Mapping the Milky Way Disk Population Structures and Galactoseismology (MWDPSG): Recent progress about Stellar Parameters and Farther Outer Disk Ridge

活动时间： 06月09日14时00分       

地            点  ： Zoom（863 5004 3883）Passcode: 253681

讲座内容：

We explore the performance of differentmachine learning methods for the mass and age of LAMOST sample, includingbayesian linear regression (BYS), gradient boosting decision Tree (GBDT),multilayer perceptron (MLP), multiple linear regression (MLR), random forest(RF), and support vector regression (SVR). We find that the performance ofnonlinear model is generally better than that of linear model, the GBDT and RFmethods are relatively better. The training dataset is cross matched from theLAMOST DR5 and high resolution asteroseismology data, mass and age arepredicted by random forest method or convex hull algorithm. The test datasetshows that the median relative error of the prediction model for the mass oflarge sample is 0.03 and meanwhile, the mass and age of red clump stars are0.04 and 0.07. We also compare the predicted age of red clump stars with therecent works and find that the final uncertainty of the RC sample could reach18% for age and 9% for mass, in the meantime, final precision of the mass forlarger sample with different type of stars could reach 13% , withoutconsidering systematics, all these are implying that this method could bewidely used in the future. Moreover, also with LAMOST data, we present the timetagging for the well-known ridge structures of the outer disk beyond 12 kpc. Wedetect six long-lived ridge structures, find that there might be two kinds ofdynamical origins with possible coupling mechanisms. Furthermore, thecomparison between the north and south hemispheres of the Galaxy does not showa clear asymmetry in the phase space location even though the amplitude isasymmetrical. Finally, we find that diagonal ridge structures may affect theshape of the rotation curve, which is manifested as fluctuations andundulations on top of a smooth profile.

主讲人介绍：

Hai-Feng Wang (王海峰) is now a Postdoctoral researcher of Enrico FermiResearch Center of Rome in Italy. He got his Ph.D in 2018 from NationalAstronomical Observatories of Chinese Academy of Sciences, then became thePostdoctoral researcher of Yunnan University as LAMOST Fellow in China from2018-2021, and CNRS-K.C.Wong Fellow of Paris Observatory in France from2021-2022. His interests focus on the Milky Way and Local Universe Seismology,Archaeology, Disk systems & Dark matter nature with the data, modeling andsimulations.

发布时间：2022-06-09 10:08:21