{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"8b86c89cdff1132b94ade03e7fea81fdb71b21b89c6c982fac4561f5acba2fcb","created":"2026-10-03T07:17:55Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"e6e4d3b1889b0480f627ffc01b614e21eaf61f7d8e1dd0edb007f95513cbf26b","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"astro.protoplanetary-disks.dispersal","kind":"phenomenon","literature_status":"open","n":"1","parents":[],"plain":"The fraction of young stars that still have disks drops sharply over a few million years, which sets the deadline for forming gas giants. Ultraviolet and X-ray light from the star, magnetized winds and radiation from nearby massive stars could each remove the gas.","posed_since":"","precise":"The fraction of stars with inner-disk infrared excess declines with an e-folding time of roughly 2-3 Myr. Determine the dominant dispersal agent: internal photoevaporation by stellar X-ray, EUV or FUV radiation, magnetized disk winds, or external photoevaporation by massive stars in the birth cluster, by matching measured wind mass-loss rates (forbidden-line profiles such as [Ne II] 12.8 micron and [O I] 6300 Angstrom), transition-disk statistics and disk lifetimes versus environment. The answer is the mass-loss rate per channel versus stellar mass and environment.","problem_ref":null,"references":"","settled_by":"A model that reproduces disk fractions versus age and environment, the transition-disk population and measured wind mass-loss rates for a large sample.","status_note":"","title":"What clears protoplanetary disks after a few million years?","topic_ref":"8ff53117308df146f6983fc1ee6578221825c827c392f4ce6c47231d3772e7ef"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"3658861b0fd4db29709e7104291203b2e6bd8a14981a8a6f94122c640fa71ca0","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"ced8b726fdb336173c1b7e03b71b697da493a82989cc9ff2da4e5d00af565ba9","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"qJzpK7hWetlxkaUbuhSgqdM3dNGCSRJsQRSggqBhea5GjBPaeuNgc5ucXmzdok6h4MgJymoL8iCOJsCwZnSwCg"},"schema":"pubphys.envelope/1"},"record_hash":"3658861b0fd4db29709e7104291203b2e6bd8a14981a8a6f94122c640fa71ca0","leaf_index":580}