标题： 爆发彗星12P/庞斯-布鲁克斯的光学和近红外光谱 显示英文标题

标题： Optical and Near-Infrared Spectroscopy of the Outbursting Comet 12P/Pons-Brooks

摘要： 我们提供了对爆发的哈雷型彗星12P/Pons-Brooks的光学和近红外（NIR）观测。在2023年10月和11月的两次爆发期间，分别使用3米红外望远镜设施和帕洛马200英寸望远镜获得了三组NIR光谱。NIR光谱在1.5和2.0$\mu$m处显示出吸收特征，与水冰的诊断吸收带一致，并叠加在红色尘埃散射连续谱上。我们发现，吸收带和红色连续谱可以通过140-170 K范围内的微米级晶体冰以及亚微米级的耐火颗粒（例如非晶碳）很好地解释。此外，在2023年11月的爆发期间，使用丽江2.4米望远镜获得了一组光学光谱，该光谱显示了气态CN、C$_3$、C$_2$和NH$_2$的发射带。 C$_3$/CN 和 C$_2$/CN 比值表明 12P/庞斯-布鲁克斯在 C$_3$丰度上是“典型”的，但在 C$_2$上有所贫化。 2023 年 11 月爆发的特定动能估计为$\sim8\times10^3$ J kg$^{-1}$，表明可能的触发机制与 332P/池谷-牟田和 17P/霍尔姆斯类似，即非晶态水冰的结晶化。 从尘埃和气体的总质量损失中得出的耐火物质与冰的比例为$\sim$1.7--3.2，与 67P/丘留莫夫-格拉西缅科和 1P/哈雷的低端估计一致。 这表明可能是核体演化程度较低，或者爆发区域相对于整个核体富含冰质物质。 显示英文摘要

摘要： We present optical and near-infrared (NIR) observations of the outbursting, Halley-type comet 12P/Pons-Brooks. Three NIR spectra were obtained during two outbursts in October and November 2023, with the 3-meter Infrared Telescope Facility and the Palomar 200-inch Telescope, respectively. The NIR spectra exhibited absorption features at 1.5 and 2.0 $\mu$m, consistent with the diagnostic absorption bands of water ice, superimposed on a red dust-scattering continuum. We find that the absorption bands and the red continuum can be well explained by micrometer-sized crystalline ice at 140--170 K, along with sub-micrometer-sized refractory grains (e.g., amorphous carbon). In addition, an optical spectrum was obtained with the Lijiang 2.4-meter Telescope during the November 2023 outburst, which exhibited the emission bands of gaseous CN, C$_3$, C$_2$ and NH$_2$. The C$_3$/CN and C$_2$/CN ratios suggest that 12P/Pons-Brooks was ''typical'' in C$_3$ abundance but somewhat depleted in C$_2$. The specific kinetic energy of the 2023 November outburst is estimated to be $\sim8\times10^3$ J kg$^{-1}$, suggesting a likely triggering mechanism similar to 332P/Ikeya--Murakami and 17P/Holmes, i.e., the crystallization of amorphous water ice. A refractory-to-ice ratio of $\sim$1.7--3.2 is derived from the total mass loss of dust and gas, aligning with the lower-end estimates for 67P/Churyumov-Gerasimenko and 1P/Halley. This suggests either a less evolved nucleus or an outburst region enriched in icy materials relative to the bulk nucleus.