CHEOPS finds KELT-1b darker than expected in visible light: discrepancy between the CHEOPS and TESS eclipse depths

H. Parviainen; T.G. Wilson; M. Lendl; D. Kitzmann; E. Pallé; L.M. Serrano; E. Meier Valdes; W. Benz; A. Deline; D. Ehrenreich; P. Guterman; K. Heng; O.D.S. Demangeon; A. Bonfanti; S. Salmon; V. Singh; N.C. Santos; S.G. Sousa; Y. Alibert; R. Alonso; G. Anglada; T. Bárczy; D. Barrado Y Navascues; S.C.C. Barros; W. Baumjohann; M. Beck; T. Beck; N. Billot; X. Bonfils; A. Brandeker; C. Broeg; J. Cabrera; S. Charnoz; A. Collier Cameron; C. Corral Van Damme; S. Csizmadia; M.B. Davies; M. Deleuil; L. Delrez; B.-O. Demory; A. Erikson; J. Farinato; A. Fortier; L. Fossati; M. Fridlund; D. Gandolfi; M. Gillon; M. Güdel; S. Hoyer; K.G. Isaak; L.L. Kiss; E. Kopp; J. Laskar; A. Lecavelier Des Etangs; C. Lovis; D. Magrin; P.F.L. Maxted; M. Mecina; V. Nascimbeni; G. Olofsson; R. Ottensamer; I. Pagano; G. Peter; D. Piazza; 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. Steller; G.M. Szabó; N. Thomas; S. Udry; V. Van Grootel; N.A. Walton

doi:10.1051/0004-6361/202244117

CHEOPS finds KELT-1b darker than expected in visible light: discrepancy between the CHEOPS and TESS eclipse depths

H. Parviainen^*, T.G. Wilson, M. Lendl, D. Kitzmann, E. Pallé, L.M. Serrano, E. Meier Valdes, W. Benz, A. Deline, D. Ehrenreich, P. Guterman, K. Heng, O.D.S. Demangeon, A. Bonfanti, S. Salmon, V. Singh, N.C. Santos, S.G. Sousa, Y. Alibert, R. AlonsoG. Anglada, T. Bárczy, D. Barrado Y Navascues, S.C.C. Barros, W. Baumjohann, M. Beck, T. Beck, N. Billot, X. Bonfils, A. Brandeker, C. Broeg, J. Cabrera, S. Charnoz, A. Collier Cameron, C. Corral Van Damme, S. Csizmadia, M.B. Davies, M. Deleuil, L. Delrez, B.-O. Demory, A. Erikson, J. Farinato, A. Fortier, L. Fossati, M. Fridlund, D. Gandolfi, M. Gillon, M. Güdel, S. Hoyer, K.G. Isaak, L.L. Kiss, E. Kopp, J. Laskar, A. Lecavelier Des Etangs, C. Lovis, D. Magrin, P.F.L. Maxted, M. Mecina, V. Nascimbeni, G. Olofsson, R. Ottensamer, I. Pagano, G. Peter, D. Piazza, 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. Steller, G.M. Szabó, N. Thomas, S. Udry, V. Van Grootel, N.A. Walton

^*Corresponding author for this work

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

Abstract

Recent studies based on photometry from the Transiting Exoplanet Survey Satellite (TESS) have suggested that the dayside of KELT-1b, a strongly irradiated brown dwarf, is significantly brighter in visible light than what would be expected based on Spitzer observations in the infrared. We observed eight eclipses of KELT-1b with CHaracterising ExOPlanet Satellite (CHEOPS) to measure its dayside brightness temperature in the bluest passband observed so far, and we jointly modelled the CHEOPS photometry with the existing optical and near-infrared photometry from TESS, LBT, CFHT, and Spitzer. Our modelling has led to a self-consistent dayside spectrum for KELT-1b covering the CHEOPS, TESS, H, Ks, and Spitzer IRAC 3.6 and 4.5 μm bands, where our TESS, H, Ks, and Spitzer band estimates largely agree with the previous studies. However, we discovered a strong discrepancy between the CHEOPS and TESS bands. The CHEOPS observations yield a higher photometric precision than the TESS observations, but they do not show a significant eclipse signal, while a deep eclipse is detected in the TESS band. The derived TESS geometric albedo of 0.36_-0.13^+0.12 is difficult to reconcile with a CHEOPS geometric albedo that is consistent with zero because the two passbands have considerable overlap. Variability in cloud cover caused by the transport of transient nightside clouds to the dayside could provide an explanation for reconciling the TESS and CHEOPS geometric albedos, but this hypothesis needs to be tested by future observations.

