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arXiv 1409.8657astro-ph.EP
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迷你克鲁兹家族彗星在哪里

Where are the Mini Kreutz-family Comets?

Quan-Zhi Ye, Man-To Hui, Rainer Kracht, Paul Wiegert

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摘要：

Kreutz族掠日彗星包含2~000多颗已知彗星，其中许多被认为是$\sim 100$ ~m大小（\textit{mini~comets}），并且仅在小日心距离（$r_\mathrm{H}$）上使用空间SOHO/STEREO航天器进行了研究。为了了解小型Kreutz彗星的增亮过程，我们在SOHO/STEREO观测的指导下，在中等$r_\mathrm{H}$上使用CFHT/MegaCam进行了一次调查。我们确定了两个彗星，应该在我们的搜索区域，但没有检测到，这表明彗星要么遵循了陡峭的增亮率在以前报道的快速增亮阶段（\textit{brightening~burst}），或增亮爆发开始早于预期。对覆盖$\sim 1$ ~AU的5颗Kreutz彗星近日点前光变曲线进行了合成分析。我们观察到的光变曲线的显着差异，可以用来粗略地将它们分为两种类型：C/Ikeya Seki和C/SWAN遵循规范的$r_\mathrm{H}^{-4}$，而其他人遵循$r_\mathrm{H}^{-7}$。特别是，C/SWAN似乎经历了一次爆发（$Δm>5$ ~mag）或快速增亮（$n\gtrsim11$），介于$r_\mathrm{H}=1.06$ ~AU和$0.52$ ~AU之间，并显示出与其他明亮的克鲁兹彗星相比结构/成分差异的迹象。我们还发现证据表明，克鲁兹彗星作为一个人口失去其质量的效率低于动态新彗星，C/ISON，并相对缺乏物种，驱动C/ISON的活动在大$r_\mathrm{H}$。在不同波长下对C/STEREO的同步观测也表明，像CN这样的蓝向物质可能是增亮爆发的主要驱动力，而不是以前认为的钠。

英文摘要：

The Kreutz family of sungrazing comets contains over 2~000 known members, many of which are believed to be under $\sim 100$~m sizes (\textit{mini~comets}) and have only been studied at small heliocentric distances ($r_\mathrm{H}$) with space-based SOHO/STEREO spacecraft. To understand the brightening process of mini Kreutz comets, we conducted a survey using CFHT/MegaCam at moderate $r_\mathrm{H}$ guided by SOHO/STEREO observations. We identify two comets that should be in our search area but are not detected, indicating that the comets have either followed a steeper brightening rate within the previously-reported rapid brighten stage (the \textit{brightening~burst}), or the brightening burst starts earlier than expected. We present a composite analysis of pre-perihelion light-curves of five Kreutz comets that covered to $\sim 1$~AU. We observe a significant diversity in the light-curves that can be used to grossly classify them into two types: C/Ikeya-Seki and C/SWAN follow the canonical $r_\mathrm{H}^{-4}$ while the others follow $r_\mathrm{H}^{-7}$. In particular, C/SWAN seems to have undergone an outburst ($Δm>5$~mag) or a rapid brightening ($n\gtrsim11$) between $r_\mathrm{H}=1.06$~AU to $0.52$~AU, and shows hints of structural/compositional differences compared to other bright Kreutz comets. We also find evidence that the Kreutz comets as a population lose their mass less efficiently than the dynamically new comet, C/ISON, and are relatively devoid of species that drive C/ISON's activity at large $r_\mathrm{H}$. Concurrent observations of C/STEREO in different wavelengths also suggest that a blue-ward species such as CN may be the main driver for brightening burst instead of previously-thought sodium.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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