Where can a Trappist-1 planetary system be produced?

Haworth, Thomas J.; Facchini, Stefano; Clarke, C. J.; Mohanty, Subhanjoy

doi:10.1093/mnras/sty168

Cited by 61 publications

(87 citation statements)

References 61 publications

(88 reference statements)

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“…Haworth et al (in prep. ) also find that the high mass ratio discs (q 0.3) required from photoevaporation models of the formation of the Trappist-1 system (Haworth et al 2016) to be entirely plausible, with our models finding discs to be gravitationally stable even when far more massive than this.…”

Section: Implications For Planet Formation Via Disc Fragmentationsupporting

confidence: 66%

Fragmentation favoured in discs around higher mass stars

Cadman

Rice

Hall

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We investigate how a protoplanetary disc's susceptibility to gravitational instabilities and fragmentation depends on the mass of its host star. We use 1D disc models in conjunction with 3D SPH simulations to determine the critical disc-to-star mass ratios at which discs become unstable against fragmentation, finding that discs become increasingly prone to the effects of self-gravity as we increase the host star mass. The actual limit for stability is sensitive to the disc temperature, so if the disc is optically thin stellar irradiation can dramatically stabilise discs against gravitational instability. However, even when this is the case we find that discs around 2 M stars are prone to fragmentation, which will act to produce wide-orbit giant planets and brown dwarfs. The consequences of this work are two-fold: that low mass stars could in principle support high disc-to-star mass ratios, and that higher mass stars have discs that are more prone to fragmentation, which is qualitatively consistent with observations that favour high-mass wide-orbit planets around higher mass stars. We also find that the initial masses of these planets depends on the temperature in the disc at large radii, which itself depends on the level of stellar irradiation.

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Section: Implications For Planet Formation Via Disc Fragmentationsupporting

confidence: 66%

Fragmentation favoured in discs around higher mass stars

Cadman

Rice

Hall

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…12). See Haworth et al (2018a) for a discussion of how photoevaporation would place very stringent requirements on planet formation efficiency in the Trappist 1 system where the mass in rocky planets is a significant fraction of the initial disc mass contained in solids.…”

Section: Discussion: Implications For Planet Formationmentioning

confidence: 99%

“…Tazzari et al 2017;Barenfeld et al 2017;Tripathi et al 2017) and iii) to consider how photoevaporation affects the planet formation potential of protoplanetary discs. In the latter regard, we will focus on the effect on the solid component, assessing whether the assembly of rocky planets is promoted by enhancement of the local dust to gas ratio in the outer disc (Throop & Bally 2005) or whether (as argued by Haworth et al 2018a) the loss of dust in the wind at early times instead suppresses rocky planet formation.…”

Section: Introductionmentioning

confidence: 99%

The evolution of dust in discs influenced by external photoevaporation

Sellek

Booth

Clarke

2019

Monthly Notices of the Royal Astronomical Society

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110

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Protoplanetary discs form and evolve in a wide variety of stellar environments and are accordingly exposed to a wide range of ambient far ultraviolet (FUV) field strengths. Strong FUV fields are known to drive vigorous gaseous flows from the outer disc. In this paper we conduct the first systematic exploration of the evolution of the solid component of discs subject to external photoevaporation. We find that the main effect of photoevaporation is to reduce the reservoir of dust at large radii and this leads to more efficient subsequent depletion of the disc dust due to radial drift. Efficient radial drift means that photoevaporation causes no significant increase of the dust to gas ratio in the disc. We show that the disc lifetime in both dust and gas is strongly dependent on the level of the FUV background and that the relationship between these two lifetimes just depends on the Shakura-Sunyaev α parameter, with the similar lifetimes observed for gas and dust in discs pointing to higher α values (∼ 10 −2 ). On the other hand the distribution of observed discs in the plane of disc size versus flux at 850 µm is better reproduced by lower α (∼ 10 −3 ). We find that photoevaporation does not assist rocky planet formation but need not inhibit mechanisms (such as pebble accretion at the water snow line) which can be effective sufficiently early in the disc's lifetime (i.e. well within a Myr).Key words: protoplanetary discs -planets and satellites: formation -submillimetre: planetary systems 1 The FUV background is conventionally denoted as a multiple of the Habing unit, G 0 , which is 1.6 × 10 −3 erg cm −2 over the energy range 6 − 13.6 eV (Habing 1968), such that the local interstellar field is 1.7 G 0

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“…Model A is a 10 M jup , 100AU disc and model B a 20 M jup , 200AU disc. The disc size can evolve quickly when external photoevaporation operates (Haworth et al 2017(Haworth et al , 2018aWinter et al 2018;Concha-Ramírez et al 2019;Winter et al 2020), and certainly would for these models which have mass loss rates ∼ 10 −6 M yr −1 , but the flow morphology and observable characteristics are similar regardless, so long as the disc is still large enough to drive an externally driven photoevaporative wind (Haworth & Clarke 2019). An illustrative example of the density, temperature and velocity for model A is given in Figure 1.…”

Section: Calculating Synthetic Alma Observationsmentioning

confidence: 99%

The observational anatomy of externally photoevaporating planet-forming discs – I. Atomic carbon

Haworth

Owen

2020

Monthly Notices of the Royal Astronomical Society

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We demonstrate the utility of CI as a tracer of photoevaporative winds that are being driven from discs by their ambient UV environment. Commonly observed CO lines only trace these winds in relatively weak UV environments and are otherwise dissociated in the wind at the intermediate to high UV fields that most young stars experience. However, CI traces unsubtle kinematic signatures of a wind in intermediate UV environments (∼ 1000 G 0 ) and can be used to place constraints on the kinematics and temperature of the wind. In CI position-velocity diagrams external photoevaporation results in velocities that are faster than those from Keplerian rotation alone, as well as emission from quadrants of position-velocity space in which there would be no Keplerian emission. This is independent of viewing angle because the wind has components that are perpendicular to the azimuthal rotation of the disc. At intermediate viewing angles (∼ 30 − 60 • ) moment 1 maps also exhibit a twisted morphology over large scales (unlike other processes that result in twists, which are typically towards the inner disc). CI is readily observable with ALMA, which means that it is now possible to identify and characterise the effect of external photoevaporation on planet-forming discs in intermediate UV environments.

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Where can a Trappist-1 planetary system be produced?

Cited by 61 publications

References 61 publications

Fragmentation favoured in discs around higher mass stars

Fragmentation favoured in discs around higher mass stars

The evolution of dust in discs influenced by external photoevaporation

The observational anatomy of externally photoevaporating planet-forming discs – I. Atomic carbon

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