The archaeology of galaxies in the local group

在过去的十年里，我（和我的研究团队）一直是哈勃太空望远镜的主要用户。我们已经非常成功地获得了大量的时间（在公开竞争中）来调查我们银河系中的一些古老的星星团。研究的主要重点是确定这些系统的年龄，然后利用这些信息来收集我们银河系何时以及如何形成的线索。我们开发了一种新的年龄测定技术，包括精确测量“死亡”恒星的冷却速度，并将其用作时钟。到目前为止，我们已经探索了银河系晕中的两个星团，并确定它们的年龄大致相同，而且非常古老（120亿年）。由于我们非常确定宇宙本身只有137亿年的历史，我们现在知道我们的银河系（可能还有大多数其他星系）是在大爆炸后不久形成的。我们还将精密时计应用于我们银河系的圆盘上，该圆盘包含其壮丽的旋臂。在这里，我们了解到，这个银河系的组成部分是显着年轻-约40亿年。目前，我们正在获得一组新的哈勃数据，该数据涉及一个星星星团，该星团包含与银河系中央隆起相似的恒星。这个系统的年龄将提供我们的银河系是由内而外形成（凸起更老）还是由外而内形成（凸起更年轻）的证据。

Over the past decade I ( and my research team) have been major users of the Hubble Space Telescope. We have been extremely successful in obtaining very large amounts of time (in open competition) to survey a number of ancient star clusters in our Galaxy. The main focus of the research is to determine the ages of these systems and then use that information to glean clues as to when and how our Milky Way Galaxy was formed. We have developed a new age-dating technique that involves measuring precisely the cooling rate of "dead" stars and using this as a clock. Thus far we have explored two clusters in the halo of our Galaxy and have determined that both are about the same age and very old (12 billion years). Since we are quite sure that the Universe itself is only 13.7 billion years old, we now know that our Galaxy (and likely most others) formed rather soon after the Big Bang. We have also applied our chronometer to the disk of our Galaxy which contains its magnificent spiral arms. Here we learned that this Galactic component is significantly younger - by about 4 billion years. Currently we are in the process of obtaining a new set of Hubble data on a star cluster that contains stars similar to those in the central bulge of our Galaxy. An age for this system will provide evidence on whether our Galaxy formed inside out (bulge is older) or from the outside in (bulge is younger).