Duration of the superwind phase of asymptotic giant branch stars
Duration of the superwind phase of asymptotic giant branch stars
复制标题
渐近巨分支星超风阶段的持续时间
作者：
T. Tanabé;S. Nishida;S. Matsumoto;T. Onaka;Y. Nakada;T. Soyano;T. Ono;K. Sekiguchi;I. Glass
在生命接近尾声时，低质量和中等质量恒星经历了一个被称为渐近巨星分支1、2的演化阶段。这一发光的红巨星阶段被认为是以超风的形式经历了一段强烈的质量损失阶段而终止的，这一阶段导致了行星状星云的形成。虽然质量损失的影响已经在许多恒星中得到了广泛的研究，但由于观测到的恒星的距离、质量、年龄和绝对光度的不确定性，这一阶段的持续时间并没有得到很好的限制。另一方面，与麦哲伦星云有关的球状星团中恒星的性质不受这些不确定性的影响，因此为定量研究质量损失现象提供了一个极好的机会。在这里，我们报告了在麦哲伦星云球状星团中发现的两颗红外线恒星，它们正在经历一段强烈的质量损失时期。这些观测，再加上之前发现的一颗红外线恒星，证实了渐近巨型分支恒星经历了一个超风阶段，并将这个阶段的持续时间限制在大约10万年。
Near the ends of their lives, low- and intermediate-mass stars go through a phase of evolution known as the asymptotic giant branch1,2. This luminous red-giant phase is thought to be terminated by a period of intense mass loss in the form of a superwind3, which leads to the formation of a planetary nebula. Although the effects of mass loss have been studied extensively in many stars, the duration of this phase is not well constrained, because of uncertainties in the distances, masses, ages, and absolute luminosities of the observed stars. On the other hand, the properties of stars in the globular clusters associated with the Magellanic Clouds are not subject to these uncertainties, and so provide an excellent opportunity for studying mass-loss phenomena in a quantitative way. Here we report the discovery of two infrared stars in Magellanic Cloud globular clusters that are undergoing a period of intense mass loss. Those observations, together with those of a previously discovered infrared star, confirm that asymptotic giant branch stars go through a superwind phase, and constrain the duration of this phase to be about 100,000 years.