Inside-Out Planet Formation. VII. Astrochemical Models of Protoplanetary Disks and Implications for Planetary Compositions
| Autor: | Soto, Arturo Cevallos, Tan, Jonathan C., Hu, Xiao, Hsu, Chia-Jung, Walsh, Catherine |
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| Rok vydání: | 2022 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1093/mnras/stac2650 |
| Popis: | Inside-Out Planet Formation (IOPF) proposes that the abundant systems of close-in Super-Earths and Mini-Neptunes form in situ at the pressure maximum associated with the Dead Zone Inner Boundary (DZIB). We present a model of physical and chemical evolution of protoplanetary disk midplanes that follows gas advection, radial drift of pebbles and gas-grain chemistry to predict abundances from 300~au down to the DZIB near 0.2 au. We consider typical disk properties relevant for IOPF, i.e., accretion rates 1E-9 < dM/dt / (Msun/yr) < 1E-8 and viscosity parameter alpha = 1E-4, and evolve for fiducial duration of t = 1E5 years. For outer, cool disk regions, we find that C and up to 90% of O nuclei start locked in CO and O2 ice, which keeps abundances of CO2 and H2O one order of magnitude lower. Radial drift of icy pebbles is influential, with gas-phase abundances of volatiles enhanced up to two orders of magnitude at ice-lines, while the outer disk becomes depleted of dust. Disks with decreasing accretion rates gradually cool, which draws in icelines closer to the star. At <~1 au, advective models yield water-rich gas with C/O ratios <~ 0.1, which may be inherited by atmospheres of planets forming here via IOPF. For planetary interiors built by pebble accretion, IOPF predicts volatile-poor compositions. However, advectively-enhanced volatile mass fractions of ~10% can occur at the water ice line. Comment: Submitted to MNRAS; comments welcome; for summary of Inside-Out Planet Formation papers see http://www.cosmicorigins.space/iopf |
| Databáze: | arXiv |
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