174P/Echeclus: a strange case of outburst
174P/Echeclus: a strange case of outburst
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174P/Echeclus：一个奇怪的爆发案例
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发表时间：
2007
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通讯作者：
P. Rousselot
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作者：
P. Rousselot
上下文现在已知有超过10颗半人马座在大日心距离（即5 - 13 Au）有彗星活动。在这些天体中，174 P/Echeclus在距离太阳13 Au处显示出彗星活动，这是一个独特的例子，因为：（i）它爆发的幅度，（ii）彗星活动的来源似乎与Echeclus本身不同。目标。本文旨在调查导致这一不寻常爆发的物理条件。其目的也是量化这种现象，并为其建模提供观测约束。方法.我们使用不同望远镜的观测结果，在爆发之前，期间和之后进行。我们在2006年3月23日和30日用8.2米的ESO甚大望远镜和FORS 1仪器进行了主要观测。它们由可见光图像和光谱组成。结果我们的主要结果是：（i）与Echeclus本身不同的彗星源，其亮度分布与漫射源兼容;（ii）总尘埃产生率Q dust $\simeq $86 kg s-1和参数Af\rho\simeq $10 000 cm;（iii）没有发射线（CN和C2）可在可见光范围内检测到;（iv）CN和C 2生成速率的上限分别为3.8times10 25和10 26分子s;（v）在爆发之前，我们没有探测到Echeclus的卫星M R $\simeq $26;（vi）产生彗发的物体的直径上限约为8公里;（vi）一年后，即2007年3月，我们没有探测到彗星活动。
Context. More than ten Centaurs are now known to have cometary activity at large heliocentric distance (i.e. $\simeq$5-13 AU). Among these objects, 174P/Echeclus which showed cometary activity at 13 AU from the Sun, is a unique case, because of: (i) the amplitude of its outburst, (ii) the source of cometary activity that appears distinct from Echeclus itself. Aims. This paper aims at investigating the physical conditions that have led to this unusual outburst. The purpose is also to quantify this phenomenon and to provide observational constraints for its modeling. Methods. We use observations from different telescopes, performed before, during, and after the outburst. We performed the main observations on March 23 and 30, 2006, with the 8.2-m ESO Very Large Telescope and FORS 1 instrument. They consist of visible images and spectra. Results. Our main results are: (i) a cometary source distinct from Echeclus itself that presents a brightness distribution compatible with a diffuse source; (ii) a total dust production rate Q dust $\simeq$ 86 kg s -1 and a parameter $Af\rho\simeq$ 10 000 cm; (iii) no emission lines (CN and C 2 ) can be detected in the visible range; (iv) the upper limits for the CN and C 2 production rates are $\simeq$3.8$\times$10 25 and $\simeq$10 26 molecules s -1 respectively; (v) we detected no Echeclus' satellite before the outburst up to M R $\simeq$ 26; (vi) the upper limit for the object generating the coma is about 8 km in diameter; (vi) and we detected no cometary activity one year later, in March 2007.