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arXiv 2504.02401astro-ph.SR
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太阳与类太阳恒星的比较：关于处理光斑/黑子主导问题的重要性

Comparing the Sun to Sun-like stars. On the importance of addressing faculae/spot domination

Konstantin Herbst, Eliana M. Amazo-Gómez, Athanasios Papaioannou

备注：
accepted at A&A as aa52999-24
发表信息：
A&A 697, A80 (2025)
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AI总结：

本研究通过改进类太阳恒星判据和功率谱梯度方法，将Kepler类太阳恒星划分为黑子主导与光斑主导两类，并发现仅KIC 11599385可与当前太阳直接比较，其耀斑能量与AD774/775事件相符。

摘要：

太阳是否是一颗普通的G型恒星，仍然是一个开放的科学问题。然而，Kepler和TESS的恒星巡天揭示，类太阳恒星往往表现出比太阳强得多的耀斑活动。本研究旨在通过微调判据，对类太阳条件进行更稳健的定义，并提高当前太阳与类太阳恒星之间的可比性，从而重新评估观测到的Kepler类太阳恒星的耀斑和黑子活动。我们更新了近期的一个类太阳恒星样本，应用新的恒星黑子大小与有效温度之间的经验关系，以推导出更可靠的黑子群大小。从265颗太阳型恒星中，我们筛选出48颗支持Kepler 30分钟采样光变曲线的恒星。通过实施功率谱梯度方法对这些恒星进行分析，以区分黑子主导型和光斑主导型恒星。我们采用α因子来量化恒星表面亮暗特征的面占比。我们能够将这48颗恒星划分为黑子主导型或光斑主导型，揭示出Kepler类太阳恒星优先分布在黑子主导区（44颗）和过渡区（4颗）。由于当前太阳是光斑主导型，只有过渡型恒星被用于进一步评估。此外，考虑到恒星质量、半径和自转周期的可比性，我们表明在Kepler样本中使用的265颗类太阳恒星中，只有一颗（即KIC 11599385）允许与当前太阳进行直接比较。我们进一步表明，在KIC 11599385上观测到的单次耀斑恰好落在根据宇宙成因放射性核素档案（10Be、14C和36Cl）中观测到的AD774/775事件所估计的耀斑能量范围内。

英文摘要：

Whether the Sun is an ordinary G-type star is still an open scientific question. Stellar surveys by Kepler and TESS, however, revealed that Sun-like stars tend to show much stronger flare activity than the Sun. This study aims to reassess observed flare and spot activity of Sun-like Kepler stars by fine-tuning the criteria for a more robust definition of Sun-like conditions and better comparability between the current Sun and Sun-like stars. We update one of the recent stellar Sun-like star samples by applying new empirical stellar relations between the starspot size and the effective stellar temperature to derive more reliable starspot group sizes. From the 265 solar-type stars, we could select 48 stars supporting the Kepler 30-minute cadence light curves. These were analyzed by implementing the gradient of the power spectra method to distinguish between spot- and faculae-dominated stars. We employed the $α$-factor to quantify the area ratio of bright and dark features on the stellar surface. We were able to group the 48 stars as being spot- or faculae-dominated, revealing a preferential distribution of the Kepler Sun-like stars towards the spot-dominated (44 stars) and transitional (four stars) regimes. As the current Sun is faculae-dominated, only the transitional stars were utilized for further evaluation. Additionally, accounting for comparability in stellar mass, radius, and rotation period, we show that only one of the utilized 265 Sun-like stars in the Kepler sample (i.e., KIC 11599385) allows for direct comparison to the current Sun. We further show that the single flare observed on KIC 11599385 falls right within the flare energy range estimated for the AD774/775 event observed in the cosmogenic radionuclide archives of $^{10}$Be, $^{14}$C, and $^{36}$Cl.

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