Original language	English
Article number	A93
Number of pages	23
Journal	Astronomy and Astrophysics
Volume	668
DOIs	https://doi.org/10.1051/0004-6361/202244117
Publication status	Published - 12 Dec 2022

Keywords

Brown dwarfs
Methods: observational
Planetary systems
Stars: atmospheres
Stars: individual: KELT-1

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Parviainen_2022_AA_CHEOPS-finds-KELT-1b_CC
© H. Parviainen et al. 2022. 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.
Final published version, 2.56 MBLicence: CC BY

Astronomy at St Andrews 2018-2021: Astronomy at St Andrews 2018-2021
Jardine, M. (PI), Bonnell, I. (CoI), Cameron, A. (CoI), Cyganowski, C. (CoI), Dominik, M. (CoI), Helling, C. (CoI), Horne, K. (CoI), Scholz, A. (CoI), Tojeiro, R. (CoI), Weijmans, A.-M. (CoI), Wild, V. (CoI), Woitke, P. (CoI), Wood, K. (CoI) & Zhao, H. (CoI)
1/04/18 → 31/03/22
Project: Standard

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Parviainen, H., Wilson, T. G., Lendl, M., Kitzmann, D., Pallé, E., Serrano, L. M., Meier Valdes, E., Benz, W., Deline, A., Ehrenreich, D., Guterman, P., Heng, K., Demangeon, O. D. S., Bonfanti, A., Salmon, S., Singh, V., Santos, N. C., Sousa, S. G., Alibert, Y., ... Walton, N. A. (2022). CHEOPS finds KELT-1b darker than expected in visible light: discrepancy between the CHEOPS and TESS eclipse depths. Astronomy and Astrophysics, 668, Article A93. https://doi.org/10.1051/0004-6361/202244117

@article{bb4f5d5b95c8499bbeaf36d5cc2fc1b3,

title = "CHEOPS finds KELT-1b darker than expected in visible light: discrepancy between the CHEOPS and TESS eclipse depths",

abstract = "Recent studies based on photometry from the Transiting Exoplanet Survey Satellite (TESS) have suggested that the dayside of KELT-1b, a strongly irradiated brown dwarf, is significantly brighter in visible light than what would be expected based on Spitzer observations in the infrared. We observed eight eclipses of KELT-1b with CHaracterising ExOPlanet Satellite (CHEOPS) to measure its dayside brightness temperature in the bluest passband observed so far, and we jointly modelled the CHEOPS photometry with the existing optical and near-infrared photometry from TESS, LBT, CFHT, and Spitzer. Our modelling has led to a self-consistent dayside spectrum for KELT-1b covering the CHEOPS, TESS, H, Ks, and Spitzer IRAC 3.6 and 4.5 μm bands, where our TESS, H, Ks, and Spitzer band estimates largely agree with the previous studies. However, we discovered a strong discrepancy between the CHEOPS and TESS bands. The CHEOPS observations yield a higher photometric precision than the TESS observations, but they do not show a significant eclipse signal, while a deep eclipse is detected in the TESS band. The derived TESS geometric albedo of 0.36-0.13+0.12 is difficult to reconcile with a CHEOPS geometric albedo that is consistent with zero because the two passbands have considerable overlap. Variability in cloud cover caused by the transport of transient nightside clouds to the dayside could provide an explanation for reconciling the TESS and CHEOPS geometric albedos, but this hypothesis needs to be tested by future observations.",

keywords = "Brown dwarfs, Methods: observational, Planetary systems, Stars: atmospheres, Stars: individual: KELT-1",

