Fragmentation favoured in discs around higher mass stars

Cadman, James; Rice, Ken; Hall, Cassandra; Haworth, Thomas J.; Biller, Beth

doi:10.1093/mnras/staa187

Cited by 25 publications

(26 citation statements)

References 70 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In optically thin regions these cooling functions clearly diverge, which results in the differing behaviour (we ran comparison models to confirm this). A full discussion of the differences between these approaches will be forthcoming in Cadman et al (2020). So again, these 1D models are consistent with the general expectation that high disc-to-star mass ratios around low-mass stars can be stable against fragmentation.…”

Section: Constraints From Self-gravitating Pseudo-viscous Accretion D...supporting

confidence: 79%

See 1 more Smart Citation

Massive discs around low-mass stars

Haworth

Cadman

Meru

et al. 2020

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

We use a suite of SPH simulations to investigate the susceptibility of protoplanetary discs to the effects of self-gravity as a function of star-disc properties. We also include passive irradiation from the host star using different models for the stellar luminosities. The critical disc-to-star mass ratio for axisymmetry (for which we produce criteria) increases significantly for low-mass stars. This could have important consequences for increasing the potential mass reservoir in a proto Trappist-1 system, since even the efficient Ormel et al. (2017) formation model will be influenced by processes like external photoevaporation, which can rapidly and dramatically deplete the dust reservoir. The aforementioned scaling of the critical M d /M * for axisymmetry occurs in part because the Toomre Q parameter has a linear dependence on surface density (which promotes instability) and only an M 1/2 * dependence on shear (which reduces instability), but also occurs because, for a given M d /M * , the thermal evolution depends on the host star mass. The early phase stellar irradiation of the disc (for which the luminosity is much higher than at the zero age main sequence, particularly at low stellar masses) can also play a key role in significantly reducing the role of self-gravity, meaning that even Solar mass stars could support axisymmetric discs a factor two higher in mass than usually considered possible. We apply our criteria to the DSHARP discs with spirals, finding that self-gravity can explain the observed spirals so long as the discs are optically thick to the host star irradiation.

show abstract

Section: Constraints From Self-gravitating Pseudo-viscous Accretion D...supporting

confidence: 79%

Section: Constraints From Self-gravitating Pseudo-viscous Accretion mentioning

confidence: 99%

Massive discs around low-mass stars

Haworth

Cadman

Meru

et al. 2020

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

show abstract

“…Common assumption is that GI requires q 0.5, therefore rendering these discs too low mass to generate prominent self-gravitating structure. However it may be possible for discs to display self-gravitating spirals for much lower mass ratios than previously thought, with the critical mass ratio having a strong dependence on the host star mass and disc opacity (Veronesi et al 2019;Cadman et al 2020;Haworth et al 2020). We therefore should caution against discarding GI as a plausible mechanism based off this simple mass criterion alone.…”

Section: Conclusion On Dsharp Samplementioning

confidence: 87%

The observational impact of dust trapping in self-gravitating discs

Cadman

Hall

Rice

et al. 2020

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

We present a 3D semi-analytical model of self-gravitating discs, and include a prescription for dust trapping in the disc spiral arms. Using Monte Carlo radiative transfer, we produce synthetic ALMA (Atacama Large Millimeter/submillimeter Array) observations of these discs. In doing so, we demonstrate that our model is capable of producing observational predictions, and able to model real image data of potentially self-gravitating discs. For a disc to generate spiral structure that would be observable with ALMA requires that the disc’s dust mass budget is dominated by millimetre- and centimetre-sized grains. Discs in which grains have grown to the grain fragmentation threshold may satisfy this criterion; thus, we predict that signatures of gravitational instability may be detectable in discs of lower mass than has previously been suggested. For example, we find that discs with disc-to-star mass ratios as low as 0.10 are capable of driving observable spiral arms. Substructure becomes challenging to detect in discs where no grain growth has occurred or in which grain growth has proceeded well beyond the grain fragmentation threshold. We demonstrate how we can use our model to retrieve information about dust trapping and grain growth through multiwavelength observations of discs, and using estimates of the opacity spectral index. Applying our disc model to the Elias 27, WaOph 6, and IM Lup systems, we find gravitational instability to be a plausible explanation for the observed substructure in all three discs, if sufficient grain growth has indeed occurred.

show abstract

“…If spirals are predominately produced by giant planets, then the detection rate of such spirals can directly inform us about the occurrence rate and properties of giant planets (Hall et al 2017;Forgan et al 2018a;Dong et al 2018a). If, on the other hand, most spirals are caused by GI, their existence and morphology can be used to infer fundamental disc properties, such as disc mass (Dong et al 2015a;Haworth et al 2020;Cadman et al 2020), and therefore constrain planetary mass budgets and formation timescales (Nayakshin et al 2020) on a comprehensive scale.…”

Section: Introductionmentioning

confidence: 99%

Predicting the Kinematic Evidence of Gravitational Instability

Hall

Dong

Teague

et al. 2020

ApJ

View full text Add to dashboard Cite

Observations with the Atacama Large Millimeter/Submillimeter Array (ALMA) have dramatically improved our understanding of the site of exoplanet formation: protoplanetary disks. However, many basic properties of these disks are not well understood. The most fundamental of these is the total disk mass, which sets the mass budget for planet formation. Disks with sufficiently high masses can excite gravitational instability and drive spiral arms that are detectable with ALMA. Although spirals have been detected in ALMA observations of the dust, their association with gravitational instability, and high disk masses, is far from clear. Here we report a prediction for kinematic evidence of gravitational instability. Using hydrodynamics simulations coupled with radiative transfer calculations, we show that a disk undergoing such instability has clear kinematic signatures in molecular line observations across the entire disk azimuth and radius, which are independent of viewing angle. If these signatures are detected, it will provide the clearest evidence for the occurrence of gravitational instability in planet-forming disks, and provide a crucial way to measure disk masses.

show abstract

Fragmentation favoured in discs around higher mass stars

Cited by 25 publications

References 70 publications

Massive discs around low-mass stars

Massive discs around low-mass stars

The observational impact of dust trapping in self-gravitating discs

Predicting the Kinematic Evidence of Gravitational Instability

Contact Info

Product

Resources

About