{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"42840bb3eeeb4410ee9cb8f37cc29ef995f14509bc4e0906e42ac4e6994f340f","created":"2026-10-03T07:17:55Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"d820032dee6732dc295dc26cbd74f607d7fc053e9b1d9a6d6cb84658f3e504df","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"astro.neutron-star-interiors.cas-a-cooling","kind":"well-posed","literature_status":"contested","n":"1","parents":[],"plain":"The young neutron star in the Cassiopeia A remnant appeared to cool by a few percent in ten years, much faster than expected. This was explained as neutrons becoming superfluid, but the measurement depends on instrument calibration.","posed_since":"2010","precise":"Chandra spectra of the Cas A neutron star (age about $340\\ \\mathrm{yr}$) have been fit with a surface temperature decline of approximately 1 to 4 percent per decade, the value and significance depending on detector mode, calibration and interstellar absorption modeling. Determine $dT_{s}/dt$ with systematics, and decide whether it requires neutrino emission from Cooper-pair formation at the onset of neutron triplet superfluidity (critical temperature of order $5e8\\text{ to }1e9\\ \\mathrm{K}$) or permits slower standard cooling.","problem_ref":null,"references":"","settled_by":"A cross-calibrated multi-instrument temperature history over about 25 yr with the absorption column fit jointly.","status_note":"An analysis of all Chandra ACIS-S data found a continued decline constraining superfluid gaps (Shternin et al., MNRAS, 2022), while 2026 papers propose alternative cooling routes such as Urca processes (Potekhin and Yakovlev, JHEAp, 2026).","title":"Is the Cassiopeia A neutron star cooling unusually fast?","topic_ref":"afd1feb0d7ec84994296c83f9c2ecba96e22fc9ddf5d5fa7c0562e1f6f4eb1d4"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"5c11047ad3e9a1cdbc536242c7229e1dc63e61211ea21ab5138f3b8586d20c31","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"5640c2ac5361054a2f4f71875a542da9d0a6e87168beeb604c9589840f48f519","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"pjD5-dp-bYj8SPd5XyvQgqhQECPXUFIz1D5j_Ld3rfzMh1NFOBY5gNmRrDuGWbL31gdZq8eTLEkOpu2ZkzMlDw"},"schema":"pubphys.envelope/1"},"record_hash":"5c11047ad3e9a1cdbc536242c7229e1dc63e61211ea21ab5138f3b8586d20c31","leaf_index":570}