Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 b

O. D. S. Demangeon; P. E. Cubillos; V. Singh; T. G. Wilson; L. Carone; A. Bekkelien; A. Deline; D. Ehrenreich; P. F. L. Maxted; B. -O. Demory; T. Zingales; M. Lendl; A. Bonfanti; S. G. Sousa; A. Brandeker; Y. Alibert; R. Alonso; J. Asquier; T. Bárczy; D. Barrado Navascues; S. C. C. Barros; W. Baumjohann; M. Beck; T. Beck; W. Benz; N. Billot; F. Biondi; L. Borsato; Ch. Broeg; M. Buder; A. Collier Cameron; Sz Csizmadia; M. B. Davies; M. Deleuil; L. Delrez; A. Erikson; A. Fortier; L. Fossati; M. Fridlund; D. Gandolfi; M. Gillon; M. Güdel; M. N. Günther; A. Heitzmann; Ch. Helling; S. Hoyer; K. G. Isaak; L. L. Kiss; K. W. F. Lam; J. Laskar; A. Lecavelier des Etangs; D. Magrin; M. Mecina; Ch. Mordasini; V. Nascimbeni; G. Olofsson; R. Ottensamer; I. Pagano; E. Palle; G. Peter; G. Piotto; D. Pollacco; D. Queloz; R. Ragazzoni; N. Rando; H. Rauer; I. Ribas; M. Rieder; S. Salmon; N. C. Santos; G. Scandariato; D. Ségransan; A. E. Simon; A. M. S. Smith; M. Stalport; Gy M. Szabó; N. Thomas; S. Udry; V. Van Grootel; J. Venturini; E. Villaver; N. A. Walton

doi:10.1051/0004-6361/202348270

Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 b

O. D. S. Demangeon^*, P. E. Cubillos, V. Singh, T. G. Wilson, L. Carone, A. Bekkelien, A. Deline, D. Ehrenreich, P. F. L. Maxted, B. -O. Demory, T. Zingales, M. Lendl, A. Bonfanti, S. G. Sousa, A. Brandeker, Y. Alibert, R. Alonso, J. Asquier, T. Bárczy, D. Barrado NavascuesS. C. C. Barros, W. Baumjohann, M. Beck, T. Beck, W. Benz, N. Billot, F. Biondi, L. Borsato, Ch. Broeg, M. Buder, A. Collier Cameron, Sz Csizmadia, M. B. Davies, M. Deleuil, L. Delrez, A. Erikson, A. Fortier, L. Fossati, M. Fridlund, D. Gandolfi, M. Gillon, M. Güdel, M. N. Günther, A. Heitzmann, Ch. Helling, S. Hoyer, K. G. Isaak, L. L. Kiss, K. W. F. Lam, J. Laskar, A. Lecavelier des Etangs, D. Magrin, M. Mecina, Ch. Mordasini, V. Nascimbeni, G. Olofsson, R. Ottensamer, I. Pagano, E. Palle, G. Peter, G. Piotto, D. Pollacco, D. Queloz, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, M. Rieder, S. Salmon, N. C. Santos, G. Scandariato, D. Ségransan, A. E. Simon, A. M. S. Smith, M. Stalport, Gy M. Szabó, N. Thomas, S. Udry, V. Van Grootel, J. Venturini, E. Villaver, N. A. Walton

