Orbital obliquity of the young planet TOI-5398 b and the evolutionary history of the system

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Hauptverfasser: Mantovan, G., Malavolta, L., Locci, D., Polychroni, D., Turrini, D., Maggio, A., Desidera, S., Spinelli, R., Benatti, S., Piotto, G., Lanza, A. F., Marzari, F., Sozzetti, A., Damasso, M., Nardiello, D., Cabona, L., D'Arpa, M., Guilluy, G., Mancini, L., Micela, G., Nascimbeni, V., Zingales, T.
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Veröffentlicht: 2024
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author Mantovan, G.
Malavolta, L.
Locci, D.
Polychroni, D.
Turrini, D.
Maggio, A.
Desidera, S.
Spinelli, R.
Benatti, S.
Piotto, G.
Lanza, A. F.
Marzari, F.
Sozzetti, A.
Damasso, M.
Nardiello, D.
Cabona, L.
D'Arpa, M.
Guilluy, G.
Mancini, L.
Micela, G.
Nascimbeni, V.
Zingales, T.
author_facet Mantovan, G.
Malavolta, L.
Locci, D.
Polychroni, D.
Turrini, D.
Maggio, A.
Desidera, S.
Spinelli, R.
Benatti, S.
Piotto, G.
Lanza, A. F.
Marzari, F.
Sozzetti, A.
Damasso, M.
Nardiello, D.
Cabona, L.
D'Arpa, M.
Guilluy, G.
Mancini, L.
Micela, G.
Nascimbeni, V.
Zingales, T.
contents Multi-planet systems exhibit remarkable architectural diversity. However, short-period giant planets are typically isolated. Compact systems like TOI-5398, with an outer close-orbit giant and an inner small-size planet, are rare among systems containing short-period giants. TOI-5398's unusual architecture coupled with its young age (650 $\pm$ 150 Myr) make it a promising system for measuring the original obliquity between the orbital axis of the giant and the stellar spin axis in order to gain insight into its formation and orbital migration. We collected in-transit (plus suitable off-transit) observations of TOI-5398 b with HARPS-N at TNG on March 25, 2023, obtaining high-precision radial velocity time series that allowed us to measure the Rossiter-McLaughlin (RM) effect. By modelling the RM effect, we obtained a sky-projected obliquity of $λ= 3.0^{+6.8}_{-4.2}$ deg for TOI-5398 b, consistent with the planet being aligned. With knowledge of the stellar rotation period, we estimated the true 3D obliquity, finding $ψ= (13.2\pm8.2)$ deg. Based on theoretical considerations, the orientation we measure is unaffected by tidal effects, offering a direct diagnostic for understanding the formation path of this planetary system. The orbital characteristics of TOI-5398, with its compact architecture, eccentricity consistent with circular orbits, and hints of orbital alignment, appear more compatible with the disc-driven migration scenario. TOI-5398, with its relative youth (compared with similar compact systems) and exceptional suitability for transmission spectroscopy studies, presents an outstanding opportunity to establish a benchmark for exploring the disc-driven migration model.
format Preprint
id arxiv_https___arxiv_org_abs_2404_02969
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Orbital obliquity of the young planet TOI-5398 b and the evolutionary history of the system
Mantovan, G.
Malavolta, L.
Locci, D.
Polychroni, D.
Turrini, D.
Maggio, A.
Desidera, S.
Spinelli, R.
Benatti, S.
Piotto, G.
Lanza, A. F.
Marzari, F.
Sozzetti, A.
Damasso, M.
Nardiello, D.
Cabona, L.
D'Arpa, M.
Guilluy, G.
Mancini, L.
Micela, G.
Nascimbeni, V.
Zingales, T.
Earth and Planetary Astrophysics
Multi-planet systems exhibit remarkable architectural diversity. However, short-period giant planets are typically isolated. Compact systems like TOI-5398, with an outer close-orbit giant and an inner small-size planet, are rare among systems containing short-period giants. TOI-5398's unusual architecture coupled with its young age (650 $\pm$ 150 Myr) make it a promising system for measuring the original obliquity between the orbital axis of the giant and the stellar spin axis in order to gain insight into its formation and orbital migration. We collected in-transit (plus suitable off-transit) observations of TOI-5398 b with HARPS-N at TNG on March 25, 2023, obtaining high-precision radial velocity time series that allowed us to measure the Rossiter-McLaughlin (RM) effect. By modelling the RM effect, we obtained a sky-projected obliquity of $λ= 3.0^{+6.8}_{-4.2}$ deg for TOI-5398 b, consistent with the planet being aligned. With knowledge of the stellar rotation period, we estimated the true 3D obliquity, finding $ψ= (13.2\pm8.2)$ deg. Based on theoretical considerations, the orientation we measure is unaffected by tidal effects, offering a direct diagnostic for understanding the formation path of this planetary system. The orbital characteristics of TOI-5398, with its compact architecture, eccentricity consistent with circular orbits, and hints of orbital alignment, appear more compatible with the disc-driven migration scenario. TOI-5398, with its relative youth (compared with similar compact systems) and exceptional suitability for transmission spectroscopy studies, presents an outstanding opportunity to establish a benchmark for exploring the disc-driven migration model.
title Orbital obliquity of the young planet TOI-5398 b and the evolutionary history of the system
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2404.02969