{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2013:SU6YF4V4W5WDIUAJFTB46FF6SI","short_pith_number":"pith:SU6YF4V4","canonical_record":{"source":{"id":"1306.5714","kind":"arxiv","version":3},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.GA","submitted_at":"2013-06-24T19:23:08Z","cross_cats_sorted":[],"title_canon_sha256":"727aa54e4550b983caa8752079b3f1eedf8c4988236fad974d4ac3a319009621","abstract_canon_sha256":"505282b048ab6d90d622a9dafe1407d03ad668b93412da306fe518e740fff946"},"schema_version":"1.0"},"canonical_sha256":"953d82f2bcb76c3450092cc3cf14be9206725bea95182aa6a4b2cf7d4f92bc1f","source":{"kind":"arxiv","id":"1306.5714","version":3},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1306.5714","created_at":"2026-05-18T01:49:08Z"},{"alias_kind":"arxiv_version","alias_value":"1306.5714v3","created_at":"2026-05-18T01:49:08Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1306.5714","created_at":"2026-05-18T01:49:08Z"},{"alias_kind":"pith_short_12","alias_value":"SU6YF4V4W5WD","created_at":"2026-05-18T12:27:59Z"},{"alias_kind":"pith_short_16","alias_value":"SU6YF4V4W5WDIUAJ","created_at":"2026-05-18T12:27:59Z"},{"alias_kind":"pith_short_8","alias_value":"SU6YF4V4","created_at":"2026-05-18T12:27:59Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2013:SU6YF4V4W5WDIUAJFTB46FF6SI","target":"record","payload":{"canonical_record":{"source":{"id":"1306.5714","kind":"arxiv","version":3},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.GA","submitted_at":"2013-06-24T19:23:08Z","cross_cats_sorted":[],"title_canon_sha256":"727aa54e4550b983caa8752079b3f1eedf8c4988236fad974d4ac3a319009621","abstract_canon_sha256":"505282b048ab6d90d622a9dafe1407d03ad668b93412da306fe518e740fff946"},"schema_version":"1.0"},"canonical_sha256":"953d82f2bcb76c3450092cc3cf14be9206725bea95182aa6a4b2cf7d4f92bc1f","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-18T01:49:08.562929Z","signature_b64":"imTW0Q+sQw2PE3I8GGKiGrijMWd+M74RkryjPWygRsJwaYVeSolOSXAEjKWHUpvsDC5mhUYYZiOYQl4aJFLqCg==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"953d82f2bcb76c3450092cc3cf14be9206725bea95182aa6a4b2cf7d4f92bc1f","last_reissued_at":"2026-05-18T01:49:08.562281Z","signature_status":"signed_v1","first_computed_at":"2026-05-18T01:49:08.562281Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"1306.5714","source_version":3,"attestation_state":"computed"},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T01:49:08Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"iwBAfRoG1dsZH3UOPspxw760in/9Sw+SV46+9weMAfM44PttPaShoewv0F5rpy+01muCUdLrQvzE75mViCeKBg==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-06-11T03:21:31.943574Z"},"content_sha256":"9682681b3997c06ee9e2359bd62a4c517aed43f0f1415f5b35269e2f3e69f17a","schema_version":"1.0","event_id":"sha256:9682681b3997c06ee9e2359bd62a4c517aed43f0f1415f5b35269e2f3e69f17a"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2013:SU6YF4V4W5WDIUAJFTB46FF6SI","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"On column density thresholds and the star formation rate","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.GA","authors_text":"Paul C. Clark, Simon C.O. Glover","submitted_at":"2013-06-24T19:23:08Z","abstract_excerpt":"We present the results of a numerical study designed to address the question of whether there is a column density threshold for star formation within molecular clouds. We have simulated a large number of different clouds, with volume and column densities spanning a wide range of different values, using a state-of-the-art model for the coupled chemical, thermal and dynamical evolution of the gas. We show that star formation is only possible in regions where the mean (area-averaged) column density exceeds $10^{21} \\: {\\rm cm^{-2}}$. Within the clouds, we also show that there is a good correlatio"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1306.5714","kind":"arxiv","version":3},"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"},"verdict_id":null},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T01:49:08Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"Zaq0YSIOvm4DEkKby88pMDDDLwdDrbvlJYRXXCSyGitGBzgoUhVfpoMEMMVIlMBmvYZIdxLMhgH19yMD6v+iBw==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-06-11T03:21:31.943916Z"},"content_sha256":"5173a6672b2dae0a72e25b0588c698b2b648c318ef7433a729df49216e8e739c","schema_version":"1.0","event_id":"sha256:5173a6672b2dae0a72e25b0588c698b2b648c318ef7433a729df49216e8e739c"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/SU6YF4V4W5WDIUAJFTB46FF6SI/bundle.json","state_url":"https://pith.science/pith/SU6YF4V4W5WDIUAJFTB46FF6SI/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/SU6YF4V4W5WDIUAJFTB46FF6SI/bundle.json","status":"primary"}],"public_keys":[{"key_id":"pith-v1-2026-05","algorithm":"ed25519","format":"raw","public_key_b64":"stVStoiQhXFxp4s2pdzPNoqVNBMojDU/fJ2db5S3CbM=","public_key_hex":"b2d552b68890857171a78b36a5dccf368a953413288c353f7c9d9d6f94b709b3","fingerprint_sha256_b32_first128bits":"RVFV5Z2OI2J3ZUO7ERDEBCYNKS","fingerprint_sha256_hex":"8d4b5ee74e4693bcd1df2446408b0d54","rotates_at":null,"url":"https://pith.science/pith-signing-key.json","notes":"Pith uses this Ed25519 key to sign canonical record SHA-256 digests. Verify with: ed25519_verify(public_key, message=canonical_sha256_bytes, signature=base64decode(signature_b64))."