Precise characterisation of HD 15337 with CHEOPS: a laboratory for planet formation and evolution

N. M. Rosário; O. D. S. Demangeon; S. C. C. Barros; D. Gandolfi; J. A. Egger; L. M. Serrano; H. P. Osborn; M. Beck; W. Benz; H. G. Florén; P. Guterman; T. G. Wilson; Y. Alibert; L. Fossati; M. J. Hooton; L. Delrez; N. C. Santos; S. G. Sousa; A. Bonfanti; S. Salmon; V. Adibekyan; A. Nigioni; J. Venturini; R. Alonso; G. Anglada; J. Asquier; T. Bárczy; D. Barrado Navascues; O. Barragán; W. Baumjohann; T. Beck; N. Billot; F. Biondi; X. Bonfils; L. Borsato; A. Brandeker; C. Broeg; V. Cessa; S. Charnoz; A. Collier Cameron; Sz Csizmadia; P. E. Cubillos; M. B. Davies; M. Deleuil; A. Deline; B. -O. Demory; D. Ehrenreich; A. Erikson; M. Esposito; A. Fortier; M. Fridlund; M. Gillon; M. Güdel; M. N. Günther; Ch Helling; S. Hoyer; K. G. Isaak; L. L. Kiss; K. W. F. Lam; J. Laskar; A. Lecavelier Des Etangs; M. Lendl; A. Luntzer; D. Magrin; P. F. L. Maxted; C. Mordasini; V. Nascimbeni; G. Olofsson; H. L. M. Osborne; R. Ottensamer; I. Pagano; E. Pallé; G. Peter; G. Piotto; D. Pollacco; D. Queloz; R. Ragazzoni; N. Rando; H. Rauer; I. Ribas; G. Scandariato; D. Ségransan; A. E. Simon; A. M. S. Smith; M. Stalport; Gy M. Szabó; N. Thomas; S. Udry; V. Van Eylen; V. Van Grootel; E. Villaver; I. Walter; N. A. Walton

doi:10.1051/0004-6361/202347759

Precise characterisation of HD 15337 with CHEOPS: a laboratory for planet formation and evolution

N. M. Rosário^*, O. D. S. Demangeon, S. C. C. Barros, D. Gandolfi, J. A. Egger, L. M. Serrano, H. P. Osborn, M. Beck, W. Benz, H. G. Florén, P. Guterman, T. G. Wilson, Y. Alibert, L. Fossati, M. J. Hooton, L. Delrez, N. C. Santos, S. G. Sousa, A. Bonfanti, S. SalmonV. Adibekyan, A. Nigioni, J. Venturini, R. Alonso, G. Anglada, J. Asquier, T. Bárczy, D. Barrado Navascues, O. Barragán, W. Baumjohann, T. Beck, N. Billot, F. Biondi, X. Bonfils, L. Borsato, A. Brandeker, C. Broeg, V. Cessa, S. Charnoz, A. Collier Cameron, Sz Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, A. Deline, B. -O. Demory, D. Ehrenreich, A. Erikson, M. Esposito, A. Fortier, M. Fridlund, M. Gillon, M. Güdel, M. N. Günther, Ch Helling, S. Hoyer, K. G. Isaak, L. L. Kiss, K. W. F. Lam, J. Laskar, A. Lecavelier Des Etangs, M. Lendl, A. Luntzer, D. Magrin, P. F. L. Maxted, C. Mordasini, V. Nascimbeni, G. Olofsson, H. L. M. Osborne, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, G. Piotto, D. Pollacco, D. Queloz, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, G. Scandariato, D. Ségransan, A. E. Simon, A. M. S. Smith, M. Stalport, Gy M. Szabó, N. Thomas, S. Udry, V. Van Eylen, V. Van Grootel, E. Villaver, I. Walter, N. A. Walton

