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THE MINIMUM MASS SOLAR NEBULA: A 3 MILLION YEAR-OLD DISK

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THE MINIMUM MASS SOLAR NEBULA: A 3 MILLION YEAR-OLD DISK

Kevin Baillie

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THE MINIMUM MASS SOLAR NEBULA:

A 3 MILLION YEAR-OLD DISK.

K. Baillié -

kevin.baillie@obspm.fr

IMCCE, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ Paris 06, Univ. Lille, 77 Av. Denfert-Rochereau, 75014 Paris, France.

Abstract

Most planetary formation simulations rely on simple protoplanetary disk models evolved from the usual, though inaccurate, Minimum Mass Solar Nebula. Here, we suggest a new consistent way of building a protoplanetary disk from the collapse of the molecular cloud: both the central star and the disk are fed by the collapse and grow jointly. We then model the star physical characteristics based on pre-calculated stellar evolution models. After the collapse, when the cloud initial gas reservoir is empty, the further evolution of the disk and star is mainly driven by the disk viscous spreading, leading to radial structures in the disk: temperature plateaux at the sublimation lines of the dust species and shadowed regions that are not irradiated by the star. These irregularities in the disk surface mass density or midplane temperature may help trap planetary embryos at these locations, eventually selecting the composition of the planet cores. In addition, we redefine the disk timeline and describe the stages that lead to the MMSN model.

Figure 1 : Star and disk mass evolution.

Cloud & star model

We interpolate the stellar physical properties from tables of pre-calculated stellar evolutions (Piau et al., 2002, 2011,

Marques et al., 2013).

Disk model

1D + 1D numerical viscous spreading (Lynden-Bell, 1974) hydrodynamical code from Baillié et al., 2014, 2015, 2016 :

 heating : irradiation + viscous + cloud

+ radiative cooling + disk self-shadowing

 coupling dynamics ⇄ thermodynamics (νturb)  coupling temperature ⇄ geometry (αgr)

 coupling temperature ⇄ composition (opacity)

Disk structure and evolution

Planetary migration maps

Conclusions

 The disk forms in 170 kyr and reaches an MMSN-like stage in 2-3 Myr  Planet traps follow the sublimation lines → « trapped migration »

 Modeling the disk formation by the cloud collapse allows to understand the

multiple trapping possibilities in the first million years of planet formation

Perspectives

 Photoevaporation

 Planetary growth, multiple-planet interactions  Variable turbulent viscosity, deadzones

 Separate treatment of gas and dust flux

Figure 3 : Opacity variations with local temperature (from Semenov et al., 2003)

Figure 4 : Evolution of the surface-mass density and temperature radial profiles for disk fed by collapse of the molecular cloud.

Figure 6 : Time evolution of the snow region and silicates sublimation zone. Figure 5 : Mid-plane temperature radial profile after 1 Myr.

Shadowed regions in gray. The ratio of the viscous heating contribution over the total heating is presented in red, the grazing angle profile in yellow and the optical depth profile in blue.

Figure 8 : Migration maps showing the direction and intensity of the migration of planetary embryos wrt location and mass.

 Most of the inner disk is

self-shadowed (up to the

heat transition barrier)

 Sharp edge and positive temperature gradient at the heat transition barrier

Enlarged snow and

sublimation zones at the temperature plateaux

References

K. Baillié and S. Charnoz. Time Evolution of a Viscous Protoplanetary Disk with a Free Geometry: Toward a More Self-consistent Picture. ApJ, 786:35, May 2014. K. Baillié, S. Charnoz and E. Pantin. Time Evolution of Snow Regions and Planet Traps in an Evolving Protoplanetary Disk. A&A, 577 : A65, May 2015.

K. Baillié, S. Charnoz and E. Pantin. Trapping planets in an evolving protoplanetary disk: preferred time, locations, and planet mass. A&A, 590 : A60, May 2016. K. Baillié, J. Marques and L. Piau. Building protoplanetary disks from the molecular cloud: redefining the disk timeline. A&A, 624 : A93, Apr. 2019.

D. Lynden-Bell and J. E. Pringle. The evolution of viscous discs and the origin of the nebular variables. MNRAS, 168:603–637, Sep. 1974.

q

L. Piau, P. Kervella, S. Dib and P. Hauschildt. Surface convection and red-giant radius measurements. A&A, 526, A100, Feb. 2011 L. Piau, S. Turck-Chièze. Lithium Depletion in Pre-Main-Sequence Solar-like Stars. ApJ, 566, 419, Feb. 2002.

J. Marques, M.J. Goupil, Y. Lebreton et al. Seismic diagnostics for transport of angular momentum in stars. I. Rotational splittings from the pre-main sequence to the red-giant branch. A&A, 549 : A74, Jan. 2013. D. Semenov, T. Henning, C. Helling, M. Ilgner, and E. Sedlmayr. Rosseland and Planck mean opacities for protoplanetary discs. A&A, 410:611–621, Nov. 2003.

LP5 - L2.116

https://perso.imcce.fr/kevin-baillie/migrationmap_movie.html

Problematic

Where and when can planetary embryos be saved ?

With what size and composition ?

Figure 2 :

Stellar temperature, radius and luminosity evolution.

The disk gains mass from the molecular cloud.

The star gains mass from the molecular cloud and accretion by the disk viscous spreading.

Torques are very sensitive to Σ and T gradients.

Disk evolved from an initial MMSN.

Assuming that disks of similar ages have

similar mass accretion rates, we can

rescale the MMSN timeline to fit the timeline of the disk formation by collapse.

The evolution from the disk formation to an MMSN-like stage seems to require about 2-3 Myr. Though the MMSN evolves faster,

disks of similar mass accretion rates will present similar planet traps and deserts at the sublimation lines and heat transitions

10 kyr

100 kyr

1 Myr

Figure 7 :

Evolution of the mass flux profile.

 The disk grows for 170 kyr before emptying on the star by viscous spreading

 It gets hotter until the end of the collapse phase and then cools down  Sublimation lines migrate as the disk evolves

Sublimation lines and therefore traps migrate outward at first and inward after the end of the collapse phase

200 kyr

3 Myr

4 Myr

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