Abstract

From the beginning of January 2021 to the end of August 2023, the radiation monitor of the Spektr-RG spacecraft registered three enhancements in the count rate, which exceed the background variations during the solar activity cycle and have a comparable maximum value. These enhancements are associated with solar proton events (SPEs) from the flares X1.0 on October 28, 2021; M6.3 on February 25, 2023; and M5.7 on July 17, 2023. Using the example of these events, as well as smaller SPEs from the flares M3.7 on February 24, 2023, and M4.0 on July 16, 2023, threshold criteria for “proton” flares are discussed. In powerful SPEs, the contribution of solar protons to the radiation dose can exceed the total contribution of galactic cosmic rays (GCR) over a sufficiently long period of time. Therefore, such SPEs are sources of increased radiation hazard and require prediction based on real-time observations. It was shown that, in these five flares, thresholds were overcome according to three criteria: plasma temperature >12 MK (soft X-ray source), duration (>5 min) of microwave or hard X-ray (HXR) radiation (electron acceleration >100 keV), and height of flare development process >60 Mm (radio emission at plasma frequencies <610 MHz). The arrival of the first solar protons >100 MeV to the Earth’s orbit was expected no earlier than 10 min relative to the beginning of HXR or microwave radiation, i.e., could have been predicted in advance. To study the relationship between solar flares and SPEs, we used data from the anticoincidence shield of the spectrometer on INTEGRAL (ACS SPI), which is an effective but uncalibrated detector of HXR >100 keV and protons >100 MeV, as well as patrol observations of radio emission at fixed frequencies (Radio Solar Telescope Network). It is noted that the X2.2 (N25E64) flare on February 17, 2023 satisfied all three “protonity” criteria and could become the source of a powerful SPE near the Earth in a case of favorable location on the Sun. In the M8.6 (N27W29) flare on February 28, 2023, the third criterion was not met, and it did not lead to an SPE as expected (it developed in a plasma with a density >2.5 × 10¹⁰ cm^–3 and plasma frequency >1415 MHz).

中文翻译：

---

2023年2月24日至25日和7月16日至17日事件中的太阳质子来源

摘要

从2021年1月上旬到2023年8月下旬，Spektr-RG航天器的辐射监测仪记录了计数率的三次增强，超过了太阳活动周期期间的背景变化，并具有可比较的最大值。这些增强与 2021 年 10 月 28 日耀斑 X1.0 的太阳质子事件 (SPE) 有关； M6.3 于 2023 年 2 月 25 日； 2023 年 7 月 17 日的 M5.7。以这些事件为例，以及 2023 年 2 月 24 日耀斑 M3.7 和 2023 年 7 月 16 日 M4.0 产生的较小的 SPE，“质子”的阈值标准讨论了耀斑。在强大的 SPE 中，在足够长的时间内，太阳质子对辐射剂量的贡献可能超过银河宇宙射线 (GCR) 的总贡献。因此，此类 SPE 是增加辐射危害的来源，需要基于实时观测进行预测。结果表明，在这五个耀斑中，根据三个标准克服了阈值：等离子体温度> 12 MK（软X射线源），微波或硬X射线（HXR）辐射（电子）的持续时间（> 5分钟）加速度> 100 keV），耀斑发展过程的高度> 60 Mm（等离子体频率< 610 MHz的无线电发射）。预计第一批大于 100 MeV 的太阳质子到达地球轨道的时间不会早于 HXR 或微波辐射开始的 10 分钟，即可以提前预测。为了研究太阳耀斑和 SPE 之间的关系，我们使用了INTEGRAL (ACS SPI)上光谱仪反符合屏蔽的数据，这是一种有效但未经校准的 HXR >100 keV 和质子 >100 MeV 探测器，以及巡逻观测固定频率的射电发射（射电太阳望远镜网络）。值得注意的是，2023 年 2 月 17 日发生的 X2.2 (N25E64) 耀斑满足了所有三个“质子”标准，如果在太阳上的有利位置，可能成为地球附近强大的 SPE 源。在2023年2月28日的M8.6（N27W29）耀斑中，没有满足第三个标准，并且没有产生预期的SPE（它在密度>2.5 × 10 ¹⁰ cm ^–3的等离子体中发展，并且等离子体频率 >1415 MHz）。