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

Abstract

Context. The HD 15337 (TIC 120896927, TOI-402) system was observed by the Transiting Exoplanet Survey Satellite (TESS), revealing the presence of two short-period planets situated on opposite sides of the radius gap. This offers an excellent opportunity to study theories of formation and evolution, as well as to investigate internal composition and atmospheric evaporation.
Aims. We aim to constrain the internal structure and composition of two short-period planets situated on opposite sides of the radius valley: HD 15337 b and c. We use new transit photometry and radial velocity data.
Methods. We acquired 6 new transit visits with the CHaracterising ExOPlanet Satellite (CHEOPS) and 32 new radial velocity measurements from the High Accuracy Radial Velocity Planet Searcher (HARPS) to improve the accuracy of the mass and radius estimates for both planets. We re-analysed the light curves from TESS sectors 3 and 4 and analysed new data from sector 30, correcting for long-term stellar activity. Subsequently, we performed a joint fit of the TESS and CHEOPS light curves, along with all available RV data from HARPS and the Planet Finder Spectrograph (PFS). Our model fit the planetary signals, stellar activity signal, and instrumental decorrelation model for the CHEOPS data simultaneously. The stellar activity was modelled using a Gaussian-process regression on both the RV and activity indicators. Finally, we employed a Bayesian retrieval code to determine the internal composition and structure of the planets.
Results. We derived updated and highly precise parameters for the HD 15337 system. Our improved precision on the planetary parameters makes HD 15337 b one of the most precisely characterised rocky exoplanets, with radius and mass measurements achieving a precision better than 2% and 7%, respectively. We were able to improve the precision of the radius measurement of HD 15337 c to 3%. Our results imply that the composition of HD 15337 b is predominantly rocky, while HD 15337 c exhibits a gas envelope with a mass of at least 0.01 M_⊕.
Conclusions. Our results lay the groundwork for future studies, which can further unravel the atmospheric evolution of these exoplanets and offer new insights into their composition and formation history as well as the causes behind the radius gap.

Original language	English
Article number	A282
Number of pages	16
Journal	Astronomy & Astrophysics
Volume	686
Early online date	21 Jun 2024
DOIs	https://doi.org/10.1051/0004-6361/202347759
Publication status	Published - Jun 2024

Keywords

Planets and satellites: composition
Stars: individual: HD 15337
Stars: individual: TIC 12089692
Stars: individual: TOI-402
Techniques: photometric
Techniques: radial velocities

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REVEAL: REVEALing Signatures of Habitable Worlds Hidden by Stellar Activity
Cameron, A. C. (PI)
UKRI (EU)
1/08/24 → 31/07/30
Project: Standard
AO2 - Professor Andrew Cameron: Project AO2 - Andrew Cameron
Cameron, A. C. (PI)
Science & Technology Facilities Council
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Project: Standard
Astronomy at St Andrews 2018-2021: Astronomy at St Andrews 2018-2021
Jardine, M. M. (PI), Bonnell, I. A. (CoI), Cameron, A. C. (CoI), Cyganowski, C. J. (CoI), Dominik, M. (CoI), Helling, C. (CoI), Horne, K. D. (CoI), Scholz, A. (CoI), Tojeiro, R. (CoI), Weijmans, A.-M. (CoI), Wild, V. (CoI), Woitke, P. (CoI), Wood, K. (CoI) & Zhao, H. (CoI)
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Project: Standard

CHEOPS light curves of HD 15337 (TOI-402)
Rosario, N. M. (Creator), Demangeon, O. D. S. (Creator), Barros, S. C. C. (Creator), Gandolfi, D. (Creator), Egger, J. A. (Creator), Serrano, L. M. (Creator), Osborn, H. P. (Creator), Beck, M. (Creator), Benz, W. (Creator), Floren, H.-G. (Creator), Guterman, P. (Creator), Wilson, T. G. (Creator), Alibert, Y. (Creator), Fossati, L. (Creator), Hooton, M. J. (Creator), Delrez, L. (Creator), Santos, N. C. (Creator), Sousa, S. G. (Creator), Bonfanti, A. (Creator), Salmon, S. (Creator), Adibekyan, V. (Creator), Nigioni, A. (Creator), Venturini, J. (Creator), Alonso, R. (Creator), Anglada, G. (Creator), Asquier, J. (Creator), Barczy, T. (Creator), Barrado Navascues, D. (Creator), Barragan, O. (Creator), Baumjohann, W. (Creator), Beck, T. (Creator), Billot, N. (Creator), Biondi, F. (Creator), Bonfils, X. (Creator), Borsato, L. (Creator), Brandeker, A. (Creator), Broeg, C. (Creator), Cessa, V. (Creator), Charnoz, S. (Creator), Collier Cameron, A. (Creator), Sz, C. (Creator), Cubillos, P. E. (Creator), Davies, M. B. (Creator), Deleuil, M. (Creator), Deline, A. (Creator), Demory, B.-O. (Creator), Ehrenreich, D. (Creator), Erikson, A. (Creator), Esposito, M. (Creator), Fortier, A. (Creator), Fridlund, M. (Creator), Gillon, M. (Creator), Guedel, M. (Creator), Guenther, M. N. (Creator), Helling, C. (Creator), Hoyer, S. (Creator), Isaak, K. G. (Creator), Kiss, L. L. (Creator), K.W.F., L. (Creator), Laskar, J. (Creator), Lecavelier Des Etangs, A. (Creator), Lendl, M. (Creator), Luntzer, A. (Creator), Magrin, D. (Creator), Maxted, P. F. L. (Creator), Mordasini, C. (Creator), Nascimbeni, V. (Creator), Olofsson, G. (Creator), Osborne, H. L. M. (Creator), Ottensamer, R. (Creator), Pagano, I. (Creator), Palle, E. (Creator), Peter, G. (Creator), Piotto, G. (Creator), Pollacco, D. (Creator), Queloz, D. (Creator), Ragazzoni, R. (Creator), Rando, N. (Creator), Rauer, H. (Creator), Ribas, I. (Creator), Scandariato, G. (Creator), Segransan, D. (Creator), Simon, A. E. (Creator), Smith, A. M. S. (Creator), Stalport, M. (Creator), GyM., S. (Creator), Thomas, N. (Creator), Udry, S. (Creator), Van Eylen, V. (Creator), Van Grootel, V. (Creator), Villaver, E. (Creator), Walter, I. (Creator) & Walton, N. A. (Creator), Centre de Donnees Strasbourg (CDS), 2024
DOI: 10.26093/cds/vizier.36860282
Dataset

