Star-spot activity, orbital obliquity, transmission spectrum, physical properties, and transit time variations of the HATS-2 planetary system
Abstract
Aims. Our aim in this paper is to refine the orbital and physical parameters of the HATS-2 planetary system and study transit timing variations and atmospheric composition thanks to transit observations that span more than 10 yr and that were collected using different instruments and pass-band filters. We also investigate the orbital alignment of the system by studying the anomalies in the transit light curves induced by starspots on the photosphere of the parent star. Methods. We analysed new transit events from both ground-based telescopes and NASA’s TESS mission. Anomalies were detected in most of the light curves and modelled as starspots occulted by the planet during transit events. We fitted the clean and symmetric light curves with the JKTEBOP code and those affected by anomalies with the PRISM+GEMC codes to simultaneously model the photometric parameters of the transits and the position, size, and contrast of each starspot. Results. We found consistency between the values we found for the physical and orbital parameters and those from the discovery paper and ATLAS9 stellar atmospherical models. We identified different sets of consecutive starspot-crossing events that temporally occurred in less than five days. Under the hypothesis that we are dealing with the same starspots, occulted twice by the planet during two consecutive transits, we estimated the rotational period of the parent star and, in turn the projected and the true orbital obliquity of the planet. We find that the system is well aligned. We identified the possible presence of transit timing variations in the system, which can be caused by tidal orbital decay, and we derived a low-resolution transmission spectrum.
Citation
Biagiotti , F , Mancini , L , Southworth , J , Tregloan-Reed , J , Naponiello , L , Jørgensen , U G , Bach-Møller , N , Basilicata , M , Bonavita , M , Bozza , V , Burgdorf , M J , Dominik , M , Jaimes , R F , Henning , T , Hinse , T C , Hundertmark , M , Khalouei , E , Longa-Peña , P , Peixinho , N , Rabus , M , Rahvar , S , Sajadian , S , Skottfelt , J , Snodgrass , C , Jongen , Y & Vignes , J -P 2024 , ' Star-spot activity, orbital obliquity, transmission spectrum, physical properties, and transit time variations of the HATS-2 planetary system ' , Astronomy & Astrophysics , vol. 685 , A131 . https://doi.org/10.1051/0004-6361/202347872
Publication
Astronomy & Astrophysics
Status
Peer reviewed
ISSN
0004-6361Type
Journal article
Description
Funding: We acknowledge funding from the Novo Nordisk Foundation Interdisciplinary Synergy Program grant no. NNF19OC0057374 and from the European Union H2020-MSCA-ITN-2019 under grant No. 860470 (CHAMELEON). Support for this project is provided by ANID’s Millennium Science Initiative through grant ICN12_009, awarded to the Millennium Institute of Astrophysics (MAS), and by ANID’s Basal project FB210003. L. M. acknowledges support from the MIUR-PRIN project No. 2022J4H55R. T.C.H. acknowledges funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 871149.Collections
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