The changing face of AU Mic b: Stellar spots, spin-orbit commensurability, and transit timing variations as seen by CHEOPS and TESS

Gy M. Szabó; D. Gandolfi; A. Brandeker; Sz Csizmadia; Z. Garai; N. Billot; C. Broeg; D. Ehrenreich; A. Fortier; L. Fossati; S. Hoyer; L. Kiss; A. Lecavelier Des Etangs; P. F.L. Maxted; I. Ribas; Y. Alibert; R. Alonso; G. Anglada Escudé; T. Bárczy; S. C.C. Barros; D. Barrado; W. Baumjohann; M. Beck; T. Beck; A. Bekkelien; X. Bonfils; W. Benz; L. Borsato; M. D. Busch; J. Cabrera; S. Charnoz; A. Collier Cameron; C. Corral Van Damme; M. B. Davies; L. Delrez; M. Deleuil; O. D.S. Demangeon; B. O. Demory; A. Erikson; M. Fridlund; D. Futyan; A. Garciá Muñoz; M. Gillon; M. Guedel; P. Guterman; K. Heng; K. G. Isaak; G. Lacedelli; J. Laskar; M. Lendl; C. Lovis; A. Luntzer; D. Magrin; V. Nascimbeni; G. Olofsson; H. P. Osborn; R. Ottensamer; I. Pagano; E. Pallé; G. Peter; D. Piazza; G. Piotto; D. Pollacco; D. Queloz; R. Ragazzoni; N. Rando; H. Rauer; N. C. Santos; G. Scandariato; D. Ségransan; L. M. Serrano; D. Sicilia; A. E. Simon; A. M.S. Smith; S. G. Sousa; M. Steller; N. Thomas; S. Udry; V. Van Grootel; N. A. Walton; T. G. Wilson

doi:10.1051/0004-6361/202140345

The changing face of AU Mic b: Stellar spots, spin-orbit commensurability, and transit timing variations as seen by CHEOPS and TESS

Gy M. Szabó, D. Gandolfi, A. Brandeker, Sz Csizmadia, Z. Garai, N. Billot, C. Broeg, D. Ehrenreich, A. Fortier, L. Fossati, S. Hoyer, L. Kiss, A. Lecavelier Des Etangs, P. F.L. Maxted, I. Ribas, Y. Alibert, R. Alonso, G. Anglada Escudé, T. Bárczy, S. C.C. BarrosD. Barrado, W. Baumjohann, M. Beck, T. Beck, A. Bekkelien, X. Bonfils, W. Benz, L. Borsato, M. D. Busch, J. Cabrera, S. Charnoz, A. Collier Cameron, C. Corral Van Damme, M. B. Davies, L. Delrez, M. Deleuil, O. D.S. Demangeon, B. O. Demory, A. Erikson, M. Fridlund, D. Futyan, A. Garciá Muñoz, M. Gillon, M. Guedel, P. Guterman, K. Heng, K. G. Isaak, G. Lacedelli, J. Laskar, M. Lendl, C. Lovis, A. Luntzer, D. Magrin, V. Nascimbeni, G. Olofsson, H. P. Osborn, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, D. Piazza, G. Piotto, D. Pollacco, D. Queloz, R. Ragazzoni, N. Rando, H. Rauer, N. C. Santos, G. Scandariato, D. Ségransan, L. M. Serrano, D. Sicilia, A. E. Simon, A. M.S. Smith, S. G. Sousa, M. Steller, N. Thomas, S. Udry, V. Van Grootel, N. A. Walton, T. G. Wilson

