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Stellar abundance of binary stars : Their role in determining the formation location of super-earths and ice giants

Bitsch, B. LU ; Forsberg, R. LU ; Liu, F. LU orcid and Johansen, A. LU (2018) In Monthly Notices of the Royal Astronomical Society 479(3). p.3690-3707
Abstract

Binary stars form from the same parent molecular cloud and thus have the same chemical composition. Forming planets take building material (solids) away from the surrounding protoplanetary disc. Assuming that the disc's accretion on to the star is the main process that clears the disc, the atmosphere of the star will show abundance reductions caused by the material accreted by the forming planet(s). If planets are only forming around one star of a binary system, the planet formation process can result in abundance differences in wide binary stars, if their natal protoplanetary discs do not interact during planet formation. Abundance differences in the atmospheres of wide binaries hosting giant planets have already been observed and... (More)

Binary stars form from the same parent molecular cloud and thus have the same chemical composition. Forming planets take building material (solids) away from the surrounding protoplanetary disc. Assuming that the disc's accretion on to the star is the main process that clears the disc, the atmosphere of the star will show abundance reductions caused by the material accreted by the forming planet(s). If planets are only forming around one star of a binary system, the planet formation process can result in abundance differences in wide binary stars, if their natal protoplanetary discs do not interact during planet formation. Abundance differences in the atmospheres of wide binaries hosting giant planets have already been observed and linked to the formation location of giant planets. Here, we model how much building material is taken away for super-Earth planets that form inside/outside of the water ice line as well as ice giants forming inside/outside of the CO ice line. Our model predicts a significant abundance difference δ[X/H] in the stellar atmospheres of the planet-hosting binary component. Our model predicts that super-Earths that form inside the water ice line (r < rH2O) will result in an δ[Fe/H]/δ[O/H] abundance difference in the their host star that is a factor of 2 larger than for super-Earths formed outside the water ice line (r > rH2O) in the water-rich parts of the disc. Additionally, our model shows that the δ[Fe/H]/δ[C/H] abundance difference in the host star is at least a factor of 3 larger for ice giants formed at r < rCO compared to ice giants formed far out in the protoplanetary disc (r > rCO). Future observations of wide binary star systems hosting super-Earths and ice giants could therefore help to constrain the migration pathway of these planets and thus constrain planet formation theories.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Accretion, accretion discs, Planet-disc interactions, Planets and satellites: formation, Protoplanetary discs
in
Monthly Notices of the Royal Astronomical Society
volume
479
issue
3
pages
18 pages
publisher
Oxford University Press
external identifiers
  • scopus:85051568977
ISSN
0035-8711
DOI
10.1093/mnras/sty1710
language
English
LU publication?
yes
id
26bc8864-6b42-4b74-b624-cb79956bee24
date added to LUP
2018-09-07 08:19:04
date last changed
2025-04-04 14:07:49
@article{26bc8864-6b42-4b74-b624-cb79956bee24,
  abstract     = {{<p>Binary stars form from the same parent molecular cloud and thus have the same chemical composition. Forming planets take building material (solids) away from the surrounding protoplanetary disc. Assuming that the disc's accretion on to the star is the main process that clears the disc, the atmosphere of the star will show abundance reductions caused by the material accreted by the forming planet(s). If planets are only forming around one star of a binary system, the planet formation process can result in abundance differences in wide binary stars, if their natal protoplanetary discs do not interact during planet formation. Abundance differences in the atmospheres of wide binaries hosting giant planets have already been observed and linked to the formation location of giant planets. Here, we model how much building material is taken away for super-Earth planets that form inside/outside of the water ice line as well as ice giants forming inside/outside of the CO ice line. Our model predicts a significant abundance difference δ[X/H] in the stellar atmospheres of the planet-hosting binary component. Our model predicts that super-Earths that form inside the water ice line (r &lt; rH<sub>2</sub>O) will result in an δ[Fe/H]/δ[O/H] abundance difference in the their host star that is a factor of 2 larger than for super-Earths formed outside the water ice line (r &gt; rH<sub>2</sub>O) in the water-rich parts of the disc. Additionally, our model shows that the δ[Fe/H]/δ[C/H] abundance difference in the host star is at least a factor of 3 larger for ice giants formed at r &lt; r<sub>CO</sub> compared to ice giants formed far out in the protoplanetary disc (r &gt; r<sub>CO</sub>). Future observations of wide binary star systems hosting super-Earths and ice giants could therefore help to constrain the migration pathway of these planets and thus constrain planet formation theories.</p>}},
  author       = {{Bitsch, B. and Forsberg, R. and Liu, F. and Johansen, A.}},
  issn         = {{0035-8711}},
  keywords     = {{Accretion, accretion discs; Planet-disc interactions; Planets and satellites: formation; Protoplanetary discs}},
  language     = {{eng}},
  month        = {{09}},
  number       = {{3}},
  pages        = {{3690--3707}},
  publisher    = {{Oxford University Press}},
  series       = {{Monthly Notices of the Royal Astronomical Society}},
  title        = {{Stellar abundance of binary stars : Their role in determining the formation location of super-earths and ice giants}},
  url          = {{http://dx.doi.org/10.1093/mnras/sty1710}},
  doi          = {{10.1093/mnras/sty1710}},
  volume       = {{479}},
  year         = {{2018}},
}