标题： 仙女座星系中弥漫星际带的调查：M31 OB星的光学光谱学 显示英文标题

标题： A survey of diffuse interstellar bands in the Andromeda galaxy: optical spectroscopy of M31 OB stars

摘要： 我们给出了有史以来最大规模的M31星系中型分辨率蓝到红光学光谱的B型超巨星样本，并首次对该星系中的弥漫星际带（DIBs）进行了调查。 我们对M31三个区域内的34颗恒星给出了光谱分类、视向速度和星际消光。 视向速度和等效宽度被提供给11颗恒星方向上的5780和6283 DIBs。 对于M31中的三条视线观测到的以下DIBs，也给出了等效宽度：4428、5705、5780、5797、6203、6269、6283、6379、6613、6660和6993。 所有这些M31 DIB载体都存在于与星际Na I和/或H I径向速度匹配的云中。 DIB等效宽度与消光（E(B-V)）之间的关系与银河系局部星际介质中观察到的关系一致。 许多观测视线显示DIB强度（每单位消光）位于银河系范围内上限附近。 以68%的置信度发现，DIB强度与星际紫外辐射场强度相关。 最强的DIB出现在星际紫外通量最低的地方。 我们三个区域的斯皮策8/24微米发射比率平均值略低于银河系测量值，但我们未发现该比率与M31中的DIB强度有任何相关性。 从一个区域内三个M31 H II区域的光谱推导出的星际氧丰度表明，该区域的星际介质平均金属丰度为12 + log[O/H] = 8.54 ± 0.18，这大约等于太阳附近的值。 显示英文摘要

摘要： We present the largest sample to-date of intermediate-resolution blue-to-red optical spectra of B-type supergiants in M31 and undertake the first survey of diffuse interstellar bands (DIBs) in this galaxy. Spectral classifications, radial velocities and interstellar reddenings are presented for 34 stars in three regions of M31. Radial velocities and equivalent widths are given for the 5780 and 6283 DIBs towards 11 stars. Equivalent widths are also presented for the following DIBs detected in three sightlines in M31: 4428, 5705, 5780, 5797, 6203, 6269, 6283, 6379, 6613, 6660, and 6993. All of these M31 DIB carriers reside in clouds at radial velocities matching those of interstellar Na I and/or H I. The relationships between DIB equivalent widths and reddening (E(B-V)) are consistent with those observed in the local ISM of the Milky Way. Many of the observed sightlines show DIB strengths (per unit reddening) which lie at the upper end of the range of Galactic values. DIB strengths per unit reddening are found (with 68% confidence), to correlate with the interstellar UV radiation field strength. The strongest DIBs are observed where the interstellar UV flux is lowest. The mean Spitzer 8/24 micron emission ratio in our three fields is slightly lower than that measured in the Milky Way, but we identify no correlation between this ratio and the DIB strengths in M31. Interstellar oxygen abundances derived from the spectra of three M31 H II regions in one of the fields indicate that the average metallicity of the ISM in that region is 12 + log[O/H] = 8.54 +- 0.18, which is approximately equal to the value in the solar neighbourhood.