stellar files are stored in ascii files (2-column files or 2 files of 1 column ; wavelength, stellar flux)
keep in mind that the Generic PCM renormalizes the stellar flux according to the top-of-the atmosphere flux prescribed in callphys.def and start/startfi files

lambda_TRAPPIST1.dat and Flux_TRAPPIST1.dat --> TRAPPIST-1 stellar flux used in the THAI intercomparison project
lambda_Proxima.dat and Flux_Proxima.dat --> Proxima Cen stellar flux used in Turbet et al. 2016
lam.txt and sol.txt --> Sun stellar flux

etc.
