Contemporaneous Imaging Comparisons of the Spotted Giant $\sigma$ Geminorum Using Interferometric, Spectroscopic, and Photometric Data

TL;DR

This study compares interferometric, spectroscopic, and photometric imaging techniques on the active star $\sigma$ Geminorum, revealing consistent spot features longitudinally but significant latitude discrepancies across methods.

Contribution

First simultaneous imaging of a star using interferometry, spectroscopy, and photometry, highlighting strengths and limitations of each method.

Findings

Good agreement in spot longitudinal features across methods

Strong disagreement in spot latitudes among techniques

Demonstrates the potential and challenges of multi-method stellar imaging

Abstract

Nearby, active stars with relatively rapid rotation and large starspot structures offer the opportunity to compare interferometric, spectroscopic, and photometric imaging techniques. In this paper, we image a spotted star with three different methods for the first time. The giant primary star of the RS Canum Venaticorum binary $\sigma$ Geminorum ($\sigma$ Gem) was imaged for two epochs of interferometric, high-resolution spectroscopic, and photometric observations. The light curves from the reconstructions show good agreement with the observed light curves, supported by the longitudinally-consistent spot features on the different maps. However, there is strong disagreement in the spot latitudes across the methods.