{"paper":{"title":"The origin of Potassium in Galactic chemical evolution - The effect of C-O shell mergers in massive stars","arxiv_id":"2611.17224","primary_cat":"astro-ph.GA","submitted_at":"2026-11-12T18:19:37+00:00","version_compiled":"v1"},"notice":"Every quoted sentence is the authors' text from the arXiv listing abstract. Labels and probabilities are the outputs of classifier-1.13.0 on the question bank abstract-p1-20260923, exactly as returned. No sentence in this record was written by a language model.","schema":"pith.compiled-record/v0","status":"compiled","abstract":{"source":"arXiv listing abstract v1","sentences":[{"i":0,"p":0.52,"id":"s0","own":false,"role":"background","text":"The Galactic chemical evolution (GCE) of potassium (K) and of most other odd-Z elements remains poorly understood: models generally underproduce the observed [K/Fe] over a wide metallicity range, depending on the adopted massive star yields.","hedge":{"p":0.98,"label":"asserted"},"own_p":0.05,"main_claim_p":0.03,"quantitative":false,"quantitative_p":0.32,"role_probabilities":{"gap":0.48,"method":0.0,"result":0.0,"background":0.52,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.0}},{"i":1,"p":1.0,"id":"s1","own":false,"role":"background","text":"A proposed site for efficient K nucleosynthesis is the merger between the oxygen and carbon shells (C-O shell merger) that can occur in massive stars a few hours before core collapse.","hedge":{"p":0.84,"label":"hedged_possibility"},"own_p":0.06,"main_claim_p":0.04,"quantitative":false,"quantitative_p":0.17,"role_probabilities":{"gap":0.0,"method":0.0,"result":0.0,"background":1.0,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.0}},{"i":2,"p":0.99,"id":"s2","own":false,"role":"background","text":"Some GCE models with specific yield sets have been shown to reconcile predictions with observations.","hedge":{"p":0.99,"label":"asserted"},"own_p":0.06,"main_claim_p":0.03,"quantitative":false,"quantitative_p":0.08,"role_probabilities":{"gap":0.01,"method":0.0,"result":0.0,"background":0.99,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.0}},{"i":3,"p":0.99,"id":"s3","own":true,"role":"contribution","text":"Here we re-analyse these yield sets to quantify the contribution of C-O shell mergers to K production and what the Galactic evolution of K implies about the occurrence of these events.","hedge":{"p":0.81,"label":"asserted"},"own_p":0.81,"main_claim_p":0.05,"quantitative":false,"quantitative_p":0.05,"role_probabilities":{"gap":0.0,"method":0.01,"result":0.0,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.99,"interpretation":0.0}},{"i":4,"p":0.97,"id":"s4","own":true,"role":"method","text":"We analyse 194 pre-supernova models from three independent yield sets, covering a wide range of initial masses, metallicities and rotational velocities, and including both single and binary-stripped stars.","hedge":{"p":0.99,"label":"asserted"},"own_p":0.92,"main_claim_p":0.03,"quantitative":true,"quantitative_p":0.97,"role_probabilities":{"gap":0.0,"method":0.97,"result":0.0,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.03,"interpretation":0.0}},{"i":5,"p":0.9,"id":"s5","own":true,"role":"method","text":"We identify the progenitors undergoing a C-O shell merger and compute GCE models with and without their contribution.","hedge":{"p":0.96,"label":"asserted"},"own_p":0.96,"main_claim_p":0.04,"quantitative":false,"quantitative_p":0.07,"role_probabilities":{"gap":0.0,"method":0.9,"result":0.0,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.1,"interpretation":0.0}},{"i":6,"p":1.0,"id":"s6","own":true,"role":"result","text":"In all three sets, the enhanced K production can be traced back to a small number of C-O merger progenitors, which eject up to ~10-50 times more K than non-merger progenitors of similar mass.","hedge":{"p":1.0,"label":"asserted"},"own_p":0.94,"main_claim_p":0.29,"quantitative":true,"quantitative_p":0.99,"role_probabilities":{"gap":0.0,"method":0.0,"result":1.0,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.0}},{"i":7,"p":1.0,"id":"s7","own":true,"role":"result","text":"Without them, no model reproduces the observations and [K/Fe] is sub-solar over most of the metallicity range.","hedge":{"p":1.0,"label":"asserted"},"own_p":0.89,"main_claim_p":0.24,"quantitative":false,"quantitative_p":0.47,"role_probabilities":{"gap":0.0,"method":0.0,"result":1.0,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.0}},{"i":8,"p":0.99,"id":"s8","own":true,"role":"result","text":"With them, [K/Fe] is enhanced only within the metallicity window where mergers occur in each grid.","hedge":{"p":1.0,"label":"asserted"},"own_p":0.92,"main_claim_p":0.17,"quantitative":false,"quantitative_p":0.11,"role_probabilities":{"gap":0.0,"method":0.0,"result":0.99,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.01}},{"i":9,"p":0.98,"id":"s9","own":true,"role":"result","text":"Binarity itself plays a minor role, as single stars alone produce similar amounts of K.","hedge":{"p":1.0,"label":"asserted"},"own_p":0.89,"main_claim_p":0.06,"quantitative":true,"quantitative_p":0.84,"role_probabilities":{"gap":0.0,"method":0.0,"result":0.98,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.02}},{"i":10,"p":0.98,"id":"s10","own":true,"role":"interpretation","text":"Since the K synthesised in a C-O merger is essentially primary, the observed nearly linear increase of [K/H] with [Fe/H] can be reproduced only if C-O shell mergers occur with a similar frequency at all metallicities.","hedge":{"p":0.77,"label":"asserted"},"own_p":0.73,"main_claim_p":0.43,"quantitative":false,"quantitative_p":0.42,"role_probabilities":{"gap":0.0,"method":0.0,"result":0.02,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.98}},{"i":11,"p":0.85,"id":"s11","own":false,"role":"interpretation","text":"K could therefore be used to infer the occurrence rate of C-O shell mergers in massive stars as a 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