AI 中文总结
本文通过最大样本强钙超新星的测光与光谱研究，发现其早期存在异常的强[Ca II]发射，提出这类超新星可能是白矮星在受前身星活动污染的延展环境中爆炸的产物。
AI 中文摘要
强钙超新星（Ca-strong SNe）是一类热核暂现源，其特征为光变演化迅速（上升时间≤16天），且星云阶段光谱以强[Ca II]7291、7324发射线为主，与[O I]6300、6364发射线的强度形成鲜明对比。尽管它们具有独特的光谱特征且与遥远环境相关联，但其起源仍不确定。利用兹威基瞬变巡天（Zwicky Transient Facility）等项目的新发现，并辅以档案数据，我们编制了包含46颗强钙超新星的样本——这是迄今为止最大的此类样本。我们对强钙超新星开展了全面的光学测光与光谱研究，旨在更好地限定其多样性、前身星系统及爆发机制。在35颗峰值光附近有光谱的强钙超新星中，我们发现32个天体在峰值后10天内表现出显著的[Ca II]发射。通常认为，禁戒[Ca II]发射应在抛射物膨胀、冷却且密度低到足以发生禁戒跃迁后才会出现，然而强钙超新星中这类早期特征的普遍性，现有爆发模型无法解释。在多个天体中，我们识别出复杂的多成分线轮廓，表明其在两种不同速度区间间存在过渡。这些过渡特征，结合早期禁戒发射的普遍存在，使我们倾向于一种场景：前身星周围存在延展物质，且早于超新星本身。我们的结果表明，强钙超新星的多样光谱行为，与在受前身星系统前期活动污染的延展环境中爆炸的白矮星是一致的。
英文摘要
Calcium-strong supernovae (Ca-strong SNe) are a class of thermonuclear transient characterised by rapid photometric evolution (rise times of <= 16 d) and nebular-phase spectra dominated by strong [Ca II]7291,7324 emission, in comparison to the strength of [O I]6300,6364 emission. Despite their distinctive spectra and association with remote environments, their origins remain uncertain. Using new discoveries from surveys such as the Zwicky Transient Facility, supplemented by archival data, we compile a sample of 46 Ca-strong SNe - the largest sample to date. We present a comprehensive optical photometric and spectroscopic study of Ca-strong SNe, aimed at better constraining their diversity, progenitor systems, and explosion mechanisms. Of the 35 Ca-strong SNe with spectra near peak light, we find that 32 objects exhibit significant [Ca II] emission within 10 days of peak. Forbidden [Ca II] emission is typically expected to emerge after the ejecta have expanded, cooled, and reached a sufficiently low density for forbidden transitions to occur. The prevalence of these early features in Ca-strong SNe, however, remains unexplained by current explosion models of these objects. In several objects, we identify complex, multi-component line profiles that suggest a transition between two distinct velocity regimes. These transitional features, combined with the common presence of early forbidden emission, lead us to favour a scenario in which extended material surrounds the progenitor and pre-dates the SN itself. Our results suggest that the diverse spectroscopic behaviours of Ca-strong SNe are consistent with white dwarfs exploding in extended environments polluted by prior activity of the progenitor system.
Comments27 pages, 14 figures
