• DOI:10.3847/1538-4357/aaa023
• Corpus ID: 54034373

Stellar Parameters for Trappist-1

@article{Grootel2018StellarPF,
  title={Stellar Parameters for Trappist-1},
  author={Val{\'e}rie Van Grootel and Catarina Silva Fernandes and Micha{\"e}l Gillon and Emmanuel Jehin and Jean Manfroid and Richard Scuflaire and Adam J. Burgasser and Artem Burdanov and Laetitia Delrez and B-O. Demory and Julien de Wit and Didier Queloz and Amaury H. M. J. Triaud},
  journal={The Astrophysical Journal},
  year={2018},
  volume={853},
  pages={30}
}

• V. Grootel, C. S. Fernandes, +10 authors A. Triaud
• Published 5 December 2017
• Physics, Geology
• The Astrophysical Journal

TRAPPIST-1 is an ultracool dwarf star transited by seven Earth-sized planets, for which thorough characterization of atmospheric properties, surface conditions encompassing habitability, and internal compositions is possible with current and next-generation telescopes. Accurate modeling of the star is essential to achieve this goal. We aim to obtain updated stellar parameters for TRAPPIST-1 based on new measurements and evolutionary models, compared to those used in discovery studies. We present a new measurement for the parallax of TRAPPIST-1, 82.4 ± 0.8 mas, based on 188 epochs of observations with the TRAPPIST and Liverpool Telescopes from 2013 to 2016. This revised parallax yields an updated luminosity of L =(5.22 ± 0.19) x 10⁻⁴ Lʘ, which is very close to the previous estimate but almost two times more precise. We next present an updated estimate for TRAPPIST-1 stellar mass, based on two approaches: mass from stellar evolution modeling, and empirical mass derived from dynamical masses of equivalently classified ultracool dwarfs in astrometric binaries. We combine them using a Monte-Carlo approach to derive a semi-empirical estimate for the mass of TRAPPIST-1. We also derive estimate for the radius by combining this mass with stellar density inferred from transits, as well as an estimate for the effective temperature from our revised luminosity and radius. Our final results are M = 0.089 ± 0.006 Mʘ, R =0.121 ± 0.003 Rʘ , and Teff= 2516 ± 41 K. Considering the degree to which the TRAPPIST-1 system will be scrutinized in coming years, these revised and more precise stellar parameters should be considered when assessing the properties of TRAPPIST-1 planets.