论文标题
在小麦哲伦云中对NGC330的观察。明亮主序列星的氦气丰度
MUSE observations of NGC330 in the Small Magellanic Cloud. Helium abundance of bright main sequence stars
论文作者
论文摘要
我们介绍了使用Integrallable Field Spectrograph Muse@vlt获得的小型麦哲伦云恒星群ngc330中最明亮的主要序列星。这种有价值的仪器的使用使我们能够研究这个年轻恒星集群的恒星种群的光度和光谱特性。 光度数据为我们提供了精确的颜色幅度图，这似乎支持了两个年龄的$ \ sim $ 18 MYR和$ \ sim $ 30 MYR的存在，假设Z = 0.002。多亏了光谱数据，我们在有效的半径reff = 20“ NGC330的氦气中得出了10个主要序列星的氦气丰度，因此导致估计$ε（HE）$ = 10.93 $ \ pm $ \ pm $ 0.05（1 $ $σ$）。结果表明，如果存在的两个恒星种群，则具有相似的原始HE丰度。 如果我们在分析中考虑出色的旋转速度，则不能排除旋转值不同的同时（30 Myr）恒星种群。在这种情况下，我们分析中获得的平均氦丰度<$ε（He）$> rot为11.00 $ \ pm $ 0.05 dex。我们还验证了由于光谱分辨率而无法通过我们的分析来识别可能的NLTE效应，并且它们在我们衍生的丰度中不确定性。 此外，对He丰度的分析是与观察到的恒星簇中心距离距离的函数的函数，没有显示任何相关性。
We present observations of the most bright main sequence stars in the Small Magellanic Cloud stellar cluster NGC330 obtained with the integral field spectrograph MUSE@VLT. The use of this valuable instrument allows us to study both photometric and spectroscopic properties of stellar populations of this young star cluster. The photometric data provide us a precise color magnitude diagram, which seems to support the presence of two stellar populations of ages of $\sim$ 18 Myr and $\sim$ 30 Myr assuming a metallicity of Z = 0.002. Thanks to the spectroscopic data, we derive helium abundance of 10 main sequence stars within the effective radius Reff= 20" of NGC330, thus leading to an estimation of $ε(He)$ = 10.93 $\pm$ 0.05 (1$σ$ ). The helium elemental abundances of stars likely belonging to the two possible stellar populations, do not show differences or dichotomy within the uncertainties. Thus, our results suggest that the two stellar populations of NGC330, if they exist, share similar original He abundances. If we consider stellar rotation velocity in our analysis, a coeval (30 Myr) stellar population, experiencing different values of rotation, cannot be excluded. In this case, the mean helium abundance < $ε(He)$ >rot obtained in our analysis is 11.00 $\pm$ 0.05 dex. We also verified that possible NLTE effects cannot be identified with our analysis because of the spectral resolution and they are within our derived abundance He uncertainties. Moreover, the analysis of the He abundance as a function of the distance from the cluster center of the observed stars do not show any correlation.
