techniques: photometric; planets and satellites: atmospheres; stars: individual: TRAPPIST-1; infrared: planetary systems; infrared: stars; Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Solar and Stellar Astrophysics
Abstract :
[en] The TRAPPIST-1 planetary system is a favourable target for the atmospheric characterization of temperate earth-sized exoplanets by means of transmission spectroscopy with the forthcoming James Webb Space Telescope (JWST). A possible obstacle to this technique could come from the photospheric heterogeneity of the host star that could affect planetary signatures in the transit transmission spectra. To constrain further this possibility, we gathered an extensive photometric data set of 25 TRAPPIST-1 transits observed in the near-IR J band (1.2 μm) with the UKIRT and the AAT, and in the NB2090 band (2.1 μm) with the VLT during the period 2015-18. In our analysis of these data, we used a special strategy aiming to ensure uniformity in our measurements and robustness in our conclusions. We reach a photometric precision of 0.003 (RMS of the residuals), and we detect no significant temporal variations of transit depths of TRAPPIST-1 b, c, e, and g over the period of 3 yr. The few transit depths measured for planets d and f hint towards some level of variability, but more measurements will be required for confirmation. Our depth measurements for planets b and c disagree with the stellar contamination spectra originating from the possible existence of bright spots of temperature 4500 K. We report updated transmission spectra for the six inner planets of the system which are globally flat for planets b and g and some structures are seen for planets c, d, e, and f.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Burdanov, Artem ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Exotic
Lederer, S. M.; NASA Johnson Space Center, 2101 NASA Parkway, Houston, TX 77058, USA
Gillon, Michaël ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Exotic
Ducrot, Elsa ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Exotic
de Wit, J.; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
Jehin, Emmanuel ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Triaud, A. H. M. J.; School of Physics & Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
Lidman, C.; The Research School of Astronomy and Astrophysics, Australian National University, ACT 2601, Australia
Spitler, L.; Research Centre for Astronomy, Astrophysics & Astrophotonics, Macquarie University, Sydney, NSW 2109, Australia ; Department of Physics & Astronomy, Macquarie University, Sydney, NSW 2109, Australia
Demory, B.-O.; University of Bern, Center for Space and Habitability, Sidlerstrasse 5, CH-3012 Bern, Switzerland
Van Grootel, Valérie ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie
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