TOI-942b: A Prograde Neptune in a ∼ 60 Myr Old Multi-transiting System*

Wirth, Christopher; Zhou, George; Quinn, Samuel N.; Mann, Andrew W.; Bouma, Luke G.; Latham, David W.; Teske, Johanna; Wang, Sharon X.; Shectman, Stephen; Butler, R. Paul; Crane, Jeffrey D.

doi:10.3847/2041-8213/ac13a9

Cited by 19 publications

(9 citation statements)

References 44 publications

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“…The amplitude of both the spot-induced trend and the jitter are somewhat larger than recent comparable measurements in systems such as AU Mic (Palle et al 2020), DS Tuc (Montet et al 2020;Zhou et al 2020) and TOI 942 (Wirth et al 2021). One possible explanation for the jitter is that it is astrophysical in origin, and that it is caused by some novel process operating on the surface of Kepler 1627A.…”

Section: B2 Interpretationcontrasting

confidence: 58%

A 38 Million Year Old Neptune-Sized Planet in the Kepler Field

Bouma,

Curtis,

Masuda

et al. 2021

Preprint

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Kepler 1627A is a G8V star previously known to host a 3.8 R ⊕ planet on a 7.2 day orbit. The star was observed by the Kepler space telescope because it is nearby (d = 329 pc) and it resembles the Sun. Here we show using Gaia kinematics, TESS stellar rotation periods, and spectroscopic lithium abundances that Kepler 1627 is a member of the 38 +6 −5 Myr old δ Lyr cluster. To our knowledge, this makes Kepler 1627Ab the youngest planet with a precise age yet found by the prime Kepler mission. The Kepler photometry shows two peculiarities: the average transit profile is asymmetric, and the individual transit times might be correlated with the local light curve slope. We discuss possible explanations for each anomaly. More importantly, the δ Lyr cluster is one of ∼10 3 coeval groups whose properties have been clarified by Gaia. Many other exoplanet hosts are candidate members of these clusters; their ages can be verified with the trifecta of Gaia, TESS, and ground-based spectroscopy.

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Section: B2 Interpretationcontrasting

confidence: 58%

A 38 Million Year Old Neptune-Sized Planet in the Kepler Field

Bouma,

Curtis,

Masuda

et al. 2021

Preprint

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“…Less challenging follow-up would be spin-orbit alignment through Rossiter-Mclaughlin, where the signal is expected to be >200 m s −1 and the transit timescale ( 5 h) is much shorter than the rotational jitter (1.65 days). Recent measurements of stellar obliquity in young planetary systems have found that they are generally aligned with their host stars (e.g., Rodriguez et al 2019;Zhou et al 2020;Wirth et al 2021), suggesting that these planets formed in situ or migrated through their protoplanetary disk. However, the number of misaligned systems even around older stars is 10% (varying with spectral type and planet mass; Fabrycky & Winn 2009; Morton & Winn 2014;Campante et al 2016).…”

Section: Summary and Discussionmentioning

confidence: 99%

TESS Hunt for Young and Maturing Exoplanets (THYME) VI: an 11 Myr giant planet transiting a very low-mass star in Lower Centaurus Crux

Mann,

Wood,

Schmidt

et al. 2021

Preprint

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Mature super-Earths and sub-Neptunes are predicted to be Jovian radius when younger than 10 Myr. Thus, we expect to find 5-15R ⊕ planets around young stars even if their older counterparts harbor none. We report the discovery and validation of TOI 1227 b, a 0.85 ± 0.05 R J (9.5R ⊕ ) planet transiting a very low-mass star (0.170 ± 0.015 M ) every 27.4 days. TOI 1227's kinematics and strong lithium absorption confirm it is a member of a previously discovered sub-group in the Lower Centaurus Crux OB association, which we designate the Musca group. We derive an age of 11±2 Myr for Musca, based on lithium, rotation, and the color-magnitude diagram of Musca members. The TESS data and ground-based followup show a deep (2.5%) transit. We use multiwavelength transit observations and radial velocities from the IGRINS spectrograph to validate the signal as planetary in nature, and we obtain an upper limit on the planet mass of 0.5 M J . Because such large planets are exceptionally rare around mature low-mass stars, we suggest that TOI 1227 b is still contracting and will eventually turn into one of the more common < 5R ⊕ planets.

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“…The other numbers refer to other works reporting additional measurements of λ or other system parameters. Note-All data were taken from TEPCat (Southworth 2011) or the following references: 1 (Hirano et al 2020a), 2 (Albrecht et al 2021), 3 (Martioli et al 2020), 4 (Palle et al 2020, 5 (Addison et al 2021), 6 (Christiansen et al 2017), 7 (Bourrier et al 2021, (Dalal et al 2019), 9 (Mann et al 2020), 10 (Dai et al 2020), 11 (Zhou et al 2018, 12 (Hjorth et al 2019a), 13 (Hjorth et al 2021, 14 (Wang et al 2018), 15 (Albrecht et al 2013), 16 (Campante et al 2016, 17 (Benomar et al 2014), 18 (Sanchis-Ojeda et al 2012, 19 , 20 (Huber et al 2013), 21 (Hirano et al 2012), 22 (Newton et al 2021, 23 (Zhou et al 2021), 24 (Wirth et al 2021), 25 (Hirano et al 2020b), 26 (David et al 2019b), 27 (Johnson et al 2021), 28 (Biddle et al 2014), 29 (Gaidos et al 2021), 30 (Feinstein et al 2021), 31 (Sanchis-Ojeda et al 2015, 32 (Wang et al 2021b), 33 (Hébrard et al 2020) 3.1.12. Interlude: Mutual orbital inclinations Most of the available RM data are for stars with closeorbiting giant planets.…”

Section: Obliquity and Eccentricitymentioning

confidence: 99%

Stellar obliquities in exoplanetary systems

Albrecht,

Dawson,

Winn

2022

Preprint

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The rotation of a star and the revolutions of its planets are not necessarily aligned. This article reviews the measurement techniques, key findings, and theoretical interpretations related to the obliquities (spin-orbit angles) of planet-hosting stars. The best measurements are for stars with short-period giant planets, which have been found on prograde, polar, and retrograde orbits. It seems likely that dynamical processes such as planet-planet scattering and secular perturbations are responsible for tilting the orbits of close-in giant planets, just as those processes are implicated in exciting orbital eccentricities. The observed dependence of the obliquity on orbital separation, planet mass, and stellar structure suggests that in some cases, tidal dissipation damps a star's obliquity within its main-sequence lifetime. The situation is not as clear for stars with smaller or wider-orbiting planets. Although the earliest measurements of such systems tended to find low obliquities, some glaring exceptions are now known in which the star's rotation is misaligned with respect to the coplanar orbits of multiple planets. In addition, statistical analyses based on projected rotation velocities and photometric variability have found a broad range of obliquities for F-type stars hosting compact multiple-planet systems. The results suggest it is unsafe to assume that stars and their protoplanetary disks are aligned. Primordial misalignments might be produced by neighboring stars or more complex events that occur during the epoch of planet formation.

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TOI-942b: A Prograde Neptune in a ∼ 60 Myr Old Multi-transiting System*

Cited by 19 publications

References 44 publications

A 38 Million Year Old Neptune-Sized Planet in the Kepler Field

A 38 Million Year Old Neptune-Sized Planet in the Kepler Field

TESS Hunt for Young and Maturing Exoplanets (THYME) VI: an 11 Myr giant planet transiting a very low-mass star in Lower Centaurus Crux

Stellar obliquities in exoplanetary systems

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