Solar CME Plasma Diagnostics Expressed as Potential Stellar CME Signatures

TL;DR

This paper proposes spectroscopic signatures, especially specific ultraviolet emission lines, as effective indicators for detecting and confirming stellar CMEs, inspired by solar CME diagnostics and their potential observability on other stars.

Contribution

It introduces a method to identify stellar CMEs through UV emission lines, emphasizing the use of multiple lines for increased detection credibility, and provides predictions on their brightness at stellar distances.

Findings

Multiple UV emission lines can improve CME detection confidence.

Specific lines like C IV, O VI, and C III are promising diagnostics.

Predicted brightness levels suggest feasible detection with current instruments.

Abstract

Solar coronal mass ejections (CMEs) have a strong association with solar flares that is not fully understood. This characteristic of our Sun's magnetic activity may also occur on other stars, but the lack of successfully detected stellar CMEs makes it difficult to perform statistical studies that might show a similar association between CMEs and flares. Because of the potentially strong association, the search for stellar CMEs often starts with a successful search for superflares on magnetically active stars. Regardless of the flare's presence, we emphasize the utility of searching for CME-specific spectroscopic signatures when attempting to find and confirm stellar CME candidates. We use solar CMEs as examples of why a multitude of ultraviolet emission lines, when detected simultaneously, can substantially improve the credibility of spectroscopically discovered stellar CME candidates. We make predictions on how bright CME-related emission lines can be if they derived from distant stars. We recommend the use of three emission lines in particular (C IV 1550 Angstroms, O VI 1032 Angstroms, and C III 977 Angstroms) due to their potentially bright signal and convenient diagnostic capabilities that can be used to confirm if an observational signature truly derives from a stellar CME.