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Title: Planets, debris and their host metallicity correlations
Authors: Fletcher, Mark
Nayakshin, Sergei
First Published: 8-Jun-2016
Publisher: Oxford University Press (OUP)
Citation: Monthly Notices of the Royal Astronomical Society, 2016, 461 (2), pp. 1850-1861
Abstract: Recent observations of debris discs (DDs), believed to be made up of remnant planetesimals, brought a number of surprises. DD presence does not correlate with the host star's metallicity, and may anticorrelate with the presence of gas giant planets. These observations contradict both assumptions and predictions of the highly successful Core Accretion model of planet formation. Here, we explore predictions of the alternative tidal downsizing (TD) scenario of planet formation. In TD, small planets and planetesimal debris is made only when gas fragments, predecessors of giant planets, are tidally disrupted. We show that these disruptions are rare in discs around high-metallicity stars but release more debris per disruption than their low [M/H] analogues. This predicts no simple relation between DD presence and host star's [M/H], as observed. A detected gas giant planet implies in TD that its predecessor fragment was not disputed, potentially explaining why DDs are less likely to be found around stars with gas giants. Less massive planets should correlate with DD presence, and sub-Saturn planets (Mp ∼ 50 M⊕) should correlate with DD presence stronger than sub-Neptunes (Mp ≲ 15 M⊕). These predicted planet–DD correlations will be diluted and weakened in observations by planetary systems’ long-term evolution and multifragment effects neglected here. Finally, although presently difficult to observe, DDs around M dwarf stars should be more prevalent than around Solar type stars.
DOI Link: 10.1093/mnras/stw1376
ISSN: 0035-8711
eISSN: 1365-2966
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. 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

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