# On the origin of the flare emission in IRIS' SJI 2832 filter: Balmer continuum or spectral lines?

## TL;DR

This study investigates whether IRIS SJI 2832 filter brightenings during solar flares are due to true continuum emission or spectral lines, finding that spectral lines often dominate but the Balmer continuum can also significantly contribute.

## Contribution

The paper provides a detailed analysis distinguishing between spectral line and continuum contributions to IRIS SJI 2832 flare emissions, highlighting the importance of careful interpretation.

## Key findings

- Spectral line emission can contribute up to 100% of SJI 2832 emission during flares.
- The relative contributions of lines and continuum vary over time.
- Highest SJI enhancements are likely due to the Balmer continuum.

## Abstract

Continuum ("White-light", WL) emission dominates the energetics of flares. Filter-based observations, such as the IRIS SJI 2832 filter, show WL-like brightenings during flares, but it is unclear whether the emission arises from real continuum emission or enhanced spectral lines, possibly turning into emission. The difficulty in filter-based observations, contrary to spectral observations, is to determine which processes contribute to the observed brightening during flares. Here we determine the contribution of the Balmer continuum and the spectral line emission to IRIS' SJI 2832 emission by analyzing the appropriate passband in simultaneous IRIS NUV spectra. We find that spectral line emission can contribute up to 100% to the observed SJI emission, that the relative contributions usually temporally vary, and that the highest SJI enhancements that are observed are most likely because of the Balmer continuum. We conclude that care should be taken when calling SJI 2832 a continuum filter during flares, because the influence of the lines on the emission can be significant.