^*Corresponding author for this work

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

Abstract

Context. WASP-76 b has been a recurrent subject of study since the detection of a signature in high-resolution transit spectroscopy data indicating an asymmetry between the two limbs of the planet. The existence of this asymmetric signature has been confirmed by multiple studies, but its physical origin is still under debate. In addition, it contrasts with the absence of asymmetry reported in the infrared (IR) phase curve.
Aims. We provide a more comprehensive dataset of WASP-76 b with the goal of drawing a complete view of the physical processes at work in this atmosphere. In particular, we attempt to reconcile visible high-resolution transit spectroscopy data and IR broadband phase curves.
Methods. We gathered 3 phase curves, 20 occultations, and 6 transits for WASP-76 b in the visible with the CHEOPS space telescope. We also report the analysis of three unpublished sectors observed by the TESS space telescope (also in the visible), which represents 34 phase curves.
Results. WASP-76 b displays an occultation of 260 ± 11 and 152 ± 10 ppm in TESS and CHEOPS bandpasses respectively. Depending on the composition assumed for the atmosphere and the data reduction used for the IR data, we derived geometric albedo estimates that range from 0.05 ± 0.023 to 0.146 ± 0.013 and from <0.13 to 0.189 ± 0.017 in the CHEOPS and TESS bandpasses, respectively. As expected from the IR phase curves, a low-order model of the phase curves does not yield any detectable asymmetry in the visible either. However, an empirical model allowing for sharper phase curve variations offers a hint of a flux excess before the occultation, with an amplitude of ∼40 ppm, an orbital offset of ∼−30^◦, and a width of ∼20^◦. We also constrained the orbital eccentricity of WASP-76 b to a value lower than 0.0067, with a 99.7% confidence level. This result contradicts earlier proposed scenarios aimed at explaining the asymmetry observed in high-resolution transit spectroscopy.
Conclusions. In light of these findings, we hypothesise that WASP-76 b could have night-side clouds that extend predominantly towards its eastern limb. At this limb, the clouds would be associated with spherical droplets or spherically shaped aerosols of an unknown species, which would be responsible for a glory effect in the visible phase curves.

Original language	English
Article number	A27
Number of pages	35
Journal	Astronomy & Astrophysics
Volume	684
Early online date	5 Apr 2024
DOIs	https://doi.org/10.1051/0004-6361/202348270
Publication status	Published - Apr 2024

Keywords

Techniques: photometric
Planets and satellites: atmospheres
Planets and satellites: composition

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Demangeon_2024_AandA_Asymmetry-atmosphere-Jupiter-WASP-76b_CC
Copyright © 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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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)
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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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WASP-76 CHEOPS light curves
O.D.S., D. (Creator), Cubillos, P. E. (Creator), Singh, V. (Creator), Wilson, T. G. (Creator), Carone, L. (Creator), Bekkelien, A. (Creator), Deline, A. (Creator), Ehrenreich, D. (Creator), Maxted, P. F. L. (Creator), Demory, B.-O. (Creator), Zingales, T. (Creator), Lendl, M. (Creator), Bonfanti, A. (Creator), Sousa, S. G. (Creator), Brandeker, A. (Creator), Alibert, Y. (Creator), R., A. (Creator), Barczy, T. (Creator), Barrado Navascues, D. (Creator), Barros, S. C. C. (Creator), Baumjohann, W. (Creator), Beck, M. (Creator), Beck, T. (Creator), Benz, W. (Creator), Billot, N. (Creator), Biondi, F. (Creator), Borsato, L. (Creator), Broeg, C. (Creator), Buder, M. (Creator), Collier Cameron, A. (Creator), Sz, C. (Creator), Davies, M. B. (Creator), Deleuil, M. (Creator), Delrez, L. (Creator), Erikson, A. (Creator), Fortier, A. (Creator), Fossati, L. (Creator), Fridlund, M. (Creator), Gandolfi, D. (Creator), Gillon, M. (Creator), Guedel, M. (Creator), Guenther M., N. (Creator), Heitzmann, A. (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), Magrin, D. (Creator), Mecina, M. (Creator), Mordasini, C. (Creator), Nascimbeni, V. (Creator), Olofsson, G. (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), Rieder, M. (Creator), Salmon, S. (Creator), Santos, N. C. (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 Grootel, V. (Creator), Venturini, J. (Creator), Villaver, E. (Creator) & Walton, N. A. (Creator), Centre de Donnees Strasbourg (CDS), 2024
DOI: 10.26093/cds/vizier.36840027
Dataset

Cite this

Demangeon, O. D. S., Cubillos, P. E., Singh, V., Wilson, T. G., Carone, L., Bekkelien, A., Deline, A., Ehrenreich, D., Maxted, P. F. L., Demory, B. .-O., Zingales, T., Lendl, M., Bonfanti, A., Sousa, S. G., Brandeker, A., Alibert, Y., Alonso, R., Asquier, J., Bárczy, T., ... Walton, N. A. (2024). Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 b. Astronomy & Astrophysics, 684, Article A27. https://doi.org/10.1051/0004-6361/202348270