}],"merge_version":"pith-open-graph-merge-v1","built_at":"2026-06-11T03:21:31Z","links":{"resolver":"https://pith.science/pith/SU6YF4V4W5WDIUAJFTB46FF6SI","bundle":"https://pith.science/pith/SU6YF4V4W5WDIUAJFTB46FF6SI/bundle.json","state":"https://pith.science/pith/SU6YF4V4W5WDIUAJFTB46FF6SI/state.json","well_known_bundle":"https://pith.science/.well-known/pith/SU6YF4V4W5WDIUAJFTB46FF6SI/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2013:SU6YF4V4W5WDIUAJFTB46FF6SI","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":"505282b048ab6d90d622a9dafe1407d03ad668b93412da306fe518e740fff946","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.GA","submitted_at":"2013-06-24T19:23:08Z","title_canon_sha256":"727aa54e4550b983caa8752079b3f1eedf8c4988236fad974d4ac3a319009621"},"schema_version":"1.0","source":{"id":"1306.5714","kind":"arxiv","version":3}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1306.5714","created_at":"2026-05-18T01:49:08Z"},{"alias_kind":"arxiv_version","alias_value":"1306.5714v3","created_at":"2026-05-18T01:49:08Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1306.5714","created_at":"2026-05-18T01:49:08Z"},{"alias_kind":"pith_short_12","alias_value":"SU6YF4V4W5WD","created_at":"2026-05-18T12:27:59Z"},{"alias_kind":"pith_short_16","alias_value":"SU6YF4V4W5WDIUAJ","created_at":"2026-05-18T12:27:59Z"},{"alias_kind":"pith_short_8","alias_value":"SU6YF4V4","created_at":"2026-05-18T12:27:59Z"}],"graph_snapshots":[{"event_id":"sha256:5173a6672b2dae0a72e25b0588c698b2b648c318ef7433a729df49216e8e739c","target":"graph","created_at":"2026-05-18T01:49:08Z","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 present the results of a numerical study designed to address the question of whether there is a column density threshold for star formation within molecular clouds. We have simulated a large number of different clouds, with volume and column densities spanning a wide range of different values, using a state-of-the-art model for the coupled chemical, thermal and dynamical evolution of the gas. We show that star formation is only possible in regions where the mean (area-averaged) column density exceeds $10^{21} \\: {\\rm cm^{-2}}$. Within the clouds, we also show that there is a good correlatio","authors_text":"Paul C. Clark, Simon C.O. Glover","cross_cats":[],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.GA","submitted_at":"2013-06-24T19:23:08Z","title":"On column density thresholds and the star formation rate"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1306.5714","kind":"arxiv","version":3},"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":"sha256:9682681b3997c06ee9e2359bd62a4c517aed43f0f1415f5b35269e2f3e69f17a","target":"record","created_at":"2026-05-18T01:49:08Z","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":"505282b048ab6d90d622a9dafe1407d03ad668b93412da306fe518e740fff946","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.GA","submitted_at":"2013-06-24T19:23:08Z","title_canon_sha256":"727aa54e4550b983caa8752079b3f1eedf8c4988236fad974d4ac3a319009621"},"schema_version":"1.0","source":{"id":"1306.5714","kind":"arxiv","version":3}},"canonical_sha256":"953d82f2bcb76c3450092cc3cf14be9206725bea95182aa6a4b2cf7d4f92bc1f","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"953d82f2bcb76c3450092cc3cf14be9206725bea95182aa6a4b2cf7d4f92bc1f","first_computed_at":"2026-05-18T01:49:08.562281Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-18T01:49:08.562281Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"imTW0Q+sQw2PE3I8GGKiGrijMWd+M74RkryjPWygRsJwaYVeSolOSXAEjKWHUpvsDC5mhUYYZiOYQl4aJFLqCg==","signature_status":"signed_v1","signed_at":"2026-05-18T01:49:08.562929Z","signed_message":"canonical_sha256_bytes"},"source_id":"1306.5714","source_kind":"arxiv","source_version":3}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:9682681b3997c06ee9e2359bd62a4c517aed43f0f1415f5b35269e2f3e69f17a","sha256:5173a6672b2dae0a72e25b0588c698b2b648c318ef7433a729df49216e8e739c"],"state_sha256":"80c4e28e3c909cf0cdac159036381812b8a1fa3e931809bfb1d33656412d1e45"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"UWQJdpvY0OZgbU2GaTpHij7tefW2o8AktgFDM0fe+5qRBVLS4Cicd3g2FbIOLtZna2ZTF+CJeScrLoSdAHc9Cg==","signed_message":"bundle_sha256_bytes","signed_at":"2026-06-11T03:21:31.946799Z","bundle_sha256":"45706b87244c33618cd4c30924b307360eaa3d8892a09f2d3ab8ceb47627392e"}}