Diversity of planetary origins and compositions traced by stellar abundance differences of co-natal star systems

@misc{bitsch2026diversity,
  title = {{Diversity of planetary origins and compositions traced by stellar abundance differences of co-natal star systems}},
  author = {Bertram Bitsch and Fan Liu and Haiyang S. Wang},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.32833},
  eprint = {2610.32833},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.32833},
}

TY  - UNPB
TI  - Diversity of planetary origins and compositions traced by stellar abundance differences of co-natal star systems
AU  - Bertram Bitsch
AU  - Fan Liu
AU  - Haiyang S. Wang
PY  - 2026
DA  - 2026/10/23
PB  - arXiv
DO  - 10.48550/arxiv.2610.32833
UR  - https://arxiv.org/abs/2610.32833
AB  - Co-natal stars, wide binaries that form from the same molecular cloud, should harbor the same stellar composition. Observations indicate stellar abundance differences in a small fraction of these co-natal systems. The stellar abundance differences have been attributed to the ingestion of planets by their host stars. We analyze a previous sample of co-natal stars to determine the composition of the planets that were ingested. The abundance differences in these co-natal pairs can show a positive abundance difference of the refractory elements (Fe, Mg, Si) paired with a positive, zero, or negative abundance difference of volatiles (O, C, S). Positive trends of refractory and volatile abundance differences can be explained (at minimum) with the ingestion of a single planet by one of the stars. Positive trends of refractory abundance differences paired with zero or negative abundance differences of oxygen and carbon imply that both stars are required to ingest planets formed at different locations (interior/exterior to the water and/or C-grain evaporation front). Some systems show a sulfur abundance difference that is a factor of a few lower than the abundance difference of Fe, Si, and Mg, even though sulfur is accreted via the moderately volatile compound FeS. This can be explained by the migration of one of the planets across the FeS evaporation front, where the planet first accretes large amounts of sulfur and then no sulfur, while still accreting the other refractory elements before being ingested by its host star. Our study shows that the planetary compositions derived from the detailed stellar abundances can explain the measured abundance differences of co-natal stars, giving a handle on the composition of exoplanets. At the same time it implies very different planetary compositions caused by the different formation location of these planets, in agreement with planet formation models.
ER  -