Massive stars as cosmic engines

大质量恒星包括所有初始质量大于8太阳质量（Msun）的恒星。在达到大约100米的太阳时，它们会连续燃烧越来越热的中心壳层中的元素，直到变成铁，然后成为核心坍缩的超新星，根据初始质量留下中子星或黑洞的遗迹。在太阳100米以上的时候，它们只会在核心燃烧出氧气，然后就会变成对不稳定的超新星，并被完全破坏。由于一颗普通恒星的辐射输出大约是其质量的立方，一颗100毫太阳的恒星相当于100万个太阳的总辐射输出。在大约20米太阳以上，大质量恒星以其强风进一步区分自己，强风的强度可达太阳的10亿倍。因此，尽管罕见且寿命短暂，但大质量恒星向星际介质输送了大量致命的紫外线辐射和丰富的物质，准备建造更多的恒星和像地球这样的行星。这在宇宙早期尤为重要，因为最初形成的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。

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.