The Dynamics and Energetics of Circumbinary Discs

该学生项目将调查银河系中不同质量比和偏心率的双星星星系统的环双星轨道。这些调查将通过计算和通过对全球喷气观测观测站的光谱数据时间序列直接成像进行。这是一个富有成果的重要研究领域，原因如下：-行星：第一颗环双星行星（开普勒16 b）是在2011年9月发现的（三周前，我和我以前的博士生发表了一篇关于3D N的论文，物体模拟已经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，以包括这些轨道中的岁差，飞机。我们发现了三个非常稳定的轨道家族，在那项工作中描述了，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。它仍然有待探索和理解如何气体可以冷却和合并的时间尺度适合行星形成-偏心率：这仍然是一个谜，为什么偏心率的一些双星星系统持续很长时间后，他们应该循环。有人认为，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，但是当第三个天体被涂抹成环或盘时，以及当这个实体进动时，这是如何发生的，还有待探索。- 质量损失：在迄今为止唯一被研究得很好的环双星盘中，即银河系微类星体SS 433，环双星盘的质量损失量与其吸积盘风损失的质量非常相似。为了正确地解释质量转移和质量损失是如何在这样的双星系统中发生的，以及更广泛地解释双星演化是如何进行的，有必要了解环双星轨道上物质的质量损失所起的作用--吸积：克罗里克（约翰霍普金斯）提出环双星盘实际上可以是双星从周围吸积物质的手段。考虑到这四个领域的重要性，这表明这是一个集体调查它们的合适时机：通过计算建模和通过我在过去一年多的时间里从我的全球喷气机观察观测站为这个学生收集的直接长期时间序列光谱。

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.