II型超新星SN 2024bch的不对称性与星周物质相互作用
Asymmetries and Circumstellar Interaction in the Type II SN 2024bch
AI总结：
本文对邻近的II型超新星SN 2024bch进行多历元测光与光谱研究，发现其早期高电离发射线、高质量损失率及光谱不对称性，揭示了与不对称星周介质的持续相互作用，为巨星复杂演化环境提供新线索。
摘要：
我们对SN 2024bch进行了全面的多历元测光和光谱研究，这是一颗距离较近（19.9 Mpc）的II型超新星（SN），具有显著的早期高电离发射线。估计爆炸后2.9天的光学光谱揭示了H I、He II、C IV和N IV的窄线，这些线在第6天消失。地面和TESS的高频次测光显示，该超新星迅速增亮，并在爆炸后一周内达到峰值M$_V \sim$ $-$17.8 mag，晚期测光表明$^{56}$Ni质量为0.050 M$_{\odot}$。第8天和第43天的高分辨率光谱追踪了未受激波加热的星周介质（CSM），并表明风速为30--40 km s$^{-1}$，该值与红超巨星（RSG）前身星一致。模型与早期光谱的比较表明，超新星前的质量损失率为$\dot{M} \sim 10^{-3}-10^{-2}\\ M_\odot\\ \mathrm{yr}^{-1}$，这太高而无法由RSG的宁静质量损失解释，但与近期对类似超新星的测量结果一致。在光学和近红外光谱中观测到的持续蓝移H I和[O I]发射线可能由超新星抛射物的不对称性产生，而多成分H$\alpha$可能表明在星云相期间与不对称CSM的持续相互作用。SN 2024bch为巨星周围的复杂环境和质量损失历史提供了另一条线索。
英文摘要：
We present a comprehensive multi-epoch photometric and spectroscopic study of SN 2024bch, a nearby (19.9 Mpc) Type II supernova (SN) with prominent early high ionization emission lines. Optical spectra from 2.9 days after the estimated explosion reveal narrow lines of H I, He II, C IV, and N IV that disappear by day 6. High cadence photometry from the ground and TESS show that the SN brightened quickly and reached a peak M$_V \sim$ $-$17.8 mag within a week of explosion, and late-time photometry suggests a $^{56}$Ni mass of 0.050 M$_{\odot}$. High-resolution spectra from day 8 and 43 trace the unshocked circumstellar medium (CSM) and indicate a wind velocity of 30--40 km s$^{-1}$, a value consistent with a red supergiant (RSG) progenitor. Comparisons between models and the early spectra suggest a pre-SN mass-loss rate of $\dot{M} \sim 10^{-3}-10^{-2}\ M_\odot\ \mathrm{yr}^{-1}$, which is too high to be explained by quiescent mass loss from RSGs, but is consistent with some recent measurements of similar SNe. Persistent blueshifted H I and [O I] emission lines seen in the optical and NIR spectra could be produced by asymmetries in the SN ejecta, while the multi-component H$α$ may indicate continued interaction with an asymmetric CSM well into the nebular phase. SN 2024bch provides another clue to the complex environments and mass-loss histories around massive stars.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
