标题： 宿主恒星在后主序阶段的宜居带 显示英文标题

标题： Habitable Zones of Host Stars During the Post-MS Phase

摘要： 恒星随着恒星演化会变得越来越亮，其宜居带的距离也会越来越远。 一些在主序阶段位于宿主恒星宜居带之外的行星可能在其他演化阶段进入宿主恒星的宜居带。 一般认为位于宿主恒星宜居带内的类地行星适合生命存在。 此外，如果行星-卫星系统位于宿主恒星的宜居带内，围绕类木巨行星的岩质卫星也可能适合生命生存。 利用Eggleton的代码和宜居带的边界通量，我们计算了太阳在主序阶段之后的宜居带。 结果发现，火星轨道和木星轨道分别会在次巨星分支阶段和红巨星分支阶段进入太阳的宜居带，而土星轨道将在氦燃烧阶段进入太阳的宜居带约1.37亿年。 然而，由于土星是一颗巨大的气态行星，任何时候都不太可能存在生命。 但是，在这段时间里，土星的岩质卫星土卫六可能适合生物进化，并成为另一个地球。 对于低质量恒星，在氦燃烧阶段也有与太阳类似的宜居带，因为在这一阶段这些恒星具有相似的核心质量和光度。 显示英文摘要

摘要： A star will become brighter and brighter with stellar evolution, and the distance of its habitable zone will become farther and farther. Some planets outside the habitable zone of a host star during the main sequence phase may enter the habitable zone of the host star during other evolutionary phases. A terrestrial planet within the habitable zone of its host star is generally thought to be suited to life existence. Furthermore, a rocky moon around a giant planet may be also suited to life survive, provided that the planet-moon system is within the habitable zone of its host star. Using Eggleton's code and the boundary flux of habitable zone, we calculate the habitable zone of our Solar after the main sequence phase. It is found that Mars' orbit and Jupiter's orbit will enter the habitable zone of Solar during the subgiant branch phase and the red giant branch phase, respectively. And the orbit of Saturn will enter the habitable zone of Solar during the He-burning phase for about 137 million years. Life is unlikely at any time on Saturn, as it is a giant gaseous planet. However, Titan, the rocky moon of Saturn, may be suitable for biological evolution and become another Earth during that time. For low-mass stars, there are similar habitable zones during the He-burning phase as our Solar, because there are similar core masses and luminosities for these stars during that phase.