{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"2975352cb68471c1b81078be2fcbfc8c77fe49eab45de222d9de159e5016fc66","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["8917c362f1aa6b4c6795bc54e645bb88ce0e2ba3e8c0534c01b2f0c22e478035","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"6735bb9385be4503feb65891c9959bb106f13d879efb8174b59f0345c803da98","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"cosmo.cosmic-dawn.population-iii-stars","kind":"well-posed","literature_status":"open","n":"2","parents":[],"plain":"The very first stars formed from pure hydrogen and helium and are predicted to have been very massive and short-lived. No such star system has been confirmed, though JWST has found candidates.","posed_since":"","precise":"Identify a stellar system with gas metallicity below the critical value $Z_{\\mathrm{crit}}$ (theoretical range about $10^{-6}\\ \\text{to}\\ 1e-3.5\\ Z_{\\mathrm{sun}}$), strong $\\mathrm{He}\\ \\mathrm{II}\\ 1640\\ \\text{Angstrom}$ emission and no detected metal lines, consistent with a top-heavy initial mass function. The leading candidate is LAP1 at $z \\sim 6.6$, lensed by the cluster MACS J0416. An answer is a confirmed detection with metal-line upper limits below $Z_{\\mathrm{crit}}$, or a measured upper bound on the Population III star-formation rate density at $z > 6$.","problem_ref":"8917c362f1aa6b4c6795bc54e645bb88ce0e2ba3e8c0534c01b2f0c22e478035","references":"","settled_by":"Deep JWST spectroscopy of lensed candidates reaching metal-line limits below $Z_{\\mathrm{crit}}$ together with He II equivalent widths.","status_note":"Visbal, Hazlett and Bryan (2025, arXiv:2508.03842) argue that LAP1-B matches three theoretical Population III predictions; confirmation is pending.","title":"Have metal-free Population III stars been observed?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"2b990fbf406d0b5ab2ad8a25b391244ebe9f57ba55b4b26553390b49ecda7a6c","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"1c22dd8295d8a19f68a20dcbb8c456df7f16dde4701c88a603a7d794bd598c55","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"0iggJsrdVl4JqDkVAmc0KTmxFRYrLDOopmhPRLh5hRZwboxYRjmihWXGV6HjanVU9Omzt7kLVeux8lZHxBDtCg"},"schema":"pubphys.envelope/1"},"record_hash":"2b990fbf406d0b5ab2ad8a25b391244ebe9f57ba55b4b26553390b49ecda7a6c","leaf_index":3116}