论文标题
红外[WC]星星
The infrared [WC] stars
论文作者
论文摘要
许多晚期[WC]恒星具有独特的红外特性，在非[WC]行星星云中未发现，并且共同定义了一类IR- [WC]恒星。它们具有不寻常的IRAS颜色，类似于最早的AGB演化后的星星，并且可能与PAH形成有关。大多数或全部显示了双重化学，具有中性（分子）富氧和富含碳的内部化学。它们致密的星云表明最近从AGB进化，表明致命的热 - 脉冲（FTP）场景。尽管颜色和恒星特征都可以预测快速演变，但表明该阶段必须持续10^4年。讨论了星云的形态。对于SGR中的一个物体，祖细胞质量（1.3太阳能质量）已知。在低金属系统（LMC，SGR）中，IR- [WC]恒星的恒星温度显得更高。这可能表明了扩展的“伪”光球。有人提出，弹出气体的重新限制可能会减慢后AGB后的进化，从而延长IR- [WC]恒星的寿命。
A number of late [WC] stars have unique infrared properties, not found among the non-[WC] planetary nebulae, and together define a class of IR-[WC] stars. They have unusual IRAS colours, resembling stars in the earliest post-AGB evolution and possibly related to PAH formation. Most or all show a double chemistry, with both a neutral (molecular) oxygen-rich and an inner carbon-rich region. Their dense nebulae indicate recent evolution from the AGB, suggesting a fatal-thermal-pulse (FTP) scenario. Although both the colours and the stellar characteristics predict fast evolution, it is shown that this phase must last for 10^4 yr. The morphologies of the nebulae are discussed. For one object in Sgr, the progenitor mass (1.3 solar masses) is known. The stellar temperatures of the IR-[WC] stars appear much higher in low metallicity systems (LMC, Sgr). This may be indicative of an extended 'pseudo' photosphere. It is proposed that re-accretion of ejected gas may slow down the post-AGB evolution and so extend the life time of the IR-[WC] stars.
