Wind-accretion induced rapid rotation and a new class of active star
Wind-accretion induced rapid rotation and a new class of active star
复制标题
风吸积引起的快速旋转和一类新的活跃恒星
DOI：
10.1093/mnras/279.1.180
复制
发表时间：
1996
影响因子：
4.8
通讯作者：
I. Stevens
中科院分区：
文献类型：
--
作者：
R. Jeffries;I. Stevens
提出了一个物理模型来解释在极紫外波段发现的宽双星系统的发生，如2 RE J 0044 + 093，它由一个热的白色矮星和一个超快速旋转的K矮星组成。由于白色矮星的演化和冷却时间尺度很长，而且没有任何径向速度变化，因此很难解释K矮星的快速旋转是年轻还是近双星的结果。据建议，吸积缓慢，大规模的风从渐近巨星分支（AGB）的祖先的白色矮星，由低质量的次要在一个分离的配置，可以传递足够的角动量，以产生这些系统。对于一系列的AGB质量，风速为10-20公里/秒-\，它被发现，二次自旋的周期小于10小时，可以发生最后的轨道分离高达100 Au。如果次级恒星是风吸积引起的快速旋转恒星（或WIRRing星），它们可能会显示出在AGB风中存在的碳和s过程元素（如钡）的化学富集迹象。这种过剩的检测将为这一假设提供坚定的支持，并提供了一个WIRRing星和钡巨星之间的进化联系。它还建议快速旋转，行星状星云的晚型中心恒星，如阿贝尔35，是WIRRing恒星的祖先，在质量吸积阶段后不久看到。
A physical model is presented to explain the occurrence of wide binary systems discovered at EUV wavelengths, such as 2RE J0044 + 093, which consist of a hot white dwarf and an ultra-rapidly rotating K-dwarf. It is difficult to explain the rapid rotation of the K-dwarf as a consequence of either youth or close binarity because of the length of the evolutionary and cooling time-scales for the white dwarf and the lack of any radial velocity variations. It is proposed that accretion of the slow, massive wind from the asymptotic giant branch (AGB) progenitor of the white dwarf, by the low-mass secondary in a detached configuration, can transfer sufficient angular momentum to produce these systems. For a range of AGB masses, and wind velocities of 10-20 km s-\ it is found that secondary spin up to periods of less than 10 h can take place for final orbital separations of up to 100 au. If the secondaries are wind-accretion induced, rapidly rotating stars (or WIRRing stars), they could show signs of chemical enrichment in carbon and s-process elements, such as barium, that were present in the AGB wind. The detection of such overabundances would lend firm support for this hypothesis and provide an evolutionary link between WIRRing stars and Barium giants. It is also suggested that the rapidly rotating, late-type central stars of planetary nebulae, such as Abell 35, are the progenitors of WIRRing stars, seen shortly after the mass accretion phase.