Modeling Coronal Mass Ejection Induced Dimmings on Epsilon Eridani and Comparing with HST Far-Ultraviolet Observations

Although solar flares and CMEs are highly relevant phenomenona on the Sun, heliophysics studies have shown that they impact the planets in the solar system in different ways. CMEs have a much larger influence than flares on stellar evolution through mass loss and angular-momentum loss, and can significantly impact the habitability of exoplanets due to their ability to erode atmospheres of exoplanets. Even though the stellar flares are frequently observed, it remains challenging to associate stellar CMEs with any of these flares. CME-induced coronal dimmings (caused by the mass loss of coronal plasmas), which have been extensively observed on the Sun, are believed to be a promising proxy for detecting stellar CMEs. In this study, we present global MHD modeling results of CME-induced coronal dimmings on K dwarf star Epsilon Eridani. The Zeeman Doppler Imaging surface magnetic map of the star is used to drive the inner boundary condition of the model. The coronal heating parameters of the model are also constrained by the Emission Measure distributions derived from the previous EUVE and XMM observations. By initiating a CME eruption through analytical flux rope insertion, we simulate the coronal dimming evolution and calculate synthetic EUV/FUV line intensities with different emission temperatures. Furthermore, we present a coronal dimming analysis of Fe XII 1349 A and Fe XXI 1354 A emission from Epsilon Eridani with archival FUV observations by Hubble Space Telescope’s Cosmic Origins Spectrograph and compare with the synthesized line emission in the model. Based on the result, we discuss the CME and wind contributions to the spin down and high observed mass loss rate from Epsilon Eridani.