Massive stars as cosmic engines

作为宇宙引擎的大质量恒星

• 批准号: 615-2011
• 负责人: Moffat, Anthony
• 金额: $ 3.5万
• 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=568136
• 关键词: Massive; stars; cosmic; engines

Massive stars comprise all stars initially above 8 solar masses (Msun). Up to about 100 Msun they burn elements in successive, ever-hotter central shells right through to iron, before becoming core-collapse supernovae, leaving a neutron star or black hole remnant depending on the initial mass. Above about 100 Msun they burn only to oxygen in their cores before becoming pair-instability supernovae with complete disruption. Since the radiative output of a normal star goes roughly as the cube of its mass, a single 100 Msun star matches the total radiation output from a million Suns. Above some 20 Msun, massive stars further distinguish themselves by their strong winds, ranging up to a billion times that of the Sun. Thus, although rare and short-lived, massive stars deliver huge quantities of mostly lethal UV radiation and enriched material to the interstellar medium, ready to build more stars and planets like Earth. This was especially important in the early Universe, when the first stars formed were probably all very massive. Clearly, massive stars dominate the ecology of the Cosmos, yet many of their basic parameters remain elusive. The main goals of this program are to explore: (A) pulsations in massive stars, which could provide additional energy to drive the winds and which will provide important and urgent clues to the internal structure of massive stars (using Canada's first space telescope aboard the MOST microsatellite, and the next venture: the nanosatellite BRITE-Constellation); (B) the nature of stellar winds, which dominate in massive stars; (C) the mysterious process of how dust grains form and survive in the hostile environments of some hot, luminous stars; (D) the upper mass limit of star formation and the boundaries between which stars end up as white dwarfs, neutron stars or black holes; (E) the content of WR stars in our own Galaxy (heretofore mostly hidden by interstellar absorption) and in many other nearby star-forming galaxies (as best-candidate, immediate precursors to supernovae of type Ib and Ic).

大质量恒星包括最初质量超过 8 个太阳质量 (Msun) 的所有恒星。在温度高达约 100 兆太阳时，它们会在不断变热的中心壳层中将元素燃烧成铁，然后成为核心塌陷的超新星，根据初始质量留下中子星或黑洞残余物。 在大约 100 兆太阳以上，它们在核心中仅燃烧成氧气，然后成为完全瓦解的配对不稳定超新星。由于普通恒星的辐射输出大致为其质量的立方，因此一颗 100 兆太阳的恒星相当于 100 万个太阳的总辐射输出。 在大约 20 米太阳以上，大质量恒星因其强风而更加引人注目，其范围可达太阳的十亿倍。 因此，虽然罕见且寿命短暂，但大质量恒星会向星际介质输送大量致命的紫外线辐射和丰富的物质，准备建造更多像地球这样的恒星和行星。 这在早期宇宙中尤其重要，当时形成的第一批恒星可能都非常巨大。显然，大质量恒星主导着宇宙的生态，但它们的许多基本参数仍然难以捉摸。 该计划的主要目标是探索：（A）大质量恒星中的脉动，它可以提供额外的能量来驱动风，并将为大质量恒星的内部结构提供重要而紧迫的线索（使用加拿大第一台太空望远镜搭载在 MOST 微型卫星上，以及下一个项目：纳米卫星 BRITE-星座）； (B) 星风的性质，在大质量恒星中占主导地位； (C) 尘埃颗粒如何在一些炽热发光恒星的恶劣环境中形成和生存的神秘过程； (D) 恒星形成的质量上限以及恒星最终形成白矮星、中子星或黑洞的边界； (E) 我们银河系（迄今为止大部分被星际吸收所隐藏）和许多其他附近的恒星形成星系（作为 Ib 和 Ic 型超新星的最佳候选者、直接前体）中 WR 恒星的含量。