Improved Constraints for the XUV Luminosity Evolution of Trappist-1

• Published in: Research notes of the AAS Vol. 5; no. 5; pp. 122 - 121
• Main Authors: Birky, Jessica, Barnes, Rory, Fleming, David P.
• Format: Journal Article
• Language: English
• Published: 2230 Support The American Astronomical Society 25.05.2021; American Astronomical Society
• Subjects: Astronomy; Low mass stars; Planet hosting stars; Stellar evolution; Stellar Evolution; Low Mass Stars; Planet Hosting Stars
• ISSN: 2515-5172; 2515-5172
• DOI: 10.3847/2515-5172/ac034c

We re-examine the XUV luminosity evolution of TRAPPIST-1 utilizing new observational constraints of the current stellar parameters (XUV and bolometric luminosity) from multi-epoch X-ray/UV photometry. Following the formalism presented on Fleming et al. (2020), we infer that TRAPPIST-1maintained a saturated XUV luminosity, relative to the bolometric luminosity, of log10(LXUV/Lbol)=−3.03+0.25−0.23at early times for a period of tsat= 3.14+2.22−1.46Gyr. After the saturation phase, we find LXUV decayed over time by an exponential rate ofβXUV=−1.17+0.27−0.28. Compared to our inferred age of the system, age = 7.96+1.78−1.87Gyr, our result for tsat suggests that there is only a∼4% chance thatTRAPPIST-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∼1030−1032erg over the star’s lifetime—that is∼15% lower than the original result.