Cite this

Rosário, N. M., Demangeon, O. D. S., Barros, S. C. C., Gandolfi, D., Egger, J. A., Serrano, L. M., Osborn, H. P., Beck, M., Benz, W., Florén, H. G., Guterman, P., Wilson, T. G., Alibert, Y., Fossati, L., Hooton, M. J., Delrez, L., Santos, N. C., Sousa, S. G., Bonfanti, A., ... Walton, N. A. (2024). Precise characterisation of HD 15337 with CHEOPS: a laboratory for planet formation and evolution. Astronomy & Astrophysics, 686, Article A282. https://doi.org/10.1051/0004-6361/202347759

@article{be622435b307449b9531eef5b867c331,

title = "Precise characterisation of HD 15337 with CHEOPS: a laboratory for planet formation and evolution",

abstract = "Context. The HD 15337 (TIC 120896927, TOI-402) system was observed by the Transiting Exoplanet Survey Satellite (TESS), revealing the presence of two short-period planets situated on opposite sides of the radius gap. This offers an excellent opportunity to study theories of formation and evolution, as well as to investigate internal composition and atmospheric evaporation. Aims. We aim to constrain the internal structure and composition of two short-period planets situated on opposite sides of the radius valley: HD 15337 b and c. We use new transit photometry and radial velocity data. Methods. We acquired 6 new transit visits with the CHaracterising ExOPlanet Satellite (CHEOPS) and 32 new radial velocity measurements from the High Accuracy Radial Velocity Planet Searcher (HARPS) to improve the accuracy of the mass and radius estimates for both planets. We re-analysed the light curves from TESS sectors 3 and 4 and analysed new data from sector 30, correcting for long-term stellar activity. Subsequently, we performed a joint fit of the TESS and CHEOPS light curves, along with all available RV data from HARPS and the Planet Finder Spectrograph (PFS). Our model fit the planetary signals, stellar activity signal, and instrumental decorrelation model for the CHEOPS data simultaneously. The stellar activity was modelled using a Gaussian-process regression on both the RV and activity indicators. Finally, we employed a Bayesian retrieval code to determine the internal composition and structure of the planets. Results. We derived updated and highly precise parameters for the HD 15337 system. Our improved precision on the planetary parameters makes HD 15337 b one of the most precisely characterised rocky exoplanets, with radius and mass measurements achieving a precision better than 2% and 7%, respectively. We were able to improve the precision of the radius measurement of HD 15337 c to 3%. Our results imply that the composition of HD 15337 b is predominantly rocky, while HD 15337 c exhibits a gas envelope with a mass of at least 0.01 M⊕. Conclusions. Our results lay the groundwork for future studies, which can further unravel the atmospheric evolution of these exoplanets and offer new insights into their composition and formation history as well as the causes behind the radius gap.",

keywords = "Planets and satellites: composition, Stars: individual: HD 15337, Stars: individual: TIC 12089692, Stars: individual: TOI-402, Techniques: photometric, Techniques: radial velocities",

