Spin-down of Solar-mass Protostars in Magnetospheric Accretion Paradigm
Stellar spin is one of the fundamental quantities that characterize a star itself and its planetary system. Nevertheless, stellar spin-down mechanisms in protostellar and pre-main-sequence stellar phases have been a long-standing problem in star formation theory. To realize the spin-down, previous a...
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2025-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ada364 |
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| author | Shinsuke Takasao Masanobu Kunitomo Takeru K. Suzuki Kazunari Iwasaki Kengo Tomida |
| author_facet | Shinsuke Takasao Masanobu Kunitomo Takeru K. Suzuki Kazunari Iwasaki Kengo Tomida |
| author_sort | Shinsuke Takasao |
| collection | DOAJ |
| description | Stellar spin is one of the fundamental quantities that characterize a star itself and its planetary system. Nevertheless, stellar spin-down mechanisms in protostellar and pre-main-sequence stellar phases have been a long-standing problem in star formation theory. To realize the spin-down, previous axisymmetric models based on the conventional magnetospheric paradigm have had to assume massive stellar winds or produce highly time-variable magnetospheric ejections. However, this picture has been challenged by both numerical simulations and observations. With a particular focus on the propeller regime for solar-mass stars, we propose a new picture of stellar spin-down based on our recent 3D magnetohydrodynamic simulation and stellar evolution calculation. We show that failed magnetospheric winds, unique to 3D models, significantly reduce the spin-up accretion torque, which make it easier for the star to spin-down. Additionally, the amplitude of time variability associated with magnetospheric ejections is reduced by 3D effects. Our simulation demonstrates that the star spins down by generating a conical disk wind, driven by a rotating stellar magnetosphere. Our theoretical estimates, inspired by the numerical model, suggest that the conical disk wind is likely to play a crucial role in extracting stellar angular momentum during the protostellar phase. As magnetospheric accretion is expected to occur in other accreting objects such as protogiant planets, this study will also contribute to the understanding of the angular momentum of such objects. |
| format | Article |
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| institution | Kabale University |
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| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| spelling | doaj-art-6e8ac8d351f147dd83d5bee9e30c4da12025-02-10T09:00:20ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01980111110.3847/1538-4357/ada364Spin-down of Solar-mass Protostars in Magnetospheric Accretion ParadigmShinsuke Takasao0https://orcid.org/0000-0003-3882-3945Masanobu Kunitomo1https://orcid.org/0000-0002-1932-3358Takeru K. Suzuki2https://orcid.org/0000-0001-9734-9601Kazunari Iwasaki3https://orcid.org/0000-0002-2707-7548Kengo Tomida4https://orcid.org/0000-0001-8105-8113Department of Earth and Space Science, Graduate School of Science, Osaka University , Toyonaka, Osaka 560-0043, JapanDepartment of Physics, Kurume University , 67 Asahimachi, Kurume, 830-0011, Fukuoka, Japan; Université Côte d’Azur , Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Bd de l’Observatoire, CS 34229, 06304 Nice cedex 4, FranceSchool of Arts & Sciences, The University of Tokyo , 3-8-1, Komaba, Meguro, Tokyo, 153-8902, Japan; Department of Astronomy, The University of Tokyo , 7-3-1, Hongo, Bunkyo, Tokyo, 113-0033, JapanCenter for Computational Astrophysics , National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, JapanAstronomical Institute, Tohoku University , Sendai, Miyagi 980-8578, JapanStellar spin is one of the fundamental quantities that characterize a star itself and its planetary system. Nevertheless, stellar spin-down mechanisms in protostellar and pre-main-sequence stellar phases have been a long-standing problem in star formation theory. To realize the spin-down, previous axisymmetric models based on the conventional magnetospheric paradigm have had to assume massive stellar winds or produce highly time-variable magnetospheric ejections. However, this picture has been challenged by both numerical simulations and observations. With a particular focus on the propeller regime for solar-mass stars, we propose a new picture of stellar spin-down based on our recent 3D magnetohydrodynamic simulation and stellar evolution calculation. We show that failed magnetospheric winds, unique to 3D models, significantly reduce the spin-up accretion torque, which make it easier for the star to spin-down. Additionally, the amplitude of time variability associated with magnetospheric ejections is reduced by 3D effects. Our simulation demonstrates that the star spins down by generating a conical disk wind, driven by a rotating stellar magnetosphere. Our theoretical estimates, inspired by the numerical model, suggest that the conical disk wind is likely to play a crucial role in extracting stellar angular momentum during the protostellar phase. As magnetospheric accretion is expected to occur in other accreting objects such as protogiant planets, this study will also contribute to the understanding of the angular momentum of such objects.https://doi.org/10.3847/1538-4357/ada364ProtostarsPre-main sequence starsStellar magnetic fieldsEarly stellar evolution |
| spellingShingle | Shinsuke Takasao Masanobu Kunitomo Takeru K. Suzuki Kazunari Iwasaki Kengo Tomida Spin-down of Solar-mass Protostars in Magnetospheric Accretion Paradigm The Astrophysical Journal Protostars Pre-main sequence stars Stellar magnetic fields Early stellar evolution |
| title | Spin-down of Solar-mass Protostars in Magnetospheric Accretion Paradigm |
| title_full | Spin-down of Solar-mass Protostars in Magnetospheric Accretion Paradigm |
| title_fullStr | Spin-down of Solar-mass Protostars in Magnetospheric Accretion Paradigm |
| title_full_unstemmed | Spin-down of Solar-mass Protostars in Magnetospheric Accretion Paradigm |
| title_short | Spin-down of Solar-mass Protostars in Magnetospheric Accretion Paradigm |
| title_sort | spin down of solar mass protostars in magnetospheric accretion paradigm |
| topic | Protostars Pre-main sequence stars Stellar magnetic fields Early stellar evolution |
| url | https://doi.org/10.3847/1538-4357/ada364 |
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