论文标题
epsilon eridani的太阳能发电机模型的应用
An application of a solar-type dynamo model for Epsilon Eridani
论文作者
论文摘要
在过去的十年中，活动周期与恒星参数之间的关系受到了特别关注。可靠的活动注册表的构建表明，太阳型恒星表现出活动周期，几年到几十年，并且在同一情况下，长期和短期活动周期共存，这表明两个发电机可以在这些恒星中运行。特别是，Epsilon Eridani是活跃的年轻K2V恒星（0.8 Gyr），其短期和长期的色球环循环近3和13岁。此外，在1985年至1992年之间，这颗星星经历了广泛的活动，类似于太阳能Maunder最低状态。在这些结果的驱动下，我们在Epsilon Eridani中发现了测试Dynamo理论的绝佳机会。基于Sraibman＆Minotti（2019）中开发的模型，在这项工作中，我们为Epsilon Eridani构建了一个非线性轴对称发电机。在所有恒星圆盘中积分的表面附近的模拟磁场成分的时间序列都表现出长的和短活度周期，其周期类似于观测值和低活性的时间间隔，这可能与宽阔的微型芒蒙相关。与磁反转相关的短期活性循环可以通过差分旋转来解释，而长周期与洛伦兹力引起的子午质量流有关。通过这种方式，我们表明，由具有准确的恒星参数的第一原理得出的单个非线性发电机模型可以再现共存的活性周期。
During the last decade, the relation between activity cycle periods with stellar parameters has received special attention. The construction of reliable registries of activity reveals that solar type stars exhibit activity cycles with periods from few years to decades and, in same cases, long and short activity cycles coexist suggesting that two dynamos could operate in these stars. In particular, Epsilon Eridani is an active young K2V star (0.8 Gyr), which exhibits a short and long-term chromospheric cycles of near 3 and 13-yr periods. Additionally, between 1985 and 1992, the star went through a broad activity minimum, similar to the solar Maunder Minimum-state. Motivated by these results, we found in Epsilon Eridani a great opportunity to test the dynamo theory. Based on the model developed in Sraibman & Minotti (2019), in this work we built a non linear axisymmetric dynamo for Epsilon Eridani. The time series of the simulated magnetic field components near the surface integrated in all the stellar disc exhibits both the long and short-activity cycles with periods similar to the ones detected from observations and also time intervals of low activity which could be associated to the broad Minimun. The short activity cycle associated to the magnetic reversal could be explained by the differential rotation, while the long cycle is associated to the meridional mass flows induced by the Lorentz force. In this way, we show that a single non-linear dynamo model derived from first principles with accurate stellar parameters could reproduce coexisting activity cycles.
