A possible misaligned orbit for the young planet AU Mic c

H. Yu; Z. Garai; M. Cretignier; Gy M. Szabó; S. Aigrain; D. Gandolfi; E. M. Bryant; A. C.M. Correia; B. Klein; A. Brandeker; J. E. Owen; M. N. Günther; J. N. Winn; A. Heitzmann; H. M. Cegla; T. G. Wilson; S. Gill; L. Kriskovics; O. Barragán; A. Boldog; L. D. Nielsen; N. Billot; M. Lafarga; A. Meech; Y. Alibert; R. Alonso; T. Bárczy; D. Barrado; S. C.C. Barros; W. Baumjohann; D. Bayliss; W. Benz; M. Bergomi; L. Borsato; C. Broeg; A. Collier Cameron; Sz Csizmadia; P. E. Cubillos; M. B. Davies; M. Deleuil; A. Deline; O. D.S. Demangeon; B. O. Demory; A. Derekas; L. Doyle; B. Edwards; J. A. Egger; D. Ehrenreich; A. Erikson; A. Fortier; L. Fossati; M. Fridlund; K. Gazeas; M. Gillon; M. Güdel; Ch Helling; K. G. Isaak; L. L. Kiss; J. Korth; K. W.F. Lam; J. Laskar; A. Lecavelier des Etangs; M. Lendl; D. Magrin; P. F.L. Maxted; J. McCormac; B. Merín; C. Mordasini; V. Nascimbeni; S. M. O’Brien; G. Olofsson; R. Ottensamer; I. Pagano; E. Pallé; G. Peter; D. Piazza; G. Piotto; D. Pollacco; D. Queloz; R. Ragazzoni; N. Rando; H. Rauer; I. Ribas; N. C. Santos; G. Scandariato; D. Ségransan; A. E. Simon; A. M.S. Smith; S. G. Sousa; R. Southworth; M. Stalport; M. Steinberger; S. Sulis; S. Udry; B. Ulmer; S. Ulmer-Moll; V. Van Grootel; J. Venturini; E. Villaver; N. A. Walton; P. J. Wheatley

doi:10.1093/mnras/stae2655

A possible misaligned orbit for the young planet AU Mic c

H. Yu, Z. Garai, M. Cretignier, Gy M. Szabó, S. Aigrain, D. Gandolfi, E. M. Bryant, A. C.M. Correia, B. Klein, A. Brandeker, J. E. Owen, M. N. Günther, J. N. Winn, A. Heitzmann, H. M. Cegla, T. G. Wilson, S. Gill, L. Kriskovics, O. Barragán, A. BoldogL. D. Nielsen, N. Billot, M. Lafarga, A. Meech, Y. Alibert, R. Alonso, T. Bárczy, D. Barrado, S. C.C. Barros, W. Baumjohann, D. Bayliss, W. Benz, M. Bergomi, L. Borsato, C. Broeg, A. Collier Cameron, Sz Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, A. Deline, O. D.S. Demangeon, B. O. Demory, A. Derekas, L. Doyle, B. Edwards, J. A. Egger, D. Ehrenreich, A. Erikson, A. Fortier, L. Fossati, M. Fridlund, K. Gazeas, M. Gillon, M. Güdel, Ch Helling, K. G. Isaak, L. L. Kiss, J. Korth, K. W.F. Lam, J. Laskar, A. Lecavelier des Etangs, M. Lendl, D. Magrin, P. F.L. Maxted, J. McCormac, B. Merín, C. Mordasini, V. Nascimbeni, S. M. O’Brien, G. Olofsson, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, D. Piazza, G. Piotto, D. Pollacco, D. Queloz, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, N. C. Santos, G. Scandariato, D. Ségransan, A. E. Simon, A. M.S. Smith, S. G. Sousa, R. Southworth, M. Stalport, M. Steinberger, S. Sulis, S. Udry, B. Ulmer, S. Ulmer-Moll, V. Van Grootel, J. Venturini, E. Villaver, N. A. Walton, P. J. Wheatley

Astrophysical Sciences

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6 Scopus citations

Abstract

The AU Microscopii planetary system is only 24 Myr old, and its geometry may provide clues about the early dynamical history of planetary systems. Here, we present the first measurement of the Rossiter–McLaughlin effect for the warm sub-Neptune AU Mic c, using two transits observed simultaneously with the European Southern Observatory’s (ESO’s) Very Large Telescope (VLT)/Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO), CHaracterising ExOPlanet Satellite (CHEOPS), and Next-Generation Transit Survey (NGTS). After correcting for flares and for the magnetic activity of the host star, and accounting for transit-timing variations, we find the sky-projected spin–orbit angle of planet c to be in the range λ_c = 67.8^+31.7_-49.0 degrees (1σ). We examine the possibility that planet c is misaligned with respect to the orbit of the inner planet b (λ_b = −2.96 ^+10.44_-10.30), and the equatorial plane of the host star, and discuss scenarios that could explain both this and the planet’s high density, including secular interactions with other bodies in the system or a giant impact. We note that a significantly misaligned orbit for planet c is in some degree of tension with the dynamical stability of the system, and with the fact that we see both planets in transit, though these arguments alone do not preclude such an orbit. Further observations would be highly desirable to constrain the spin–orbit angle of planet c more precisely.

