Turbulent Vortex with Moderate Dust Settling Probed by Scattering-induced Polarization in the IRS 48 System
We investigate the crescent-shaped dust trap in the transition disk Oph IRS 48 using well-resolved (sub)millimeter polarimetric observations at ALMA Band 7 (870 μ m). The dust polarization map reveals patterns consistent with dust-scattering-induced polarization. There is a relative displacement bet...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2024-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ad2346 |
| _version_ | 1797271147940675584 |
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| author | Haifeng Yang Manuel Fernández-López Zhi-Yun Li Ian W. Stephens Leslie W. Looney Zhe-Yu Daniel Lin Rachel Harrison |
| author_facet | Haifeng Yang Manuel Fernández-López Zhi-Yun Li Ian W. Stephens Leslie W. Looney Zhe-Yu Daniel Lin Rachel Harrison |
| author_sort | Haifeng Yang |
| collection | DOAJ |
| description | We investigate the crescent-shaped dust trap in the transition disk Oph IRS 48 using well-resolved (sub)millimeter polarimetric observations at ALMA Band 7 (870 μ m). The dust polarization map reveals patterns consistent with dust-scattering-induced polarization. There is a relative displacement between the polarized flux and the total flux, which holds the key to understanding the dust scale heights in this system. We model the polarization observations, focusing on the effects of dust scale heights. We find that the interplay between the inclination-induced polarization and the polarization arising from radiation anisotropy in the crescent determines the observed polarization; the anisotropy is controlled by the dust optical depth along the midplane, which is, in turn, determined by the dust scale height in the vertical direction. We find that the dust grains can be neither completely settled nor well mixed with the gas. The completely settled case produces little radial displacement between the total and polarized flux, while the well-mixed case produces an azimuthal pattern in the outer (radial) edge of the crescent that is not observed. Our best model has a gas-to-dust scale height ratio of 2 and can reproduce both the radial displacement and the azimuthal displacement between the total and polarized flux. We infer an effective turbulence α parameter of approximately 0.0001–0.005. The scattering-induced polarization provides insight into a turbulent vortex with a moderate level of dust settling in the IRS 48 system, which is hard to achieve otherwise. |
| first_indexed | 2024-04-25T02:15:33Z |
| format | Article |
| id | doaj.art-f3de445fb82e430a9ce57d039605376b |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-04-25T02:15:33Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-f3de445fb82e430a9ce57d039605376b2024-03-07T10:03:02ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01963213410.3847/1538-4357/ad2346Turbulent Vortex with Moderate Dust Settling Probed by Scattering-induced Polarization in the IRS 48 SystemHaifeng Yang0https://orcid.org/0000-0002-8537-6669Manuel Fernández-López1https://orcid.org/0000-0001-5811-0454Zhi-Yun Li2https://orcid.org/0000-0002-7402-6487Ian W. Stephens3https://orcid.org/0000-0003-3017-4418Leslie W. Looney4https://orcid.org/0000-0002-4540-6587Zhe-Yu Daniel Lin5https://orcid.org/0000-0001-7233-4171Rachel Harrison6Kavli Institute for Astronomy and Astrophysics, Peking University , Yi He Yuan Lu 5, Haidian Qu, Beijing 100871, People’s Republic of China ; hfyang@pku.edu.cn; Institute for Astronomy, School of Physics, Zhejiang University , 866 Yu Hang Tang Road, Hangzhou, Zhejiang 310027, People's Republic of ChinaInstituto Argentino de Radioastronomía (CCT-La Plata, CONICET; CICPBA; UNLP), C. C. No. 5, 1894, Villa Elisa, Buenos Aires, ArgentinaDepartment of Astronomy, University of Virginia , Charlottesville, VA 22903, USADepartment of Earth, Environment, and Physics, Worcester State University , Worcester, MA 01602, USADepartment of Astronomy, University of Illinois , 1002 West Green Street, Urbana, IL 61801, USA; National Radio Astronomy Observatory , 520 Edgemont Road, Charlottesville, VA 22903, USADepartment of Astronomy, University of Virginia , Charlottesville, VA 22903, USADepartment of Astronomy, University of Illinois , 1002 West Green Street, Urbana, IL 61801, USA; School of Physics and Astronomy, Monash University , Clayton VIC 3800, AustraliaWe investigate the crescent-shaped dust trap in the transition disk Oph IRS 48 using well-resolved (sub)millimeter polarimetric observations at ALMA Band 7 (870 μ m). The dust polarization map reveals patterns consistent with dust-scattering-induced polarization. There is a relative displacement between the polarized flux and the total flux, which holds the key to understanding the dust scale heights in this system. We model the polarization observations, focusing on the effects of dust scale heights. We find that the interplay between the inclination-induced polarization and the polarization arising from radiation anisotropy in the crescent determines the observed polarization; the anisotropy is controlled by the dust optical depth along the midplane, which is, in turn, determined by the dust scale height in the vertical direction. We find that the dust grains can be neither completely settled nor well mixed with the gas. The completely settled case produces little radial displacement between the total and polarized flux, while the well-mixed case produces an azimuthal pattern in the outer (radial) edge of the crescent that is not observed. Our best model has a gas-to-dust scale height ratio of 2 and can reproduce both the radial displacement and the azimuthal displacement between the total and polarized flux. We infer an effective turbulence α parameter of approximately 0.0001–0.005. The scattering-induced polarization provides insight into a turbulent vortex with a moderate level of dust settling in the IRS 48 system, which is hard to achieve otherwise.https://doi.org/10.3847/1538-4357/ad2346Dust continuum emissionInterferometryPolarimetryProtoplanetary disksSubmillimeter astronomy |
| spellingShingle | Haifeng Yang Manuel Fernández-López Zhi-Yun Li Ian W. Stephens Leslie W. Looney Zhe-Yu Daniel Lin Rachel Harrison Turbulent Vortex with Moderate Dust Settling Probed by Scattering-induced Polarization in the IRS 48 System The Astrophysical Journal Dust continuum emission Interferometry Polarimetry Protoplanetary disks Submillimeter astronomy |
| title | Turbulent Vortex with Moderate Dust Settling Probed by Scattering-induced Polarization in the IRS 48 System |
| title_full | Turbulent Vortex with Moderate Dust Settling Probed by Scattering-induced Polarization in the IRS 48 System |
| title_fullStr | Turbulent Vortex with Moderate Dust Settling Probed by Scattering-induced Polarization in the IRS 48 System |
| title_full_unstemmed | Turbulent Vortex with Moderate Dust Settling Probed by Scattering-induced Polarization in the IRS 48 System |
| title_short | Turbulent Vortex with Moderate Dust Settling Probed by Scattering-induced Polarization in the IRS 48 System |
| title_sort | turbulent vortex with moderate dust settling probed by scattering induced polarization in the irs 48 system |
| topic | Dust continuum emission Interferometry Polarimetry Protoplanetary disks Submillimeter astronomy |
| url | https://doi.org/10.3847/1538-4357/ad2346 |
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