{"record_type":"pith_number_record","schema_url":"https://pith.science/schemas/pith-number/v1.json","pith_number":"pith:2019:DY5GF5DUDPQOC267YK4PE5GGFU","short_pith_number":"pith:DY5GF5DU","schema_version":"1.0","canonical_sha256":"1e3a62f4741be0e16bdfc2b8f274c62d163d9d8b2e838d911406ce6aaed41148","source":{"kind":"arxiv","id":"1904.03689","version":1},"attestation_state":"computed","paper":{"title":"Variable Stars in M13. III. The Cepheid Variables and their Relation to Evolutionary Changes in Metal-poor BL Her Stars","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.SR","authors_text":"Barton J. Pritzl, Charles Kuehn, Grzegorz Kopacki, Horace A. Smith, Mary Anderson, Wayne Osborn","submitted_at":"2019-04-07T17:04:33Z","abstract_excerpt":"New CCD photometry has been combined with published and unpublished earlier observations to study the three Cepheid variables in M13: V1, V2 and V6. The light curve characteristics in $B$, $V$ and $I_{\\rm C}$ have been determined and the periods updated. A period change analysis shows all three stars have increasing periods but for V1 and V2 the rate of period increase does not appear to be constant over the 118 years of observation. The observed rates of period increase are in good agreement with the predictions of the Pisa theoretical models with helium abundance $Y = 0.25$. Theory suggests "},"verification_status":{"content_addressed":true,"pith_receipt":true,"author_attested":false,"weak_author_claims":0,"strong_author_claims":0,"externally_anchored":false,"storage_verified":false,"citation_signatures":0,"replication_records":0,"graph_snapshot":true,"references_resolved":false,"formal_links_present":false},"canonical_record":{"source":{"id":"1904.03689","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.SR","submitted_at":"2019-04-07T17:04:33Z","cross_cats_sorted":[],"title_canon_sha256":"03a01132d119dd32868fa2bed9dd0062e5d73fe4b7e2df5dcf2f1c934bfaa1bb","abstract_canon_sha256":"fb28ed4ec9f66b9e36de7cca9d5418d1b7c0577780f72a5b61825cfddcdc326e"},"schema_version":"1.0"},"receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-17T23:39:54.308840Z","signature_b64":"QXm5zO2qVCw97Fsn+psmP+yGCrMaKG/fky0jhz1OxSwIZJEV7I/748Xz1uOIUuobzqj50ImrS3tpa53C536tDQ==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"1e3a62f4741be0e16bdfc2b8f274c62d163d9d8b2e838d911406ce6aaed41148","last_reissued_at":"2026-05-17T23:39:54.308226Z","signature_status":"signed_v1","first_computed_at":"2026-05-17T23:39:54.308226Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"graph_snapshot":{"paper":{"title":"Variable Stars in M13. III. The Cepheid Variables and their Relation to Evolutionary Changes in Metal-poor BL Her Stars","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.SR","authors_text":"Barton J. Pritzl, Charles Kuehn, Grzegorz Kopacki, Horace A. Smith, Mary Anderson, Wayne Osborn","submitted_at":"2019-04-07T17:04:33Z","abstract_excerpt":"New CCD photometry has been combined with published and unpublished earlier observations to study the three Cepheid variables in M13: V1, V2 and V6. The light curve characteristics in $B$, $V$ and $I_{\\rm C}$ have been determined and the periods updated. A period change analysis shows all three stars have increasing periods but for V1 and V2 the rate of period increase does not appear to be constant over the 118 years of observation. The observed rates of period increase are in good agreement with the predictions of the Pisa theoretical models with helium abundance $Y = 0.25$. Theory suggests "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1904.03689","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"},"aliases":[{"alias_kind":"arxiv","alias_value":"1904.03689","created_at":"2026-05-17T23:39:54.308320+00:00"},{"alias_kind":"arxiv_version","alias_value":"1904.03689v1","created_at":"2026-05-17T23:39:54.308320+00:00"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1904.03689","created_at":"2026-05-17T23:39:54.308320+00:00"},{"alias_kind":"pith_short_12","alias_value":"DY5GF5DUDPQO","created_at":"2026-05-18T12:33:15.570797+00:00"},{"alias_kind":"pith_short_16","alias_value":"DY5GF5DUDPQOC267","created_at":"2026-05-18T12:33:15.570797+00:00"},{"alias_kind":"pith_short_8","alias_value":"DY5GF5DU","created_at":"2026-05-18T12:33:15.570797+00:00"}],"events":[],"event_summary":{},"paper_claims":[],"inbound_citations":{"count":0,"internal_anchor_count":0,"sample":[]},"formal_canon":{"evidence_count":0,"sample":[],"anchors":[]},"links":{"html":"https://pith.science/pith/DY5GF5DUDPQOC267YK4PE5GGFU","json":"https://pith.science/pith/DY5GF5DUDPQOC267YK4PE5GGFU.json","graph_json":"https://pith.science/api/pith-number/DY5GF5DUDPQOC267YK4PE5GGFU/graph.json","events_json":"https://pith.science/api/pith-number/DY5GF5DUDPQOC267YK4PE5GGFU/events.json","paper":"https://pith.science/paper/DY5GF5DU"},"agent_actions":{"view_html":"https://pith.science/pith/DY5GF5DUDPQOC267YK4PE5GGFU","download_json":"https://pith.science/pith/DY5GF5DUDPQOC267YK4PE5GGFU.json","view_paper":"https://pith.science/paper/DY5GF5DU","resolve_alias":"https://pith.science/api/pith-number/resolve?arxiv=1904.03689&json=true","fetch_graph":"https://pith.science/api/pith-number/DY5GF5DUDPQOC267YK4PE5GGFU/graph.json","fetch_events":"https://pith.science/api/pith-number/DY5GF5DUDPQOC267YK4PE5GGFU/events.json","actions":{"anchor_timestamp":"https://pith.science/pith/DY5GF5DUDPQOC267YK4PE5GGFU/action/timestamp_anchor","attest_storage":"https://pith.science/pith/DY5GF5DUDPQOC267YK4PE5GGFU/action/storage_attestation","attest_author":"https://pith.science/pith/DY5GF5DUDPQOC267YK4PE5GGFU/action/author_attestation","sign_citation":"https://pith.science/pith/DY5GF5DUDPQOC267YK4PE5GGFU/action/citation_signature","submit_replication":"https://pith.science/pith/DY5GF5DUDPQOC267YK4PE5GGFU/action/replication_record"}},"created_at":"2026-05-17T23:39:54.308320+00:00","updated_at":"2026-05-17T23:39:54.308320+00:00"}