author = "H. Parviainen and T.G. Wilson and M. Lendl and D. Kitzmann and E. Pall{\'e} and L.M. Serrano and {Meier Valdes}, E. and W. Benz and A. Deline and D. Ehrenreich and P. Guterman and K. Heng and O.D.S. Demangeon and A. Bonfanti and S. Salmon and V. Singh and N.C. Santos and S.G. Sousa and Y. Alibert and R. Alonso and G. Anglada and T. B{\'a}rczy and {Barrado Y Navascues}, D. and S.C.C. Barros and W. Baumjohann and M. Beck and T. Beck and N. Billot and X. Bonfils and A. Brandeker and C. Broeg and J. Cabrera and S. Charnoz and {Collier Cameron}, A. and {Corral Van Damme}, C. and S. Csizmadia and M.B. Davies and M. Deleuil and L. Delrez and B.-O. Demory and A. Erikson and J. Farinato and A. Fortier and L. Fossati and M. Fridlund and D. Gandolfi and M. Gillon and M. G{\"u}del and S. Hoyer and K.G. Isaak and L.L. Kiss and E. Kopp and J. Laskar and {Lecavelier Des Etangs}, A. and C. Lovis and D. Magrin and P.F.L. Maxted and M. Mecina and V. Nascimbeni and G. Olofsson and R. Ottensamer and I. Pagano and G. Peter and D. Piazza 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 A.E. Simon and A.M.S. Smith and M. Steller and G.M. Szab{\'o} and N. Thomas and S. Udry and {Van Grootel}, V. and N.A. Walton",

note = "Funding: A.C.C. and T.G.W. acknowledge support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1.",

year = "2022",

month = dec,

day = "12",

doi = "10.1051/0004-6361/202244117",

language = "English",

volume = "668",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

Parviainen, H, Wilson, TG, Lendl, M, Kitzmann, D, Pallé, E, Serrano, LM, Meier Valdes, E, Benz, W, Deline, A, Ehrenreich, D, Guterman, P, Heng, K, Demangeon, ODS, Bonfanti, A, Salmon, S, Singh, V, Santos, NC, Sousa, SG, Alibert, Y, Alonso, R, Anglada, G, Bárczy, T, Barrado Y Navascues, D, Barros, SCC, Baumjohann, W, Beck, M, Beck, T, Billot, N, Bonfils, X, Brandeker, A, Broeg, C, Cabrera, J, Charnoz, S, Collier Cameron, A, Corral Van Damme, C, Csizmadia, S, Davies, MB, Deleuil, M, Delrez, L, Demory, B-O, Erikson, A, Farinato, J, Fortier, A, Fossati, L, Fridlund, M, Gandolfi, D, Gillon, M, Güdel, M, Hoyer, S, Isaak, KG, Kiss, LL, Kopp, E, Laskar, J, Lecavelier Des Etangs, A, Lovis, C, Magrin, D, Maxted, PFL, Mecina, M, Nascimbeni, V, Olofsson, G, Ottensamer, R, Pagano, I, Peter, G, Piazza, D, Piotto, G, Pollacco, D, Queloz, D, Ragazzoni, R, Rando, N, Rauer, H, Ribas, I, Scandariato, G, Ségransan, D, Simon, AE, Smith, AMS, Steller, M, Szabó, GM, Thomas, N, Udry, S, Van Grootel, V & Walton, NA 2022, 'CHEOPS finds KELT-1b darker than expected in visible light: discrepancy between the CHEOPS and TESS eclipse depths', Astronomy and Astrophysics, vol. 668, A93. https://doi.org/10.1051/0004-6361/202244117

TY - JOUR

T1 - CHEOPS finds KELT-1b darker than expected in visible light

T2 - discrepancy between the CHEOPS and TESS eclipse depths

AU - Parviainen, H.

AU - Wilson, T.G.

AU - Lendl, M.

AU - Kitzmann, D.

AU - Pallé, E.

AU - Serrano, L.M.

AU - Meier Valdes, E.

AU - Benz, W.

AU - Deline, A.

AU - Ehrenreich, D.

AU - Guterman, P.

AU - Heng, K.

AU - Demangeon, O.D.S.

AU - Bonfanti, A.

AU - Salmon, S.

AU - Singh, V.

AU - Santos, N.C.

AU - Sousa, S.G.

AU - Alibert, Y.

AU - Alonso, R.

AU - Anglada, G.

AU - Bárczy, T.

AU - Barrado Y Navascues, D.

AU - Barros, S.C.C.

AU - Baumjohann, W.

AU - Beck, M.

AU - Beck, T.

AU - Billot, N.

AU - Bonfils, X.

AU - Brandeker, A.

AU - Broeg, C.

AU - Cabrera, J.

AU - Charnoz, S.

AU - Collier Cameron, A.

AU - Corral Van Damme, C.

AU - Csizmadia, S.

AU - Davies, M.B.

AU - Deleuil, M.

AU - Delrez, L.

AU - Demory, B.-O.

