2023年7月彗星12P/Pons-Brooks的爆发：尘埃彗发与弧状结构的观测和建模
The July 2023 Outburst of Comet 12P/Pons-Brooks: Observations and Modeling of Dust Coma and Arc Structure
- National Astronomical Observatory of Japan（日本国立天文台）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究观测并建模了彗星12P/Pons-Brooks在2023年7月的爆发，确定了三次爆发的膨胀速度，并发现7月爆发产生的弧状结构由中纬度活动区喷射的尘埃组成，其膨胀速度较慢，模型计算成功重现了观测结果。
AI中文摘要：
我们对自2023年7月以来经历多次爆发的彗星12P/Pons-Brooks进行了连续成像观测。在这些爆发中，我们确定了三次爆发的尘埃彗发膨胀速度和发生时间。2023年7月20.39±0.05日的爆发膨胀速度为207.5±0.1 [单位]。2023年11月14.52±0.10日的爆发膨胀速度为305.8±13.7 [单位]，2024年4月2.23±0.06日的爆发膨胀速度为408.9±14.3 [单位]。在7月的爆发期间，除了各向同性膨胀的尘埃彗发外，还观测到一个半圆形结构（弧状结构）。该结构在两个月内（直至9月中旬）以较外部彗发更慢的速度（52.0±1.7 [单位]）膨胀，且形状保持不变。我们假设该弧状结构由爆发期间从彗核中纬度活动区喷射出的尘埃组成，且旋转轴接近视线方向。我们进行了模型计算以重现该结构。结果表明，假设旋转轴方向为RA = [值]，Dec = [值]至[值]，且7月爆发期间活动区纬度为[值]时，观测结果得到很好的重现。爆发的活跃期短于旋转周期，约为旋转周期的0.7倍。由于构成弧状结构的尘埃粒子未因太阳辐射压力而消散，我们推断它们是辐射压力与重力之比为[值]的尘埃，对应尘埃粒子大小约为10 [单位]。
英文摘要：
We conducted continuous imaging observations of comet 12P/Pons-Brooks, which has experienced multiple outbursts since 2023 July. Among these, we determined the dust coma expansion velocities and the occurrence times for three outbursts. The outburst on 2023 July 20.39$\pm$0.05 had an expansion velocity of 207.5$\pm$0.1 m s$^{-1}$. The outburst on 2023 November 14.52$\pm$0.10 had an expansion velocity of 305.8$\pm$13.7 m s$^{-1}$, and the outburst on April 2.23$\pm$0.06, 2024 had an expansion velocity of 408.9$\pm$14.3 m s$^{-1}$. During the July outburst, in addition to the isotropically expanding dust coma, a semicircular structure (arc structure) was observed. This structure expanded without changing shape over two months, until mid-September, at a slower velocity of 52.0$\pm$1.7 m s$^{-1}$ compared to the outer coma. We hypothesize that this arc structure consists of dust ejected over a certain period during the outburst from an active region at mid-latitudes on the comet's nucleus, with a rotation axis near the line of sight. We performed model calculations to reproduce the structure. As a result, we found that the observations were well reproduced by assuming a rotation axis direction of RA = $85^\circ$, Dec = $-30^\circ$ to $-35^\circ$ and an active region latitude of $70^\circ$ during the July outburst. The active period of the outburst was shorter than the rotation period, approximately 0.7 times the rotation period. Since the dust particles comprising the arc structure escaped dissipation due to solar radiation pressure, we infer that they are dust with a ratio of radiation pressure to gravity of $β\sim 0.1$, which corresponds to a dust particle size of about $10\,μ\mathrm{m}$.