author = "Ros{\'a}rio, {N. M.} and Demangeon, {O. D. S.} and Barros, {S. C. C.} and D. Gandolfi and Egger, {J. A.} and Serrano, {L. M.} and Osborn, {H. P.} and M. Beck and W. Benz and Flor{\'e}n, {H. G.} and P. Guterman and Wilson, {T. G.} and Y. Alibert and L. Fossati and Hooton, {M. J.} and L. Delrez and Santos, {N. C.} and Sousa, {S. G.} and A. Bonfanti and S. Salmon and V. Adibekyan and A. Nigioni and J. Venturini and R. Alonso and G. Anglada and J. Asquier and T. B{\'a}rczy and {Barrado Navascues}, D. and O. Barrag{\'a}n and W. Baumjohann and T. Beck and N. Billot and F. Biondi and X. Bonfils and L. Borsato and A. Brandeker and C. Broeg and V. Cessa and S. Charnoz and {Collier Cameron}, A. and Sz Csizmadia and Cubillos, {P. E.} and Davies, {M. B.} and M. Deleuil and A. Deline and Demory, {B. -O.} and D. Ehrenreich and A. Erikson and M. Esposito and A. Fortier and M. Fridlund and M. Gillon and M. G{\"u}del and G{\"u}nther, {M. N.} and Ch Helling and S. Hoyer and Isaak, {K. G.} and Kiss, {L. L.} and Lam, {K. W. F.} and J. Laskar and {Lecavelier Des Etangs}, A. and M. Lendl and A. Luntzer and D. Magrin and Maxted, {P. F. L.} and C. Mordasini and V. Nascimbeni and G. Olofsson and Osborne, {H. L. M.} and R. Ottensamer and I. Pagano and E. Pall{\'e} and G. Peter and G. Piotto and D. Pollacco and D. Queloz and R. Ragazzoni and N. Rando and H. Rauer and I. Ribas and G. Scandariato and D. S{\'e}gransan and Simon, {A. E.} and Smith, {A. M. S.} and M. Stalport and Szab{\'o}, {Gy M.} and N. Thomas and S. Udry and {Van Eylen}, V. and {Van Grootel}, V. and E. Villaver and I. Walter and Walton, {N. A.}",

note = "Funding: CHEOPS is an ESA mission in partnership with Switzerland with important contributions to the payload and the ground segment from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom. The CHEOPS Consortium would like to gratefully acknowledge the support received by all the agencies, offices, universities, and industries involved. Their flexibility and willingness to explore new approaches were essential to the success of this mission. This work was supported by FCT – Funda{\c c}{\~a}o para a Ci{\^e}ncia e a Tecnologia through national funds by these grants: UIDB/04434/2020, UIDP/04434/2020, 2022.06962. PTDC, 2022.04416.PTDC. N.M.R. acknowledges support from FCT through grant DFA/BD/5472/2020. O.D.S.D. is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by national funds through FCT. S.C.C.B. acknowledges support from FCT through FCT contracts nr. IF/01312/2014/CP1215/CT0004. D.G. gratefully acknowledges financial support from the CRT foundation under Grant No. 2018.2323 “Gaseous or rocky? Unveiling the nature of small worlds”. J.A.Eg. and Y.Al. acknowledge support from the Swiss National Science Foundation (SNSF) under grant 200020_192038. LMS gratefully acknowledges financial support from the CRT foundation under Grant No. 2018.2323 “Gaseous or rocky? Unveiling the nature of small worlds”. This work has been carried out within the framework of the NCCR PlanetS supported by the Swiss National Science Foundation under grants 51NF40_182901 and 51NF40_205606. T.Wi. and A.C.Ca. acknowledge support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. The Belgian participation to CHEOPS has been supported by the Belgian Federal Science Policy Office (BELSPO) in the framework of the PRODEX Program, and by the University of Li{\`e}ge through an ARC grant for Concerted Research Actions financed by the Wallonia-Brussels Federation. L.D. is an F.R.S.-FNRS Postdoctoral Researcher. NCSa acknowledges funding by the European Union (ERC, FIERCE, 101052347). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. S.G.S. acknowledges support from FCT through FCT contract nr. CEECIND/00826/2018 and POPH/FSE (EC). V.A. is supported by FCT through national funds by the following grant: 2022.06962.PTDC (http://doi.org/ 10.54499/2022.06962.PTDC). RAl, DBa, EPa, and IRi acknowledge financial support from the Agencia Estatal de Investigaci{\'o}n of the Ministerio de Ciencia e Innovaci{\'o}n MCIN/AEI/10.13039/501100011033 and the ERDF “A way of making Europe” through projects PID2019-107061GB-C61, PID2019- 107061GB-C66, PID2021-125627OB-C31, and PID2021-125627OB-C32, from the Centre of Excellence “Severo Ochoa” award to the Instituto de Astrof{\'i}sica de Canarias (CEX2019-000920-S), from the Centre of Excellence “Mar{\'i}a de Maeztu” award to the Institut de Ci{\`e}ncies de l{\textquoteright}Espai (CEX2020-001058-M), and from the Generalitat de Catalunya/CERCA programme. X.B., S.C., D.G., A282, page 12 of 16 Ros{\'a}rio, N. M., et al.: A&A, 686, A282 (2024) M.F. and J.L. acknowledge their role as ESA-appointed CHEOPS science team members. L.Bo., V.Na., I.Pa., G.Pi., R.Ra., and G.Sc. acknowledge support from CHEOPS ASI-INAF agreement no. 2019-29-HH.0. P.E.C. is funded by the Austrian Science Fund (FWF) Erwin Schroedinger Fellowship, program J4595-N. ABr was supported by the SNSA. This project was supported by the CNES. B.-O.D. acknowledges support from the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number MB22.00046. This project has received funding from the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation programme (project FOUR ACES, grant agreement no. 724427). It has also been carried out in the frame of the National Centre for Competence in Research PlanetS supported by the Swiss National Science Foundation (SNSF). DE acknowledges financial support from the Swiss National Science Foundation for project 200021_200726. MF and CMP gratefully acknowledge the support of the Swedish National Space Agency (DNR 65/19, 174/18). M.G. is an F.R.S.-FNRS Senior Research Associate. MNG is the ESA CHEOPS Project Scientist and Mission Representative, and as such also responsible for the Guest Observers (GO) Programme. MNG does not relay proprietary information between the GO and Guaranteed Time Observation (GTO) Programmes, and does not decide on the definition and target selection of the GTO Programme. CHe acknowledges support from the European Union H2020-MSCA-ITN-2019 under Grant Agreement no. 860470 (CHAMELEON). SH gratefully acknowledges CNES funding through the grant 837319. KGI is the ESA CHEOPS Project Scientist and is responsible for the ESA CHEOPS Guest Observers Programme. She does not participate in, or contribute to, the definition of the Guaranteed Time Programme of the CHEOPS mission through which observations described in this paper have been taken, nor to any aspect of target selection for the programme. K.W.F.L. was supported by Deutsche Forschungsgemeinschaft grants RA714/14-1 within the DFG Schwerpunkt SPP 1992, Exploring the Diversity of Extrasolar Planets. This work was granted access to the HPC resources of MesoPSL financed by the R{\'e}gion Ile de France and the project Equip@Meso (reference ANR-10-EQPX29-01) of the programme Investissements d{\textquoteright}Avenir supervised by the Agence Nationale pour la Recherche. M.L. acknowledges support of the Swiss National Science Foundation under grant number PCEFP2_194576. P.M. acknowledges support from STFC research grant number ST/M001040/1. This work was also partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127). GyMSz acknowledges the support of the Hungarian National Research, Development and Innovation Office (NKFIH) grant K-125015, a PRODEX Experiment Agreement No. 4000137122, the Lend{\"u}let LP2018-7/2021 grant of the Hungarian Academy of Science and the support of the city of Szombathely. V.V.G. is an F.R.S-FNRS Research Associate. NAW acknowledges UKSA grant ST/R004838/1. AN and JV acknowledge support from the Swiss National Science Foundation (SNSF) under grant PZ00P2_208945.",

