Laboratory Spectroscopy in Support of Studies of Metal-Poor Galactic Halo Stars

Stephen Thorset加州大学圣克鲁斯分校脉冲星干涉测量法摘要银河系包含1亿到10亿颗中子星，这些中子星是超新星爆炸后遗留下来的，超新星爆炸使重元素分布在整个银河系。了解这些星的分布和性质对于理解银河系的化学演化、约束超新星爆炸的动力学以及阐明各种类型的奇异致密双星系统的形成和生命周期都是非常重要的，而对中子星星分布的最直接的约束来自于对它们的弛豫和自行的测量。在大多数情况下，这些测量只能对中子星的子类进行，它们在无线电波长上发光：无线电中子星。即便如此，距离最近的无线电脉冲星的距离也是距离最近的恒星的100倍，视差和自行的影响也相应较小。只有大约1%的天文学家测量过恒星的松弛，只有大约10%的天文学家甚至粗略地测量过恒星的自行。在这里，Thorsett和Dewey将继续他们非常成功的干涉测量计划，使用甚大天线阵和甚长基线天线阵对大样本的恒星进行非常精确的天体测量，并解决几个重要的问题。在接下来的三年里，这项研究将测量中子星的出生速度分布，其精度足以限制高速和低速尾部（分别用于理解超新星的不对称性和球状星团中中子星的保留），并将提高对局部脉冲星距离和局部脉冲星出生率的理解。该计划主要基于正在进行或已经批准的观察结果。调查将包括学生培训和支持，项目数据构成博士学位的基础。论文学生和主要研究人员也将保持正式的联系，并参加与探索科学博物馆和COSMOS夏季计划的活动。合作研究员杜威也是加州大学加州分校Calspace分部的教育和公共推广主任，提供进一步的推广机会。外部科学调查也将通过网络和传统出版物来实现这里收集的数据。其中包括确定伽马射线大面积空间望远镜和其他卫星任务的主要目标清单，以及解释多波长脉冲反射数据。局部脉冲星的出生率与大质量星星的出生率的比较，限制了II型超新星祖先的性质。脉冲星的速度测量不仅约束了其诞生事件的模型，而且是双星系统总体合成研究的重要输入参数。为确定甚长基线阵列测量的校准源而进行的观测包括河外源21厘米快照的大型测量样本。

AST-0506453Stephen ThorsettUniversity of California-Santa CruzPulsar InterferometryABSTRACTThe Milky Way contains between 100 million and one billion neutron stars, left behind after thesupernova explosions that distributed heavy elements throughout the Galaxy. Understanding thedistribution and properties of these stars is important for understanding Galactic chemical evolution,as well as for constraining the dynamics of supernova explosions and for illuminating the formationand life-cycles of various type of exotic compact binary systems.The most direct constraints on the neutron star distribution come from measurements of parallaxesand proper motions. In most cases, these measurements can be made only for the subclass ofneutron stars that are luminous at radio wavelengths: the radio pulsars. Even then, the closest radiopulsars are a hundred times the distance of the closest stars, and the effects of parallax and propermotion are correspondingly smaller. Only about 1% of pulsars have measured parallaxes and onlyabout 10% of pulsars have even crudely measured proper motions.Here, Thorsett and Dewey will continue their highly successful interferometry program, using theVery Large Array and the Very Long Baseline Array to make very precise astrometricmeasurements of a large sample of pulsars and address several important questions. Theinvestigation will, over the next three years, measure the birth velocity distribution of neutron starswith sufficient accuracy to constrain both the high and low velocity tails (needed to understandsupernova asymmetries and retention of neutron stars in globular clusters, respectively), and willimprove understanding of local pulsar distances and the local pulsar birthrate. This plan is basedprimarily on observations that are either underway or already approved.The investigations will include student training and support, with project data forming the basis of aPh.D. thesis. The student and the principle investigators will also maintain formal connections andparticipate in activities with the Exploratorium science museum and the COSMOS summerprogram. Co-investigator Dewey is also Education and Public Outreach Director for the UCSCbranch of Calspace, providing further outreach opportunities.External science investigations will also be enabled by both web and traditional publication of thedata gathered here. These include identification of the primary target lists for The Gamma-ray LargeArea Space Telescope and other satellite missions, and interpretation of multiwavelength pulsaremission data. Comparison of the local pulsar birthrate to the massive star birthrate, constrains theproperties of the progenitors of Type II supernovae. Pulsar velocity measurements not onlyconstrain models of their birth events, and are important input parameters to population synthesisstudies of binary systems. The observations made to identify calibration sources for the Very LongBaseline Array surveys comprise a large survey sample of 21-cm snapshots of extragalactic sources.