The structure of protoplanetary discs around evolving young stars

By B. Bitsch, Anders Johansen, Michiel Lambrechts, A. Morbidelli. 2014

220 citations recorded by the source corpus.

The formation of planets with gaseous envelopes takes place in protoplanetary accretion discs on time scales of several million years. Small dust particles stick to each other to form pebbles, pebbles concentrate in the turbulent flow to form planetesimals and planetary embryos and grow to planets, which undergo substantial radial migration. All these processes are influenced by the underlying structure of the protoplanetary disc, specifically the profiles of temperature, gas scale height, and density. The commonly used disc structure of the minimum mass solar nebula (MMSN) is a simple power law in all these quantities. However, protoplanetary disc models with both viscous and stellar heating show several bumps and dips in temperature, scale height, and density caused by transitions in opacity, which are missing in the MMSN model. These play an important role in the formation of planets, since they can act as sweet spots for forming planetesimals via the streaming instability and affect the direction and magnitude of type-I migration. We present 2D simulations of accretion discs that feature radiative cooling and viscous and stellar heating, and they are linked to the observed evolutionary stages of protoplanetary discs and their host stars. These models allow us to identify preferred planetesimal and planet formation regions in the protoplanetary disc as a function of the disc's metallicity, accretion rate, and lifetime. We derive simple fitting formulae that feature all structural characteristics of protoplanetary discs during the evolution of several Myr. These fits are straightforward for applying to modelling any growth stage of planets where detailed knowledge of the underlying disc structure is required. (Less)

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/d4d9860cff3d1e7d21da8d52338475f14be211af

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Citations in the corpus

Close-in planetesimal formation by pile-up of drifting pebbles (2016, methodology): “By way of contrast, models including irradiation from the star predict higher temperatures (see, e.g. Bitsch et al. 2015), but these models assume that the accretion rate in the disc is uniform, which is correct close to the star, but questionable at larger distances.”
Concentrating small particles in protoplanetary disks through the streaming instability (2016, background): “…two magnitudes higher (we refer to e.g., Dutrey et al. 2014, and references therein), and a gas density of 10−8–10−10 g cm−3 for a < 5 au can also be seen in numerical simulations of star-irradiated accretion disk models at their earliest evolution stages (Bitsch et al. 2015; Baillié et al. 2016).”
Pebble-isolation mass: Scaling law and implications for the formation of super-Earths and gas giants (2018, methodology): “The dominant particle size in the planet formation simulations of Bitsch et al. (2015b) with α = 0.0054 presented below is of the order of 0.1 (Fig.”
Origin of water in the inner Solar System: Planetesimals scattered inward during Jupiter and Saturn's rapid gas accretion (2017, methodology): “Motivated by observations (Andrews et al., 2009, 2010) and viscous disk theory (Lynden-Bell and Pringle, 1974; Chambers, 2006; Bitsch et al., 2015) we chose a simple power-law profile for the disk.”
An ALMA Survey of Protoplanetary Disks in the σ Orionis Cluster (2017, background): “Indeed, exoplanet population synthesis models indicate that planetary properties and architectures are dictated by the initial dust and gas content of protoplanetary disks and their subsequent evolution (e.g., Thommes et al. 2008; Mordasini et al. 2012; Bitsch et al. 2015; Mordasini et al. 2016).”
ALMA SURVEY OF LUPUS PROTOPLANETARY DISKS. I. DUST AND GAS MASSES (2016, background): “…emission are needed to probe the evolution of bulk dust and gas content; these fundamental properties dictate the planet-forming capacity of disks (e.g., Alibert et al. 2005; Mordasini et al. 2009; Bitsch et al. 2015) and thus can help explain the diverse nature of the resulting exoplanet systems.”
Breaking the chains: hot super-Earth systems from migration and disruption of compact resonant chains (2017, methodology): “There are locations within the disc where the net torque is zero (Lyra et al 2010; Horn et al 2012; Bitsch et al. 2013, 2014, 2015; Cossou et al 2013; Pierens et al 2013).”
Formation of planetary systems by pebble accretion and migration (2018, methodology): “(1) We thus have a flat aspect ratio with orbital distance (zero flaring), which is approximately realised in the inner disc, where viscous heating dominates over irradiation (Bitsch et al. 2015b; Ida et al. 2016).”
The great dichotomy of the Solar System: Small terrestrial embryos and massive giant planet cores (2015, background): “Consequently, viscous heating drops and the transition between the inner region of the disk with roughly constant aspect ratio and the outer flared region dominated by stellar irradiation moves towards the star (Bitsch et al., 2015).”
IN SITU FORMATION AND DYNAMICAL EVOLUTION OF HOT JUPITER SYSTEMS (2015, background): “For type-I migration, state-of-the-art protoplanetary disk models (e.g. Bitsch et al. 2015 and the references therein) suggest that entropy gradients in the inner nebula can halt or even reverse the migration direction (see also Beńıtez-Llambay et al. 2015).”
Planetesimal formation starts at the snow line (2017, methodology): “To test the effect of stellar irradiation, we implement a simple analytical model proposed by Bitsch et al. (2015) (B15 in the following), which was designed to fit 2-”
Fossilized condensation lines in the Solar System protoplanetary disk (2015, background): “When the accretion rate drops to 5–10 × 10−9M /y the snowline on the midplane has moved to 1 AU (Hueso and Guillot, 2005; Davis, 2005; Garaud and Lin, 2007; Oka et al., 2011; Baillié et al., 2015; Bitsch et al., 2015).”