The Dynamics and Energetics of Circumbinary Discs

学生项目将包括研究银河系中不同质量比和离心率的双星系统周围的环双星轨道。这些调查将通过计算计算和直接成像来自全球喷气观察天文台的光谱数据的时间序列来进行。这是一个富有成果和重要的研究领域，有以下四个原因：-行星：第一颗环双星（开普勒16b）是在2011年9月发现的(三周后，我以前的博士生和我发表了一篇关于3D n体模拟的论文，毫无疑问地证明了稳定的环双星轨道的存在，如果稳定的定义被充分解放，包括这些轨道平面的进动。我们发现了三个非常稳定的轨道家族，在那项工作中描述过，在过去的几年里，开普勒和其他任务发现了更多的环双星行星。气体是如何在适合行星形成的时间尺度上冷却并结合的，这仍有待探索和理解——偏心率：为什么一些双星系统的偏心率在它们应该旋转很久之后仍然存在，这仍然是一个谜。有人提出，在环双星轨道上的天体不仅可以保持而且可以驱动这种偏心率，但当第三个天体被涂抹成一个环或圆盘时，以及当这个实体正在进动时，这种偏心率是如何发生的，还有待探索。-质量损失：迄今为止，银河系微类星体SS433是唯一一个被充分研究过的环双星盘，它的质量损失与吸积盘风造成的质量损失相当。为了正确地解释质量传递和质量损失是如何在这样的双星系统中发生的，以及更广泛地说，双星的演化是如何进行的，有必要了解环双星轨道上物质的质量损失在其中起了什么作用——吸积：Krolik（约翰霍普金斯大学）提出，环双星盘实际上是双星从周围吸积物质的手段。考虑到这四个领域各自的重要性，这表明现在是一个合适的时机来共同研究它们：通过计算模型和直接长期时间序列光谱，我在过去一年多的时间里从我的全球喷气观察天文台为这个学生收集了这些数据。

The student project will entail investigations of circumbinary orbits around binary star systems in the Galaxy of varying mass ratio and eccentricity. These investigations will take place via computational calculation and via direct imaging of time series of spectroscopic data from the Global Jet Watch observatories. This is a fruitful and important area of study for the following four reasons:- PLANETS: The first circumbinary planet (Kepler 16b) was discovered in September 2011 (three weeks after my previous Doctoral student and I published a paper on 3D N-body simulations that had demonstrated beyond doubt the existence of stable circumbinary orbits if the definition of stable is sufficiently liberated as to include precession in these orbital planes. We discovered three remarkably stable families of orbits, described in that work, and in the last few years Kepler and other missions have discovered further circumbinary planets. It remains to be explored and understood how the gas can cool and coalesce on a timescale appropriate to planet formation- ECCENTRICITY: It remains a mystery why the eccentricity of some binary star systems persists long after they should have circularised. It has been suggested that a body in a circumbinary orbit can not only preserve but drive this eccentricity, but it remains to be explored how this can take place when that third body is smeared out into a ring or disc, and furthermore, when this entity is precessing. - MASS-LOSS: in the only circumbinary disc well-studied to date, that of the Galactic microquasar SS433, the amount of mass-loss from the circumbinary disc is very comparable with that lost via its accretion disc wind. In order to properly account for how mass-transfer and mass-loss takes place in such binary systems, and more broadly how binary evolution proceeds, it is essential to understand what part is played by mass lost from the matter on circumbinary orbits- ACCRETION: Krolik (Johns Hopkins) has suggested that circumbinary discs can actually be the means by which binaries can accrete material from their surroundings. Given the importance of these four areas separately, this suggests that this is an opportune time to investigate them collectively: via computational modelling and via direct long-term times series spectroscopy that I have been collecting for this student over the last 1+ year from my Global Jet Watch observatories.