Explosive Event Contribution to the IRIS Si IV Transition Region Lines of the Sun-as-a-Star

Abstract:

This study aims to uncover the signature of FUV explosive events (EEs) in Si IV full-disk mosaics (FDMs) taken by the Interface Region Imaging Spectrograph (IRIS). The IRIS FDMs allow for the opportunity to detect individual EEs across the disk and accurately measure the disk-integrated spectrum both with and without the EE contribution. To this end, we have taken careful account of sources of error in the IRIS data such as bias estimation and backgrounds. The expected signature in summed spectra of the full disk is a small enhancement of the tails of the emission line, which is challenging to measure accurately. If the disk-integrated EE contribution to the wings of TR lines can be separated from the continuum and instrumental backgrounds, then EE detection in the Sun-as-a-star and in Sun-like stars may be possible. This research is motivated by the NASA suborbital sounding rocket mission known as the Full-sun Ultraviolet Rocket SpecTrograph (FURST), which is set to launch in late 2022, and also by the prospect of comparing FURST data with Hubble Space Telescope (HST) spectra of Sun-like stars.