{"id":{"repo_id":"milano","oai_identifier":"oai:air.unimi.it:2434/1202519"},"canonical_url":"https://search.dev.ndltd.org/etd/milano/oai:air.unimi.it:2434/1202519","repository":{"repo_id":"milano","name":"Università degli Studi di Milano","base_url":"https://air.unimi.it/oai/request"},"display":{"title":"ASSESSING THE ROLE OF EXTERNAL PHOTOEVAPORATION OF PROTOPLANETARY DISCS IN NEARBY STAR-FORMING REGIONS","abstract":"Characterising the physical processes driving protoplanetary disc evolution and the connection to the star-forming environment is essential to understanding planet formation and diversity. Most stars (and their discs) in the Galaxy form in massive clusters where the intense UV radiation emitted by OBA-type stars heats the outermost layers of protoplanetary discs, producing thermal winds that are launched from the disc surface. This causes outside-in disc depletion throughout external photoevaporation. In this thesis, I investigate how external photoevaporation shapes disc dynamics across a broad range of far-ultraviolet (FUV) radiation fields, focusing on nearby star-forming regions within 500 pc. Using numerical disc evolution models, I show that external photoevaporation can efficiently truncate discs and shorten their lifetime even under weak FUV fields (<1000 G0), where no direct observational evidence of ongoing photoevaporation (i.e., proplyds) is currently available. I demonstrate that external photoevaporation must be included alongside with viscous evolution to explain the gas sizes and masses of the Upper Scorpius discs investigated by the AGE-PRO ALMA Large Program. However, I discuss that obtaining model-independent evidence of external photoevaporation in moderately irradiated discs (1-100 G0), as in Upper Scorpius, remains challenging. I introduce a new method to evaluate the FUV flux at the position of stars that accounts for parallax uncertainty. Using the 2D geometry of a star-forming region, I derive the probability distribution of 3D separations from OBA-type stars. I apply this technique to provide an FUV flux map of the Orion region. Moreover, I investigate how the observed dust disc masses and stellar accretion luminosities depend on the FUV radiation field. This thesis emphasises the importance of accounting for external photoevaporation in typical planet-forming environments in the solar neighbourhood and provides new tools that will be fundamental for future observations.","abstract_html":"Characterising the physical processes driving protoplanetary disc evolution and the connection to the star-forming environment is essential to understanding planet formation and diversity. Most stars (and their discs) in the Galaxy form in massive clusters where the intense UV radiation emitted by OBA-type stars heats the outermost layers of protoplanetary discs, producing thermal winds that are launched from the disc surface. This causes outside-in disc depletion throughout external photoevaporation. In this thesis, I investigate how external photoevaporation shapes disc dynamics across a broad range of far-ultraviolet (FUV) radiation fields, focusing on nearby star-forming regions within 500 pc. Using numerical disc evolution models, I show that external photoevaporation can efficiently truncate discs and shorten their lifetime even under weak FUV fields (&lt;1000 G0), where no direct observational evidence of ongoing photoevaporation (i.e., proplyds) is currently available. I demonstrate that external photoevaporation must be included alongside with viscous evolution to explain the gas sizes and masses of the Upper Scorpius discs investigated by the AGE-PRO ALMA Large Program. However, I discuss that obtaining model-independent evidence of external photoevaporation in moderately irradiated discs (1-100 G0), as in Upper Scorpius, remains challenging. I introduce a new method to evaluate the FUV flux at the position of stars that accounts for parallax uncertainty. Using the 2D geometry of a star-forming region, I derive the probability distribution of 3D separations from OBA-type stars. I apply this technique to provide an FUV flux map of the Orion region. Moreover, I investigate how the observed dust disc masses and stellar accretion luminosities depend on the FUV radiation field. This thesis emphasises the importance of accounting for external photoevaporation in typical planet-forming environments in the solar neighbourhood and provides new tools that will be fundamental for future observations.","abstract_has_math":false,"creators":["ANANIA, ROSSELLA"],"institution":"Università degli Studi di Milano","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["supervisor: G. P. Rosotti ; co-supervisor: A. J. Winter ; coordinator: A. Mennella","WINTER","ANDREW","R. 