期刊
ASTROPHYSICAL JOURNAL
卷 895, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.3847/1538-4357/ab88a3
关键词
Magnetohydrodynamical simulations; Solar flares; Stellar flares; Solar coronal mass ejections; Solar coronal mass ejection shocks; Stellar winds; Solar wind; Solar radio emission; Stellar magnetic fields; Solar magnetic fields; Stellar coronae; Radio bursts
资金
- Chandra grant [GO5-16021X]
- HST grant [GO-15326]
- NASA Living with a Star grant [NNX16AC11G]
- NASA [NAS8-03060, SMD-17-1330]
- NASA [NNX16AC11G, 907625] Funding Source: Federal RePORTER
Coronal mass ejections (CMEs) on stars other than the Sun have proven very difficult to detect. One promising pathway lies in the detection of type II radio bursts. Their appearance and distinctive properties are associated with the development of an outward propagating CME-driven shock. However, dedicated radio searches have not been able to identify these transient features in other stars. Large Alfven speeds and the magnetic suppression of CMEs in active stars have been proposed to render stellar eruptions radio-quiet. Employing 3D magnetohydrodynamic simulations, we study the distribution of the coronal Alfven speed, focusing on two cases representative of a young Sun-like star and a mid-activity M-dwarf (Proxima Centauri). These results are compared with a standard solar simulation and used to characterize the shock-prone regions in the stellar corona and wind. Furthermore, using a flux-rope eruption model, we drive realistic CME events within our M-dwarf simulation. We consider eruptions with different energies to probe the regimes of weak and partial CME magnetic confinement. While these CMEs are able to generate shocks in the corona, those are pushed much farther out compared to their solar counterparts. This drastically reduces the resulting type II radio burst frequencies down to the ionospheric cutoff, which impedes their detection with ground-based instrumentation.
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