标题： 氦在化学特殊星中的情况 显示英文标题

标题： Helium in Chemically Peculiar Stars

摘要： 为了推导化学异常恒星中的氦丰度，已经研究了假设正确的氦丰度在确定主序B型恒星的有效温度和重力的重要性，充分利用了目前再现其氦线的能力。即使主序B型恒星的通量分布似乎仅取决于有效温度，无论氦丰度如何，必须通过匹配巴尔末线轮廓同时确定有效温度、重力和氦丰度。采用ATLAS9模型大气和更新的氦原子参数进行的新MULTI非局部热平衡计算，再现了主序B型恒星大部分观测到的中性氦线的等值宽度，这使我们对正确推导化学异常恒星中的氦丰度的可能性充满信心。将以前的方法应用于富氦恒星HD 37017表明，在存在质量损失的情况下，根据扩散理论框架，氦可能在磁极区域分层。 显示英文摘要

摘要： For the purpose of deriving the helium abundances in chemically peculiar stars, the importance of assuming a correct helium abundance has been investigated for determining the effective temperature and gravity of main sequence B-type stars, making full use of the present capability of reproducing their helium lines. Even if the flux distribution of main sequence B-type stars appears to depend only on the effective temperature for any helium abundance, the effective temperature, gravity and helium abundance have to be determined simultaneously by matching the Balmer line profiles. New MULTI NLTE calculations, performed adopting ATLAS9 model atmospheres and updated helium atomic parameters, reproduce most of the observed equivalent widths of neutral helium lines for main sequence B-type stars and they make us confident of the possibility to correctly derive the helium abundance in chemically peculiar stars. An application of previous methods to the helium rich star HD 37017 shows that helium could be stratified in the magnetic pole regions, as expected in the framework of the diffusion theory in the presence of mass loss.