Modelling spectra of pre-main sequence and magnetic sequence stars

前主序星和磁序星的光谱建模

• 批准号: 6377-2010
• 负责人: Landstreet, John
• 金额: $ 2.33万
• 依托单位: University of Western Ontario
• 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=568462
• 关键词: Modelling; spectra; pre; main; sequence

Astronomers now understand the broad outlines of how stars form, how they change through their lives, and what happens to them when they run out of fuel and collapse or explode. However, important steps in this life story are still poorly or hardly understood. One of the most important tools for increasing our understanding of stars is the study of stellar spectra, which are produced by spreading starlight out into a rainbow of colour with a prism or other device. When we look closely at this rainbow, we find that some specific colours are relatively brighter or fainter than the immediately neighbouring colours. These specific weakened or strengthened colours are called absorption or emission lines, and they carry an astonishing amount of information about the star that emitted the light: we can deduce the surface temperature and the chemical composition, and tell whether the star is rotating or pulsing or magnetic, or is actually two stars in orbit around each other. This proposal has two goals. One is to study spectral lines in stars a few times more massive than the Sun, that have strong magnetic fields, and are members of open clusters (groups of stars like the Pleiades that formed together and have a known common age). These magnetic stars have very different surface chemical composition than commoner, non-magnetic stars, and by studying such stars in open clusters of various ages between a few and a thousand million years, we hope to find some clues to the various processes that bring unusual mixes of elements to the surface of these stars. A second goal is to study spectral lines in stars that have formed so recently that they are still surrounded by a disk containing some of the gas and dust that will eventually fall onto the central star. The actual process of incorporating gas into the new star involves the intermediary of the disk of gas and dust, but conditions in such disks are still not well understood. We hope to clarify how gas and dust move through the disk to the star by detailed study of spectral emission lines produced in the disk.

天文学家现在了解了恒星如何形成的大致轮廓，它们在生命中如何变化，以及当它们耗尽燃料并崩溃或爆炸时会发生什么。然而，这个生命故事中的重要步骤仍然很少或几乎不被理解。 增加我们对恒星的了解的最重要的工具之一是研究恒星光谱，恒星光谱是通过棱镜或其他装置将星光扩散成彩虹而产生的。当我们仔细观察这道彩虹时，我们发现一些特定的颜色比紧邻的颜色相对更亮或更暗。这些特定的减弱或增强的颜色被称为吸收线或发射线，它们携带着关于发射光的星星的惊人数量的信息：我们可以推导出表面温度和化学成分，并判断该星星是否正在旋转、脉冲或磁性，或者实际上是两颗相互绕轨道运行的星星。 这项建议有两个目标。一个是研究质量比太阳大几倍的恒星的光谱线，这些恒星具有强大的磁场，并且是疏散星团的成员（像昴星团这样的恒星群一起形成，并且具有已知的共同年龄）。这些磁星的表面化学成分与普通的非磁星有很大的不同，通过研究疏散星团中的这些恒星，这些恒星的年龄在几百万年到十亿年之间，我们希望找到一些线索，了解将不寻常的元素混合物带到这些恒星表面的各种过程。 第二个目标是研究恒星的光谱线，这些恒星形成时间很短，以至于它们仍然被一个包含一些气体和尘埃的圆盘包围，这些气体和尘埃最终将落在中心星星上。将气体并入新星星的实际过程涉及到气体和尘埃盘的中介，但这种盘中的条件仍然没有得到很好的理解。我们希望通过详细研究圆盘中产生的光谱发射线来阐明气体和尘埃如何通过圆盘移动到星星。