolve the puzzle. They reveal that the unusual behaviour of these lines stems from the fact that the two pairs have effective Landé factors of similar magnitude, but of opposite signs.