终点线附近的奇特行为：Ibn型超新星SN 2020able及其分层环境
Wild behaviour near the finish line: the Type Ibn SN 2020able and its stratified environment
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中文总结 AI 辅助
本研究观测分析Ibn型超新星SN 2020ble，发现其分层星周环境，证实其前身星为晚期WN型至WC型WR星，完善了Ibn型超新星的演化模型。
中文摘要 AI 辅助
我们呈现了Ibn型超新星SN 2020able的分光光度观测结果，以及对其演化的综合分析与建模。该暂现源位于SDSS J092602.93+243115.1，这是一个暗弱的宿主星系，具有显著低于太阳的金属丰度（12+log(O/H)≃8.28 dex）。早期光度演化和高峰光度（L_peak≃4.4×10^43 erg s^-1）表明，通过与星周介质的相互作用，抛射物的动能被高效转化为辐射。光变曲线建模显示，这种相互作用涉及质量M_ej≃1.3 M⊙的抛射物撞击质量M_CSM≃0.6 M⊙的壳层。然而，发现这种相互作用在爆炸后数天内就受到几何和时间限制，暂现源的后期演化由抛射物的自由膨胀主导。光谱分析揭示了复杂的分层星周环境。除了最内侧的激波区域，我们还识别出另外两个富氦壳层：一个致密的内壳（n_e≃1.4×10^9 cm^-3），位于R≳9.3×10^14 cm处；以及一个更延展的外组分，达到R_out≃3.3×10^15 cm，膨胀速度约为1.2×10^3 km s^-1。前者的物理参数表明它由类似SN 2006jc的离散超新星前爆发事件产生，该事件抛射出约1.8×10^-2 M⊙的物质。相反，最外层壳层的膨胀速度与沃尔夫-拉叶星（WR星）的逃逸速度一致，表明晚期WN型到WC型前身星是SN 2020able最可能的候选者。
英文摘要
We present spectrophotometric observations of the Type Ibn supernova SN~2020able, along with a comprehensive analysis and modelling of its evolution. The transient occurred in SDSS J092602.93+243115.1, a faint host galaxy characterised by significantly sub-solar metallicity ($12+\log(\rm{O/H})\simeq8.28\,\rm{dex}$). The early photometric evolution and high peak luminosity ($L_{peak}\simeq4.4\times10^{43}\,\rm{erg}\,\rm{s^{-1}}$) indicate an efficient conversion of ejecta kinetic energy into radiation via interaction with the circumstellar medium. Light-curve modelling suggests that this interaction involves ejecta with a mass of $M_{\rm{ej}}\simeq1.3\,M_{\odot}$ impacting a shell of $M_{\rm{CSM}}\simeq0.6\,M_{\odot}$. However, interaction is found to be geometrically and temporally confined within a few days after explosion, with the later evolution of the transient being dominated by the free expansion of the ejecta. Spectroscopic analysis reveals a complex, stratified circumstellar environment. In addition to the innermost shocked region, we identify two additional He-rich shells: a dense inner one ($n_{\rm{e}}\simeq1.4\times10^{9}\,\rm{cm^{-3}}$) located at $R\gtrsim9.3\times10^{14}\,\rm{cm}$, and a more extended outer component reaching $R_{out}\simeq3.3\times10^{15}\,\rm{cm}$ and expanding at approximately $1.2\times10^3\,\rm{km}\,\rm{s^{-1}}$. The physical parameters of the former suggest it was produced by a discrete pre-supernova eruptive event similar to that of SN~2006jc, which expelled approximately $1.8\times10^{-2}\,M_{\odot}$ of material. Conversely, the expansion velocity of the outermost shell is consistent with the escape velocity of WR stars, pointing towards a late WN to WC-type progenitor as the most viable candidate for SN~2020able.