Original language	English (US)
Pages (from-to)	2046-2063
Number of pages	18
Journal	Monthly Notices of the Royal Astronomical Society
Volume	536
Issue number	3
DOIs	https://doi.org/10.1093/mnras/stae2655
State	Published - Jan 1 2025

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

Keywords

planets and satellites: dynamical evolution and stability
planets and satellites: formation
stars: activity
stars: individual: AU Microscopii
techniques: photometric
techniques: radial velocities

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10.1093/mnras/stae2655

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Yu, H., Garai, Z., Cretignier, M., Szabó, G. M., Aigrain, S., Gandolfi, D., Bryant, E. M., Correia, A. C. M., Klein, B., Brandeker, A., Owen, J. E., Günther, M. N., Winn, J. N., Heitzmann, A., Cegla, H. M., Wilson, T. G., Gill, S., Kriskovics, L., Barragán, O., ... Wheatley, P. J. (2025). A possible misaligned orbit for the young planet AU Mic c. Monthly Notices of the Royal Astronomical Society, 536(3), 2046-2063. https://doi.org/10.1093/mnras/stae2655

@article{97d764fa296444af8b265c74c1271197,

title = "A possible misaligned orbit for the young planet AU Mic c",

abstract = "The AU Microscopii planetary system is only 24 Myr old, and its geometry may provide clues about the early dynamical history of planetary systems. Here, we present the first measurement of the Rossiter–McLaughlin effect for the warm sub-Neptune AU Mic c, using two transits observed simultaneously with the European Southern Observatory{\textquoteright}s (ESO{\textquoteright}s) Very Large Telescope (VLT)/Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO), CHaracterising ExOPlanet Satellite (CHEOPS), and Next-Generation Transit Survey (NGTS). After correcting for flares and for the magnetic activity of the host star, and accounting for transit-timing variations, we find the sky-projected spin–orbit angle of planet c to be in the range λc = 67.8+31.7-49.0 degrees (1σ). We examine the possibility that planet c is misaligned with respect to the orbit of the inner planet b (λb = −2.96 +10.44-10.30), and the equatorial plane of the host star, and discuss scenarios that could explain both this and the planet{\textquoteright}s high density, including secular interactions with other bodies in the system or a giant impact. We note that a significantly misaligned orbit for planet c is in some degree of tension with the dynamical stability of the system, and with the fact that we see both planets in transit, though these arguments alone do not preclude such an orbit. Further observations would be highly desirable to constrain the spin–orbit angle of planet c more precisely.",

keywords = "planets and satellites: dynamical evolution and stability, planets and satellites: formation, stars: activity, stars: individual: AU Microscopii, techniques: photometric, techniques: radial velocities",

author = "H. Yu and Z. Garai and M. Cretignier and Szab{\'o}, \{Gy M.\} and S. Aigrain and D. Gandolfi and Bryant, \{E. M.\} and Correia, \{A. C.M.\} and B. Klein and A. Brandeker and Owen, \{J. E.\} and G{\"u}nther, \{M. N.\} and Winn, \{J. N.\} and A. Heitzmann and Cegla, \{H. M.\} and Wilson, \{T. G.\} and S. Gill and L. Kriskovics and O. Barrag{\'a}n and A. Boldog and Nielsen, \{L. D.\} and N. Billot and M. Lafarga and A. Meech and Y. Alibert and R. Alonso and T. B{\'a}rczy and D. Barrado and Barros, \{S. C.C.\} and W. Baumjohann and D. Bayliss and W. Benz and M. Bergomi and L. Borsato and C. Broeg and Cameron, \{A. Collier\} and Sz Csizmadia and Cubillos, \{P. E.\} and Davies, \{M. B.\} and M. Deleuil and A. Deline and Demangeon, \{O. D.S.\} and Demory, \{B. O.\} and A. Derekas and L. Doyle and B. Edwards and Egger, \{J. A.\} and D. Ehrenreich and A. Erikson and A. Fortier and L. Fossati and M. Fridlund and K. Gazeas and M. Gillon and M. G{\"u}del and Ch Helling and Isaak, \{K. G.\} and Kiss, \{L. L.\} and J. Korth and Lam, \{K. W.F.\} and J. Laskar and \{Lecavelier des Etangs\}, A. and M. Lendl and D. Magrin and Maxted, \{P. F.L.\} and J. McCormac and B. Mer{\'i}n and C. Mordasini and V. Nascimbeni and O{\textquoteright}Brien, \{S. M.\} and G. Olofsson 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 I. Ribas and Santos, \{N. C.\} and G. Scandariato and D. S{\'e}gransan and Simon, \{A. E.\} and Smith, \{A. M.S.\} and Sousa, \{S. G.\} and R. Southworth and M. Stalport and M. Steinberger and S. Sulis and S. Udry and B. Ulmer and S. Ulmer-Moll and \{Van Grootel\}, V. and J. Venturini and E. Villaver and Walton, \{N. A.\} and Wheatley, \{P. J.\}",

