Please use this identifier to cite or link to this item:
Title: Core-assisted gas capture instability: a new mode of giant planet formation by gravitationally unstable discs
Authors: Nayakshin, Sergei
Helled, R.
Boley, A. C.
First Published: 18-Apr-2014
Publisher: Oxford University Press (OUP)
Citation: Monthly Notices of the Royal Astronomical Society, 2014, 440 (4), pp. 3797-3808 (12)
Abstract: Giant planet formation in the core accretion plus gas capture (CA) paradigm is predicated by the formation of a core, assembled by the coagulation of grains and later by planetesimals within a protoplanetary disc. As the core mass increases beyond a critical value, the hydrogen-dominated atmosphere around the core becomes self-gravitating and collapses on to the core, triggering rapid gas accretion which can lead to the formation of a gaseous planet. In contrast, in the disc instability paradigm, giant planet formation is believed to be independent of core formation: massive self-gravitating gas fragments cool radiatively and collapse as a whole independently of whether there is a core. In this paper, we show that giant planet formation in the disc instability model may be also enhanced by core formation for reasons physically very similar to the CA paradigm. In the model explored here, efficient grain sedimentation within an initial fragment (rather than the disc) leads to the formation of a core composed of heavy elements. We find that massive atmospheres form around cores and undergo collapse as a critical core mass is exceeded, analogous to CA theory. The critical mass of the core to initiate such a collapse depends on the fragment mass and metallicity, as well as core luminosity, but ranges from less than 1 to as much as ∼80 Earth masses. We therefore suggest that there are two channels for the collapse of a gaseous fragment to planetary scales within the disc instability model: (i) H[subscript: 2] dissociative collapse of the entire gaseous clump and (ii) core-assisted gas capture, as presented here. We suggest that the first of these two is favoured in metal-poor environments and for fragments y ≳ 5–10 Jupiter masses, whereas the second is favoured in metal-rich environments and fragments of lower mass.
DOI Link: 10.1093/mnras/stu473
ISSN: 0035-8711
eISSN: 1365-2966
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Deposited with reference to the publisher’s archiving policy available on the SHERPA/RoMEO website.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

Files in This Item:
File Description SizeFormat 
MNRAS-2014-Nayakshin-3797-808.pdfPublished (publisher PDF)691.7 kBAdobe PDFView/Open

Items in LRA are protected by copyright, with all rights reserved, unless otherwise indicated.