Rutgers University Astrophysics Seminar

Differential chromatic refraction (DCR) manifests as a wavelength dependent shift in source position towards the zenith of an observer, and must be corrected for in terrestrial surveys to ensure accurate astrometric solutions. Despite this, DCR can also be employed as a tool to extract additional color information from astrometry. M dwarf flares are particularly well suited to this technique due to their ubiquity across various regions of the sky, and the dramatic contrast between the red photosphere and blue flare emission. While flares are challenging targets for sky surveys due to their short durations, DCR can be used to infer color temperatures across the unprecedentedly large sample of flares that will be detected in next-generation astronomical surveys, such as the Legacy Survey of Space and Time (LSST) that will be carried out by the Vera C. Rubin Observatory, starting in 2025. By combining Rubin’s high image quality and astrometric precision with the truly massive amount of data it will produce over 10 years, DCR can be used to carry out a population-level statistical analysis of stellar flare temperatures, constraining models of energy release in stellar atmospheres and informing habitability surveys. We additionally validated this technique on flare data obtained from an LSST precursor, the Deeper, Wider, Faster Programme, and showed how certain choices made when modeling the spectral and geometric properties of the flare could lead to overestimating the true flare temperature.