论文标题
估计Lamost DR6的M31星团的年龄和金属性
Estimating ages and metallicities of M31 star clusters from LAMOST DR6
论文作者
论文摘要
语境。确定M31簇的金属性和年龄对于研究M31本身的形成和进化至关重要。大型天空区域多对象光纤光谱望远镜（Lamost）在M31中进行了集群和候选者的系统光谱运动。目标。我们构建了一个由Lamost观察到的346 M31簇的目录。通过结合Lamost光谱和多波段光度法的信息，我们开发了一种新算法来估计这些簇的金属性和年龄。方法。我们根据从文献中选择的经验训练数据集使用随机森林分类器将年轻的群集与旧簇区分开。年轻簇的年龄来自其多波段光度测量的光谱能分布（SED）。通过拟合从Lamost光谱中提取的观察到的光谱主成分与年轻金属富含金属的单恒星种群（SSP）模型的光谱主成分（SSP）模型来估计它们的金属性。对于旧群集，我们根据基于SSP模型构建的训练数据集，在光谱主组件和/或多波段颜色以及群集的参数之间构建了非参数随机森林模型。然后，通过拟合从Lamost光谱中提取的观察到的光谱主成分和从光度测量结果中提取的光度测量值，并与所得的随机森林模型中提取的旧簇的年龄和金属性估计。结果。我们在目录中得出了53名Young和293个旧簇的参数。我们由此产生的参数与文献中的参数非常吻合。首次得出了大约30个分类群集和金属性的年龄。
Context. Determining the metallicities and ages of M31 clusters is fundamental to the study of the formation and evolution of M31 itself. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) has carried out a systematic spectroscopic campaign of clusters and candidates in M31. Aims. We constructed a catalogue of 346 M31 clusters observed by LAMOST. By combining the information of the LAMOST spectra and the multi-band photometry, we developed a new algorithm to estimate the metallicities and ages of these clusters. Methods. We distinguish young clusters from old using random forest classifiers based on a empirical training data set selected from the literature. Ages of young clusters are derived from the spectral energy distribution (SED) fits of their multi-band photometric measurements. Their metallicities are estimated by fitting their observed spectral principal components extracted from the LAMOST spectra with those from the young metal-rich single stellar population (SSP) models. For old clusters, we built non-parameter random forest models between the spectral principal components and/or multi-band colours and the parameters of the clusters based on a training data set constructed from the SSP models. The ages and metallicities of the old clusters are then estimated by fitting their observed spectral principal components extracted from the LAMOST spectra and multi-band colours from the photometric measurements with the resultant random forest models. Results. We derived parameters of 53 young and 293 old clusters in our catalogue. Our resultant parameters are in good agreement with those from the literature. The ages of about 30 catalogued clusters and metallicities of about 40 sources are derived for the first time.