note = "Publisher Copyright: {\textcopyright} 2024 The Author(s).",

year = "2025",

month = jan,

day = "1",

doi = "10.1093/mnras/stae2655",

language = "English (US)",

volume = "536",

pages = "2046--2063",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "Oxford University Press",

number = "3",

}

Yu, H, Garai, Z, Cretignier, M, Szabó, GM, Aigrain, S, Gandolfi, D, Bryant, EM, Correia, ACM, Klein, B, Brandeker, A, Owen, JE, Günther, MN, Winn, JN, Heitzmann, A, Cegla, HM, Wilson, TG, Gill, S, Kriskovics, L, Barragán, O, Boldog, A, Nielsen, LD, Billot, N, Lafarga, M, Meech, A, Alibert, Y, Alonso, R, Bárczy, T, Barrado, D, Barros, SCC, Baumjohann, W, Bayliss, D, Benz, W, Bergomi, M, Borsato, L, Broeg, C, Cameron, AC, Csizmadia, S, Cubillos, PE, Davies, MB, Deleuil, M, Deline, A, Demangeon, ODS, Demory, BO, Derekas, A, Doyle, L, Edwards, B, Egger, JA, Ehrenreich, D, Erikson, A, Fortier, A, Fossati, L, Fridlund, M, Gazeas, K, Gillon, M, Güdel, M, Helling, C, Isaak, KG, Kiss, LL, Korth, J, Lam, KWF, Laskar, J, Lecavelier des Etangs, A, Lendl, M, Magrin, D, Maxted, PFL, McCormac, J, Merín, B, Mordasini, C, Nascimbeni, V, O’Brien, SM, Olofsson, G, Ottensamer, R, Pagano, I, Pallé, E, Peter, G, Piazza, D, Piotto, G, Pollacco, D, Queloz, D, Ragazzoni, R, Rando, N, Rauer, H, Ribas, I, Santos, NC, Scandariato, G, Ségransan, D, Simon, AE, Smith, AMS, Sousa, SG, Southworth, R, Stalport, M, Steinberger, M, Sulis, S, Udry, S, Ulmer, B, Ulmer-Moll, S, Van Grootel, V, Venturini, J, Villaver, E, Walton, NA & Wheatley, PJ 2025, 'A possible misaligned orbit for the young planet AU Mic c', Monthly Notices of the Royal Astronomical Society, vol. 536, no. 3, pp. 2046-2063. https://doi.org/10.1093/mnras/stae2655

TY - JOUR

T1 - A possible misaligned orbit for the young planet AU Mic c

AU - Yu, H.

AU - Garai, Z.

AU - Cretignier, M.

AU - Szabó, Gy M.

AU - Aigrain, S.

AU - Gandolfi, D.

AU - Bryant, E. M.

AU - Correia, A. C.M.

AU - Klein, B.

AU - Brandeker, A.

AU - Owen, J. E.

AU - Günther, M. N.

AU - Winn, J. N.

AU - Heitzmann, A.

AU - Cegla, H. M.

AU - Wilson, T. G.

AU - Gill, S.

AU - Kriskovics, L.

AU - Barragán, O.

AU - Boldog, A.

AU - Nielsen, L. D.

AU - Billot, N.

AU - Lafarga, M.

AU - Meech, A.

AU - Alibert, Y.

AU - Alonso, R.

AU - Bárczy, T.

AU - Barrado, D.

AU - Barros, S. C.C.

AU - Baumjohann, W.

AU - Bayliss, D.

AU - Benz, W.

AU - Bergomi, M.

AU - Borsato, L.

AU - Broeg, C.

AU - Cameron, A. Collier

AU - Csizmadia, Sz

AU - Cubillos, P. E.

AU - Davies, M. B.

AU - Deleuil, M.

