{"about":{"site":"https://codewithpapers.app","non_affiliation":"Code with Papers and Syntology are not affiliated with, endorsed by, or sponsored by Papers with Code, Meta, or the pwc-archive mirror.","licence":"CC BY-SA 4.0","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","attribution":"https://codewithpapers.app/attribution","modified":"archive material modified by Syntology; see the attribution page"},"url":"/paper/the-first-dynamical-mass-measurement-in-the","title":"The First Dynamical Mass Measurement in the HR 8799 System","arxiv_id":"2105.12820","date":"2021-05-26","proceeding":null,"authors":["G. Mirek Brandt","Timothy D. Brandt","Trent J. Dupuy","Daniel Michalik","Gabriel-Dominique Marleau"],"abstract":"HR 8799 hosts four directly imaged giant planets, but none has a mass measured from first principles. We present the first dynamical mass measurement in this planetary system, finding that the innermost planet HR~8799~e has a mass of $9.6^{+1.9}_{-1.8} \\, M_{\\rm Jup}$. This mass results from combining the well-characterized orbits of all four planets with a new astrometric acceleration detection (5$\\sigma$) from the Gaia EDR3 version of the Hipparcos-Gaia Catalog of Accelerations. We find with 95\\% confidence that HR~8799~e is below $13\\, M_{\\rm Jup}$, the deuterium-fusing mass limit. We derive a hot-start cooling age of $42^{+24}_{-16}$\\,Myr for HR~8799~e that agrees well with its hypothesized membership in the Columba association but is also consistent with an alternative suggested membership in the $\\beta$~Pictoris moving group. We exclude the presence of any additional $\\gtrsim$5-$M_{\\rm Jup}$ planets interior to HR~8799~e with semi-major axes between $\\approx$3-16\\,au. We provide proper motion anomalies and a matrix equation to solve for the mass of any of the planets of HR~8799 using only mass ratios between the planets.","url_abs":"https://arxiv.org/abs/2105.12820v1","url_pdf":"https://arxiv.org/pdf/2105.12820v1.pdf","source":{"archive":"pwc-archive (Hugging Face), CC BY-SA 4.0","snapshot":"2025-07-28","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","row_kind":"links_only","authors_date_abstract":"arXiv metadata, CC0 1.0 (https://info.arxiv.org/help/license), from the Kaggle arXiv metadata snapshot of 2026-09-12"},"code_links":[{"paper_slug":"the-first-dynamical-mass-measurement-in-the","repo_url":"https://github.com/gmbrandt/HTOF","is_official":1,"mentioned_in_paper":1,"mentioned_in_github":0,"framework":"none","reach":null}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"syntology_url":null,"atlas_url":null,"mcp":null,"developers":"https://syntology.ai/developers"},"arxiv_metadata":null,"syntology_extracted_results":null}