Two-epoch Zeeman–Doppler imaging of the close binary ER Vulpeculae
Year: 2026
Type: article
Abstract: We present simultaneous magnetic reconstructions of both components of ER Vulpeculae from spectropolarimetric observationsobtained in 2013 and 2015. An SB2 extension of a Zeeman–Doppler imaging framework fits the two stars together using a spherical-harmonicexpansion through degree six, processed Stokes I profiles and observed Stokes V , with a reduced treatment of binary surface distortion. Bothcomponents exhibit the same directions of change in the reconstructed harmonic energy distribution. The toroidal fraction rises from 13.73%to 33.09% in component A and from 14.68% to 37.18% in component B; the dipole fraction decreases by 14.74 and 13.76 percentage points,respectively. The corresponding mean reconstructed fields are approximately 36/33 G in 2013 and 97/90 G in 2015. Known-field recovery testsreveal substantial topology bias in some noisy cases, and the saved fixed-mean refinements are limited by their iteration budgets. We thereforereport the parallel changes as properties of these reconstructions, while distinguishing them from a uniquely determined evolutionary signal orevidence for intercomponent dynamo coupling.
Authors: Wang, Yusong, Hao, Yanzhi
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225117305