The dynamics of the TRAPPIST-1 system in the context of its formation

Huang, Shuo; Ormel, Chris W.

doi:10.48550/arxiv.2109.10984

“…As a different formation model, Ormel et al (2017) proposed that planets grow near the water snowline (r < 1 au), mainly by pebble accretion. In this model, the average planetary mass (Schoonenberg et al 2019) and resonant relation (Lin et al 2021;Huang & Ormel 2021) could be reproduced. In contrast, the mass was determined by the pebble isolation mass; therefore, the planetary mass was almost uniform in the system.…”

Section: Planetmentioning

confidence: 87%

“…The TRAPPIST-1 system is characterized by resonant relations. Previous studies (e.g., Coleman et al 2019;Lin et al 2021;Huang & Ormel 2021) investigated how the resonant relations are reproduced. Although this study does not focus on reproducing the resonance relations, we also investigated whether the period ratio agrees with that of the TRAPPIST-1 system.…”

Section: Mean-motion Resonancesmentioning

confidence: 99%

“…The origin of the Laplace resonance in the TRAPPIST-1 system has been studied (e.g. Papaloizou et al 2018;Huang & Ormel 2021), and it is likely that additional dissipation mechanisms are required to reproduce all resonant angles. Future studies of the evolution of three-body resonances by combining simulations of the formation stage and evolution stage are needed.…”

Section: Mean-motion Resonancesmentioning

confidence: 99%

See 1 more Smart Citation

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

Ogihara,

Kokubo,

Nakano

et al. 2022

Preprint

0

View full text Add to dashboard Cite

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. Key words. planets and satellites: formation -planets and satellites: dynamical evolution and stability -planet-disk interactions -Protoplanetary disks c1.580 ± 0.013 1.308 ± 0.056 5.447 +0.222 −0.235 d 2.227 ± 0.019 0.388 ± 0.012 4.354 +0.156 −0.163 e 2.925 ± 0.025 0.692 ± 0.022 4.885 +0.168 −0.182 f 3.849 ± 0.033 1.039 ± 0.031 5.009 +0.138 −0.158 g 4.683 ± 0.040 1.321 ± 0.038 5.042 +0.136 −0.158 h 6.189 ± 0.053 0.326 ± 0.020 4.147 +0.322 −0.302 Notes. The second column, a, indicates the semimajor axis. Data are obtained from Agol et al. (2021).2018; Acuña et al. 2021). The estimates consistently indicate that all seven planets have rocky interiors with a small water mass fraction ( 10wt%). In particular, the water fraction of the three inner planets is near zero ( 10 −3 wt%). In addition, it has been reported that the densities of the planets can be described with a single mass-radius relation (Agol et al. 2021). The orbital configuration of the TRAPPIST-1 planets is also characteristic. The outer planets d-h are in first-order mean-motion resonancesArticle number, page 1 of 7

show abstract

“…Such a configuration is stable on very long timescales, as opposed to the early N-body simulations by Gillon et al (2017) which typically showed instability on a timescale of 0.5 Myr. Finally Papaloizou et al (2018, see also Brasser et al 2019Huang & Ormel 2021) studied the migration and tidal evolution of the system, arguing that the planets may have migrated in two distinct groups, re-assembling later on, thanks to outward migration of the inner planets driven by tidal interactions with the central star.…”

Section: Introductionmentioning

confidence: 98%

“…Using formation models based either on pebble accretion or planetesimal accretion, several studies have shown that resonant chains such as the one seen in TRAPPIST-1 ⋆ E-mail: jean.teyssandier@unamur.be can naturally arise during the early stages of formation and migration in a disc (Ormel et al 2017;Schoonenberg et al 2019;Coleman et al 2019;Huang & Ormel 2021). As noted by Coleman et al (2019), the majority of pairs end up in first-order resonances (mainly the 2:1, 3:2 and 4:3 MMRs), with a few in second-order resonance (such as the 5:3 MMR which is relevant for this work), but no pair ends up in third-order resonance (which may be relevant for TRAPPIST-1 since the inner pair has a period ratio of ∼ 1.6, and therefore lies near the 8:5 MMR).…”

Section: Introductionmentioning

confidence: 99%

TRAPPIST-1: Dynamical analysis of the transit-timing variations and origin of the resonant chain

Teyssandier,

Libert,

Agol

2021

Preprint

0

View full text Add to dashboard Cite

We analyze the recently published best-fit solution of the TRAPPIST-1 system, which consists of seven Earth-size planets appearing to be in a resonant chain around a red dwarf. We show that all the planets are simultaneously in 2-planet and 3-planet resonances, apart from the innermost pair for which the 2-planet resonant angles circulate. By means of a frequency analysis, we highlight that the transit-timing variation (TTV) signals possess a series of common periods varying from days to decades, which are also present in the variations of the dynamical variables of the system. Shorter periods (e.g., the TTVs characteristic timescale of 1.3 yr) are associated with 2-planet mean-motion resonances, while longer periods arise from 3-planet resonances. By use of N-body simulations with migration forces, we explore the origin of the resonant chain of TRAPPIST-1 and find that for particular disc conditions, a chain of resonances -similar to the observed one -can be formed which accurately reproduces the observed TTVs. Our analysis suggests that while the 4-yr collected data of observations hold key information on the 2-planet resonant dynamics, further monitoring of TRAPPIST-1 will soon provide signatures of 3-body resonances, in particular the 3.3 and 5.1 yr periodicities expected for the current best-fit solution. Additional observations would also give more precise information on the peculiar resonant dynamics of the innermost pair of planets, and therefore additional constraints on formation scenarios.

show abstract

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

Ogihara

¹

,

Kokubo

²

,

Nakano

³

et al. 2022

A&A

View full text Add to dashboard Cite

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.

show abstract

The dynamics of the TRAPPIST-1 system in the context of its formation

Cited by 6 publications

References 81 publications

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

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

TRAPPIST-1: Dynamical analysis of the transit-timing variations and origin of the resonant chain

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

Contact Info

Product

Resources

About