AU - Deline, A.

AU - Demangeon, O. D.S.

AU - Demory, B. O.

AU - Derekas, A.

AU - Doyle, L.

AU - Edwards, B.

AU - Egger, J. A.

AU - Ehrenreich, D.

AU - Erikson, A.

AU - Fortier, A.

AU - Fossati, L.

AU - Fridlund, M.

AU - Gazeas, K.

AU - Gillon, M.

AU - Güdel, M.

AU - Helling, Ch

AU - Isaak, K. G.

AU - Kiss, L. L.

AU - Korth, J.

AU - Lam, K. W.F.

AU - Laskar, J.

AU - Lecavelier des Etangs, A.

AU - Lendl, M.

AU - Magrin, D.

AU - Maxted, P. F.L.

AU - McCormac, J.

AU - Merín, B.

AU - Mordasini, C.

AU - Nascimbeni, V.

AU - O’Brien, S. M.

AU - Olofsson, G.

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 - Ribas, I.

AU - Santos, N. C.

AU - Scandariato, G.

AU - Ségransan, D.

AU - Simon, A. E.

AU - Smith, A. M.S.

AU - Sousa, S. G.

AU - Southworth, R.

AU - Stalport, M.

AU - Steinberger, M.

AU - Sulis, S.

AU - Udry, S.

AU - Ulmer, B.

AU - Ulmer-Moll, S.

AU - Van Grootel, V.

AU - Venturini, J.

AU - Villaver, E.

AU - Walton, N. A.

AU - Wheatley, P. J.

PY - 2025/1/1

Y1 - 2025/1/1

N2 - The AU Microscopii planetary system is only 24 Myr old, and its geometry may provide clues about the early dynamical history of planetary systems. Here, we present the first measurement of the Rossiter–McLaughlin effect for the warm sub-Neptune AU Mic c, using two transits observed simultaneously with the European Southern Observatory’s (ESO’s) Very Large Telescope (VLT)/Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO), CHaracterising ExOPlanet Satellite (CHEOPS), and Next-Generation Transit Survey (NGTS). After correcting for flares and for the magnetic activity of the host star, and accounting for transit-timing variations, we find the sky-projected spin–orbit angle of planet c to be in the range λc = 67.8+31.7-49.0 degrees (1σ). We examine the possibility that planet c is misaligned with respect to the orbit of the inner planet b (λb = −2.96 +10.44-10.30), and the equatorial plane of the host star, and discuss scenarios that could explain both this and the planet’s high density, including secular interactions with other bodies in the system or a giant impact. We note that a significantly misaligned orbit for planet c is in some degree of tension with the dynamical stability of the system, and with the fact that we see both planets in transit, though these arguments alone do not preclude such an orbit. Further observations would be highly desirable to constrain the spin–orbit angle of planet c more precisely.

AB - The AU Microscopii planetary system is only 24 Myr old, and its geometry may provide clues about the early dynamical history of planetary systems. Here, we present the first measurement of the Rossiter–McLaughlin effect for the warm sub-Neptune AU Mic c, using two transits observed simultaneously with the European Southern Observatory’s (ESO’s) Very Large Telescope (VLT)/Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO), CHaracterising ExOPlanet Satellite (CHEOPS), and Next-Generation Transit Survey (NGTS). After correcting for flares and for the magnetic activity of the host star, and accounting for transit-timing variations, we find the sky-projected spin–orbit angle of planet c to be in the range λc = 67.8+31.7-49.0 degrees (1σ). We examine the possibility that planet c is misaligned with respect to the orbit of the inner planet b (λb = −2.96 +10.44-10.30), and the equatorial plane of the host star, and discuss scenarios that could explain both this and the planet’s high density, including secular interactions with other bodies in the system or a giant impact. We note that a significantly misaligned orbit for planet c is in some degree of tension with the dynamical stability of the system, and with the fact that we see both planets in transit, though these arguments alone do not preclude such an orbit. Further observations would be highly desirable to constrain the spin–orbit angle of planet c more precisely.

KW - planets and satellites: dynamical evolution and stability

KW - planets and satellites: formation

KW - stars: activity

KW - stars: individual: AU Microscopii

KW - techniques: photometric

KW - techniques: radial velocities

UR - https://www.scopus.com/pages/publications/85215549660

UR - https://www.scopus.com/inward/citedby.url?scp=85215549660&partnerID=8YFLogxK

U2 - 10.1093/mnras/stae2655

DO - 10.1093/mnras/stae2655

M3 - Article

AN - SCOPUS:85215549660

SN - 0035-8711

VL - 536

SP - 2046

EP - 2063

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 3

ER -

A possible misaligned orbit for the young planet AU Mic c

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