标题： zeta Puppis的X射线发射线轮廓的定量分析确定的质量损失率 显示英文标题

标题： A mass-loss rate determination for zeta Puppis from the quantitative analysis of X-ray emission line profiles

摘要： 我们用一个经验线轮廓模型拟合了zeta Pup的高分辨率Chandra光栅光谱中的每条发射线，该模型考虑了多普勒展宽和整体风的衰减效应。对于十六条可以可靠测量的线或线复合体，我们确定了一个最佳拟合的参考光学深度，tau_* = kappa*Mdot/4{π}R_{\ast }v_{\infty }，并对此参数设置了置信限。这十六条线包括七条以前文献中未报道过的线。这些线的扩展波长范围使我们首次推断出tau_*随线波长增加而明显增加，这与束缚-自由吸收不透明度随波长增加的预期一致。tau_*的整体较小值反映在线轮廓的不对称性相当小，而且都可以通过简单地假设一个适度的质量损失率3.5 \pm 0.3 \times 10^{-6} Msun/yr来同时拟合，而无需在风中引入多孔性效应。所引用的不确定性是统计性的，但推导出的质量损失率最大的不确定性来源于zeta Pup元素丰度的不确定性，这会影响风的连续谱不透明度，我们估计这一不确定性为两倍。尽管如此，我们找到的质量损失率显著低于zeta Pup最近的平滑风H-alpha质量损失率测定结果，但与考虑小尺度风团的新测定结果一致。如果zeta Pup代表其他大质量恒星，这些结果将对恒星和星系演化产生重要影响。 显示英文摘要

摘要： We fit every emission line in the high-resolution Chandra grating spectrum of zeta Pup with an empirical line profile model that accounts for the effects of Doppler broadening and attenuation by the bulk wind. For each of sixteen lines or line complexes that can be reliably measured, we determine a best-fitting fiducial optical depth, tau_* = kappa*Mdot/4{pi}R_{\ast}v_{\infty}, and place confidence limits on this parameter. These sixteen lines include seven that have not previously been reported on in the literature. The extended wavelength range of these lines allows us to infer, for the first time, a clear increase in tau_* with line wavelength, as expected from the wavelength increase of bound-free absorption opacity. The small overall values of tau_*, reflected in the rather modest asymmetry in the line profiles, can moreover all be fit simultaneously by simply assuming a moderate mass-loss rate of 3.5 \pm 0.3 \times 10^{-6} Msun/yr, without any need to invoke porosity effects in the wind. The quoted uncertainty is statistical, but the largest source of uncertainty in the derived mass-loss rate is due to the uncertainty in the elemental abundances of zeta Pup, which affects the continuum opacity of the wind, and which we estimate to be a factor of two. Even so, the mass-loss rate we find is significantly below the most recent smooth-wind H-alpha mass-loss rate determinations for zeta Pup, but is in line with newer determinations that account for small-scale wind clumping. If zeta Pup is representative of other massive stars, these results will have important implications for stellar and galactic evolution.