Asteroseismology of Compact Objects

Winget，DonaldWhole Earth Telescope（WET）项目涉及世界各地的十几个天文台，它们协调观测白色矮星。 在一个为期数周的国际活动中，目标恒星被24小时观察。 从这些光度变化的连续记录中，可以检测到许多不同的振荡频率。 每一个都与恒星内部给定的深度、不透明度、密度和电离状态直接相关。 对所观察到的频率进行详细分析，可以获得任何其他方法都无法实现的高精度冷却速率、成分和质量。 类似于地球内部的地震研究，星震学提供了对恒星内部理论模型的少数观测验证之一。 在迄今为止研究的所有时间尺度上--从数小时到数年--都发现了白色矮星脉动幅度的变化。 模型所暗示的星星的基本结构保持稳定，但在改进的观测数据中出现了额外的振幅调制，这表明当前的模型在重要方面是不完整的。 该项目将监测这些正在进行的变化，并寻找数据中的模式。 其主要重点是努力改进理论模型，特别是结晶，H和He气氛层厚度，和内部C/O丰度的影响。

ABSTRACTAST-9876730Winget, DonaldThe Whole Earth Telescope (WET) project involves over a dozen observatories around the world in coordinated observational campaign to observe white dwarfs. During a given multi-week international campaign, target stars are observed around-the-clock. From these continuous records of photometric variability, many different frequencies of oscillation can be detected. Each is related directly to a given depth, opacity, density, and ionization state in the stellar interior. Detailed analysis of the frequencies observed yields high precision cooling rates, composition and masses that are unachievable by any other means. Analogous to earthquake studies of the Earth's interior, asteroseismology provides one of the few observational verifications of theoretical models of stellar interiors. Variability in pulsation amplitudes of white dwarfs has been found on all of the timescales studied to date-from hours to years. The basic structure of the star implied by the models remains stable, but additional amplitude modulation appears in the improved observational data, suggesting that current models are incomplete in significant ways. This project will monitor these ongoing changes and look for patterns in the data. Its primary focus is the effort to improve the theoretical models, especially the effects of crystallization, H and He atmosphere layer thickness, and interior C/O abundance.