Exploring the rapid variability of pulsating white dwarfs and cataclysmic variables

将在阿帕奇点观测站3.5米望远镜上建造一台用于可变物体测光的高速照相机，并用于开展与白色矮星脉动有关的几个项目。其中包括：1）通过斯隆数字巡天发现的脉动大质量白矮星的观测，将用于（通过星震学）确定这些恒星是否已经结晶以及结晶到什么程度。结晶在确定白色矮星冷却时间方面起着重要作用（这反过来又有助于确定银河系及其组成部分的年龄），也是中子星和中子星地壳的可能但知之甚少的组成部分。2)斯隆数字巡天还发现了150多个新的激变变星，其中一些包含一颗脉动的白色矮星。对这些恒星的计划观测将允许研究各种条件下的脉动（包括吸积，甚至可能在爆发期间），这反过来将被用来探测具有不同演化历史的白色矮星的内部。3)超短周期（小于1小时）的激变变星称为AM CVn双星，将在斯隆发现的候选变星中搜索。一个已知的食AM CVn将被长期监测，以测量半径和寻找可能归因于引力辐射的轨道变化。在执行这一项目时，一名研究生将接受建造天文仪器和脉动白色矮星科学方面的培训。这里建造的仪器也将有助于研究发生在短时间尺度上的天文事件（例如，磁活跃恒星之间的耀斑，寻找伽马射线爆发的变化，测量系外行星凌日等）and will be available提供to all observers观察者using使用the Apache阿帕奇Point点3.5 meter米telescope望远镜.

A high speed camera for photometry of variable objects on the Apache Point Observatory3.5-m telescope will be constructed and used to undertake several projects related to thepulsation of white dwarf stars. These include: 1) Observations of pulsating massive whitedwarfs discovered through the Sloan Digital Sky Survey which will be used (viaasteroseismology) to determine whether these stars have crystallized and to what extent.Crystallization plays an important role in determining white dwarf cooling times (whichin turn help date the age of the Galaxy and its components) and is also a likely but poorlyunderstood component of the crusts of neutron stars and pulsars. 2) The Sloan DigitalSky Survey has also identified over 150 new cataclysmic variables, some of whichcontain a pulsating white dwarf. Planned observations of these stars will allow the studyof pulsations across a variety of conditions (including accretion and possibly even duringoutburst) which will in turn be used to probe the interiors of white dwarfs with differentevolutionary histories. 3) Ultrashort period (less than 1hour) cataclysmic variables calledAM CVn binaries will be searched for among candidates discovered by Sloan. The oneknown eclipsing AM CVn will be monitored over a long term to measure radii and tosearch for orbital changes that may be attributed to gravitational radiation.In carrying out this project, a graduate student will be trained in the construction ofastronomical instruments and in the science of pulsating white dwarfs. The instrumentbuilt here will also be useful for studying astronomical events which occur on shorttimescales (e.g., flares among magnetically active stars, searching for variability ingamma ray bursts, measuring exo-planetary transits, etc.) and will be made available toall observers using the Apache Point 3.5-meter telescope.