Nondetection of Helium in the Upper Atmospheres of TRAPPIST-1b, e, and f*

Krishnamurthy, Vigneshwaran; Hirano, Teruyuki; Stefánsson, Gumundur Kári; Ninan, Joe P.; Mahadevan, Suvrath; Gaidos, Eric; Kopparapu, R.; Sato, Bun’ei; Hori, Yasunori; Bender, Chad F.; Cañas, Caleb I.; Diddams, Scott A.; Halverson, Samuel; Harakawa, Hiroki; Hawley, Suzanne L.; Hearty, Fred; Hebb, Leslie; Hodapp, Klaus W.; Jacobson, Shane; Kanodia, Shubham; Konishi, Mihoko; Kotani, Takayuki; Kowalski, Adam F.; Kudo, Tomoyuki; Kurokawa, Takashi; Kuzuhara, Masayuki; Lin, Andrea S. J.; Maney, Marissa; Metcalf, Andrew J.; Morris, Brett M.; Nishikawa, Jun; Omiya, Masashi; Robertson, Paul; Roy, Arpita; Schwab, Christian; Serizawa, Takuma; Tamura, Motohide; Ueda, Akitoshi; Vievard, Sébastien; Wisniewski, John P.

doi:10.3847/1538-3881/ac0d57

Cited by 26 publications

(17 citation statements)

References 79 publications

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“…Previous studies have detected the He I 10830Å absorption lines in the atmosphere of about a half-dozen Jupiter and Neptune sized planets (e.g., Spake et al 2018;Nortmann et al 2018;Allart et al 2018), but only in two sub-Neptunes: GJ3470b (Palle et al 2020) and GJ1214b (Orell-Miquel et al 2022). Other studies of sub-Neptunes have been able to place only upper limits on He I absorption, but they still helps to constrain the mass-loss rate (e.g., Krishnamurthy et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Validation and atmospheric exploration of the sub-Neptune TOI-2136b around a nearby M3 dwarf

K.¹,

Murgas²,

Palle³

et al. 2022

Preprint

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Context. The NASA space telescope TESS is currently in the extended mission of its all-sky search for new transiting planets. Of the thousands of candidates that TESS is expected to deliver, transiting planets orbiting nearby M dwarfs are particularly interesting targets since they provide a great opportunity to characterize their atmospheres by transmission spectroscopy. Aims. We aim to validate and characterize the new sub-Neptune sized planet candidate TOI-2136.01 orbiting a nearby M dwarf (d = 33.36 ± 0.02 pc, T e f f = 3373 ± 108 K) with an orbital period of 7.852 days. Methods. We use TESS data, ground-based multi-color photometry, and radial velocity measurements with the InfraRed Doppler (IRD) instrument on the Subaru Telescope to validate the planetary nature of TOI-2136.01 and estimate the stellar and planetary parameters. We also conduct highresolution transmission spectroscopy to search for helium in its atmosphere. Results. We confirmed that TOI-2136.01 (now named as TOI-2136b) is a bona fide planet with a planetary radius of R p = 2.2 ± 0.07 R ⊕ and a mass of M p = 4.7 +3.1 −2.6 M ⊕ . We also search for helium 10830 Å absorption lines and place an upper limit on the equivalent width of < 7.8 mÅ (95% confidence) and on the absorption signal of < 1.44 % (95% confidence). Conclusions. TOI-2136b is a sub-Neptune transiting a nearby and bright star (J=10.8) and is a potential hycean planet, making it an excellent target for atmospheric studies to understand the formation, evolution, and habitability of the small planets.

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Section: Introductionmentioning

confidence: 99%

Validation and atmospheric exploration of the sub-Neptune TOI-2136b around a nearby M3 dwarf

K.¹,

Murgas²,

Palle³

et al. 2022

Preprint

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“…Other studies of transiting planets around M dwarfs have only placed upper limits on the presence of He (e.g. GJ 436 b, Nortmann et al 2018;AU Mic b, Hirano et al 2020; TRAPPIST-1 b, e, and f, Krishnamurthy et al 2021).…”

