FU Orionis disk outburst: evidence for a gravitational instability scenario triggered in a magnetically dead zone
| Autor: | Bourdarot, G., Berger, J-P., Lesur, G., Perraut, K., Malbet, F., Millan-Gabet, R., Bouquin, J-B. Le, Garcia-Lopez, R., Monnier, J. D., Labdon, A., Kraus, S., Labadie, L., Aarnio, A. |
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| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | A&A 676, A124 (2023) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/202245757 |
| Popis: | Context: FUors outbursts are a crucial stage of accretion in young stars. However a complete mechanism at the origin of the outburst still remains missing. Aims: We aim at constraining the instability mechanism in FU Orionis star itself, by directly probing the size and the evolution in time of the outburst region with near-infrared interferometry, and to confront it to physical models of this region. Methods: FU Orionis has been a regular target of near-infrared interferometry. In this paper, we analyze more than 20 years of interferometric observations to perform a temporal monitoring of the region of the outburst, and compare it to the spatial structure deduced from 1D MHD simulations. Results: We measure from the interferometric observations that the size variation of the outburst region is compatible with a constant or slightly decreasing size over time in the H and K band. The temporal variation and the mean sizes are consistently reproduced by our 1D MHD simulations. We find that the most compatible scenario is a model of an outburst occurring in a magnetically layered disk, where a Magneto-Rotational Instability (MRI) is triggered by a Gravitational Instability (GI) at the outer edge of a dead-zone. The scenario of a pure Thermal Instability (TI) fails to reproduce our interferometric sizes since it can only be sustained in a very compact zone of the disk <0.1 AU. The scenario of MRI-GI could be compatible with an external perturbation enhancing the GI, such as tidal interactions with a stellar companion, or a planet at the outer edge of the dead-zone. Conclusions: The layered disk model driven by MRI turbulence is favored to interpret the spatial structure and temporal evolution of FU Orionis outburst region. Understanding this phase gives a crucial link between the early phase of disk evolution and the process of planet formation in the first inner AUs. Comment: Accepted for publication in A&A |
| Databáze: | arXiv |
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