English

Improved Constraints for the XUV Luminosity Evolution of Trappist-1

Earth and Planetary Astrophysics 2021-05-27 v1 Solar and Stellar Astrophysics

Abstract

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 in Fleming et al. (2020), we infer that TRAPPIST-1 maintained a saturated XUV luminosity, relative to the bolometric luminosity, of log10\log_{10}(LXUV_{\rm XUV}/Lbol_{\rm bol}) =3.030.23+0.25= -3.03_{-0.23}^{+0.25} at early times for a period of tsat=3.141.46+2.22t_{sat} = 3.14_{-1.46}^{+2.22} Gyr. After the saturation phase, we find LXUV_{\rm XUV} decayed over time by an exponential rate of βXUV=1.170.28+0.27\beta_{\rm XUV} = -1.17_{-0.28}^{+0.27}. Compared to our inferred age of the system, age=7.961.87+1.78{\rm age} = 7.96_{-1.87}^{+1.78} Gyr, our result for tsatt_{sat} suggests that there is only a 4%\sim4\%~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 tsatt_{sat}, 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 10301032\sim10^{30}-10^{32} erg over the star's lifetime.

Keywords

Cite

@article{arxiv.2105.12562,
  title  = {Improved Constraints for the XUV Luminosity Evolution of Trappist-1},
  author = {Jessica Birky and Rory Barnes and David P. Fleming},
  journal= {arXiv preprint arXiv:2105.12562},
  year   = {2021}
}

Comments

4 pages, 1 figure