Circumstellar Disks Surrounding Massive Stars

在可观测的宇宙中，可以发现许多不同类型的气体、恒星和行星的盘状分布。 我们的太阳位于银河系中恒星、气体和尘埃盘状分布的旋臂中。地球形成于太阳形成时遗留下来的物质盘中。 黑洞有物质盘围绕着它们旋转，还有更多的例子可以证明这种盘的普遍性。 因此，了解盘的形成和理解其中的过程对于理解天体物理学中的许多对象至关重要。 我的研究项目主要集中在大质量恒星，特别是B-发射星（Be星），被磁盘包围。 各种技术被用来观察这些非常明亮的物体，这为研究盘提供了理想的环境。恒星每秒可以喷出比我们的太阳多一千倍的能量，在我们自己的银河系中就有数千颗恒星。由于盘是由从星星发射的气体形成的，它往往不会被星星形成区域的尘埃盘所笼罩，这使得Be星星盘更容易观察，化学组成也更简单。星星的快速旋转导致星星内部的物质被搅动，最终影响能量的产生及其寿命。 当一颗Be星星到达生命的终点并成为超新星时，它可以引发新一代恒星的出现，直接影响其母星系的演化。 尽管经过了几十年的研究，但在这一研究领域需要解决的基本问题是为什么磁盘形成。星星的快速旋转当然有助于推动物质离开表面进入圆盘，但必须有其他东西帮助喷射物质，也许是来自轨道星星的引力，恒星表面的波或脉动，或者来自恒星辐射的推力。 当来自Be星星的光穿过圆盘时，它被散射，吸收和重新发射，这导致了发射光的变化。 我建立了详细的计算机模型，预测在很大的波长范围内（颜色）发射光的签名。圆盘中的温度分布非常复杂，这导致圆盘的不同区域产生不同的波长。这个想法是，如果我们得到恒星的参数和磁盘条件，如化学成分，温度和密度正确，我们将能够在这个广泛的范围内匹配光的签名。 然后，我们可以构建模型，随着时间的推移可靠地遵循磁盘结构，以更好地理解磁盘的工作原理。 在加拿大，特别是西方大学，对Be星星盘的专门研究和专业知识有着悠久的历史。我的计划的结果不仅将为理解这种类型的磁盘提供关键结果，而且将帮助世界各地的研究人员应用洞察力来更好地了解其他磁盘品种，限制大质量恒星的形成以及恒星和星系的演化。

Many different types of disk-like distributions of gas, stars, and planets can be found in the observable universe. Our own Sun is located in a spiral arm within a disk-like distribution of stars, gas and dust in our Milky Way Galaxy. The Earth formed in a disk of material left over from the formation of the Sun. Black holes have disks of material swirling about them, and there are many more examples of the ubiquity of such disks. Consequently, knowing how disks form and appreciating the processes operating in them are critical to understanding many objects in astrophysics. My research program focuses on massive stars, in particular B-emission stars (Be stars), that are surrounded by disks. A variety of technologies are employed to observe these remarkably bright objects which provide an ideal environment for studying disks. Be stars can spew out one thousand times more energy per second than our Sun and thousands exist right in our own Galaxy. Since the disk is formed from gas launched from the star, it tends not to be shrouded in dust like disks in star forming regions which makes Be star disks easier to observe and the chemical makeup simpler. The star's fast rotation causes materials inside the star to be stirred up, ultimately affecting the production of energy and its lifetime. When a Be star reaches the end of its life and goes supernova, it can trigger the emergence of a new generation of stars, directly affecting the evolution of its parent galaxy. Despite decades of study, the fundamental question to be solved in this field of study is why the disk forms. The rapid rotation of the star certainly helps to propel material off the surface into the disk, but something else must help to eject the material perhaps gravity from an orbiting star, a wave or pulsation on the stellar surface or a push from the stellar radiation. When the light from the Be star goes through the disk, it is scattered, absorbed and re-emitted and this causes changes in the light emitted. I build detailed computer models that predict signatures in the emitted light over a large range of wavelength (colour). The temperature distribution in the disk is highly complex which causes different areas of the disk to produce different wavelengths. The idea is that if we get stellar parameters and disk conditions such as the chemical composition, temperature and density correct, we will be able to match the signatures in the light over this wide range. Then we can build models that reliably follow the disk structures over time to better understand how disks work. There is a long history of discipline-specific study and expertise in Canada, in particular at Western University, of Be star disks. The results of my program will not only provide key results for understanding this type of disk but will help researchers worldwide apply the insight to better understand other disk varieties, placing constraints on the formation of massive stars and on the evolution of stars and galaxies.