The evolution of the protosolar disk

原太阳盘的演化

基本信息

批准号：
PP/D001714/1
负责人：
Sara Russell
金额：
$ 21.4万
依托单位：
Natural History Museum
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=PP%2FD001714%2F1
关键词：
evolution protosolar disk

项目摘要

The aim of this proposal is to determine the formation environment of the solid materials that later made up the planets in the Solar System. From studies of meteorites, combined with astronomical observations and modelling, we believe that the planets formed from a disk around the Sun (the protosolar disk) composed of dust and gas. Much of this disk spiralled into the forming Sun, but some remained, that probably accreted firstly into mm-cm sized solid lumps that went on to become part of bigger and bigger objects and eventually into the terrestrial planets. These millimetre-sized objects have been preserved inside some meteorites and are called chondrules. By looking at them in detail we can learn about what the disk was made of, how these first solids formed and how the conditions in the disk may have evolved. The chemistry / specifically, the abundance of each of the elements- of chondrules can tell us something about their origins and evolution. Each element has a different chemical character, and their behaviour will be dictated by conditions such as temperature, pressure and the amount of oxygen and hydrogen present. By measuring the abundance of as many elements as possible, we can build up a picture of the conditions in which the chondrules formed, as well as an idea about what the chondrule precursors were made of. Some elements have more than one isotope- nuclei of the same element that have different mass. Isotopes of a single element will have broadly the same chemical properties, but will slightly differ in their physical properties, for example their volatility. We plan to measure the isotopic composition of the four most common elements silicon, iron, oxygen and magnesium in chondrules, we can build up a better picture of their history. In addition to thermal history, a couple of the elements we propose to measure for isotopes have some special properties. The oxygen isotopic composition of solar system objects is very diverse, and points to an initial variation in the composition of solar system oxygen. This initial heterogeneity can be used as a tracer of the original composition of the solid. Magnesium isotopes are also particularly interesting for another reason. The isotope 26Mg can be radiogenic, formed from the decay of the radioactive, and now extinct, isotope 26Al. Monitoring the abundance of 26Mg can tell us something about the distribution of 26Al, a potentially critical heat source, in the early solar system. These measurements can also potentially tell us something about timescales / early-formed objects are likely to have contained more 26Al when they solidified than solids that formed when most of the 26Al had already decayed away. Measuring silicon and iron isotopes is somewhat more exploratory / there are not very many measurements already reported of these two elements, and so we do not already have a good picture of what diversity in isotopic composition we can expect. It is likely that these isotopes can be used as tools to determine the thermal history of chondrules and how they interacted with the neighbouring gas (that may have contained some Fe and Si in gaseous form). There is a lack of accurate, systematically acquired data about the chemistry and isotopic composition of these objects, and especially of several of these parameters on the same object. By building up a database of the major and minor element composition of these objects, and the isotopic composition of the major elements oxygen, silicon, iron and magnesium, we can determine the diversity of compositions of material in the accretion disk. This in turn will allow us to determine the degree of mixing and turbulence in the disk, the timescales of formation of disk solids and the thermal history of these objects. We can use this information to compare to astronomical disk observations, and assess if there was anything unusual about the evolution of our own planetary system.

该提案的目的是确定固体材料的形成环境，后来构成了太阳系中的行星。从对陨石的研究，结合天文观测和建模，我们认为，这些行星是由太阳周围（原始磁盘）形成的行星。这些磁盘的大部分螺旋式呈阳光呈阳光，但有些磁盘仍然存在，可能首先会积聚成MM-CM尺寸的实心团块，后来成为越来越大的物体的一部分，并最终成为地球行星的一部分。这些毫米大小的物体已保存在某些陨石中，称为软骨。通过详细查看它们，我们可以了解磁盘的制成，这些固体如何形成以及磁盘中的条件如何发展。化学 /具体来说，每个元素的丰度都可以告诉我们一些有关它们的起源和进化的信息。每个元素具有不同的化学特征，其行为将由温度，压力以及氧气和氢的量等条件决定。通过测量尽可能多的元素的丰富度，我们可以建立一幅形成软骨形成的条件的图片，以及关于软骨前体的想法。某些元素具有具有不同质量的同一元素的一个以上的同位素核。单个元素的同位素将具有相同的化学特性，但其物理特性会略有不同，例如它们的挥发性。我们计划测量在软骨中硅，铁，氧和镁的四个最常见元素的同位素组成，我们可以更好地了解它们的历史。除热史外，我们提出的几个要测量同位素的元素具有一些特殊的特性。太阳系对象的氧同位素组成非常多样化，并指出太阳系氧的组成的初始变化。这种初始异质性可以用作固体原始组成的示踪剂。由于另一个原因，镁同位素也特别有趣。同位素26mg可以是放射性的，它是由放射性的衰减形成的，现在已经灭绝，同位素26AL。监测26mg的丰度可以告诉我们一些关于早期太阳系中26AL的分布，这是一种潜在的关键热源。这些测量值还可能告诉我们一些有关时间标准 /早期形成的物体固化时可能包含26AL的东西，而与26AL中大多数已经衰减时形成的固体相比，它们的固体固化时可能会含有更多。测量硅和铁同位素的探索性或没有太多的测量已经报道了这两个元素，因此我们还没有很好地了解我们可以期望的同位素组合物的多样性。这些同位素可能被用作确定软骨的热史以及它们如何与相邻气体相互作用的工具（可能以气态形式含有Fe和Si）。缺乏有关这些对象的化学和同位素组成的准确，系统获取的数据，尤其是在同一对象上的其中几个参数的数据。通过建立这些物体的主要元素组成和次要元素组成的数据库，以及主要元素氧，硅，铁和镁的同位素组成，我们可以确定积聚磁盘中材料组成的多样性。反过来，这将使我们能够确定磁盘中的混合和湍流程度，磁盘固体形成的时间尺度以及这些物体的热历史记录。我们可以使用这些信息与天文磁盘观测值进行比较，并评估我们自己的行星系统的演变是否有什么不同寻常的。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Insights into the thermal history of AOAs in carbonaceous chondrites

深入了解碳质球粒陨石中 AOA 的热历史

DOI：
发表时间：
2007
期刊：
METEORITICS & PLANETARY SCIENCE
影响因子：
2.2
作者：
Howard L. E.
通讯作者：
Howard L. E.

Origin and chronology of chondritic components: A review

DOI：
10.1016/j.gca.2008.09.039
发表时间：
2009-09-01
期刊：
GEOCHIMICA ET COSMOCHIMICA ACTA
影响因子：
5
作者：
Krot, A. N.;Amelin, Y.;Yin, Q. -Z.
通讯作者：
Yin, Q. -Z.

A nebula setting as the origin for bulk chondrule Fe isotope variations in CV chondrites

DOI：
10.1016/j.epsl.2010.05.029
发表时间：
2010-08
期刊：
Earth and Planetary Science Letters
影响因子：
5.3
作者：
D. Hezel;A. Needham;R. Armytage;B. Georg;R. Abel;E. Kurahashi;B. Coles;M. Rehkämper;S. Russell
通讯作者：
D. Hezel;A. Needham;R. Armytage;B. Georg;R. Abel;E. Kurahashi;B. Coles;M. Rehkämper;S. Russell

EVOLUTION OF CHONDRULE MG ISOTOPE COMPOSITIONS DURING MULTIPLE HEATING EVENTS

多次加热事件期间球粒 MG 同位素组成的演变