Collaborative Research: Variable Circumstellar Disks: Prevalence, Timescales, and Physical Mechanisms

质量比太阳大许多倍的恒星并不多见，但自然界中几乎所有较重的元素都是由它们产生的。通过戏剧性的超新星爆炸，它们产生这种物质，并在整个银河系中释放出来，与形成下一代恒星和行星的物质混合。一类有趣的恒星被称为Be恒星，它们旋转得如此之快，以至于它们以某种方式释放出物质，然后形成围绕其赤道的圆盘。为了更好地了解这些圆盘是如何形成的，以及为什么它们偶尔似乎会消失，俄克拉荷马大学、洛厄尔天文台和托莱多大学的研究人员组成了一个团队，对这些系统进行了密集的研究。他们将使用一系列地面望远镜来观察这些事件，他们正在开发复杂的计算机代码来帮助解释这些观察结果。该计划将支持俄克拉荷马大学和托莱多大学的研究生，以及所有这三个机构的本科生。他们将开发符合国家教育标准的研究型天文表演。本科生将接受培训，以开发内容和进行推广，并使用便携式天文馆和数字投影仪将这些节目带到K-12学生的道路上。这些节目将免费发布以供其他场景使用。该程序将确定经典BE恒星的磁盘丢失和磁盘重建事件的时间尺度、相对流行率和物理机制。这些目标将通过对疏散星团中的Be星群体的盘丢失/更新事件的流行率进行统计评估，以及对活跃经历盘丢失/更新事件的单个Be星进行密集的多波长研究来实现。对最先进的辐射传输和流体力学模型代码的预测将与该计划中获得的数据进行比较，以测试已经提出的一系列情景，以解释在主星的生命周期中可能会产生和摧毁星盘。

Stars many times more massive than our Sun are rare, but they are responsible for producing nearly all of the heavier elements found in nature. Through dramatic supernova explosions, they produce and shed this material throughout the galaxy, mixing it with material out of which the next generation of stars, and planets, are formed. One interesting class of stars, known as Be stars, rotate so rapidly that they somehow shed material that then forms in a disk around their equators. In order to better understand how these disks are formed and why they occasionally seem to disappear, researchers at the University of Oklahoma, Lowell Observatory, and the University of Toledo have formed a team to carry out an intensive study of these systems. They will use an array of ground-based telescopes to observe these events, and they are developing sophisticated computer codes to aid the interpretation of these observations. This program will support graduate students at the University of Oklahoma and at the University of Toledo, as well as undergraduate students at all three institutions. They will develop research-based planetarium shows that satisfy state education standards. Undergraduates will be trained to develop content and conduct outreach and to take these shows on the road to K-12 students using a portable planetarium and a digital projector. These shows will be freely released for use in other settings.This program will determine the timescales, relative prevalence, and physical mechanisms of disk-loss and disk rebuilding episodes of classical Be stars. These goals will be accomplished by carrying out a statistical assessment of the prevalence of disk-loss/renewal episodes of populations of Be stars in open clusters, as well as intensive multi wavelength studies of individual Be stars actively experiencing disk-loss/renewal episodes. Predictions of state-of-the-art radiation transfer and hydrodynamical modeling codes will be compared against the data obtained in this program, to test a range of scenarios that have been proposed to explain how circumstellar disks may be created and destroyed during the lifetime of the host star.