发表机构
Nanjing University; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education; Leibniz Institute for Astrophysics Potsdam; University of Birmingham; Aalto University; Max-Planck-Institut für Sonnensystemforschung; Nordita, KTH Royal Institute of Technology & Stockholm University（南京大学; 教育部现代天文与天体物理重点实验室（南京大学）; 波茨坦莱布尼茨天体物理研究所; 伯明翰大学; 阿尔托大学; 马克斯·普朗克太阳系研究所; 诺迪塔，皇家理工学院与斯德哥尔摩大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文通过统一建模框架模拟不同旋转速率太阳型恒星的阿尔文波加热风，首次获得自洽的活动-风关系（质量损失率随X射线通量呈指数约0.67的幂律），并量化了超级地球轨道处的恒星风压。
AI 中文摘要
观测表明，低质量主序恒星的稳态风质量损失与其冕X射线活动之间存在关联。解释这一关联颇具挑战性，因为风主要受大尺度开放磁场控制，而X射线发射则追踪小尺度闭合磁场中的加热过程，这些闭合磁场在全球风模型中往往无法分辨。本文采用空间天气建模框架-阿尔文波太阳模型，结合全球对流发电机产生的磁图和太阳磁图。我们对四颗太阳型恒星以及太阳的阿尔文波加热风进行建模，旋转速率覆盖太阳速率的1.0至23.3倍，磁场强度覆盖6.0至1200高斯。我们的模型表明，更快的旋转会产生更紧密缠绕的螺旋结构、更大的阿尔文面、更高的终端风速，以及更严酷的风压环境（对轨道系外行星而言），这与当今太阳的情况不同。我们估算了质量损失率和角动量损失率，并发现其与基于塞曼-多普勒成像的预测存在系统性差异。在论文I成功再现X射线冕的基础上，我们在统一建模框架中首次获得了自洽的活动-风关系：质量损失率随表面X射线通量变化遵循幂律，指数约为0.67。我们还通过开放通量磁化重新审视了磁制动，发现有效阿尔文杠杆臂取决于磁化参数，幂律指数约为0.35。最后，我们量化了多颗超级地球轨道处的恒星风压。结合论文I，这一系列结果展示了多尺度磁场的不同作用，并为评估宜居带空间天气提供了基于物理的输入。
英文摘要
Observations suggest a connection between steady-wind mass loss and coronal X-ray activity in low-mass main-sequence stars. Interpreting this connection is challenging because the wind is controlled mainly by the large-scale open field, whereas X-ray emission traces heating in small-scale closed fields often unresolved in global wind models. Here we use Space Weather Modelling Framework-Alfvén-Wave Solar Model with global convective dynamo-generated magnetic maps and solar magnetograms. We model Alfvén-wave-heated winds for four solar-type stars plus the Sun, spanning rotation rates of $1.0$--$23.3$ times the solar rate, and magnetic field strengths of $6.0$--$1200$ G. Our models show that faster rotation yields a more tightly wound spiral, a larger Alfvén surface, higher terminal wind speeds, and a harsher wind-pressure environment for orbiting exoplanets, different from that of the present-day Sun. We estimate the mass- and angular-momentum-loss rates and find systematic differences from Zeeman-Doppler Imaging-based predictions. Building on the successful reproduction of X-ray coronae in our Paper~I, we obtain the first self-consistent activity--wind relation in a unified modelling framework: the mass-loss rate scales with the surface X-ray flux following a power law with an index of ${\sim}0.67$. We also re-examine magnetic braking via open-flux magnetisation, finding that the effective Alfvénic lever arm depends on the magnetisation parameter with a power-law index of ${\sim}0.35$. Finally, we quantify the stellar wind pressure at the orbits of several super-Earths. Together with our Paper~I, the series of results shows the distinct roles of multi-scale magnetic fields and provides physically grounded inputs for assessing habitable-zone space weather.
CommentsAccepted by ApJ
