Zeeman-Doppler Imaging of II Peg - Magnetic field restructuring from 2004 to 2007

TL;DR

This study uses Zeeman-Doppler imaging to analyze the magnetic field evolution of the active star II Peg between 2004 and 2007, revealing significant restructuring of its large-scale magnetic topology.

Contribution

The paper introduces a new ZDI code 'iMap' for simultaneous reconstruction of temperature and magnetic fields, applied to II Peg over multiple years.

Findings

Magnetic field is mainly at high latitudes and active longitudes.

A shift from a unipolar to bipolar magnetic structure occurred between 2004 and 2007.

Significant magnetic restructuring observed over three years.

Abstract

We present Zeeman-Doppler images of the active K2 star II Peg for the years 2004 and 2007. The surface magnetic field was reconstructed with our new ZDI code "iMap" which provides a full polarized radiative transfer driven inversion to simultaneously reconstruct the surface temperature and magnetic vector field distribution. II Peg shows a remarkable large scale magnetic field structure for both years. The magnetic field is predominantly located at high latitudes and is arranged in active longitudes. A dramatic evolution in the magnetic field structure is visible for the two years, where a dominant and largely unipolar field in 2004 has developed into two distinct and large scale bipolar structures in 2007.