Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published May 2023 | Published
Journal Article Open

Planet engulfment detections are rare according to observations and stellar modelling


Dynamical evolution within planetary systems can cause planets to be engulfed by their host stars. Following engulfment, the stellar photosphere abundance pattern will reflect accretion of rocky material from planets. Multistar systems are excellent environments to search for such abundance trends because stellar companions form from the same natal gas cloud and are thus expected to share primordial chemical compositions to within 0.03–0.05 dex. Abundance measurements have occasionally yielded rocky enhancements, but a few observations targeted known planetary systems. To address this gap, we carried out a Keck-HIRES survey of 36 multistar systems, where at least one star is a known planet host. We found that only HAT-P-4 exhibits an abundance pattern suggestive of engulfment but is more likely primordial based on its large projected separation (30 000 ± 140 au) that exceeds typical turbulence scales in molecular clouds. To understand the lack of engulfment detections among our systems, we quantified the strength and duration of refractory enrichments in stellar photospheres using mesa stellar models. We found that observable signatures from 10 M_⊕ engulfment events last for ∼90 Myr in 1 M_⊙ stars. Signatures are largest and longest lived for 1.1–1.2 M_⊙ stars, but are no longer observable ∼2 Gyr post-engulfment. This indicates that engulfment will rarely be detected in systems that are several Gyr old.

Additional Information

© 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). We thank Jim Fuller and Heather Knutson for insightful comments that improved the final manuscript. AB acknowledges funding from the National Science Foundation Graduate Research Fellowship under Grant No. DGE1745301. This work benefitted from involvement in ExoExplorers, which is sponsored by the Exoplanets Program Analysis Group (ExoPAG) and NASA's Exoplanet Exploration Program Office (ExEP). Software: NUMPY (Harris et al. 2020), MATPLOTLIB (Hunter 2007), PANDAS (Wes McKinney 2010), SCIPY (Virtanen et al. 2020), ASTROPY (Astropy Collaboration 2013, 2018), and DYNESTY (Speagle 2020). DATA AVAILABILITY. The data underlying this article will be shared on reasonable request to the corresponding author.

Attached Files

Published - stad745.pdf


Files (2.5 MB)
Name Size Download all
2.5 MB Preview Download

Additional details

August 22, 2023
August 22, 2023