year = "2024",

month = jun,

doi = "10.1051/0004-6361/202347759",

language = "English",

volume = "686",

journal = "Astronomy & Astrophysics",

issn = "0004-6361",

publisher = "EDP SCIENCES S A",

}

Rosário, NM, Demangeon, ODS, Barros, SCC, Gandolfi, D, Egger, JA, Serrano, LM, Osborn, HP, Beck, M, Benz, W, Florén, HG, Guterman, P, Wilson, TG, Alibert, Y, Fossati, L, Hooton, MJ, Delrez, L, Santos, NC, Sousa, SG, Bonfanti, A, Salmon, S, Adibekyan, V, Nigioni, A, Venturini, J, Alonso, R, Anglada, G, Asquier, J, Bárczy, T, Barrado Navascues, D, Barragán, O, Baumjohann, W, Beck, T, Billot, N, Biondi, F, Bonfils, X, Borsato, L, Brandeker, A, Broeg, C, Cessa, V, Charnoz, S, Collier Cameron, A, Csizmadia, S, Cubillos, PE, Davies, MB, Deleuil, M, Deline, A, Demory, B-O, Ehrenreich, D, Erikson, A, Esposito, M, Fortier, A, Fridlund, M, Gillon, M, Güdel, M, Günther, MN, Helling, C, Hoyer, S, Isaak, KG, Kiss, LL, Lam, KWF, Laskar, J, Lecavelier Des Etangs, A, Lendl, M, Luntzer, A, Magrin, D, Maxted, PFL, Mordasini, C, Nascimbeni, V, Olofsson, G, Osborne, HLM, Ottensamer, R, Pagano, I, Pallé, E, Peter, G, Piotto, G, Pollacco, D, Queloz, D, Ragazzoni, R, Rando, N, Rauer, H, Ribas, I, Scandariato, G, Ségransan, D, Simon, AE, Smith, AMS, Stalport, M, Szabó, GM, Thomas, N, Udry, S, Van Eylen, V, Van Grootel, V, Villaver, E, Walter, I & Walton, NA 2024, 'Precise characterisation of HD 15337 with CHEOPS: a laboratory for planet formation and evolution', Astronomy & Astrophysics, vol. 686, A282. https://doi.org/10.1051/0004-6361/202347759

TY - JOUR

T1 - Precise characterisation of HD 15337 with CHEOPS

T2 - a laboratory for planet formation and evolution

AU - Rosário, N. M.