@article{ff18e146f64b41bf8bcf53812680926f,

title = "Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 b",

abstract = "Context. WASP-76 b has been a recurrent subject of study since the detection of a signature in high-resolution transit spectroscopy data indicating an asymmetry between the two limbs of the planet. The existence of this asymmetric signature has been confirmed by multiple studies, but its physical origin is still under debate. In addition, it contrasts with the absence of asymmetry reported in the infrared (IR) phase curve. Aims. We provide a more comprehensive dataset of WASP-76 b with the goal of drawing a complete view of the physical processes at work in this atmosphere. In particular, we attempt to reconcile visible high-resolution transit spectroscopy data and IR broadband phase curves. Methods. We gathered 3 phase curves, 20 occultations, and 6 transits for WASP-76 b in the visible with the CHEOPS space telescope. We also report the analysis of three unpublished sectors observed by the TESS space telescope (also in the visible), which represents 34 phase curves. Results. WASP-76 b displays an occultation of 260 ± 11 and 152 ± 10 ppm in TESS and CHEOPS bandpasses respectively. Depending on the composition assumed for the atmosphere and the data reduction used for the IR data, we derived geometric albedo estimates that range from 0.05 ± 0.023 to 0.146 ± 0.013 and from <0.13 to 0.189 ± 0.017 in the CHEOPS and TESS bandpasses, respectively. As expected from the IR phase curves, a low-order model of the phase curves does not yield any detectable asymmetry in the visible either. However, an empirical model allowing for sharper phase curve variations offers a hint of a flux excess before the occultation, with an amplitude of ∼40 ppm, an orbital offset of ∼−30◦, and a width of ∼20◦. We also constrained the orbital eccentricity of WASP-76 b to a value lower than 0.0067, with a 99.7% confidence level. This result contradicts earlier proposed scenarios aimed at explaining the asymmetry observed in high-resolution transit spectroscopy. Conclusions. In light of these findings, we hypothesise that WASP-76 b could have night-side clouds that extend predominantly towards its eastern limb. At this limb, the clouds would be associated with spherical droplets or spherically shaped aerosols of an unknown species, which would be responsible for a glory effect in the visible phase curves.",

keywords = "Techniques: photometric, Planets and satellites: atmospheres, Planets and satellites: composition",

author = "Demangeon, {O. D. S.} and Cubillos, {P. E.} and V. Singh and Wilson, {T. G.} and L. Carone and A. Bekkelien and A. Deline and D. Ehrenreich and Maxted, {P. F. L.} and Demory, {B. -O.} and T. Zingales and M. Lendl and A. Bonfanti and Sousa, {S. G.} and A. Brandeker and Y. Alibert and R. Alonso and J. Asquier and T. B{\'a}rczy and {Barrado Navascues}, D. and Barros, {S. C. C.} and W. Baumjohann and M. Beck and T. Beck and W. Benz and N. Billot and F. Biondi and L. Borsato and Ch. Broeg and M. Buder and Cameron, {A. Collier} and Sz Csizmadia and Davies, {M. B.} and M. Deleuil and L. Delrez and A. Erikson and A. Fortier and L. Fossati and M. Fridlund and D. Gandolfi and M. Gillon and M. G{\"u}del and G{\"u}nther, {M. N.} and A. Heitzmann 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 D. Magrin and M. Mecina and Ch. Mordasini and V. Nascimbeni and G. Olofsson and R. Ottensamer and I. Pagano and E. Palle 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 M. Rieder and S. Salmon and Santos, {N. C.} 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 Grootel}, V. and J. Venturini and E. Villaver 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 UK. 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. CHEOPS data analysed in this article will be made available in the CHEOPS mission archive (https://cheops.unige.ch/archive_browser/). This work was supported by FCT – Funda{\c c}{\~a}o para a Ci{\^e}ncia e a Tecnologia through national funds and by FEDER through COMPETE2020 through the research grants UIDB/04434/2020, UIDP/04434/2020, 2022.06962.PTDC. O.D.S.D. is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by national funds through FCT. P.E.C. is funded by the Austrian Science Fund (FWF) Erwin Schroedinger Fellowship, program J4595-N. V.Si., T.Zi., 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. T.Wi. acknowledges support from the UKSA and the University of Warwick. L.Ca. and C.He. acknowledge support from the European Union H2020-MSCA-ITN-2019 under Grant Agreement no. 860470 (CHAMELEON). 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). D.E. acknowledges financial support from the Swiss National Science Foundation for project 200021_200726. PM acknowledges support from STFC research grant number ST/M001040/1. B.-O.D. acknowledges support from the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number MB22.00046. M.L. acknowledges support of the Swiss National Science Foundation under grant number PCEFP2_194576. S.G.S. acknowledge support from FCT through FCT contract nr. CEECIND/00826/2018 and POPH/FSE (EC). A.Br. was supported by the SNSA. Y.Al. acknowledges support from the Swiss National Science Foundation (SNSF) under grant 200020_192038. R.Al., D.Ba., E.Pa., and I.Ri. 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. S.C.C.B. acknowledges support from FCT through FCT contracts nr. IF/01312/2014/CP1215/CT0004. C.Br. and A.Si. acknowledge support from the Swiss Space Office through the ESA PRODEX program. A.C.C. acknowledges support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. This project was supported by the CNES. 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. M.F. and C.M.P. gratefully acknowledge the support of the Swedish National Space Agency (DNR 65/19, 174/18). D.G. gratefully acknowledges financial support from the CRT foundation under Grant No. 2018.2323 “Gaseousor rocky? Unveiling the nature of small worlds”. M.G. is an F.R.S.-FNRS Senior Research Associate. M.N.G. is the ESA CHEOPS Project Scientist and Mission Representative, and as such also responsible for the Guest Observers (GO) Programme. M.N.G. 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. S.H. gratefully acknowledges CNES funding through the grant 837319. 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 {\^I}le de France and the project Equip@Meso (reference ANR-10-EQPX-29-01) of the programme Investissements d{\textquoteright}Avenir supervised by the Agence Nationale pour la Recherche. This work was also partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127). N.C.Sa. 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. Gy.M.Sz. 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. N.A.W. acknowledges UKSA grant ST/R004838/1.",

