The bias of stellar flares on the measure of exoatmospheres

Abstract

There are a few planetary systems already observed with JWST transmission spectra, such as TRAPPIST-1, and K2-18. As can be seen in [1,2], stellar activity (flares in particular) is the key limitation to measuring exoatmospheres of planets orbiting M dwarfs (e.g. TRAPPIST-1). This is also shown in [3].

There has been some controversy in the community when attributing signal excursions in planetary transits either to flares or starspots signatures. See for example the assigned starspot apparently mistaken in [4], which is summarized in [5].

When observing a transmission spectra, the previous controversy and the key limitation can imply biases in the exoatmospheric retrieval of certain species, especially biomarkers. Therefore, improving the measurement of flares/starspots signals is crucial.

I propose the following items in this MSc thesis:

1-compile as many JWST transmission and available spectra as possible from M-dwarfs with rocky planets. A semiautomatic data gathering process which queryies several databases (e.g. [6]) should be tailored for this purpose.

2-conduct the necessary spectral analysis to get the transit light curves in broadband and H_alpha bands, as it is done in [2], with all systems observed by the technique of JWST transmission in the previous item.

3-conduct exoatmospheric retrieval for all exoplanets observed and analyzed in items 1- and 2-.

4-compare the relative flux increased by the flare at the peak versus the typical atmospheric signal [7] at certain species, especially biomarkers. This will give you a quantitative goodness metric for a flare fit along the spectral range to compare to these species flux.
 

Advisors
Octavi Fors
Requirements
Interest in stellar activity, flares, and exoatmospheres. Excellent skills in stellar and planetary physics, and Python computing.