AU - Demangeon, O. D. S.

AU - Barros, S. C. C.

AU - Gandolfi, D.

AU - Egger, J. A.

AU - Serrano, L. M.

AU - Osborn, H. P.

AU - Beck, M.

AU - Benz, W.

AU - Florén, H. G.

AU - Guterman, P.

AU - Wilson, T. G.

AU - Alibert, Y.

AU - Fossati, L.

AU - Hooton, M. J.

AU - Delrez, L.

AU - Santos, N. C.

AU - Sousa, S. G.

AU - Bonfanti, A.

AU - Salmon, S.

AU - Adibekyan, V.

AU - Nigioni, A.

AU - Venturini, J.

AU - Alonso, R.

AU - Anglada, G.

AU - Asquier, J.

AU - Bárczy, T.

AU - Barrado Navascues, D.

AU - Barragán, O.

AU - Baumjohann, W.

AU - Beck, T.

AU - Billot, N.

AU - Biondi, F.

AU - Bonfils, X.

AU - Borsato, L.

AU - Brandeker, A.

AU - Broeg, C.

AU - Cessa, V.

AU - Charnoz, S.

AU - Collier Cameron, A.

AU - Csizmadia, Sz

AU - Cubillos, P. E.

AU - Davies, M. B.

AU - Deleuil, M.

AU - Deline, A.

AU - Demory, B. -O.

AU - Ehrenreich, D.

AU - Erikson, A.

AU - Esposito, M.

AU - Fortier, A.

AU - Fridlund, M.

AU - Gillon, M.

AU - Güdel, M.

AU - Günther, M. N.

AU - Helling, Ch

AU - Hoyer, S.

AU - Isaak, K. G.

AU - Kiss, L. L.

AU - Lam, K. W. F.

AU - Laskar, J.

AU - Lecavelier Des Etangs, A.

AU - Lendl, M.

AU - Luntzer, A.

AU - Magrin, D.

AU - Maxted, P. F. L.

AU - Mordasini, C.

AU - Nascimbeni, V.

AU - Olofsson, G.

AU - Osborne, H. L. M.

AU - Ottensamer, R.

AU - Pagano, I.

AU - Pallé, E.

AU - Peter, G.

AU - Piotto, G.

AU - Pollacco, D.

AU - Queloz, D.

AU - Ragazzoni, R.

AU - Rando, N.

AU - Rauer, H.

AU - Ribas, I.

AU - Scandariato, G.

AU - Ségransan, D.

AU - Simon, A. E.

AU - Smith, A. M. S.

AU - Stalport, M.

AU - Szabó, Gy M.

AU - Thomas, N.

AU - Udry, S.

AU - Van Eylen, V.

AU - Van Grootel, V.

AU - Villaver, E.

AU - Walter, I.

AU - Walton, N. A.

