A Binary Model for the UV-upturn of Elliptical Galaxies
A Binary Model for the UV-upturn of Elliptical Galaxies
复制标题
DOI：
10.1111/j.1365-2966.2007.12151.x
复制
发表时间：
2006-12
期刊：
影响因子：
--
通讯作者：
Zhanwen Han;P. Podsiadlowski;A. Lynas-Gray;K. Schawinski
中科院分区：
文献类型：
--
作者：
Zhanwen Han;P. Podsiadlowski;A. Lynas-Gray;K. Schawinski
1969年在椭圆星系中发现了远紫外线（UV）过剩的光，这是一个重大的惊喜。虽然现在很清楚，这种紫外线过剩（紫外线上升）可能是由一群古老的氦燃烧恒星引起的。Han et al.（2002,2003）提出了热亚矮星（氦燃烧恒星）形成的二元模型，该模型可以再现我们银河系的观测结果。通过将二元模型应用于进化种群综合的研究，我们得到了椭圆星系紫外线上升的先验模型。该模型表明，uv的上升很可能是由二元相互作用引起的，并且它在椭圆中是普遍的（不太依赖于金属丰度）。这对于理解紫外线上升和椭圆星系的演化具有重要意义；与之前的假设相反，这意味着紫外线的上升并不是年龄的标志，而是最近恒星形成活动小爆发的潜在有力指标。
Abstract The discovery of an excess of light in the far-ultraviolet (UV) in 1969 in elliptical galaxies was a major surprise. While it is now clear that this UV excess (UV-upturn) is probably caused by an old population of helium-burning stars. Han et al. (2002, 2003) proposed a binary model for the formation of hot subdwarfs (helium burning stars) and the model can reproduce the observations in our Galaxy. By applying the binary model to the study of evolutionary population synthesis, we have obtained an a priori model for the UV-upturn of elliptical galaxies. The model shows that the UV-upturn is most likely resulted from binary interactions and it is universal (not very much metallicity-dependant) in ellipticals. This has major implications for understanding the evolution of the UV-upturn and elliptical galaxies in general; contrary to previous postulates, it implies that the UV-upturn is not a sign of age, but could be a potentially powerful indicator for a recent minor burst of star-forming activity.