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Influence of the water content in protoplanetary discs on planet migration and formation

Bitsch, Bertram LU and Johansen, Anders LU (2016) In Astronomy & Astrophysics 590.
Abstract

The temperature and density profiles of protoplanetary discs depend crucially on the mass fraction of micrometre-sized dust grains and on their chemical composition. A larger abundance of micrometre-sized grains leads to an overall heating of the disc, so that the water ice line moves further away from the star. An increase in the water fraction inside the disc, maintaining a fixed dust abundance, increases the temperature in the icy regions of the disc and lowers the temperature in the inner regions. Discs with a larger silicate fraction have the opposite effect. Here we explore the consequence of the dust composition and abundance for the formation and migration of planets. We find that discs with low water content can only sustain... (More)

The temperature and density profiles of protoplanetary discs depend crucially on the mass fraction of micrometre-sized dust grains and on their chemical composition. A larger abundance of micrometre-sized grains leads to an overall heating of the disc, so that the water ice line moves further away from the star. An increase in the water fraction inside the disc, maintaining a fixed dust abundance, increases the temperature in the icy regions of the disc and lowers the temperature in the inner regions. Discs with a larger silicate fraction have the opposite effect. Here we explore the consequence of the dust composition and abundance for the formation and migration of planets. We find that discs with low water content can only sustain outwards migration for planets up to 4 Earth masses, while outwards migration in discs with a larger water content persists up to 8 Earth masses in the late stages of the disc evolution. Icy planetary cores that do not reach run-away gas accretion can thus migrate to orbits close to the host star if the water abundance is low. Our results imply that hot and warm super-Earths found in exoplanet surveys could have formed beyond the ice line and thus contain a significant fraction in water. These water-rich super-Earths should orbit primarily around stars with a low oxygen abundance, where a low oxygen abundance is caused by either a low water-to-silicate ratio or by overall low metallicity.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Accretion, accretion disks, Planet-disk interactions, Planets and satellites: formation, Protoplanetary disks
in
Astronomy & Astrophysics
volume
590
publisher
EDP Sciences
external identifiers
  • scopus:84971221638
  • wos:000378106800049
ISSN
0004-6361
DOI
10.1051/0004-6361/201527676
language
English
LU publication?
yes
id
006ec2d5-e05c-4a1d-b9b0-c2a5fb5b4434
date added to LUP
2016-06-16 09:54:14
date last changed
2017-01-01 08:28:02
@article{006ec2d5-e05c-4a1d-b9b0-c2a5fb5b4434,
  abstract     = {<p>The temperature and density profiles of protoplanetary discs depend crucially on the mass fraction of micrometre-sized dust grains and on their chemical composition. A larger abundance of micrometre-sized grains leads to an overall heating of the disc, so that the water ice line moves further away from the star. An increase in the water fraction inside the disc, maintaining a fixed dust abundance, increases the temperature in the icy regions of the disc and lowers the temperature in the inner regions. Discs with a larger silicate fraction have the opposite effect. Here we explore the consequence of the dust composition and abundance for the formation and migration of planets. We find that discs with low water content can only sustain outwards migration for planets up to 4 Earth masses, while outwards migration in discs with a larger water content persists up to 8 Earth masses in the late stages of the disc evolution. Icy planetary cores that do not reach run-away gas accretion can thus migrate to orbits close to the host star if the water abundance is low. Our results imply that hot and warm super-Earths found in exoplanet surveys could have formed beyond the ice line and thus contain a significant fraction in water. These water-rich super-Earths should orbit primarily around stars with a low oxygen abundance, where a low oxygen abundance is caused by either a low water-to-silicate ratio or by overall low metallicity.</p>},
  articleno    = {A101},
  author       = {Bitsch, Bertram and Johansen, Anders},
  issn         = {0004-6361},
  keyword      = {Accretion, accretion disks,Planet-disk interactions,Planets and satellites: formation,Protoplanetary disks},
  language     = {eng},
  month        = {06},
  publisher    = {EDP Sciences},
  series       = {Astronomy & Astrophysics},
  title        = {Influence of the water content in protoplanetary discs on planet migration and formation},
  url          = {http://dx.doi.org/10.1051/0004-6361/201527676},
  volume       = {590},
  year         = {2016},
}