N1 - Funding: CHEOPS is an ESA mission in partnership with Switzerland with important contributions to the payload and the ground segment from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom. The CHEOPS Consortium would like to gratefully acknowledge the support received by all the agencies, offices, universities, and industries involved. Their flexibility and willingness to explore new approaches were essential to the success of this mission. This work was supported by FCT – Fundação para a Ciência e a Tecnologia through national funds by these grants: UIDB/04434/2020, UIDP/04434/2020, 2022.06962. PTDC, 2022.04416.PTDC. N.M.R. acknowledges support from FCT through grant DFA/BD/5472/2020. O.D.S.D. is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by national funds through FCT. S.C.C.B. acknowledges support from FCT through FCT contracts nr. IF/01312/2014/CP1215/CT0004. D.G. gratefully acknowledges financial support from the CRT foundation under Grant No. 2018.2323 “Gaseous or rocky? Unveiling the nature of small worlds”. J.A.Eg. and Y.Al. acknowledge support from the Swiss National Science Foundation (SNSF) under grant 200020_192038. LMS gratefully acknowledges financial support from the CRT foundation under Grant No. 2018.2323 “Gaseous or rocky? Unveiling the nature of small worlds”. This work has been carried out within the framework of the NCCR PlanetS supported by the Swiss National Science Foundation under grants 51NF40_182901 and 51NF40_205606. T.Wi. and A.C.Ca. acknowledge support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. The Belgian participation to CHEOPS has been supported by the Belgian Federal Science Policy Office (BELSPO) in the framework of the PRODEX Program, and by the University of Liège through an ARC grant for Concerted Research Actions financed by the Wallonia-Brussels Federation. L.D. is an F.R.S.-FNRS Postdoctoral Researcher. NCSa acknowledges funding by the European Union (ERC, FIERCE, 101052347). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. S.G.S. acknowledges support from FCT through FCT contract nr. CEECIND/00826/2018 and POPH/FSE (EC). V.A. is supported by FCT through national funds by the following grant: 2022.06962.PTDC (http://doi.org/ 10.54499/2022.06962.PTDC). RAl, DBa, EPa, and IRi acknowledge financial support from the Agencia Estatal de Investigación of the Ministerio de Ciencia e Innovación MCIN/AEI/10.13039/501100011033 and the ERDF “A way of making Europe” through projects PID2019-107061GB-C61, PID2019- 107061GB-C66, PID2021-125627OB-C31, and PID2021-125627OB-C32, from the Centre of Excellence “Severo Ochoa” award to the Instituto de Astrofísica de Canarias (CEX2019-000920-S), from the Centre of Excellence “María de Maeztu” award to the Institut de Ciències de l’Espai (CEX2020-001058-M), and from the Generalitat de Catalunya/CERCA programme. X.B., S.C., D.G., A282, page 12 of 16 Rosário, N. M., et al.: A&A, 686, A282 (2024) M.F. and J.L. acknowledge their role as ESA-appointed CHEOPS science team members. L.Bo., V.Na., I.Pa., G.Pi., R.Ra., and G.Sc. acknowledge support from CHEOPS ASI-INAF agreement no. 2019-29-HH.0. P.E.C. is funded by the Austrian Science Fund (FWF) Erwin Schroedinger Fellowship, program J4595-N. ABr was supported by the SNSA. This project was supported by the CNES. B.-O.D. acknowledges support from the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number MB22.00046. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (project FOUR ACES, grant agreement no. 724427). It has also been carried out in the frame of the National Centre for Competence in Research PlanetS supported by the Swiss National Science Foundation (SNSF). DE acknowledges financial support from the Swiss National Science Foundation for project 200021_200726. MF and CMP gratefully acknowledge the support of the Swedish National Space Agency (DNR 65/19, 174/18). M.G. is an F.R.S.-FNRS Senior Research Associate. MNG is the ESA CHEOPS Project Scientist and Mission Representative, and as such also responsible for the Guest Observers (GO) Programme. MNG does not relay proprietary information between the GO and Guaranteed Time Observation (GTO) Programmes, and does not decide on the definition and target selection of the GTO Programme. CHe acknowledges support from the European Union H2020-MSCA-ITN-2019 under Grant Agreement no. 860470 (CHAMELEON). SH gratefully acknowledges CNES funding through the grant 837319. KGI is the ESA CHEOPS Project Scientist and is responsible for the ESA CHEOPS Guest Observers Programme. She does not participate in, or contribute to, the definition of the Guaranteed Time Programme of the CHEOPS mission through which observations described in this paper have been taken, nor to any aspect of target selection for the programme. K.W.F.L. was supported by Deutsche Forschungsgemeinschaft grants RA714/14-1 within the DFG Schwerpunkt SPP 1992, Exploring the Diversity of Extrasolar Planets. This work was granted access to the HPC resources of MesoPSL financed by the Région Ile de France and the project Equip@Meso (reference ANR-10-EQPX29-01) of the programme Investissements d’Avenir supervised by the Agence Nationale pour la Recherche. M.L. acknowledges support of the Swiss National Science Foundation under grant number PCEFP2_194576. P.M. acknowledges support from STFC research grant number ST/M001040/1. This work was also partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127). GyMSz acknowledges the support of the Hungarian National Research, Development and Innovation Office (NKFIH) grant K-125015, a PRODEX Experiment Agreement No. 4000137122, the Lendület LP2018-7/2021 grant of the Hungarian Academy of Science and the support of the city of Szombathely. V.V.G. is an F.R.S-FNRS Research Associate. NAW acknowledges UKSA grant ST/R004838/1. AN and JV acknowledge support from the Swiss National Science Foundation (SNSF) under grant PZ00P2_208945.

