Doppler images of the eclipsing binary ER Vulpeculae

TL;DR

This paper presents Doppler imaging of ER Vulpeculae, revealing persistent high-latitude starspots and non-uniform spot distribution on both stars over multiple years, indicating active magnetic phenomena.

Contribution

It provides new surface images of ER Vul from three epochs, demonstrating the presence and stability of high-latitude starspots using advanced spectral analysis techniques.

Findings

Both stars show strong, high-latitude starspots.

Starspots are non-uniformly distributed and stable over years.

Active regions are mainly on the hemisphere facing the companion star.

Abstract

We present Doppler images of both components of the eclipsing binary system ER Vul, based on the spectra obtained in 2004 November, 2006 September and 2008 November. The least-squares deconvolution technique is used for enhancing the signal-to-noise ratios of the observed profiles. The new surface images reveal that both stars of ER Vul show strong starspot activities and the starspots appear at various latitudes. The surface maps of 2006 and 2008 both show the presence of large high-latitude starspots on each component of ER Vul. We find no obvious phase shift of the active regions during our observations. The longitude distributions of starspots are non-uniform on both stars. At low-to-mid latitudes, the active regions are almost exclusively found in the hemisphere facing the other star. However, we find no pronounced concentration of spots at the sub-stellar points.