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

Abstract

AU Mic is a young planetary system with a resolved debris disc showing signs of planet formation and two transiting warm Neptunes near mean-motion resonances. Here we analyse three transits of AU Mic b observed with the CHaracterising ExOPlanet Satellite (CHEOPS), supplemented with sector 1 and 27 Transiting Exoplanet Survey Satellite (TESS) photometry, and the All-Sky Automated Survey from the ground. The refined orbital period of AU Mic b is 8.462995 ± 0.000003 d, whereas the stellar rotational period is Prot = 4.8367 ± 0.0006 d. The two periods indicate a 7:4 spin-orbit commensurability at a precision of 0.1%. Therefore, all transits are observed in front of one of the four possible stellar central longitudes. This is strongly supported by the observation that the same complex star-spot pattern is seen in the second and third CHEOPS visits that were separated by four orbits (and seven stellar rotations). Using a bootstrap analysis we find that flares and star spots reduce the accuracy of transit parameters by up to 10% in the planet-to-star radius ratio and the accuracy on transit time by 3-4 min. Nevertheless, occulted stellar spot features independently confirm the presence of transit timing variations (TTVs) with an amplitude of at least 4 min. We find that the outer companion, AU Mic c, may cause the observed TTVs.

Original language	English
Article number	A159
Journal	Astronomy and Astrophysics
Volume	654
DOIs	https://doi.org/10.1051/0004-6361/202140345
Publication status	Published - 1 Oct 2021
Externally published	Yes

Keywords

Planetary systems

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10.1051/0004-6361/202140345

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Szabó, G. M., Gandolfi, D., Brandeker, A., Csizmadia, S., Garai, Z., Billot, N., Broeg, C., Ehrenreich, D., Fortier, A., Fossati, L., Hoyer, S., Kiss, L., Des Etangs, A. L., Maxted, P. F. L., Ribas, I., Alibert, Y., Alonso, R., Escudé, G. A., Bárczy, T., ... Wilson, T. G. (2021). The changing face of AU Mic b: Stellar spots, spin-orbit commensurability, and transit timing variations as seen by CHEOPS and TESS. Astronomy and Astrophysics, 654, Article A159. https://doi.org/10.1051/0004-6361/202140345

@article{e0e883b16c1b40c59f037034c6eb8a26,

title = "The changing face of AU Mic b: Stellar spots, spin-orbit commensurability, and transit timing variations as seen by CHEOPS and TESS",

abstract = "AU Mic is a young planetary system with a resolved debris disc showing signs of planet formation and two transiting warm Neptunes near mean-motion resonances. Here we analyse three transits of AU Mic b observed with the CHaracterising ExOPlanet Satellite (CHEOPS), supplemented with sector 1 and 27 Transiting Exoplanet Survey Satellite (TESS) photometry, and the All-Sky Automated Survey from the ground. The refined orbital period of AU Mic b is 8.462995 ± 0.000003 d, whereas the stellar rotational period is Prot = 4.8367 ± 0.0006 d. The two periods indicate a 7:4 spin-orbit commensurability at a precision of 0.1\%. Therefore, all transits are observed in front of one of the four possible stellar central longitudes. This is strongly supported by the observation that the same complex star-spot pattern is seen in the second and third CHEOPS visits that were separated by four orbits (and seven stellar rotations). Using a bootstrap analysis we find that flares and star spots reduce the accuracy of transit parameters by up to 10\% in the planet-to-star radius ratio and the accuracy on transit time by 3-4 min. Nevertheless, occulted stellar spot features independently confirm the presence of transit timing variations (TTVs) with an amplitude of at least 4 min. We find that the outer companion, AU Mic c, may cause the observed TTVs.",

keywords = "Planetary systems",

author = "Szab{\'o}, \{Gy M.\} and D. Gandolfi and A. Brandeker and Sz Csizmadia and Z. Garai and N. Billot and C. Broeg and D. Ehrenreich and A. Fortier and L. Fossati and S. Hoyer and L. Kiss and \{Des Etangs\}, \{A. Lecavelier\} and Maxted, \{P. F.L.\} and I. Ribas and Y. Alibert and R. Alonso and Escud{\'e}, \{G. Anglada\} and T. B{\'a}rczy and Barros, \{S. C.C.\} and D. Barrado and W. Baumjohann and M. Beck and T. Beck and A. Bekkelien and X. Bonfils and W. Benz and L. Borsato and Busch, \{M. D.\} and J. Cabrera and S. Charnoz and Cameron, \{A. Collier\} and \{Van Damme\}, \{C. Corral\} and Davies, \{M. B.\} and L. Delrez and M. Deleuil and Demangeon, \{O. D.S.\} and Demory, \{B. O.\} and A. Erikson and M. Fridlund and D. Futyan and Mu{\~n}oz, \{A. Garci{\'a}\} and M. Gillon and M. Guedel and P. Guterman and K. Heng and Isaak, \{K. G.\} and G. Lacedelli and J. Laskar and M. Lendl and C. Lovis and A. Luntzer and D. Magrin and V. Nascimbeni and G. Olofsson and Osborn, \{H. P.\} and R. Ottensamer and I. Pagano and E. Pall{\'e} 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 Santos, \{N. C.\} and G. Scandariato and D. S{\'e}gransan and Serrano, \{L. M.\} and D. Sicilia and Simon, \{A. E.\} and Smith, \{A. M.S.\} and Sousa, \{S. G.\} and M. Steller and N. Thomas and S. Udry and \{Van Grootel\}, V. and Walton, \{N. A.\} and Wilson, \{T. G.\}",

