Isotopic Enrichment Of Planetary Systems From Asymptotic Giant Branch Star

By Keith Cowing
Status Report
July 27, 2023
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Isotopic Enrichment Of Planetary Systems From Asymptotic Giant Branch Star
Gaia DR3 colour–absolute–magnitude diagram of stars within 100 pc of NGC 2264 identifying RW (>30 km s−1 , shown in red) and WW (>5 km s−1 , shown in blue) stars. The WW at the top right of the giant branch (Gaia DR3 3131012157848982272) is a likely AGB star. — astro-ph.EP

Short-lived radioisotopes, in particular 26-Al and 60-Fe, are thought to contribute to the internal heating of the Earth, but are significantly more abundant in the Solar System compared to the Interstellar Medium.

The presence of their decay products in the oldest Solar System objects argues for their inclusion in the Sun’s protoplanetary disc almost immediately after the star formation event that formed the Sun. Various scenarios have been proposed for their delivery to the Solar System, usually involving one or more core-collapse supernovae of massive stars.

An alternative scenario involves the young Sun encountering an evolved Asymptotic Giant Branch (AGB) star. AGBs were previously discounted as a viable enrichment scenario for the Solar System due to the presumed low probability of an encounter between an old, evolved star and a young pre-main sequence star.

We report the discovery in Gaia data of an interloping AGB star in the star-forming region NGC2264, demonstrating that old, evolved stars can encounter young forming planetary systems. We use simulations to calculate the yields of 26-Al and 60-Fe from AGBs and their contribution to the long-term geophysical heating of a planet, and find that these are comfortably within the range previously calculated for the Solar System.

Richard J. Parker (1), Christina Schoettler (2) ((1) University of Sheffield, UK, (2) Imperial College London, UK)

Comments: 8 pages, 4 figures, accepted for publication in ApJL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2307.11147 [astro-ph.EP] (or arXiv:2307.11147v1 [astro-ph.EP] for this version)
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Submission history
From: Richard Parker
[v1] Thu, 20 Jul 2023 18:00:01 UTC (719 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