利用Aditya-L1卫星的耀斑前演化多波段诊断：从太阳色球层到日冕
Multi-Wavelength Diagnostics of Pre-Flare Evolution with Aditya-L1: From the Solar Chromosphere to the Corona
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中文总结 AI 辅助
该研究借助Aditya-L1卫星多仪器观测，分析7个M/X级耀斑的色球层耀斑前瞬变，揭示其特性与起源，为理解大耀斑前活动区不稳定过程提供了观测依据。
中文摘要 AI 辅助
太阳耀斑的耀斑前阶段为理解驱动活动区走向不稳定的过程提供了重要线索。我们利用Aditya-L1卫星搭载的太阳紫外成像望远镜（SUIT）的观测数据，结合高能L1轨道X射线光谱仪（HEL1OS）和太阳低能X射线光谱仪（SoLEXS）的X射线测量数据，研究色球层的耀斑前活动。我们分析了7个M级和X级耀斑，重点关注SUIT获取的空间分辨Mg II h（2803 Å）观测数据。在耀斑爆发前的感兴趣区域内，我们识别出102个耀斑前瞬变现象，这些瞬变现象在Mg II h通道中被探测到，在连续谱滤光片上无对应信号，证实了其色球层起源。多数情况下，这些瞬变现象与极性反转线（PILs）及最终的耀斑区域共空间。约28%的瞬变现象在HEL1OS（10-30 keV）中存在X射线对应体；成像X射线光谱仪望远镜（STIX）的光谱分析显示，部分瞬变现象存在非热辐射，表明部分瞬变是小尺度类耀斑事件。4个案例中识别出热X射线起始阶段，剩余3个案例中，背景之上的信噪比不足以确定是否存在热起始阶段。这些瞬变的峰值流量分布遵循折断幂律，指数为α₁=1.64⁺⁰·⁵⁹₋₀·₅₇和α₂=3.12⁺⁰·⁶⁴₋₀·₆₁，高能斜率与Ly-α耀斑分布一致。这些结果表明，色球层耀斑前瞬变代表小尺度磁能释放事件，在大耀斑爆发前会加剧活动区的不稳定。
英文摘要
The pre-flare phase of solar flares provides important insight into the processes that drive active regions toward instability. We investigate chromospheric pre-flare activity using observations from the Solar Ultraviolet Imaging Telescope (SUIT) onboard Aditya-L1, complemented with X-ray measurements from High Energy L1 Orbiting X-ray Spectrometer (HEL1OS) and Solar Low Energy X-ray Spectrometer (SoLEXS). We analyse seven M- and X-class flares, focusing on spatially resolved Mg II h (2803~Å) observations from SUIT. We identify 102 pre-flare transients within regions of interest prior to flare onset. These transients are detected in the Mg II h channel, with no counterparts in continuum filters, confirming their chromospheric origin. In most cases, the transients are co-spatial with polarity inversion lines (PILs) and the eventual flaring region. Approximately 28~\% of transients have X-ray counterparts in HEL1OS (10-30~keV); The Spectrometer Telescope for Imaging X-rays (STIX) spectral analysis reveals non-thermal emission in a subset, indicating that some transients are small-scale flare-like events. A hot X-ray onset is identified in four cases. For the remaining three cases, the signal-to-noise ratio above the background is insufficient to determine whether a hot-onset phase is present. The peak-flux distribution of the transients follows a broken power law with indices $α_1 = 1.64^{+0.59}_{-0.57}$ and $α_2 = 3.12^{+0.64}_{-0.61}$, with the higher-energy slope consistent with the Ly-$α$ flare distribution. These results suggest that chromospheric pre-flare transients represent small-scale magnetic energy-release events that contribute to the progressive destabilisation of active regions prior to major flare onset.
