{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2013:QLG7RPPYEIQUUIQ4GZ664AJ7DW","merge_version":"pith-open-graph-merge-v1","event_count":2,"valid_event_count":2,"invalid_event_count":0,"equivocation_count":0,"current":{"canonical_record":{"metadata":{"abstract_canon_sha256":"711ab5e79e814088b76f97ee4cb6a8e83849db65ceb1301ec25b53693cd582be","cross_cats_sorted":["astro-ph.SR"],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.HE","submitted_at":"2013-06-28T14:56:23Z","title_canon_sha256":"cf2fea9a5d913a7d0078f3388fc69147e1ef2fc50f29bc9d535282c9e31704bc"},"schema_version":"1.0","source":{"id":"1306.6861","kind":"arxiv","version":1}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1306.6861","created_at":"2026-05-18T03:19:42Z"},{"alias_kind":"arxiv_version","alias_value":"1306.6861v1","created_at":"2026-05-18T03:19:42Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1306.6861","created_at":"2026-05-18T03:19:42Z"},{"alias_kind":"pith_short_12","alias_value":"QLG7RPPYEIQU","created_at":"2026-05-18T12:27:57Z"},{"alias_kind":"pith_short_16","alias_value":"QLG7RPPYEIQUUIQ4","created_at":"2026-05-18T12:27:57Z"},{"alias_kind":"pith_short_8","alias_value":"QLG7RPPY","created_at":"2026-05-18T12:27:57Z"}],"graph_snapshots":[{"event_id":"sha256:e906ce7fd8cef37408f8bd1ea7c5c9fb408bc5a45f4b9db667f779c4baed4746","target":"graph","created_at":"2026-05-18T03:19:42Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"graph_snapshot":{"author_claims":{"count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","strong_count":0},"builder_version":"pith-number-builder-2026-05-17-v1","claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"paper":{"abstract_excerpt":"We report on the results we obtained with XMM-Newton observations of HD49798 and BD+37 442, the only two sdO stars for which X-ray emission has been observed so far. HD is a single-lined spectroscopic binary with orbital period of 1.5 days. We could establish that its companion is a massive white dwarf with M = 1.28 Msun, which makes it a candidate type Ia supernova progenitor; we also detected a significant X-ray emission during the white-dwarf eclipse, which could be X-ray emission of the sdO star itself. In the case of BD+37 442, a luminous He-rich sdO that up to now was believed to be a si","authors_text":"2), 2 - IUSS Pavia, 3 - INAF / OA Roma, A. Tiengo (1, G.L. Israel (3) (1 - INAF / IASF Milano, Italy, Italy), L. Stella (3), N. La Palombara (1), P. Esposito (1), S. Mereghetti (1)","cross_cats":["astro-ph.SR"],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.HE","submitted_at":"2013-06-28T14:56:23Z","title":"Observations of the unique X-ray emitting subdwarf stars HD49798 and BD+37 442"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1306.6861","kind":"arxiv","version":1},"verdict":{"created_at":null,"id":null,"model_set":{},"one_line_summary":"","pipeline_version":null,"pith_extraction_headline":"","strongest_claim":"","weakest_assumption":""}},"verdict_id":null}}],"author_attestations":[],"timestamp_anchors":[],"storage_attestations":[],"citation_signatures":[],"replication_records":[],"corrections":[],"mirror_hints":[],"record_created":{"event_id":"sha256:6ba0e2d2a39a8feb98ac3453de07e6e314779d03075749b3a2fa7265c0228b91","target":"record","created_at":"2026-05-18T03:19:42Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"attestation_state":"computed","canonical_record":{"metadata":{"abstract_canon_sha256":"711ab5e79e814088b76f97ee4cb6a8e83849db65ceb1301ec25b53693cd582be","cross_cats_sorted":["astro-ph.SR"],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.HE","submitted_at":"2013-06-28T14:56:23Z","title_canon_sha256":"cf2fea9a5d913a7d0078f3388fc69147e1ef2fc50f29bc9d535282c9e31704bc"},"schema_version":"1.0","source":{"id":"1306.6861","kind":"arxiv","version":1}},"canonical_sha256":"82cdf8bdf822214a221c367dee013f1da3b8ab5aff2e9ad965c5ccc263c205d2","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"82cdf8bdf822214a221c367dee013f1da3b8ab5aff2e9ad965c5ccc263c205d2","first_computed_at":"2026-05-18T03:19:42.707535Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-18T03:19:42.707535Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"5azCWne7PKyUZUQDQDiH8q6GNP7KhZkPKQ63ZxA4s2Drm/8sOooQe7n/yIRH+H1LGWKCp+63WXhh8mgefSuoCA==","signature_status":"signed_v1","signed_at":"2026-05-18T03:19:42.708268Z","signed_message":"canonical_sha256_bytes"},"source_id":"1306.6861","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:6ba0e2d2a39a8feb98ac3453de07e6e314779d03075749b3a2fa7265c0228b91","sha256:e906ce7fd8cef37408f8bd1ea7c5c9fb408bc5a45f4b9db667f779c4baed4746"],"state_sha256":"d3dfe810fceabb46b3923dd9a3b090d48e7a9f5d8396508a1c4b260bf4470dc3"}