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Inside-out planet formation. IV. Pebble evolution and planet formation timescales

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Title: Inside-out planet formation. IV. Pebble evolution and planet formation timescales
Authors: Hu, X
Tan, JC
Zhu, Z
Chatterjee, S
Birnstiel, T
Youdin, AN
Mohanty, S
Item Type: Journal Article
Abstract: Systems with tightly packed inner planets (STIPs) are very common. Chatterjee & Tan proposed Inside-out Planet Formation (IOPF), an in situ formation theory, to explain these planets. IOPF involves sequential planet formation from pebble-rich rings that are fed from the outer disk and trapped at the pressure maximum associated with the dead zone inner boundary (DZIB). Planet masses are set by their ability to open a gap and cause the DZIB to retreat outwards. We present models for the disk density and temperature structures that are relevant to the conditions of IOPF. For a wide range of DZIB conditions, we evaluate the gap-opening masses of planets in these disks that are expected to lead to the truncation of pebble accretion onto the forming planet. We then consider the evolution of dust and pebbles in the disk, estimating that pebbles typically grow to sizes of a few centimeters during their radial drift from several tens of astronomical units to the inner, lesssim1 au scale disk. A large fraction of the accretion flux of solids is expected to be in such pebbles. This allows us to estimate the timescales for individual planet formation and the entire planetary system formation in the IOPF scenario. We find that to produce realistic STIPs within reasonable timescales similar to disk lifetimes requires disk accretion rates of ~10−9 M ⊙ yr−1 and relatively low viscosity conditions in the DZIB region, i.e., a Shakura–Sunyaev parameter of α ~ 10−4.
Issue Date: 10-Apr-2018
Date of Acceptance: 1-Feb-2018
URI: http://hdl.handle.net/10044/1/60600
DOI: https://dx.doi.org/10.3847/1538-4357/aaad08
ISSN: 0004-637X
Publisher: American Astronomical Society
Journal / Book Title: Astrophysical Journal
Volume: 857
Issue: 1
Copyright Statement: © 2018. The American Astronomical Society. All rights reserved.
Sponsor/Funder: Science and Technology Facilities Council
Science and Technology Facilities Council (STFC)
Funder's Grant Number: ST-N000838
Keywords: Science & Technology
Physical Sciences
Astronomy & Astrophysics
accretion, accretion disks
planet-disk interactions
planetary systems
planets and satellites: formation
protoplanetary disks
0201 Astronomical And Space Sciences
0305 Organic Chemistry
0306 Physical Chemistry (Incl. Structural)
Publication Status: Published
Article Number: 20
Online Publication Date: 2018-04-09
Appears in Collections:Physics
Faculty of Natural Sciences