year = "2024",

month = apr,

doi = "10.1051/0004-6361/202348270",

language = "English",

volume = "684",

journal = "Astronomy & Astrophysics",

issn = "0004-6361",

publisher = "EDP SCIENCES S A",

}

Demangeon, ODS, Cubillos, PE, Singh, V, Wilson, TG, Carone, L, Bekkelien, A, Deline, A, Ehrenreich, D, Maxted, PFL, Demory, B-O, Zingales, T, Lendl, M, Bonfanti, A, Sousa, SG, Brandeker, A, Alibert, Y, Alonso, R, Asquier, J, Bárczy, T, Barrado Navascues, D, Barros, SCC, Baumjohann, W, Beck, M, Beck, T, Benz, W, Billot, N, Biondi, F, Borsato, L, Broeg, C, Buder, M, Cameron, AC, Csizmadia, S, Davies, MB, Deleuil, M, Delrez, L, Erikson, A, Fortier, A, Fossati, L, Fridlund, M, Gandolfi, D, Gillon, M, Güdel, M, Günther, MN, Heitzmann, A, Helling, C, Hoyer, S, Isaak, KG, Kiss, LL, Lam, KWF, Laskar, J, Lecavelier des Etangs, A, Magrin, D, Mecina, M, Mordasini, C, Nascimbeni, V, Olofsson, G, Ottensamer, R, Pagano, I, Palle, E, Peter, G, Piotto, G, Pollacco, D, Queloz, D, Ragazzoni, R, Rando, N, Rauer, H, Ribas, I, Rieder, M, Salmon, S, Santos, NC, Scandariato, G, Ségransan, D, Simon, AE, Smith, AMS, Stalport, M, Szabó, GM, Thomas, N, Udry, S, Van Grootel, V, Venturini, J, Villaver, E & Walton, NA 2024, 'Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 b', Astronomy & Astrophysics, vol. 684, A27. https://doi.org/10.1051/0004-6361/202348270

TY - JOUR

T1 - Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 b

AU - Demangeon, O. D. S.

AU - Cubillos, P. E.

AU - Singh, V.

AU - Wilson, T. G.

AU - Carone, L.

AU - Bekkelien, A.

AU - Deline, A.

AU - Ehrenreich, D.

AU - Maxted, P. F. L.

AU - Demory, B. -O.

AU - Zingales, T.

AU - Lendl, M.

AU - Bonfanti, A.

