Issue |
A&A
Volume 671, March 2023
|
|
---|---|---|
Article Number | L3 | |
Number of page(s) | 4 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/202345937 | |
Published online | 01 March 2023 |
Letter to the Editor
Temporal albedo variability in the phase curve of KELT-1b
1
Instituto de Astrofísica de Canarias (IAC), 38200 La Laguna, Tenerife, Spain
e-mail: hannu@iac.es
2
Departamento de Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain
Received:
18
January
2023
Accepted:
9
February
2023
The dayside brightness spectrum of a highly irradiated transiting brown dwarf KELT-1b is challenging to explain based on current brown dwarf atmosphere models. The spectrum has been measured from observations spanning ten years and covering high-precision secondary eclipses and phase curves from space in blue-visible (CHaracterising ExOPlanet Satellite, CHEOPS), red-visible (Transiting Exoplanet Survey Satellite, TESS), and near-infrared (Spitzer), as well as secondary eclipse observations in near-infrared from the ground. First, the dayside of KELT-1b was observed to be brighter in the TESS passband than expected, based on earlier near-infrared phase curve observations with Spitzer, and, recently, the dayside was observed to be extremely dark in the CHEOPS passband. While several theories have been proposed to reconcile the discrepancy between the TESS and Spitzer bands, explaining the difference between the largely overlapping CHEOPS and TESS bands has proven more difficult. In this work, I model the TESS photometry from Sector 17 together with the new TESS photometry from Sector 57 and show that the discrepancies in KELT-1b’s dayside brightness spectrum are best explained by temporal variability in KELT-1b’s albedo. This variability is most likely due to changes in the weather, namely, variations in the silicate cloud coverage on the brown dwarf’s dayside.
Key words: stars: individual: KELT-1 / brown dwarfs / planetary systems / planets and satellites: atmospheres / stars: atmospheres / methods: observational
© The Authors 2023
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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