Parkes observations for project P1189 semester 2023APRS_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 $2^{+3}_{-1}$ 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（space weather）事件对太阳系具有至关重要的影响，且会对太空及地面技术设施构成威胁。因此，探明太阳风与空间天气的起源至关重要——这不仅能帮助我们更深入地理解此类事件的驱动机制，还可助力空间天气预报能力的提升。具体而言，低日冕（lower corona）中的冕洞（coronal holes）、盔状冕流（helmet streamers）与日珥（prominences）等磁结构，被认为是驱动太阳风及日冕物质抛射（CME，coronal mass ejections）的核心诱因。然而，在太阳低高度区域（<20倍太阳半径，solar radii），针对太阳风与空间天气事件的观测约束极为匮乏，这是由于该区域无法通过空间探测器（space probes）直接抵达。
在本研究方案中，我们计划对一组脉冲星（pulsars）开展监测，即当它们行经距离太阳5.7度以内的空域时进行观测。我们将借助帕克斯射电望远镜（Parkes Radio Telescope）上的UWL接收机（UWL receiver），对脉冲信号的色散群时延（dispersive group delay）与法拉第旋转（Faraday rotation）进行高精度测量。此举将使我们得以探测驱动太阳风的日冕结构的密度与磁场，并在$2^{+3}_{-1}$次日冕物质抛射（CME）偶然掠过脉冲星时完成对其的观测。
我们将把这些观测信息与多项互补性研究工作相结合：包括通过行星际闪烁（interplanetary scintillation）探测太阳风、利用空间探测器获取的观测约束，以及数值模拟结果。这将为我们提供难得的契机，以构建太阳风与空间天气的完整认知图景。