| Issue |
A&A
Volume 693, January 2025
|
|
|---|---|---|
| Article Number | A64 | |
| Number of page(s) | 16 | |
| Section | Planets, planetary systems, and small bodies | |
| DOI | https://doi.org/10.1051/0004-6361/202451621 | |
| Published online | 03 January 2025 | |
Host star and exoplanet composition: Polluted white dwarf reveals depletion of moderately refractory elements in planetary material★
1
Instituto de Astrofísica, Pontificia Universidad Católica de Chile,
Av. Vicuña Mackenna 4860,
782-0436
Macul, Santiago,
Chile
2
Millennium Nucleus ERIS,
Chile
3
Institute of Astronomy, University of Cambridge,
Madingley Road,
Cambridge
CB3 0HA,
UK
4
Instituto de Estudios Astrofísicos, Universidad Diego Portales,
Av. Ejército Libertador 441,
Santiago,
Chile
5
Department of Physics and Astronomy, University of Victoria,
Victoria,
BC V8W 2Y2,
Canada
6
Department of Physics, University of Warwick,
Coventry
CV4 7AL,
UK
7
Gemini Observatory/NSF’s NOIRLab,
670 N. A’ohoku Place,
Hilo,
HI
96720,
USA
★★ Corresponding author; craguile@uc.cl
Received:
23
July
2024
Accepted:
1
November
2024
Context. Planets form from the same cloud of molecular gas and dust as their host stars. Confirming if planetary bodies acquire the same refractory element composition as their natal disk during formation and how efficiently volatile elements are incorporated into growing planets is key to linking the poorly constrained interior composition of rocky exoplanets to the observationally constrained composition of their host star. Such comparisons also afford insight into the planet formation process.
Aims. This work compares planetary composition with host star composition using observations of a white dwarf that has accreted planetary material and its F-type star wide binary companion as a reference for the composition of the natal molecular gas and dust.
Methods. Spectroscopic analysis reveals abundances of Fe, Mg, Si, Ca, and Ti in both stars. We used the white dwarf measurements to estimate the composition of the exoplanetary material and the F-type companion to constrain the composition of the material the planet formed from.
Results. Our results from comparing planetary material to the composition of its natal cloud reveal that the planetary material is depleted in moderate refractories (Mg, Si, and Fe) relative to the refractory material (Ca, Ti). Grouping elements based on their condensation temperatures is key to linking stellar and planetary compositions.
Conclusions. Fractionation during formation or subsequent planetary evolution leads to the depletion of moderate refractories from the planetary material accreted by the white dwarf. This signature, as seen for bulk Earth, will likely be present in the composition of many exoplanets relative to their host stars.
Key words: planets and satellites: composition / planets and satellites: formation / stars: abundances / binaries: general / white dwarfs
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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