Isotopic, elemental, and structural analysis of presolar matter

在原始陨石、行星际尘埃粒子和NASA星尘任务收集的彗星样本中都发现了太阳系前颗粒，即太阳形成前的颗粒。它们是通过高度反常的同位素组成来识别的，这表明它们在末期恒星周围凝聚，这些恒星在巨大爆炸或恒星风增强期间喷射出这种物质。现代分析工具可以对单个的太阳系前颗粒及其成分进行调查，从而揭示恒星内部发生的过程的证据。我们打算用TOF-SIMS、TEM和NanoSIMS原位研究不同类型的原始太阳系样品中的太阳系前颗粒的化学和结构。我们的分析将集中在太阳系早期物质中的太阳系前颗粒是如何结合的，以及它们如何存活到现在。特别是，NASA前往彗星Wild 2的星尘任务的样本是这项研究中必不可少的，这是自月球任务以来太空任务返回实验室进行分析的第一个外星固体样本。我们将获得太阳系起始物质的元素、同位素和矿物学组成，以确定太阳系起始物质的恒星来源，并描绘可能涉及彗星颗粒的恒星、星际和原行星过程。

Presolar grains, or grains originating prior to the formation of the Sun, have been found in primitive meteorites, interplanetary dust particles, and in the cometary samples collected by the NASA mission Stardust. They are identified by their highly anomalous isotopic composition, which is indicative of their condensation around final stage stars, which eject such material in giant explosions or during increased stellar winds. Modern analytical tools permit the investigation of individual presolar grains and their constituents, which reveal evidence of the processes occurring within stars. We intend to study in situ with TOF-SIMS, TEM, and NanoSIMS the chemistry and structure of presolar grains in the various types of primitive Solar System samples. Our analyses will focus on how presolar grains are incorporated into early Solar System materials and their survival to present time. In particular, samples from NASA's Stardust mission to comet Wild 2, the first extraterrestrial solid samples returned for laboratory analysis by a space mission since the lunar missions, are essential in this study. We will obtain the elemental, isotopic, and mineralogical composition of presolar grains in order to identify the stellar sources of the starting material of the Solar System, and to delineate the stellar, interstellar, and protoplanetary processes in which cometary grains may be involved.