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

^*Corresponding author for this work

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

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 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

Original language	English
Pages (from-to)	2046-2063
Number of pages	18
Journal	Monthly Notices of the Royal Astronomical Society
Volume	536
Issue number	3
Early online date	27 Nov 2024
DOIs	https://doi.org/10.1093/mnras/stae2655
Publication status	Published - Jan 2025

Keywords

Techniques: photometric
Techniques: radial velocities
Planets and satellites: dynamical evolution and stability
Planets and satellites: formation
Stars: activity
Stars: individual: AU Microscopii

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Yu-2024-A-possible-misaligned-orbit-MNRAS-536-3-2046-CCBY
Copyright © 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Final published version, 4.22 MBLicence: CC BY

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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
1/04/21 → 31/03/24
Project: Standard
H2020 MSCA ITN EJD 2019: H2020 MSCA ITN EJD 2019 CHAMELEON
Helling, C. (PI)
European Commission
1/06/20 → 31/05/24
Project: Standard

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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{6cdde77175e743ec89ddba2c3d7b39ad,

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 dynamicalhistory 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) VeryLarge 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 forthe magnetic activity of the host star, and accounting for transit-timing variations, we find the sky-projected spin–orbit angle ofplanet 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 theorbit 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 explainboth this and the planet{\textquoteright}s high density, including secular interactions with other bodies in the system or a giant impact. We notethat a significantly misaligned orbit for planet c is in some degree of tension with the dynamical stability of the system, and withthe fact that we see both planets in transit, though these arguments alone do not preclude such an orbit. Further observationswould be highly desirable to constrain the spin–orbit angle of planet c more precisely",

keywords = "Techniques: photometric, Techniques: radial velocities, Planets and satellites: dynamical evolution and stability, Planets and satellites: formation, Stars: activity, Stars: individual: AU Microscopii",

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'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 = "Funding: ACC acknowledges support from STFC consolidated grant number ST/V000861/1, and UKSA grant number ST/X002217/1. HY, SA, BK, and OB acknowledge funding from the European Research Council under the European Union{\textquoteright}s Horizon 2020 research and innovation programme (grant agreement no. 865624, GPRV). HMC acknowledges funding from a UKRI Future Leader Fellowship, grant number MR/S035214/1. The contributions at the Mullard Space Science Laboratory by EMB have been supported by STFC through the consolidated grant ST/W001136/1. JEO was supported by a Royal Society University Research Fellowship, and JEO{\textquoteright}s contribution received funding from the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation programme (grant agreement no. 853022). CH acknowledges the European Union H2020-MSCA-ITN-2019 under grant agreement no. 860470 (CHAMELEON). PFLM acknowledges support from STFC research grant number ST/R000638/1. NCS acknowledges funding by the European Union (ERC, FIERCE, 101052347) NAW acknowledges UKSA grant ST/R004838/1. ML acknowledges the support from the UKRI grant (grant number: EP/X027562/1).",

year = "2025",

month = jan,

doi = "10.1093/mnras/stae2655",

language = "English",

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.

N1 - Funding: ACC acknowledges support from STFC consolidated grant number ST/V000861/1, and UKSA grant number ST/X002217/1. HY, SA, BK, and OB acknowledge funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 865624, GPRV). HMC acknowledges funding from a UKRI Future Leader Fellowship, grant number MR/S035214/1. The contributions at the Mullard Space Science Laboratory by EMB have been supported by STFC through the consolidated grant ST/W001136/1. JEO was supported by a Royal Society University Research Fellowship, and JEO’s contribution received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 853022). CH acknowledges the European Union H2020-MSCA-ITN-2019 under grant agreement no. 860470 (CHAMELEON). PFLM acknowledges support from STFC research grant number ST/R000638/1. NCS acknowledges funding by the European Union (ERC, FIERCE, 101052347) NAW acknowledges UKSA grant ST/R004838/1. ML acknowledges the support from the UKRI grant (grant number: EP/X027562/1).

PY - 2025/1

Y1 - 2025/1

N2 - The AU Microscopii planetary system is only 24 Myr old, and its geometry may provide clues about the early dynamicalhistory 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) VeryLarge 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 forthe magnetic activity of the host star, and accounting for transit-timing variations, we find the sky-projected spin–orbit angle ofplanet 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 theorbit 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 explainboth this and the planet’s high density, including secular interactions with other bodies in the system or a giant impact. We notethat a significantly misaligned orbit for planet c is in some degree of tension with the dynamical stability of the system, and withthe fact that we see both planets in transit, though these arguments alone do not preclude such an orbit. Further observationswould 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 dynamicalhistory 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) VeryLarge 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 forthe magnetic activity of the host star, and accounting for transit-timing variations, we find the sky-projected spin–orbit angle ofplanet 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 theorbit 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 explainboth this and the planet’s high density, including secular interactions with other bodies in the system or a giant impact. We notethat a significantly misaligned orbit for planet c is in some degree of tension with the dynamical stability of the system, and withthe fact that we see both planets in transit, though these arguments alone do not preclude such an orbit. Further observationswould be highly desirable to constrain the spin–orbit angle of planet c more precisely

KW - Techniques: photometric

KW - Techniques: radial velocities

KW - Planets and satellites: dynamical evolution and stability

KW - Planets and satellites: formation

KW - Stars: activity

KW - Stars: individual: AU Microscopii

U2 - 10.1093/mnras/stae2655

DO - 10.1093/mnras/stae2655

M3 - Article

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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