标题： WC和WN星在沃尔夫-拉叶星系中的群体 显示英文标题

标题： Populations of WC and WN stars in Wolf-Rayet galaxies

摘要： 我们报告了在5个沃尔夫-拉叶（WR）星系中检测到WC型恒星：He 2-10、NGC 3049、NGC 3125、NGC 5253和Tol 89。 由于微弱且宽的CIV5808线需要足够高的信噪比才能被检测到，这解释了之前观测中未能发现这一WC特征的原因。 从WR发射线得出结论，所有区域（除NGC 3049外）都包含WNL和早期WC星的混合种群。 在两个天体中观察到星云发射与恒星光的空间偏移现象。 由于年龄差异，WR区域周围的星云结构可能小于主要由超新星激发的结构。 WR恒星的空间分布遵循恒星连续谱。 我们计算了不同子类型的WR恒星的绝对数量。 WC/WN比率通常在0.2-0.4之间，且与金属丰度（Z）无明显趋势。 对于低金属丰度的天体，这些值大于本地星团中观测到的WC/WN比率，但在使用具有高质量损失率的恒星演化模型时与短爆发期的预期相符。 星暴区的年龄为3-6百万年；为了说明WR恒星的高人口密度，即使类似于R136和NGC 3603中的发射线恒星在星暴中普遍存在，爆发持续时间不得超过2-4百万年。 在不确定性范围内，大多数观测量可以通过Salpeter初始质量函数（IMF）的模型重现。 尽管某些WR谱线比预测的更强，但没有发现明确需要显著平坦IMF的情况。 然而，比Salpeter更陡峭的IMF斜率可能与我们的数据不兼容。 （摘要简化版） 显示英文摘要

摘要： We report the detection of WC stars in 5 Wolf-Rayet (WR) galaxies: He 2-10, NGC 3049, NGC 3125, NGC 5253 and Tol 89. The faint broad CIV5808 line requires sufficiently high S/N to be detected explaining the non-detection of this WC feature in previous observations. From the WR emission lines we conclude that all regions (except NGC 3049) contain a mixed population of WNL, and early WC stars. A spatial offset between the nebular emission and stellar light is observed in 2 objects. Due to age differences the nebular structures around the WR regions are possibly smaller than those mainly energized by SNe. The spatial distribution of WR stars follows the stellar continuum. We derive the absolute number of WR stars of different subtypes. The WC/WN ratios have typical values between 0.2-0.4, and show no clear trend with metallicity (Z). For low-Z objects, these values are larger than the observed WC/WN ratios in Local Group objects, but compatible with expectations for short bursts of if stellar evolution models with high mass loss are used. The ages of the starburst regions are 3-6 Myr; the burst duration must not exceed 2-4 Myr to account for the high population of WR stars, even if emission line stars similar to those in R136 and NGC 3603 are common in starbursts. Within the uncertainties most of the observed quantities are reproduced by models with a Salpeter IMF. Although some WR lines are stronger than predicted, no clear case requiring a significantly flatter IMF is found. IMF slopes much steeper than Salpeter may, however, not be compatible with our data. (Abridged abstract)