Dynamical Surface Imaging of λ Andromedae

Abstract

Abstract We present temperature maps of RS CVn star λ Andromedae, reconstructed from interferometric data acquired in 2010 and 2011 by the Michigan Infra-Red Combiner instrument at the Center for High Angular Resolution Astronomy Array. To constrain the stellar parameters required for this imaging task, we first modeled the star using our GPU-accelerated code SImulation and Modeling Tool for Optical Interferometry. The stellar surface was then imaged using our open source interferometric imaging code ROTational Image Reconstruction, in the process further refining the estimation of stellar parameters. We report that the measured angular diameter is 2.742 ± 0.010 mas with a limb-darkening coefficient of 0.231 ± 0.024. While our images are consistent with those of prior works, we provide updated physical parameters for λ Andromedae (R ⋆ = 7.78 ± 0.05 R ⊙, M ⋆ = 1.24 ± 0.72 M ⊙, and log L/L ⊙ = 1.46 ± 0.04).