The Winds of Wolf-Rayet Stars: Their strength and Structure

沃尔夫拉叶星的风：它们的强度和结构

• 批准号: 227518-2012
• 负责人: StLouis, Nicole
• 金额: $ 1.82万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=570276
• 关键词: Winds; Wolf; Rayet; Stars; Their

The Universe would be very different without massive stars. Indeed, they constitute the principal means by which material, and more particularly chemically enriched material, is exchanged between stars and the interstellar medium in galaxies. Most elements heavier than Carbon are fabricated within their core and they are injected into their surrounding medium in a spectacular way via supernova explosions. But throughout their short lives, massive stars also steadily inject matter, energy and momentum into the interstellar medium of galaxies in the form of a strong stellar wind. My research is about determining not only how much mass is lost by massive stars but also how it is lost; what is the structure of the wind. The stars I work on the most are named Wolf-Rayet (WR) stars in honor of the two scientists that discovered them at the end of the 19th century. These are generally massive stars that have reached the stage of burning Helium in their core. In recent years, I have become interested in a particular form of structure that are present in the winds of approximately 20% of WR stars and that break the spherical symmetry of the winds. These structures are called Corotating Interaction Regions (CIRs). What is interesting about CIRs is that they are thought to be generated by either a magnetic field or stellar pulsations very close to the surface of the star, a region which is well hidden by the dense wind and therefore very difficult to study. As a consequence of having CIRs in their winds, WR stars show large-scale periodic variability in their light and spectrum. As CIRs are thought to be pinned to a region close to the stellar surface, this period is related to the rotation rate of the star. Rotation rates of WR stars have no other way of being measured, as traditional methods fail because of the dense winds. By studying CIRs in WR winds, I hope to measure the rotation rate of a sample of WR stars and to learn about physical mechanisms, i.e. magnetic fields and pulsations, about which we presently know almost nothing.

如果没有大质量恒星，宇宙将会非常不同。事实上，它们构成了物质，特别是化学富集物质在恒星和星系星际介质之间交换的主要手段。大多数比碳重的元素都是在它们的核心内制造的，它们通过超新星爆炸以壮观的方式注入周围的介质。但在它们短暂的生命中，大质量恒星也以强烈的恒星风的形式稳定地向星系的星际介质注入物质、能量和动量。我的研究不仅要确定大质量恒星损失了多少质量，还要确定质量是如何损失的;风的结构是什么。我研究最多的恒星被命名为沃尔夫-拉叶（WR）星，以荣誉在世纪末发现它们的两位科学家。这些恒星通常是大质量恒星，其核心已经达到燃烧氦的阶段。 近年来，我对大约20%的WR恒星的风中存在的一种特定形式的结构产生了兴趣，这种结构打破了风的球对称性。这些结构被称为共旋相互作用区（CIR）。有趣的是，CIR被认为是由磁场或非常接近星星表面的恒星脉动产生的，这一区域被密集的风很好地隐藏，因此很难研究。 由于风中存在CIR，WR星的光线和光谱表现出大规模的周期性变化。由于CIR被认为固定在靠近恒星表面的区域，因此这个周期与星星的旋转速率有关。WR星的旋转速率没有其他方法可以测量，因为传统的方法由于密集的风而失败。 通过研究WR风中的CIR，我希望测量WR星样本的旋转速率，并了解物理机制，即磁场和脉动，我们目前几乎一无所知。