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Author Mulders, G.D.; Drazkowska, J.; van der Marel, N.; Ciesla, F.J.; Pascucci, I.
Title Why Do M Dwarfs Have More Transiting Planets? Type
Year 2021 Publication Astrophysical Journal Letters Abbreviated Journal Astrophys. J. Lett.
Volume 920 Issue 1 Pages L1
Keywords TERRESTRIAL PLANETS; GRADUAL ACCUMULATION; GIANT PLANETS; EMBRYOS
Abstract We propose a planet formation scenario to explain the elevated occurrence rates of transiting planets around M dwarfs compared to Sun-like stars discovered by Kepler. We use a pebble drift and accretion model to simulate the growth of planet cores inside and outside of the snow line. A smaller pebble size interior to the snow line delays the growth of super-Earths, allowing giant planet cores in the outer disk to form first. When those giant planets reach pebble isolation mass they cut off the flow of pebbles to the inner disk and prevent the formation of close-in super-Earths. We apply this model to stars with masses between 0.1 and 2 M (circle dot) and for a range of initial disk masses. We find that the masses of hot super-Earths and of cold giant planets are anticorrelated. The fraction of our simulations that form hot super-Earths is higher around lower-mass stars and matches the exoplanet occurrence rates from Kepler. The fraction of simulations forming cold giant planets is consistent with the stellar mass dependence from radial-velocity surveys. A key testable prediction of the pebble accretion hypothesis is that the occurrence rates of super-Earths should decrease again for M dwarfs near the substellar boundary like Trappist-1.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2041-8205 ISBN Medium
Area Expedition Conference
Notes WOS:000703719200001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1478
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Author Mulders, G.D.; Pascucci, I.; Ciesla, F.J.; Fernandes, R.B.
Title The Mass Budgets and Spatial Scales of Exoplanet Systems and Protoplanetary Disks Type
Year 2021 Publication Astrophysical Journal Abbreviated Journal Astrophys. J.
Volume 920 Issue 2 Pages 66
Keywords MINIMUM-MASS; PLANET OCCURRENCE; DEBRIS DISCS; CLASS-II; NEBULA; STAR; MULTIPLICITY; PROJECT
Abstract Planets are born from disks of gas and dust, and observations of protoplanetary disks are used to constrain the initial conditions of planet formation. However, dust mass measurements of Class II disks with ALMA have called into question whether they contain enough solids to build the exoplanets that have been detected to date. In this paper, we calculate the mass and spatial scale of solid material around Sun-like stars probed by transit and radial velocity exoplanet surveys and compare those to the observed dust masses and sizes of Class II disks in the same stellar-mass regime. We show that the apparent mass discrepancy disappears when accounting for observational selection and detection biases. We find a discrepancy only when the planet formation efficiency is below 100%, or if there is a population of undetected exoplanets that significantly contributes to the mass in solids. We identify a positive correlation between the masses of planetary systems and their respective orbital periods, which is consistent with the trend between the masses and the outer radii of Class II dust disks. This implies that, despite a factor 100 difference in spatial scale, the properties of protoplanetary disks seem to be imprinted on the exoplanet population.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0004-637X ISBN Medium
Area 0004-637X Expedition Conference
Notes WOS:000707456200001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1475
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