来自73 P/Schwassmann-Wachmann 3彗星的近同时光学和近红外光度测量和偏振测量的尘埃粒子碎裂证据
Evidence of Fragmenting Dust Particles from Near-Simultaneous Optical and Near-IR Photometry and Polarimetry of Comet 73P/Schwassmann-Wachmann 3
摘要：
我们报告成像偏振的B段和C段的彗星73 P/Schwassmann-Wachmann 3在I和H带通在太阳相位角约35和85度。偏振的程度是典型的活跃彗星，但比预期的彗星家族更大。在约35度的相位角下，偏振颜色为微红色（dP/dL = +1.2 +/-0.4），在约85度的相位角下为中性或微蓝色。在2006年5月11日至13日的最接近过程中，观测在核心处达到了35公里的分辨率。在距离核心的前50 - 200公里内，这两个部分明显偏离了1/rho的表面亮度。辐射驱动的尘埃动力学的模拟可以重现一些观察到的彗发形态，但只有广泛的分布的初始尘埃速度（至少是一个因素的10）为一个给定的颗粒半径。颗粒聚集体的破碎和碎裂能够再现垂直于太阳-彗星轴的观测剖面，但沿该轴（进入尾部）的观测结果不太吻合。所需的破碎是显着的，在平均颗粒聚集体尺寸减少约10倍。这两个过程的结合可能解释彗星的表面亮度轮廓。
英文摘要：
We report imaging polarimetry of segments B and C of the Jupiter-family Comet 73P/Schwassmann-Wachmann 3 in the I and H bandpasses at solar phase angles of approximately 35 and 85deg. The level of polarization was typical for active comets, but larger than expected for a Jupiter-family comet. The polarimetric color was slightly red (dP/dL = +1.2 +/- 0.4) at a phase angle of ~ 35deg and either neutral or slightly blue at a phase angle of ~ 85deg. Observations during the closest approach from 2006 May 11-13 achieved a resolution of 35 km at the nucleus. Both segments clearly depart from a 1/rho surface brightness for the first 50 - 200 km from the nucleus. Simulations of radiation driven dust dynamics can reproduce some of the observed coma morphology, but only with a wide distribution of initial dust velocities (at least a factor of 10) for a given grain radius. Grain aggregate breakup and fragmentation are able to reproduce the observed profile perpendicular to the Sun-Comet axis, but fit the observations less well along this axis (into the tail). The required fragmentation is significant, with a reduction in the mean grain aggregate size by about a factor of 10. A combination of the two processes could possibly explain the surface brightness profile of the comet.
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