AU - Erikson, A.

AU - Farinato, J.

AU - Fortier, A.

AU - Fossati, L.

AU - Fridlund, M.

AU - Gandolfi, D.

AU - Gillon, M.

AU - Güdel, M.

AU - Hoyer, S.

AU - Isaak, K.G.

AU - Kiss, L.L.

AU - Kopp, E.

AU - Laskar, J.

AU - Lecavelier Des Etangs, A.

AU - Lovis, C.

AU - Magrin, D.

AU - Maxted, P.F.L.

AU - Mecina, M.

AU - Nascimbeni, V.

AU - Olofsson, G.

AU - Ottensamer, R.

AU - Pagano, I.

AU - Peter, G.

AU - Piazza, D.

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 - Steller, M.

AU - Szabó, G.M.

AU - Thomas, N.

AU - Udry, S.

AU - Van Grootel, V.

AU - Walton, N.A.

N1 - Funding: A.C.C. and T.G.W. acknowledge support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1.

PY - 2022/12/12

Y1 - 2022/12/12

N2 - Recent studies based on photometry from the Transiting Exoplanet Survey Satellite (TESS) have suggested that the dayside of KELT-1b, a strongly irradiated brown dwarf, is significantly brighter in visible light than what would be expected based on Spitzer observations in the infrared. We observed eight eclipses of KELT-1b with CHaracterising ExOPlanet Satellite (CHEOPS) to measure its dayside brightness temperature in the bluest passband observed so far, and we jointly modelled the CHEOPS photometry with the existing optical and near-infrared photometry from TESS, LBT, CFHT, and Spitzer. Our modelling has led to a self-consistent dayside spectrum for KELT-1b covering the CHEOPS, TESS, H, Ks, and Spitzer IRAC 3.6 and 4.5 μm bands, where our TESS, H, Ks, and Spitzer band estimates largely agree with the previous studies. However, we discovered a strong discrepancy between the CHEOPS and TESS bands. The CHEOPS observations yield a higher photometric precision than the TESS observations, but they do not show a significant eclipse signal, while a deep eclipse is detected in the TESS band. The derived TESS geometric albedo of 0.36-0.13+0.12 is difficult to reconcile with a CHEOPS geometric albedo that is consistent with zero because the two passbands have considerable overlap. Variability in cloud cover caused by the transport of transient nightside clouds to the dayside could provide an explanation for reconciling the TESS and CHEOPS geometric albedos, but this hypothesis needs to be tested by future observations.

AB - Recent studies based on photometry from the Transiting Exoplanet Survey Satellite (TESS) have suggested that the dayside of KELT-1b, a strongly irradiated brown dwarf, is significantly brighter in visible light than what would be expected based on Spitzer observations in the infrared. We observed eight eclipses of KELT-1b with CHaracterising ExOPlanet Satellite (CHEOPS) to measure its dayside brightness temperature in the bluest passband observed so far, and we jointly modelled the CHEOPS photometry with the existing optical and near-infrared photometry from TESS, LBT, CFHT, and Spitzer. Our modelling has led to a self-consistent dayside spectrum for KELT-1b covering the CHEOPS, TESS, H, Ks, and Spitzer IRAC 3.6 and 4.5 μm bands, where our TESS, H, Ks, and Spitzer band estimates largely agree with the previous studies. However, we discovered a strong discrepancy between the CHEOPS and TESS bands. The CHEOPS observations yield a higher photometric precision than the TESS observations, but they do not show a significant eclipse signal, while a deep eclipse is detected in the TESS band. The derived TESS geometric albedo of 0.36-0.13+0.12 is difficult to reconcile with a CHEOPS geometric albedo that is consistent with zero because the two passbands have considerable overlap. Variability in cloud cover caused by the transport of transient nightside clouds to the dayside could provide an explanation for reconciling the TESS and CHEOPS geometric albedos, but this hypothesis needs to be tested by future observations.

KW - Brown dwarfs

KW - Methods: observational

KW - Planetary systems

KW - Stars: atmospheres

KW - Stars: individual: KELT-1

U2 - 10.1051/0004-6361/202244117

DO - 10.1051/0004-6361/202244117

M3 - Article

SN - 0004-6361

VL - 668

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A93

ER -

CHEOPS finds KELT-1b darker than expected in visible light: discrepancy between the CHEOPS and TESS eclipse depths

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Keywords

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

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