note = "Publisher Copyright: {\textcopyright} ESO 2021.",

year = "2021",

month = oct,

day = "1",

doi = "10.1051/0004-6361/202140345",

language = "English",

volume = "654",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

}

Szabó, GM, Gandolfi, D, Brandeker, A, Csizmadia, S, Garai, Z, Billot, N, Broeg, C, Ehrenreich, D, Fortier, A, Fossati, L, Hoyer, S, Kiss, L, Des Etangs, AL, Maxted, PFL, Ribas, I, Alibert, Y, Alonso, R, Escudé, GA, Bárczy, T, Barros, SCC, Barrado, D, Baumjohann, W, Beck, M, Beck, T, Bekkelien, A, Bonfils, X, Benz, W, Borsato, L, Busch, MD, Cabrera, J, Charnoz, S, Cameron, AC, Van Damme, CC, Davies, MB, Delrez, L, Deleuil, M, Demangeon, ODS, Demory, BO, Erikson, A, Fridlund, M, Futyan, D, Muñoz, AG, Gillon, M, Guedel, M, Guterman, P, Heng, K, Isaak, KG, Lacedelli, G, Laskar, J, Lendl, M, Lovis, C, Luntzer, A, Magrin, D, Nascimbeni, V, Olofsson, G, Osborn, HP, Ottensamer, R, Pagano, I, Pallé, E, Peter, G, Piazza, D, Piotto, G, Pollacco, D, Queloz, D, Ragazzoni, R, Rando, N, Rauer, H, Santos, NC, Scandariato, G, Ségransan, D, Serrano, LM, Sicilia, D, Simon, AE, Smith, AMS, Sousa, SG, Steller, M, Thomas, N, Udry, S, Van Grootel, V, Walton, NA & Wilson, TG 2021, 'The changing face of AU Mic b: Stellar spots, spin-orbit commensurability, and transit timing variations as seen by CHEOPS and TESS', Astronomy and Astrophysics, vol. 654, A159. https://doi.org/10.1051/0004-6361/202140345

TY - JOUR

T1 - The changing face of AU Mic b

T2 - Stellar spots, spin-orbit commensurability, and transit timing variations as seen by CHEOPS and TESS

AU - Szabó, Gy M.

AU - Gandolfi, D.

AU - Brandeker, A.

AU - Csizmadia, Sz

AU - Garai, Z.

AU - Billot, N.

AU - Broeg, C.

AU - Ehrenreich, D.

AU - Fortier, A.

AU - Fossati, L.

AU - Hoyer, S.

AU - Kiss, L.

AU - Des Etangs, A. Lecavelier

AU - Maxted, P. F.L.

AU - Ribas, I.

AU - Alibert, Y.

AU - Alonso, R.

AU - Escudé, G. Anglada

AU - Bárczy, T.

AU - Barros, S. C.C.

AU - Barrado, D.

AU - Baumjohann, W.

AU - Beck, M.

AU - Beck, T.

AU - Bekkelien, A.

AU - Bonfils, X.

AU - Benz, W.

AU - Borsato, L.

AU - Busch, M. D.

AU - Cabrera, J.

AU - Charnoz, S.

AU - Cameron, A. Collier

AU - Van Damme, C. Corral

AU - Davies, M. B.

