Limits on the Spin–Orbit Angle and Atmospheric Escape for the 22 Myr Old Planet AU Mic b*

Hirano, Teruyuki; Krishnamurthy, Vigneshwaran; Gaidos, Eric; Flewelling, H.; Mann, Andrew W.; Narita, Norio; Plavchan, Peter; Kotani, Takayuki; Tamura, Motohide; Harakawa, Hiroki; Hodapp, Klaus W.; Ishizuka, Masato; Jacobson, Shane; Konishi, Mihoko; Kudo, Tomoyuki; Kurokawa, Takashi; Kuzuhara, Masayuki; Nishikawa, Jun; Omiya, Masashi; Serizawa, Takuma; Ueda, Akitoshi; Vievard, Sébastien

doi:10.3847/2041-8213/aba6eb

Cited by 71 publications

(52 citation statements)

References 58 publications

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“…TOI837 joins a number of other young planetary systems reported from TESS, including DSTucAb, HIP67522b, TOI1726, and AUMicb (Newton et al 2019;Addison et al 2020;Hirano et al 2020;Mann et al 2020;Martioli et al 2020;Montet et al 2020;Palle et al 2020;Plavchan et al 2020;Rizzuto et al 2020;Zhou et al 2020). In the space of planet sizes and ages, the top panel of Figure 11 shows that TOI837 is among the youngest transiting planets known.…”

Section: Discussionsupporting

confidence: 54%

Cluster Difference Imaging Photometric Survey. II. TOI 837: A Young Validated Planet in IC 2602

Bouma

Hartman

Brahm

et al. 2020

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We report the discovery of TOI 837b and its validation as a transiting planet. We characterize the system using data from the NASA Transiting Exoplanet Survey Satellite mission, the ESA Gaia mission, ground-based photometry from El Sauce and ASTEP400, and spectroscopy from CHIRON, FEROS, and Veloce. We find that TOI 837 is a T=9.9 mag G0/F9 dwarf in the southern open cluster IC 2602. The star and planet are therefore -+ Unified Astronomy Thesaurus concepts: Exoplanets (498); Transits (1711); Exoplanet evolution (491); Stellar ages (1581); Young star clusters (1833)

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Section: Discussionsupporting

confidence: 54%

Cluster Difference Imaging Photometric Survey. II. TOI 837: A Young Validated Planet in IC 2602

Bouma

Hartman

Brahm

et al. 2020

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“…The AU Mic host is an M1 star with a spatially resolved edge-on debris disk (Kalas et al 2004) and at least one transiting planet, AU Mic b (Plavchan et al 2020). This Neptune-size planet is in a 8.5-d prograde orbit aligned with the stellar rotation axis (Martioli et al 2020;Hirano et al 2020;Palle et al 2020). While Plavchan et al (2020) only reported an upper limit on the mass of AU Mic b, Klein et al (2021) measured 17.1 +4.7 −4.5 M ⊕ thanks to infrared observations secured with the SPIRou spectropolarimeter (Donati et al 2020).…”

Section: Introductionmentioning

confidence: 98%

New constraints on the planetary system around the young active star AU Mic

Martioli

Hébrard

Correia

et al. 2021

A&A

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AU Microscopii (AU Mic) is a young, active star whose transiting planet was recently detected. Here, we report our analysis of its TESS light curve, where we modeled the BY Draconis type quasi-periodic rotational modulation by starspots simultaneously to the flaring activity and planetary transits. We measured a flare occurrence rate in AU Mic of 6.35 flares per day for flares with amplitudes in the range of 0.06% < fmax < 1.5% of the star flux. We employed a Bayesian Markov chain Monte Carlo analysis to model the five transits of AU Mic b observed by TESS, improving the constraints on the planetary parameters. The measured planet-to-star effective radius ratio of Rp∕R⋆ = 0.0496 ± 0.0007 implies a physical radius of 4.07 ± 0.17 R⊕ and a planet density of 1.4 ± 0.4 g cm−3, confirming that AU Mic b is a Neptune-size moderately inflated planet. While a single feature possibly due to a second planet was previously reported in the former TESS data, we report the detection of two additional transit-like events in the new TESS observations of July 2020. This represents substantial evidence for a second planet (AU Mic c) in the system. We analyzed its three available transits and obtained an orbital period of 18.859019 ± 0.000016 d and a planetary radius of 3.24 ± 0.16 R⊕, which defines AU Mic c as a warm Neptune-size planet with an expected mass in the range of 2.2 M⊕ < Mc < 25.0 M⊕, estimated from the population of exoplanets of similar sizes. The two planets in the AU Mic system are in near 9:4 mean-motion resonance. We show that this configuration is dynamically stable and should produce transit-timing variations (TTV). Our non-detection of significant TTV in AU Mic b suggests an upper limit for the mass of AU Mic c of <7 M⊕, indicating that this planet is also likely to be inflated. As a young multi-planet system with at least two transiting planets, AU Mic becomes a key system for the study of atmospheres of infant planets and of planet-planet and planet-disk dynamics at the early stages of planetary evolution.

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“…Although hundreds of obliquities have been measured with the RM effect, the current list includes only three M dwarfs: GJ 436 (Bourrier et al 2018a), TRAPPIST-1 (Hirano et al 2020a), and AU Mic (Addison et al 2020;Hirano et al 2020b;Palle et al 2020). The obliquity of GJ 436b was found to be l =  -+ 72 24 33 , suggesting a strong misalignment, and AU Mic was found to be well aligned with the equator of its host star.…”

Section: Introductionmentioning

confidence: 99%

The Habitable Zone Planet Finder Reveals a High Mass and Low Obliquity for the Young Neptune K2-25b

Stefánsson

Mahadevan

Maney

et al. 2020

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Using radial velocity data from the Habitable Zone Planet Finder, we have measured the mass of the Neptune-sized planet K2-25b, as well as the obliquity of its M4.5 dwarf host star in the 600-800 Myr Hyades cluster. This is one of the youngest planetary systems for which both of these quantities have been measured and one of the very few M dwarfs with a measured obliquity. Based on a joint analysis of the radial velocity data, time-series photometry from the K2 mission, and new transit light curves obtained with diffuser-assisted photometry, the planet's radius and mass are 3.44±0.12 R ⊕ and -+ Å M 24.5 5.2 5.7. These properties are compatible with a rocky core enshrouded by a thin hydrogen-helium atmosphere (5% by mass). We measure an orbital eccentricity of e=0.43±0.05. The skyprojected stellar obliquity is λ=3°±16°, compatible with spin-orbit alignment, in contrast to other "hot Neptunes" that have been studied around older stars.

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Limits on the Spin–Orbit Angle and Atmospheric Escape for the 22 Myr Old Planet AU Mic b*

Cited by 71 publications

References 58 publications

Cluster Difference Imaging Photometric Survey. II. TOI 837: A Young Validated Planet in IC 2602

Cluster Difference Imaging Photometric Survey. II. TOI 837: A Young Validated Planet in IC 2602

New constraints on the planetary system around the young active star AU Mic

The Habitable Zone Planet Finder Reveals a High Mass and Low Obliquity for the Young Neptune K2-25b

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