Exploring the rapid variability of pulsating white dwarfs and cataclysmic variables

将在阿帕奇点天文台3.5米望远镜上建造一个用于测量可变物体光度的高速相机，并用于进行与白矮星脉动有关的几个项目。这些包括：1)通过斯隆数字巡天（Sloan Digital Sky Survey）发现的脉动大质量白矮星的观测，这将被用于（viaasteroseismology）确定这些恒星是否已经结晶以及在何种程度上结晶。结晶在确定白矮星冷却时间（这反过来有助于确定银河系及其组成部分的年龄）方面起着重要作用，也是中子星和脉冲星外壳的一个可能但鲜为人知的组成部分。2)斯隆数字天空调查还发现了150多个新的灾难性变量，其中一些包含一个脉动白矮星。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），这将反过来用于探测具有不同进化历史的白矮星的内部。3)超短周期（小于1小时）的突变变量（称为dam CVn二进制）将在斯隆发现的候选变量中搜索。一个已知的日蚀AM CVn将被长期监测，以测量半径，并寻找可能归因于引力辐射的轨道变化。在实施这个项目的过程中，一名研究生将接受天文仪器构造和脉动白矮星科学方面的培训。在这里建造的仪器也将用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），并将提供给所有使用阿帕奇点3.5米望远镜的观测者。

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.