How Large Is a Disk—What Do Protoplanetary Disk Gas Sizes Really Mean?
It remains unclear what mechanism is driving the evolution of protoplanetary disks. Direct detection of the main candidates, either turbulence driven by magnetorotational instabilities or magnetohydrodynamical disk winds, has proven difficult, leaving the time evolution of the disk size as one of th...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2023-01-01
|
| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/ace7d1 |
| _version_ | 1797697937344561152 |
|---|---|
| author | Leon Trapman Giovanni Rosotti Ke Zhang Benoît Tabone |
| author_facet | Leon Trapman Giovanni Rosotti Ke Zhang Benoît Tabone |
| author_sort | Leon Trapman |
| collection | DOAJ |
| description | It remains unclear what mechanism is driving the evolution of protoplanetary disks. Direct detection of the main candidates, either turbulence driven by magnetorotational instabilities or magnetohydrodynamical disk winds, has proven difficult, leaving the time evolution of the disk size as one of the most promising observables able to differentiate between these two mechanisms. But to do so successfully, we need to understand what the observed gas disk size actually traces. We studied the relation between R _CO,90% , the radius that encloses 90% of the ^12 CO flux, and R _c , the radius that encodes the physical disk size, in order to provide simple prescriptions for conversions between these two sizes. For an extensive grid of thermochemical models, we calculate R _CO,90% from synthetic observations and relate properties measured at this radius, such as the gas column density, to bulk disk properties, such as R _c and the disk mass M _disk . We found an empirical correlation between the gas column density at R _CO,90% and disk mass: ${N}_{\mathrm{gas}}{({R}_{\mathrm{CO},90 \% })\approx 3.73\,\times \,{10}^{21}({M}_{\mathrm{disk}}/{M}_{\odot })}^{0.34}\ {\mathrm{cm}}^{-2}$ . Using this correlation we derive an analytical prescription of R _CO,90% that only depends on R _c and M _disk . We derive R _c for disks in Lupus, Upper Sco, Taurus, and the DSHARP sample, finding that disks in the older Upper Sco region are significantly smaller (〈 R _c 〉 = 4.8 au) than disks in the younger Lupus and Taurus regions (〈 R _c 〉 = 19.8 and 20.9 au, respectively). This temporal decrease in R _c goes against predictions of both viscous and wind-driven evolution, but could be a sign of significant external photoevaporation truncating disks in Upper Sco. |
| first_indexed | 2024-03-12T03:47:06Z |
| format | Article |
| id | doaj.art-02c747787b0446bfa71bdce629b696c7 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T03:47:06Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-02c747787b0446bfa71bdce629b696c72023-09-03T12:38:50ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0195414110.3847/1538-4357/ace7d1How Large Is a Disk—What Do Protoplanetary Disk Gas Sizes Really Mean?Leon Trapman0https://orcid.org/0000-0002-8623-9703Giovanni Rosotti1https://orcid.org/0000-0003-4853-5736Ke Zhang2https://orcid.org/0000-0002-0661-7517Benoît Tabone3https://orcid.org/0000-0002-1103-3225Department of Astronomy, University of Wisconsin-Madison , 475 N Charter St, Madison, WI 53706, USA ; ltrapman@wisc.eduDipartimento di Fisica, Università degli Studi di Milano , Via Giovanni Celoria, 16, I-20133 Milano, Italy; School of Physics and Astronomy, University of Leicester , Leicester, LE1 7RH, UK; Leiden Observatory, Leiden University , 2300 RA Leiden, The NetherlandsDepartment of Astronomy, University of Wisconsin-Madison , 475 N Charter St, Madison, WI 53706, USA ; ltrapman@wisc.eduLeiden Observatory, Leiden University , 2300 RA Leiden, The Netherlands; Université Paris-Saclay , CNRS, Institut d’Astrophysique Spatiale, F-91405 Orsay, FranceIt remains unclear what mechanism is driving the evolution of protoplanetary disks. Direct detection of the main candidates, either turbulence driven by magnetorotational instabilities or magnetohydrodynamical disk winds, has proven difficult, leaving the time evolution of the disk size as one of the most promising observables able to differentiate between these two mechanisms. But to do so successfully, we need to understand what the observed gas disk size actually traces. We studied the relation between R _CO,90% , the radius that encloses 90% of the ^12 CO flux, and R _c , the radius that encodes the physical disk size, in order to provide simple prescriptions for conversions between these two sizes. For an extensive grid of thermochemical models, we calculate R _CO,90% from synthetic observations and relate properties measured at this radius, such as the gas column density, to bulk disk properties, such as R _c and the disk mass M _disk . We found an empirical correlation between the gas column density at R _CO,90% and disk mass: ${N}_{\mathrm{gas}}{({R}_{\mathrm{CO},90 \% })\approx 3.73\,\times \,{10}^{21}({M}_{\mathrm{disk}}/{M}_{\odot })}^{0.34}\ {\mathrm{cm}}^{-2}$ . Using this correlation we derive an analytical prescription of R _CO,90% that only depends on R _c and M _disk . We derive R _c for disks in Lupus, Upper Sco, Taurus, and the DSHARP sample, finding that disks in the older Upper Sco region are significantly smaller (〈 R _c 〉 = 4.8 au) than disks in the younger Lupus and Taurus regions (〈 R _c 〉 = 19.8 and 20.9 au, respectively). This temporal decrease in R _c goes against predictions of both viscous and wind-driven evolution, but could be a sign of significant external photoevaporation truncating disks in Upper Sco.https://doi.org/10.3847/1538-4357/ace7d1Protoplanetary disksAstrochemistry |
| spellingShingle | Leon Trapman Giovanni Rosotti Ke Zhang Benoît Tabone How Large Is a Disk—What Do Protoplanetary Disk Gas Sizes Really Mean? The Astrophysical Journal Protoplanetary disks Astrochemistry |
| title | How Large Is a Disk—What Do Protoplanetary Disk Gas Sizes Really Mean? |
| title_full | How Large Is a Disk—What Do Protoplanetary Disk Gas Sizes Really Mean? |
| title_fullStr | How Large Is a Disk—What Do Protoplanetary Disk Gas Sizes Really Mean? |
| title_full_unstemmed | How Large Is a Disk—What Do Protoplanetary Disk Gas Sizes Really Mean? |
| title_short | How Large Is a Disk—What Do Protoplanetary Disk Gas Sizes Really Mean? |
| title_sort | how large is a disk what do protoplanetary disk gas sizes really mean |
| topic | Protoplanetary disks Astrochemistry |
| url | https://doi.org/10.3847/1538-4357/ace7d1 |
| work_keys_str_mv | AT leontrapman howlargeisadiskwhatdoprotoplanetarydiskgassizesreallymean AT giovannirosotti howlargeisadiskwhatdoprotoplanetarydiskgassizesreallymean AT kezhang howlargeisadiskwhatdoprotoplanetarydiskgassizesreallymean AT benoittabone howlargeisadiskwhatdoprotoplanetarydiskgassizesreallymean |