{"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/hot-jupiter-and-ultra-cold-saturn-formation","title":"Hot Jupiter and ultra-cold Saturn formation in dense star clusters","arxiv_id":"2011.01236","date":"2020-11-02","proceeding":null,"authors":["Yi-Han Wang","Nathan W. C. Leigh","Rosalba Perna","Michael M. Shara"],"abstract":"The discovery of high incidence of hot Jupiters in dense clusters challenges the field-based hot Jupiter formation theory. In dense clusters, interactions between planetary systems and flyby stars are relatively common. This has a significant impact on planetary systems, dominating hot Jupiter formation. In this paper, we perform high precision, few-body simulations of stellar flybys and subsequent planet migration in clusters. A large parameter space exploration demonstrates that close flybys that change the architecture of the planetary system can activate high eccentricity migration mechanisms: Lidov-Kozai and planet-planet scattering, leading to high hot Jupiter formation rate in dense clusters. Our simulations predict that many of the hot Jupiters are accompanied by \"ultra-cold Saturns\", expelled to apastra of thousands of AU. This increase is particularly remarkable for planetary systems originally hosting two giant planets with semi-major axis ratios $\\sim$ 4 and the flyby star approaching nearly perpendicular to the planetary orbital plane. The estimated lower limit to the hot Jupiter formation rate of a virialized cluster is $\\sim 1.6\\times10^{-4}({\\sigma}/{\\rm 1kms^{-1}})^5({a_{\\rm p}}/{\\rm 20 AU})({M_{\\rm c}}/{\\rm 1000M_\\odot})^{-2}$Gyr$^{-1}$ per star, where $\\sigma$ is the cluster velocity dispersion, $a_{\\rm p}$ is the size of the planetary system and $M_{\\rm c}$ is the mass of the cluster. Our simulations yield a hot Jupiter abundance which is $\\sim$ 50 times smaller than that observed in the old open cluster M67. We expect that interactions involving binary stars, as well as a third or more giant planets, will close the discrepancy.","url_abs":"https://arxiv.org/abs/2011.01236v1","url_pdf":"https://arxiv.org/pdf/2011.01236v1.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":"hot-jupiter-and-ultra-cold-saturn-formation","repo_url":"https://github.com/aaronmaas/SpaceHub_simulation","is_official":0,"mentioned_in_paper":0,"mentioned_in_github":1,"framework":"none","reach":null}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"atlas_url":null,"mcp":null,"developers":"https://syntology.ai/developers"},"arxiv_metadata":null,"syntology_extracted_results":null}