AU - Delrez, L.

AU - Deleuil, M.

AU - Demangeon, O. D.S.

AU - Demory, B. O.

AU - Erikson, A.

AU - Fridlund, M.

AU - Futyan, D.

AU - Muñoz, A. Garciá

AU - Gillon, M.

AU - Guedel, M.

AU - Guterman, P.

AU - Heng, K.

AU - Isaak, K. G.

AU - Lacedelli, G.

AU - Laskar, J.

AU - Lendl, M.

AU - Lovis, C.

AU - Luntzer, A.

AU - Magrin, D.

AU - Nascimbeni, V.

AU - Olofsson, G.

AU - Osborn, H. P.

AU - Ottensamer, R.

AU - Pagano, I.

AU - Pallé, E.

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 - Santos, N. C.

AU - Scandariato, G.

AU - Ségransan, D.

AU - Serrano, L. M.

AU - Sicilia, D.

AU - Simon, A. E.

AU - Smith, A. M.S.

AU - Sousa, S. G.

AU - Steller, M.

AU - Thomas, N.

AU - Udry, S.

AU - Van Grootel, V.

AU - Walton, N. A.

AU - Wilson, T. G.

PY - 2021/10/1

Y1 - 2021/10/1

N2 - AU Mic is a young planetary system with a resolved debris disc showing signs of planet formation and two transiting warm Neptunes near mean-motion resonances. Here we analyse three transits of AU Mic b observed with the CHaracterising ExOPlanet Satellite (CHEOPS), supplemented with sector 1 and 27 Transiting Exoplanet Survey Satellite (TESS) photometry, and the All-Sky Automated Survey from the ground. The refined orbital period of AU Mic b is 8.462995 ± 0.000003 d, whereas the stellar rotational period is Prot = 4.8367 ± 0.0006 d. The two periods indicate a 7:4 spin-orbit commensurability at a precision of 0.1%. Therefore, all transits are observed in front of one of the four possible stellar central longitudes. This is strongly supported by the observation that the same complex star-spot pattern is seen in the second and third CHEOPS visits that were separated by four orbits (and seven stellar rotations). Using a bootstrap analysis we find that flares and star spots reduce the accuracy of transit parameters by up to 10% in the planet-to-star radius ratio and the accuracy on transit time by 3-4 min. Nevertheless, occulted stellar spot features independently confirm the presence of transit timing variations (TTVs) with an amplitude of at least 4 min. We find that the outer companion, AU Mic c, may cause the observed TTVs.

AB - AU Mic is a young planetary system with a resolved debris disc showing signs of planet formation and two transiting warm Neptunes near mean-motion resonances. Here we analyse three transits of AU Mic b observed with the CHaracterising ExOPlanet Satellite (CHEOPS), supplemented with sector 1 and 27 Transiting Exoplanet Survey Satellite (TESS) photometry, and the All-Sky Automated Survey from the ground. The refined orbital period of AU Mic b is 8.462995 ± 0.000003 d, whereas the stellar rotational period is Prot = 4.8367 ± 0.0006 d. The two periods indicate a 7:4 spin-orbit commensurability at a precision of 0.1%. Therefore, all transits are observed in front of one of the four possible stellar central longitudes. This is strongly supported by the observation that the same complex star-spot pattern is seen in the second and third CHEOPS visits that were separated by four orbits (and seven stellar rotations). Using a bootstrap analysis we find that flares and star spots reduce the accuracy of transit parameters by up to 10% in the planet-to-star radius ratio and the accuracy on transit time by 3-4 min. Nevertheless, occulted stellar spot features independently confirm the presence of transit timing variations (TTVs) with an amplitude of at least 4 min. We find that the outer companion, AU Mic c, may cause the observed TTVs.

KW - Planetary systems

U2 - 10.1051/0004-6361/202140345

DO - 10.1051/0004-6361/202140345

M3 - Article

AN - SCOPUS:85118444840

SN - 0004-6361

VL - 654

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A159

ER -

The changing face of AU Mic b: Stellar spots, spin-orbit commensurability, and transit timing variations as seen by CHEOPS and TESS

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Keywords

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