AU - Sousa, S. G.

AU - Brandeker, A.

AU - Alibert, Y.

AU - Alonso, R.

AU - Asquier, J.

AU - Bárczy, T.

AU - Barrado Navascues, D.

AU - Barros, S. C. C.

AU - Baumjohann, W.

AU - Beck, M.

AU - Beck, T.

AU - Benz, W.

AU - Billot, N.

AU - Biondi, F.

AU - Borsato, L.

AU - Broeg, Ch.

AU - Buder, M.

AU - Cameron, A. Collier

AU - Csizmadia, Sz

AU - Davies, M. B.

AU - Deleuil, M.

AU - Delrez, L.

AU - Erikson, A.

AU - Fortier, A.

AU - Fossati, L.

AU - Fridlund, M.

AU - Gandolfi, D.

AU - Gillon, M.

AU - Güdel, M.

AU - Günther, M. N.

AU - Heitzmann, A.

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 - Magrin, D.

AU - Mecina, M.

AU - Mordasini, Ch.

AU - Nascimbeni, V.

AU - Olofsson, G.

AU - Ottensamer, R.

AU - Pagano, I.

AU - Palle, 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 - Rieder, M.

AU - Salmon, S.

AU - Santos, N. C.

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 Grootel, V.

AU - Venturini, J.

AU - Villaver, E.

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 UK. 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. CHEOPS data analysed in this article will be made available in the CHEOPS mission archive (https://cheops.unige.ch/archive_browser/). This work was supported by FCT – Fundação para a Ciência e a Tecnologia through national funds and by FEDER through COMPETE2020 through the research grants UIDB/04434/2020, UIDP/04434/2020, 2022.06962.PTDC. O.D.S.D. is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by national funds through FCT. P.E.C. is funded by the Austrian Science Fund (FWF) Erwin Schroedinger Fellowship, program J4595-N. V.Si., T.Zi., 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. T.Wi. acknowledges support from the UKSA and the University of Warwick. L.Ca. and C.He. acknowledge support from the European Union H2020-MSCA-ITN-2019 under Grant Agreement no. 860470 (CHAMELEON). 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). D.E. acknowledges financial support from the Swiss National Science Foundation for project 200021_200726. PM acknowledges support from STFC research grant number ST/M001040/1. B.-O.D. acknowledges support from the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number MB22.00046. M.L. acknowledges support of the Swiss National Science Foundation under grant number PCEFP2_194576. S.G.S. acknowledge support from FCT through FCT contract nr. CEECIND/00826/2018 and POPH/FSE (EC). A.Br. was supported by the SNSA. Y.Al. acknowledges support from the Swiss National Science Foundation (SNSF) under grant 200020_192038. R.Al., D.Ba., E.Pa., and I.Ri. 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. S.C.C.B. acknowledges support from FCT through FCT contracts nr. IF/01312/2014/CP1215/CT0004. C.Br. and A.Si. acknowledge support from the Swiss Space Office through the ESA PRODEX program. A.C.C. acknowledges support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. This project was supported by the CNES. 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. M.F. and C.M.P. gratefully acknowledge the support of the Swedish National Space Agency (DNR 65/19, 174/18). D.G. gratefully acknowledges financial support from the CRT foundation under Grant No. 2018.2323 “Gaseousor rocky? Unveiling the nature of small worlds”. M.G. is an F.R.S.-FNRS Senior Research Associate. M.N.G. is the ESA CHEOPS Project Scientist and Mission Representative, and as such also responsible for the Guest Observers (GO) Programme. M.N.G. 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. S.H. gratefully acknowledges CNES funding through the grant 837319. 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 Île de France and the project Equip@Meso (reference ANR-10-EQPX-29-01) of the programme Investissements d’Avenir supervised by the Agence Nationale pour la Recherche. This work was also partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127). N.C.Sa. 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. Gy.M.Sz. 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. N.A.W. acknowledges UKSA grant ST/R004838/1.

