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Towards an initial mass function for giant planets

Carrera, Daniel LU ; Davies, Melvyn B. LU and Johansen, Anders LU (2018) In Monthly Notices of the Royal Astronomical Society 478(1). p.961-970
Abstract

The distribution of exoplanet masses is not primordial. After the initial stage of planet formation, gravitational interactions between planets can lead to the physical collision of two planets, or the ejection of one or more planets from the system. When this occurs, the remaining planets are typically left in more eccentric orbits. In this report we demonstrate how the present-day eccentricities of the observed exoplanet population can be used to reconstruct the initial mass function of exoplanets before the onset of dynamical instability. We developed a Bayesian framework that combines data from N-body simulations with present-day observations to compute a probability distribution for the mass of the planets that were ejected or... (More)

The distribution of exoplanet masses is not primordial. After the initial stage of planet formation, gravitational interactions between planets can lead to the physical collision of two planets, or the ejection of one or more planets from the system. When this occurs, the remaining planets are typically left in more eccentric orbits. In this report we demonstrate how the present-day eccentricities of the observed exoplanet population can be used to reconstruct the initial mass function of exoplanets before the onset of dynamical instability. We developed a Bayesian framework that combines data from N-body simulations with present-day observations to compute a probability distribution for the mass of the planets that were ejected or collided in the past. Integrating across the exoplanet population, one can estimate the initial mass function of exoplanets. We find that the ejected planets are primarily sub-Saturn-type planets. While the present-day distribution appears to be bimodal, with peaks around ~1MJ and ~20M?, this bimodality does not seem to be primordial. Instead, planets around ~60M⊕ appear to be preferentially removed by dynamical instabilities. Attempts to reproduce exoplanet populations using population synthesis codes should be mindful of the fact that the present population may have been depleted of sub-Saturn-mass planets. Future observations may reveal that young giant planets have a more continuous size distribution with lower eccentricities and more sub-Saturn-type planets. Lastly, there is a need for additional data and for more research on how the system architecture and multiplicity might alter our results.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Planets and satellites: dynamical evolution and stability, Planets and satellites: formation, Planets and satellites: gaseous planets
in
Monthly Notices of the Royal Astronomical Society
volume
478
issue
1
pages
10 pages
publisher
Oxford University Press
external identifiers
  • scopus:85052517403
ISSN
0035-8711
DOI
10.1093/MNRAS/STY1091
language
English
LU publication?
yes
id
2d737ef5-f8d1-4c25-a028-4d98adb12637
date added to LUP
2018-09-27 09:37:21
date last changed
2020-03-24 06:23:08
@article{2d737ef5-f8d1-4c25-a028-4d98adb12637,
  abstract     = {<p>The distribution of exoplanet masses is not primordial. After the initial stage of planet formation, gravitational interactions between planets can lead to the physical collision of two planets, or the ejection of one or more planets from the system. When this occurs, the remaining planets are typically left in more eccentric orbits. In this report we demonstrate how the present-day eccentricities of the observed exoplanet population can be used to reconstruct the initial mass function of exoplanets before the onset of dynamical instability. We developed a Bayesian framework that combines data from N-body simulations with present-day observations to compute a probability distribution for the mass of the planets that were ejected or collided in the past. Integrating across the exoplanet population, one can estimate the initial mass function of exoplanets. We find that the ejected planets are primarily sub-Saturn-type planets. While the present-day distribution appears to be bimodal, with peaks around ~1MJ and ~20M?, this bimodality does not seem to be primordial. Instead, planets around ~60M<sub>⊕</sub> appear to be preferentially removed by dynamical instabilities. Attempts to reproduce exoplanet populations using population synthesis codes should be mindful of the fact that the present population may have been depleted of sub-Saturn-mass planets. Future observations may reveal that young giant planets have a more continuous size distribution with lower eccentricities and more sub-Saturn-type planets. Lastly, there is a need for additional data and for more research on how the system architecture and multiplicity might alter our results.</p>},
  author       = {Carrera, Daniel and Davies, Melvyn B. and Johansen, Anders},
  issn         = {0035-8711},
  language     = {eng},
  month        = {07},
  number       = {1},
  pages        = {961--970},
  publisher    = {Oxford University Press},
  series       = {Monthly Notices of the Royal Astronomical Society},
  title        = {Towards an initial mass function for giant planets},
  url          = {http://dx.doi.org/10.1093/MNRAS/STY1091},
  doi          = {10.1093/MNRAS/STY1091},
  volume       = {478},
  year         = {2018},
}