彗星7P/Pons-Winnecke在2021年出现期间的活动
Activity of comet 7P/Pons-Winnecke during the 2021 apparition
AI总结：
本研究结合Calar Alto、ZTF成像与光谱及Monte Carlo尘埃尾模型，测定7P/Pons-Winnecke在2021年近日点前后的尘埃、气体产生率与成分，指出其富尘且C3略亏损。
摘要：
在2021年向内太阳系接近的出现期间，彗星7P/Pons-Winnecke在西班牙Calar Alto天文台被观测了四个月。宽带可见光图像拍摄于过近日点前日心距1.71至1.25 AU之间，而长缝分光光度数据则在过近日点前约1.25 AU时获取。该数据集还补充了来自Zwicky Transient Facility（ZTF）的三幅r-Sloan图像，以便利用正向Monte Carlo尘埃尾代码模拟尘埃的物理性质和损失率。对于大多数观测，该模型都能很好地拟合观测到的等照度线。测得的峰值尘埃产生率为83 kg s^-1，出现在过近日点后15天。粒子终端速度范围从0.1 m粒子的3 m s^-1到5 μm粒子的23 m s^-1。关于由光谱得到的气体产生，CN和C2在朝日方向和背日方向之间表现出超出数据不确定度和误差传播范围的不对称发射，而无法明确断言C3存在清晰的不对称性。2021年近日点附近CN、C2和C3的平均产生率分别为1.15×10^24、2.32×10^24和1.69×10^23 s^-1。尘埃与气体的质量比估计约为2，表明其成分富含尘埃。基于气体成分和Afρ值，我们将7P/Pons-Winnecke归类为具有Jupiter族彗星的典型成分，并存在一定程度的C3亏损。鉴于以往认识有限，我们的工作有助于拓展对7P/Pons-Winnecke活动和特征的理解。
英文摘要：
Comet 7P/Pons-Winnecke was observed from the Calar Alto Observatory (Spain) for four months during the 2021 inbound apparition. Broad-band visible images were taken between 1.71 and 1.25 AU pre-perihelion, while long-slit spectrophotometric data were taken at $\sim$ 1.25 AU pre-perihelion. This dataset has been complemented with three $r$-Sloan images observed from Zwicky Transient Facility (ZTF) to model the physical properties and loss rate of the dust with a forward Monte Carlo dust tail code. The model fits the observed isophotes well for most observations. The peak dust production rate was measured at 83 kg s$^{-1}$, 15 days after perihelion. The particle terminal speed ranges from 3 m s$^{-1}$ for 0.1 m particles to 23 m s$^{-1}$ for 5 $μ$m particles. Regarding the gas production from spectra, CN and C$_2$ show asymmetric emission between the sunward and antisunward directions beyond the data uncertainties and error propagation, while a clear asymmetry for C$_3$ cannot be definitively claimed. Average production rates for CN, C$_2$, and C$_3$ near 2021 perihelion are 1.15 $\times 10^{24}$, 2.32$\times 10^{24}$, and 1.69$\times 10^{23}$ s$^{-1}$, respectively. The dust-to-gas mass ratio value is estimated to be around 2, suggesting a dust-rich composition. Based on the gas composition and the $Afρ$ value, we classify 7P/Pons-Winnecke as having a typical composition for Jupiter Family comets, with some C$_3$ depletion. Given the limited previous knowledge, our work contributes to expanding the understanding of the activity and characteristics of 7P/Pons-Winnecke.
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