Parkes observations for project P1189 semester 2023OCTS_04

The solar wind and space weather events have a crucial influence on the solar system, and can present a hazard to space and Earth-based technologies. Understanding the origins of the solar wind and space weather is therefore crucial, so that we can better understand how these events are driven, and to improve space weather prediction efforts. In particular, magnetic structures such as coronal holes, helmet streamers, and prominences in the lower corona are thought to be crucial drivers of the winds and coronal mass ejections (CMEs). However, there are very few observational constraints on the solar wind and space weather events at low solar altitudes (< 20 solar radii), as this region is inaccessible to space probes. In this proposal, we seek to monitor a set of pulsars as they pass within 5.7 degrees of the Sun. We will use the UWL receiver on the Parkes Radio Telescope to make precision measurements of the dispersive group delay and Faraday rotation of the pulses. This will enable us to probe the densities and magnetic fields of the coronal structures driving the wind, and probe $6 \\pm 4$ CMEs as they pass by the pulsars serendipitously. We will tie this information together with complementary efforts to probe the solar wind via interplanetary scintillation, constraints from space probes, and simulations. This will give us an exciting opportunity to form a holistic picture of the solar wind and space weather.

太阳风（solar wind）与空间天气事件对太阳系具有至关重要的影响，同时会对太空及地面技术设施构成安全威胁。因此，探明太阳风与空间天气的起源机制至关重要，这将助力我们更好地理解此类事件的驱动原理，并提升空间天气预报工作的精度与效能。具体而言，日冕低层的冕洞（coronal holes）、盔状冕流（helmet streamers）以及日珥（prominences）等磁结构，被认为是太阳风与日冕物质抛射（coronal mass ejections，CMEs）的核心驱动源。然而，由于该区域无法通过空间探测器直接抵达，目前针对太阳低高度区域（<20倍太阳半径）内的太阳风与空间天气事件的观测约束极为有限。在本研究提案中，我们计划对一组脉冲星（pulsars）开展监测，观测其运行至距离太阳5.7度范围内的时段。我们将借助帕克斯射电望远镜（Parkes Radio Telescope）上的UWL接收机，对脉冲信号的色散群延迟与法拉第旋转（Faraday rotation）开展高精度测量。此举将使我们能够探测驱动太阳风的日冕结构的密度与磁场，并对偶然掠过脉冲星的6±4次日冕物质抛射开展观测研究。我们还将结合通过行星际闪烁（interplanetary scintillation）探测太阳风的相关研究、空间探测器的观测约束以及数值模拟结果，整合所有相关信息。这将为我们全面构建太阳风与空间天气的完整认知图景提供宝贵契机。