Issue |
A&A
Volume 688, August 2024
|
|
---|---|---|
Article Number | A192 | |
Number of page(s) | 15 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202348013 | |
Published online | 23 August 2024 |
New ephemerides and detection of transit-timing variations in the K2-138 system using high-precision CHEOPS photometry
1
Aix Marseille Univ, CNRS, CNES, Institut Origines, LAM,
Marseille,
France
e-mail: hugo.vivien@pm.me
2
Caltech/IPAC-NASA Exoplanet Science Institute,
Pasadena,
CA
91125,
USA
3
Steward Observatory, The University of Arizona,
Tucson,
AZ
85721,
USA
Received:
18
September
2023
Accepted:
2
May
2024
Context. Multi-planet systems are a perfect laboratory for constraining planetary formation models. A few of these systems present planets that come very close to mean motion resonance, potentially leading to significant transit-timing variations (TTVs) due to their gravitational interactions. Of these systems, K2-138 represents an excellent laboratory for studying the dynamics of its six small planets (with radii ranging between ~1.5–3.3 R⊕), as the five innermost planets are in a near 3:2 resonant chain.
Aims. In this work, we aim to constrain the orbital properties of the six planets in the K2-138 system by monitoring their transits with CHaracterising ExOPlanets Satellite (CHEOPS). We also seek to use this new data to lead a TTV study on this system.
Methods. We obtained twelve light curves of the system with transits of planets d, e, f, and g. With these data, we were able to update the ephemerides of the transits for these planets and search for timing transit variations.
Results. With our measurements, we reduced the uncertainties in the orbital periods of the studied planets, typically by an order of magnitude. This allowed us to correct for large deviations, on the order of hours, in the transit times predicted by previous studies. This is key to enabling future reliable observations of the planetary transits in the system. We also highlight the presence of potential TTVs ranging from 10 min to as many as 60 min for planet d.
Key words: techniques: photometric / planets and satellites: detection / planets and satellites: fundamental parameters / stars: individual: K2-138
© The Authors 2024
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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