关于17P爆发的一种较好的解释（By J Bortle）
I would have to say that the spectacular event we are currentlywitnessing in conjunction with P/Holmes is on a scale far beyond what
simply can be explained by any normal outgassing, yet still not so
totally cataclysmic as to destroy the comet. Remember, P/Holmes did
this in 1892 as well and has survived down to today. At the moment,
P/Holmes appears about 1,000,000 times brighter than it did 48 hours
ago, so whatever caused this mega-outburst would have to be on a truly
grand scale.
While there may be other possible explanations, I think one I saw
proposed quite a number of years ago (perhaps by Z.Sekanina?) to
explain cometary mega-outbursts, still seems the most plausible in my
eyes. It is perhaps even more so today since we have, via space probe,
actually seen (and sampled!) some cometary nucleii close up.
The explanation has been bolstered by the fact that we now know
cometary nucleii come in a considerable range of densities, running the
gamut from a fluffy snow and ice matrix, to an accumulation of "dust
bunnies"(!). Toward the less dense end of this broad spectrum, one can
conceive of a low density nucleus that, over time and through
outgassing, develops a large region with a very fragile fairly castle
or highly tenuous honeycomb-like structure.
Cometary nucleii being irregular in shape, rotation or perhaps even the
minute gravity of the nucleus itself, will create increasing shear
forces if the area is remote from the center of rotation. At some point
the highly fragile bonds connecting the honeycomb of material will
reach the failing point and a collapse, or more likely a sudden
crushing/consolidat ing event on a grand scale perhaps covering several
square kilometers wide and deep, will occur. This crushing collapse
would expel a truly gigantic volume of dust in the process. However,
such an event would not necessarily be nearly so catastrophic as to
cause the nucleus to disrupt or fragment. Actual loss of total mass
might be only a few percent.
Such a scenario also fits well with the observed occurence of a
secondary brightening some weeks after the first event. Those who are
familiar with terrestrial structural collapse situations are aware that
the primary event often leaves a large amount of instability in the
material involved. This remaining instability will only remain for a
short time before a further adjustment toward stability occurs,
resulting in a major second collapse, with an outward physical
appearance very similar to that of the initial event.
Additionally, such a mega-outburst would be almost totally dust-driven
and this fits very nicely with the B-V color index we see in P/Holmes'
coma and nucleus currently.
JBortle Please give the source if it's not a private mail.
Q. 弄点中文吧
看着吃力::070821_13.jpg:: B-V滤镜？::070821_11.jpg:: 谁翻译给我看啊。::070821_03.jpg:: 要推广普通话！凑字凑字凑字凑字凑字 英文高手，这会儿，怎么也都不见了？……::42:: 连南十字版发言都要说普通话，怎么摄影版反而用鸟语呢::0015:: 抗议LZ转载E文不给中文摘要的做法，搭车斜视小龙也不给中文的做法 翻译啊，极度需要翻译啊::070821_18.jpg:: 这东西就是学英语也不太容易看，专业名词太多了，我也看不太懂::070821_05.jpg:: ::070821_05.jpg:: 厄 大家稍等下 我在CMCN 给出中文翻译
中国彗星和流星资讯网
http://cmcn.y234.cn/
回复 #14 佛山陈谷 的帖子
太感谢了！（同时谢谢13楼，期待。。。）合着是山体滑坡+天崩地陷。。。 引用: 活动星图 在文中说道:
抗议LZ转载E文不给中文摘要的做法，搭车斜视小龙也不给中文的做法
这是professional pieces，用英文来得理直气壮。如果有不懂英文的各位可以学嘛，或者也可以不看，反正业余天文我就不会用英文。 呵呵
中文看到了
我也是这么解释这次爆发的：
http://www.astronomy.com.cn/bbs/thread-81070-5-1.html
吻合 原帖由 小龙·哈勃 于 2007-10-26 07:28 PM 发表 http://www.astronomy.com.cn/bbs/images/common/back.gif
这是professional pieces，用英文来得理直气壮。如果有不懂英文的各位可以学嘛，或者也可以不看，反正业余天文我就不会用英文。
囧神在上。。。
来不及了。。。 原帖由 佛山陈谷 于 2007-10-26 19:46 发表 http://www.astronomy.com.cn/bbs/images/common/back.gif
彗星由17.8变为2等,一听到这消息,很容易联想到这是一次撞击事件.认为它的高亮度仅会保持很短的一段时间,所以昨晚就抓紧时间观测了.怎料昨晚看到的彗星仍然是2等.当时不禁对自己认为很肯定的"撞击"说打了一个大问号. ... 呵呵 我觉得翻译成坍塌不太好我觉得他的意思更接近一个内部实心的物体外部像棉花糖一样弥散着很多物质
随着时间的堆积 远离实心部分的棉花丝突然瓦解纷纷被抛出去 然后亮度迅速上升 这部分密度很低质量也很少 但是引起的亮度变化很大
这篇文章 J似乎想强调的是 这种爆发与内部结构的巨大变动关系不大 不会伤害到内部结构 所以不会裂解 甚至和裂解无关
就是 只是棉花糖少了 但是内部实心几乎没有什么变化
坍塌给人的感觉是内部结构的变化 只是变化没有大到分裂 那似乎又回到传统彗星爆发的解释上了
不知道你的看法如何 呵呵::42::
有点忙 有时间我全文翻译下
[ 本帖最后由 赵晋_木木 于 2007-10-27 08:16 编辑 ] 难下定论。国外也有其他的几种解释，比如Hoenig认为是彗星内部什么气体压缩造成的。
我就都不大同意。他们的解释都得假定一个前提：17P彗星构造十分特殊。这几天做dust production rate和近核喷流来看看吧。 的确是一个比较合理的说法
刚才处理图片的时候发现今天早上拍的17P看起来像是分裂了
不知道是不是，大家看看
D50+BORG76ED
ISO 400，4 seconds at 01:29
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