HSTbanner

AR 15803 (Archival Research)

Sat Jul 20 08:51:31 GMT 2024

Principal Investigator: R. O. Loyd
PI Institution: Eureka Scientific Inc.
Investigators (xml)

Title: Constraining CME Masses on the Active K Star and Planet Host Epsilon Eridani
Cycle: 27

Abstract
If the frequent, energetic flares of active stars are each accompanied by a coronal mass ejection (CME), the effect on stellar and planetary evolution could be strong. Every CME event carries mass and angular momentum away from the star, and each has the potential to impact and strip atmospheric gas from orbiting planets. Developing observational constraints on stellar CMEs is essential to assessing their true impact on stellar and planetary evolution. Such constraints are possible via the unique FUV capabilities of HST. In the FUV, photometry of the coronal Fe XXI 1354 A emission line can constrain the mass of CMEs that accompany flares through an effect known as coronal dimming. Coronal dimming is a direct result of the ejection of emitting coronal material, which leaves behind a dark void reliably detected in Sun-as-a-star observations as a drop in the disk-integrated emission of coronal lines. We propose a coronal dimming analysis of 10 h of high S/N archival COS G130M data of the K dwarf planet host Epsilon Eridani (Eps Eri), containing several flares to constrain the masses of associated CMEs. We will accompany this analysis with detailed MHD modeling of Eps Eri's corona to simulate the dimming in Fe XXI 1354 A emission following CMEs. This analysis will lay fundamental groundwork for future dedicated HST CME observations, develop theoretical tools for interpreting dimming signals through MHD analysis, and test whether CMEs could be a dominant contributor to Eps Eri's high observed mass loss rate.