Section: Introductionmentioning

confidence: 99%

A tentative detection of He I in the atmosphere of GJ 1214 b

Orell-Miquel

Murgas

Πάλλη

et al. 2022

A&A

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The He I λ10833 Å triplet is a powerful tool for characterising the upper atmosphere of exoplanets and tracing possible mass loss. Here, we analysed one transit of GJ 1214 b observed with the CARMENES high-resolution spectrograph to study its atmosphere via transmission spectroscopy around the He I triplet. Although previous studies using lower resolution instruments have reported non-detections of He I in the atmosphere of GJ 1214 b, we report here the first potential detection. We reconcile the conflicting results arguing that previous transit observations did not present good opportunities for the detection of He I, due to telluric H2O absorption and OH emission contamination. We simulated those earlier observations, and show evidence that the planetary signal was contaminated. From our single non-telluric-contaminated transit, we determined an excess absorption of 2.10−0.50+0.45% (4.6 σ) with a full width at half maximum (FWHM) of 1.30−0.25+0.30 Å. The detection of He I is statistically significant at the 4.6 σ level, but repeatability of the detection could not be confirmed due to the availability of only one transit. By applying a hydrodynamical model and assuming an H/He composition of 98/2, we found that GJ 1214 b would undergo hydrodynamic escape in the photon-limited regime, losing its primary atmosphere with a mass-loss rate of (1.5–18) × 1010 g s−1 and an outflow temperature in the range of 2900–4400 K. Further high-resolution follow-up observations of GJ 1214 b are needed to confirm and fully characterise the detection of an extended atmosphere surrounding GJ 1214 b. If confirmed, this would be strong evidence that this planet has a primordial atmosphere accreted from the original planetary nebula. Despite previous intensive observations from space- and ground-based observatories, our He I excess absorption is the first tentative detection of a chemical species in the atmosphere of this benchmark sub-Neptune planet.

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“…This system will continue to attract attention from various perspectives. For example, theoretical and observational studies of planetary atmospheres will be extensively conducted in the next decade (e.g., de Wit et al 2016de Wit et al , 2018Zhang et al 2018;Hori & Ogihara 2020;Krishnamurthy et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Rapid-then-slow migration reproduces mass distribution of TRAPPIST-1 system

Ogihara

Kokubo

Nakano

et al. 2022

A&A

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Context. The TRAPPIST-1 system is an iconic planetary system in various aspects (e.g., habitability, resonant relation, and multiplicity) and hence has attracted considerable attention. The mass distribution of the TRAPPIST-1 planets is characterized by two features: the two inner planets are large, and the masses of the four planets in the outer orbit increase with orbital distance. The origin of these features cannot be explained by previous formation models. Aims. We investigate whether the mass distribution of the TRAPPIST-1 system can be reproduced by a planet formation model using N-body simulations. Methods. We used a gas disk evolution model around a low-mass star constructed by considering disk winds and followed the growth and orbital migration from planetary embryos with the isolation mass, which increases with orbital distance. Results. As a result, we find that from the initial phase, planets in inner orbits undergo rapid orbital migration, and the coalescence growth near the inner disk edge is enhanced. This allows the inner planets to grow larger. Meanwhile, compared with the inner planets, planets in outer orbits migrate more slowly and do not frequently collide with neighboring planets. Therefore, the trend of increasing mass toward the outer orbit, called reversed mass ranking, is maintained. The final mass distribution approximately agrees with the two features of the mass distribution in the TRAPPIST-1 system. Conclusions. We discover that the mass distribution in the TRAPPIST-1 system can be reproduced when embryos experience rapid migration and become trapped near the disk inner edge, and then more massive embryos undergo slower migration. This migration transition can be achieved naturally in a disk evolution model with disk winds.

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Nondetection of Helium in the Upper Atmospheres of TRAPPIST-1b, e, and f*

Cited by 26 publications

References 79 publications

Validation and atmospheric exploration of the sub-Neptune TOI-2136b around a nearby M3 dwarf

Validation and atmospheric exploration of the sub-Neptune TOI-2136b around a nearby M3 dwarf

A tentative detection of He I in the atmosphere of GJ 1214 b

Rapid-then-slow migration reproduces mass distribution of TRAPPIST-1 system

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Nondetection of Helium in the Upper Atmospheres of TRAPPIST-1b, e, and f*

Cited by 26 publications

References 79 publications

Validation and atmospheric exploration of the sub-Neptune TOI-2136b around a nearby M3 dwarf

Validation and atmospheric exploration of the sub-Neptune TOI-2136b around a nearby M3 dwarf

A tentative detection of He I in the atmosphere of GJ 1214 b

Rapid-then-slow migration reproduces mass distribution of TRAPPIST-1 system

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A tentative detection of He I in the atmosphere of GJ 1214 b