Jessica Birky, Rory Barnes, and David P. Fleming
We re-examine the XUV luminosity evolution of TRAPPIST-1 utilizing new observational constraints (XUV and bolometric luminosity) from multi-epoch X-ray/UV photometry. Following the formalism presented on , we infer that TRAPPIST-1 maintained a saturated XUV luminosity, relative to the bolometric luminosity, of log(Lxuv/Lbol) = -3.03_{-0.23}^{+0.25} at early times for a period of tsat = 3.14_{-1.46}^{+2.22} Gyr. After the saturation phase, we find Lxuv decayed over time by an exponential rate of beta = -1.17_{-0.28}^{+0.27}. Compared to our inferred age of the system age = 7.96_{-1.87}^{+1.78} Gyr, our result for tsat suggests that there is only a ~4% chance that TRAPPIST-1 still remains in the saturated phase today, which is significantly lower than the previous estimate of 40%. Despite this reduction in \tsat, our results remain consistent in the conclusion that the TRAPPIST-1 planets likely received an extreme amount XUV energy---an estimated integrated XUV energy of ~10^{30}-10^{32} erg} over the star's lifetime.
- Updated study: https://github.com/jbirky/trappist_xuv
- Original study: https://github.com/dflemin3/trappist
Main files:
mcmc/
runAPMCMCTrappist1.py
trappist1.py
corner.ipynb
flux_calc/
integratedFlux.ipynb
Usage:
- To reproduce the MCMC results with approxposterior, see runAPMCMCTrappist1.py
- To change the prior or likelihood assumptions for the model fitting, see trappist1.py
- To analyze the the the burned-in posterior samples, (from Figure 1 from this study) without re-running approxposterior, see corner.ipynb
- To reproduce the integrated flux calculations, see integratedFlux.ipynb