PY - 2024/6

Y1 - 2024/6

N2 - Context. The HD 15337 (TIC 120896927, TOI-402) system was observed by the Transiting Exoplanet Survey Satellite (TESS), revealing the presence of two short-period planets situated on opposite sides of the radius gap. This offers an excellent opportunity to study theories of formation and evolution, as well as to investigate internal composition and atmospheric evaporation. Aims. We aim to constrain the internal structure and composition of two short-period planets situated on opposite sides of the radius valley: HD 15337 b and c. We use new transit photometry and radial velocity data. Methods. We acquired 6 new transit visits with the CHaracterising ExOPlanet Satellite (CHEOPS) and 32 new radial velocity measurements from the High Accuracy Radial Velocity Planet Searcher (HARPS) to improve the accuracy of the mass and radius estimates for both planets. We re-analysed the light curves from TESS sectors 3 and 4 and analysed new data from sector 30, correcting for long-term stellar activity. Subsequently, we performed a joint fit of the TESS and CHEOPS light curves, along with all available RV data from HARPS and the Planet Finder Spectrograph (PFS). Our model fit the planetary signals, stellar activity signal, and instrumental decorrelation model for the CHEOPS data simultaneously. The stellar activity was modelled using a Gaussian-process regression on both the RV and activity indicators. Finally, we employed a Bayesian retrieval code to determine the internal composition and structure of the planets. Results. We derived updated and highly precise parameters for the HD 15337 system. Our improved precision on the planetary parameters makes HD 15337 b one of the most precisely characterised rocky exoplanets, with radius and mass measurements achieving a precision better than 2% and 7%, respectively. We were able to improve the precision of the radius measurement of HD 15337 c to 3%. Our results imply that the composition of HD 15337 b is predominantly rocky, while HD 15337 c exhibits a gas envelope with a mass of at least 0.01 M⊕. Conclusions. Our results lay the groundwork for future studies, which can further unravel the atmospheric evolution of these exoplanets and offer new insights into their composition and formation history as well as the causes behind the radius gap.

AB - Context. The HD 15337 (TIC 120896927, TOI-402) system was observed by the Transiting Exoplanet Survey Satellite (TESS), revealing the presence of two short-period planets situated on opposite sides of the radius gap. This offers an excellent opportunity to study theories of formation and evolution, as well as to investigate internal composition and atmospheric evaporation. Aims. We aim to constrain the internal structure and composition of two short-period planets situated on opposite sides of the radius valley: HD 15337 b and c. We use new transit photometry and radial velocity data. Methods. We acquired 6 new transit visits with the CHaracterising ExOPlanet Satellite (CHEOPS) and 32 new radial velocity measurements from the High Accuracy Radial Velocity Planet Searcher (HARPS) to improve the accuracy of the mass and radius estimates for both planets. We re-analysed the light curves from TESS sectors 3 and 4 and analysed new data from sector 30, correcting for long-term stellar activity. Subsequently, we performed a joint fit of the TESS and CHEOPS light curves, along with all available RV data from HARPS and the Planet Finder Spectrograph (PFS). Our model fit the planetary signals, stellar activity signal, and instrumental decorrelation model for the CHEOPS data simultaneously. The stellar activity was modelled using a Gaussian-process regression on both the RV and activity indicators. Finally, we employed a Bayesian retrieval code to determine the internal composition and structure of the planets. Results. We derived updated and highly precise parameters for the HD 15337 system. Our improved precision on the planetary parameters makes HD 15337 b one of the most precisely characterised rocky exoplanets, with radius and mass measurements achieving a precision better than 2% and 7%, respectively. We were able to improve the precision of the radius measurement of HD 15337 c to 3%. Our results imply that the composition of HD 15337 b is predominantly rocky, while HD 15337 c exhibits a gas envelope with a mass of at least 0.01 M⊕. Conclusions. Our results lay the groundwork for future studies, which can further unravel the atmospheric evolution of these exoplanets and offer new insights into their composition and formation history as well as the causes behind the radius gap.

KW - Planets and satellites: composition

KW - Stars: individual: HD 15337

KW - Stars: individual: TIC 12089692

KW - Stars: individual: TOI-402

KW - Techniques: photometric

KW - Techniques: radial velocities

U2 - 10.1051/0004-6361/202347759

DO - 10.1051/0004-6361/202347759

M3 - Article

AN - SCOPUS:85201062544

SN - 0004-6361

VL - 686

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

M1 - A282

ER -

Precise characterisation of HD 15337 with CHEOPS: a laboratory for planet formation and evolution

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Projects

REVEAL: REVEALing Signatures of Habitable Worlds Hidden by Stellar Activity

AO2 - Professor Andrew Cameron: Project AO2 - Andrew Cameron

Astronomy at St Andrews 2018-2021: Astronomy at St Andrews 2018-2021

Datasets

CHEOPS light curves of HD 15337 (TOI-402)

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