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Most stars (and their discs) in the Galaxy form in massive clusters where the intense UV radiation emitted by OBA-type stars heats the outermost layers of protoplanetary discs, producing thermal winds that are launched from the disc surface. This causes outside-in disc depletion throughout external photoevaporation. In this thesis, I investigate how external photoevaporation shapes disc dynamics across a broad range of far-ultraviolet (FUV) radiation fields, focusing on nearby star-forming regions within 500 pc. Using numerical disc evolution models, I show that external photoevaporation can efficiently truncate discs and shorten their lifetime even under weak FUV fields (<1000 G0), where no direct observational evidence of ongoing photoevaporation (i.e., proplyds) is currently available. I demonstrate that external photoevaporation must be included alongside with viscous evolution to explain the gas sizes and masses of the Upper Scorpius discs investigated by the AGE-PRO ALMA Large Program. However, I discuss that obtaining model-independent evidence of external photoevaporation in moderately irradiated discs (1-100 G0), as in Upper Scorpius, remains challenging. I introduce a new method to evaluate the FUV flux at the position of stars that accounts for parallax uncertainty. Using the 2D geometry of a star-forming region, I derive the probability distribution of 3D separations from OBA-type stars. I apply this technique to provide an FUV flux map of the Orion region. Moreover, I investigate how the observed dust disc masses and stellar accretion luminosities depend on the FUV radiation field. This thesis emphasises the importance of accounting for external photoevaporation in typical planet-forming environments in the solar neighbourhood and provides new tools that will be fundamental for future observations."]},{"key":"dc:title","label":"Title","values":["ASSESSING THE ROLE OF EXTERNAL PHOTOEVAPORATION OF PROTOPLANETARY DISCS IN NEARBY STAR-FORMING REGIONS"]}]}],"canonical_facts":{"dc:contributor":["supervisor: G. P. Rosotti ; co-supervisor: A. J. Winter ; coordinator: A. Mennella","WINTER","ANDREW","R. Anania","ROSOTTI, GIOVANNI PIETRO","MENNELLA, ANIELLO"],"dc:creator":["ANANIA, ROSSELLA"],"dc:date":["2025-12-15"],"dc:description":["Characterising the physical processes driving protoplanetary disc evolution and the connection to the star-forming environment is essential to understanding planet formation and diversity. 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I demonstrate that external photoevaporation must be included alongside with viscous evolution to explain the gas sizes and masses of the Upper Scorpius discs investigated by the AGE-PRO ALMA Large Program. However, I discuss that obtaining model-independent evidence of external photoevaporation in moderately irradiated discs (1-100 G0), as in Upper Scorpius, remains challenging. I introduce a new method to evaluate the FUV flux at the position of stars that accounts for parallax uncertainty. Using the 2D geometry of a star-forming region, I derive the probability distribution of 3D separations from OBA-type stars. I apply this technique to provide an FUV flux map of the Orion region. Moreover, I investigate how the observed dust disc masses and stellar accretion luminosities depend on the FUV radiation field. This thesis emphasises the importance of accounting for external photoevaporation in typical planet-forming environments in the solar neighbourhood and provides new tools that will be fundamental for future observations."],"dc:identifier":["https://hdl.handle.net/2434/1202519","http://dx.doi.org/10.13130/anania-rossella_phd2025-12-15","10.13130/anania-rossella_phd2025-12-15"],"dc:language":["eng"],"dc:publisher":["Università degli Studi di Milano"],"dc:relation":["numberofpages:216","alleditors:WINTER, ANDREW"],"dc:rights":["info:eu-repo/semantics/openAccess","license:Creative commons","license uri:http://creativecommons.org/licenses/by-sa/4.0/"],"dc:subject":["protoplanetary discs","accretion discs","planet formation","external photoevaporation","Settore PHYS-05/A - Astrofisica, cosmologia e scienza dello spazio"],"dc:title":["ASSESSING THE ROLE OF EXTERNAL PHOTOEVAPORATION OF PROTOPLANETARY DISCS IN NEARBY STAR-FORMING REGIONS"],"dc:type":["info:eu-repo/semantics/doctoralThesis"]},"updated_at":"2026-07-27T20:19:08Z"}