彗星生自我们的太阳

Rojer

和星际尘埃有些关系的彗星尘埃的消息
http://www.nature.com/news/2006/061211/full/061211-14.html

==============================================


When scientists first analysed comet dust collected by the Stardust spacecraft earlier this year, they were surprised that the grains seemed to have all originated in very hot environments - the heart of a star (see 'Comet chasers get mineral shock'). Astronomers were confused at the idea that the star in question could be our own Sun. How was this material transported from the hot interior of our early Solar System to the cold, outer reaches where the comet actually coalesced? Their models of the Solar System, they feared, might have to be rethought.
当科学家年初首次分析由“星尘”号飞船收集的彗星尘埃时，为这些颗粒看上去全都起源自非常热的环境——一颗恒星中心所惊讶。天文学家所困惑的是这颗恒星可能就是我们的太阳。这些物质是如何从我们早期太阳系的内部转移到寒冷的外围地区的？而那里正是彗星成长的地方。他们担心现有的太阳系模型恐怕要重新考虑了。

An isotopic analysis of the grains has made that fear come true. A large chunk of comet Wild 2 does indeed come from the beginnings of our own Sun. But how it got there remains a mystery.
一项对这些颗粒的同位素分析让这种担心成真了。“怀尔特2”彗星的一大部分确实来自早期的太阳。但这些物质是怎么到达外围的就成了迷。

The samples, collected from a comet in 2004 and returned to Earth in January of this year, have revealed a mixed bag of material. "We have seen materials that predate the Solar System and were formed around other stars or in interstellar space," says Don Brownlee of the University of Washington in Seattle, who co-authored a raft of seven papers outlining the main results from Stardust to date in Science this week1-7. "But the surprising thing is that we also find large components that formed in the inner regions of the solar nebula."
这些样品于2004年采集自一颗彗星，并于今年一月返回地球，展现了一袋混杂的物质。Don Brownlee 说：“我们看到了前太阳系物质也就是形成其他恒星或存在于星际空间中的物质。但让人惊奇的是我们也发现了大量在太阳星云中心区域形成的成分。”

Just the one
只有一个

Only a single grain of dust found in the sample so far seems to have been sourced from a cold place beyond our Solar System many years before its birth. Prior to the Stardust mission there was a theory that the entire comet would be made of these pre-solar grains, but early analysis found none. "There was a sigh of relief when we found the grain," said Frank Stadermann, at Washington University in St Louis and part of the isotope analysis team. One such grain is better than none, when it comes to trying to understand where the comet came from.
迄今为止在样品中仅找到一个尘埃颗粒似乎是来自太阳系诞生之前许多年的寒冷场所。在“星尘”任务之前的一种理论是全部彗星都是由这些前太阳系颗粒制造的，但早期的分析一个也没发现。Frank Stadermann （来自华盛顿大学也是同位素分析小组的一部分）表示：“我们找到这个颗粒时松了口气。”在试图了解彗星起源的时候，有这么一个总比没有强。

Pre-solar grains are now estimated to make up a small part — only 100 parts per million — of the comet.
前太阳系颗粒估计填补了一小部分彗星成分——只有万分之一。

As for the material that came from our own solar nebula, how the material got as far out as Pluto (where the comet Wild 2 originated) remains a puzzle. It shows that the mixing of particles within our Solar System was far more extensive than expected, says Michael A'Hearn, who led the Deep Impact mission to probe a different comet in 2005.
至于来自我们太阳系星云的物质，是如何到达比冥王星还远的地方（“怀尔特2”起源之处）依旧是迷。 Michael A'Hearn 认为这表明太阳系中颗粒的混合要比预想的要广泛得多。

It also means that analysing a comet's material won't necessarily tell much about the bit of space where it was actually born. "This will make it much harder for us, in future, to say that the composition of a comet tells us uniquely about the place in the solar system where... the comet formed," says A'Hearn.
这也意味着分析一颗彗星的物质并不能确定它是在哪里诞生的。