PY - 2024/4

Y1 - 2024/4

N2 - Context. WASP-76 b has been a recurrent subject of study since the detection of a signature in high-resolution transit spectroscopy data indicating an asymmetry between the two limbs of the planet. The existence of this asymmetric signature has been confirmed by multiple studies, but its physical origin is still under debate. In addition, it contrasts with the absence of asymmetry reported in the infrared (IR) phase curve. Aims. We provide a more comprehensive dataset of WASP-76 b with the goal of drawing a complete view of the physical processes at work in this atmosphere. In particular, we attempt to reconcile visible high-resolution transit spectroscopy data and IR broadband phase curves. Methods. We gathered 3 phase curves, 20 occultations, and 6 transits for WASP-76 b in the visible with the CHEOPS space telescope. We also report the analysis of three unpublished sectors observed by the TESS space telescope (also in the visible), which represents 34 phase curves. Results. WASP-76 b displays an occultation of 260 ± 11 and 152 ± 10 ppm in TESS and CHEOPS bandpasses respectively. Depending on the composition assumed for the atmosphere and the data reduction used for the IR data, we derived geometric albedo estimates that range from 0.05 ± 0.023 to 0.146 ± 0.013 and from <0.13 to 0.189 ± 0.017 in the CHEOPS and TESS bandpasses, respectively. As expected from the IR phase curves, a low-order model of the phase curves does not yield any detectable asymmetry in the visible either. However, an empirical model allowing for sharper phase curve variations offers a hint of a flux excess before the occultation, with an amplitude of ∼40 ppm, an orbital offset of ∼−30◦, and a width of ∼20◦. We also constrained the orbital eccentricity of WASP-76 b to a value lower than 0.0067, with a 99.7% confidence level. This result contradicts earlier proposed scenarios aimed at explaining the asymmetry observed in high-resolution transit spectroscopy. Conclusions. In light of these findings, we hypothesise that WASP-76 b could have night-side clouds that extend predominantly towards its eastern limb. At this limb, the clouds would be associated with spherical droplets or spherically shaped aerosols of an unknown species, which would be responsible for a glory effect in the visible phase curves.

AB - Context. WASP-76 b has been a recurrent subject of study since the detection of a signature in high-resolution transit spectroscopy data indicating an asymmetry between the two limbs of the planet. The existence of this asymmetric signature has been confirmed by multiple studies, but its physical origin is still under debate. In addition, it contrasts with the absence of asymmetry reported in the infrared (IR) phase curve. Aims. We provide a more comprehensive dataset of WASP-76 b with the goal of drawing a complete view of the physical processes at work in this atmosphere. In particular, we attempt to reconcile visible high-resolution transit spectroscopy data and IR broadband phase curves. Methods. We gathered 3 phase curves, 20 occultations, and 6 transits for WASP-76 b in the visible with the CHEOPS space telescope. We also report the analysis of three unpublished sectors observed by the TESS space telescope (also in the visible), which represents 34 phase curves. Results. WASP-76 b displays an occultation of 260 ± 11 and 152 ± 10 ppm in TESS and CHEOPS bandpasses respectively. Depending on the composition assumed for the atmosphere and the data reduction used for the IR data, we derived geometric albedo estimates that range from 0.05 ± 0.023 to 0.146 ± 0.013 and from <0.13 to 0.189 ± 0.017 in the CHEOPS and TESS bandpasses, respectively. As expected from the IR phase curves, a low-order model of the phase curves does not yield any detectable asymmetry in the visible either. However, an empirical model allowing for sharper phase curve variations offers a hint of a flux excess before the occultation, with an amplitude of ∼40 ppm, an orbital offset of ∼−30◦, and a width of ∼20◦. We also constrained the orbital eccentricity of WASP-76 b to a value lower than 0.0067, with a 99.7% confidence level. This result contradicts earlier proposed scenarios aimed at explaining the asymmetry observed in high-resolution transit spectroscopy. Conclusions. In light of these findings, we hypothesise that WASP-76 b could have night-side clouds that extend predominantly towards its eastern limb. At this limb, the clouds would be associated with spherical droplets or spherically shaped aerosols of an unknown species, which would be responsible for a glory effect in the visible phase curves.

KW - Techniques: photometric

KW - Planets and satellites: atmospheres

KW - Planets and satellites: composition

U2 - 10.1051/0004-6361/202348270

DO - 10.1051/0004-6361/202348270

M3 - Article

AN - SCOPUS:85190485487

SN - 0004-6361

VL - 684

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

M1 - A27

ER -

Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 b

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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

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WASP-76 CHEOPS light curves

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