An Asymmetric Galactic Stellar Disk Traced by OB-type Stars from LAMOST DR7  

作　　者：Xiaopeng Liu Hao Tian Wenyuan Cui Linlin Li Jiaming Liu Zhenyan Huo Yawei Gao 

机构地区：[1]Department of Physics,Hebei Normal University,Shijiazhuang 050024,China [2]Guo Shoujing Institute for Astronomy,Hebei Normal University,Shijiazhuang 050024,China [3]Key Laboratory of Space Astronomy and Technology,National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100101,China [4]Institute for Frontiers in Astronomy and Astrophysics,Beijing Normal University,Beijing 102206,China

出　　处：《Research in Astronomy and Astrophysics》2024年第6期38-51,共14页天文和天体物理学研究（英文版）

基　　金：supported by the National Natural Science Foundation of China(NSFC,grant Nos.12173013,12103062,12003045,and 11903012);the National Key Basic R&D Program of China via 2019YFA0405500;supported by the Natural Science Foundation of Hebei Province under grant A2021205006 and A2019205166;by the project of the Hebei provincial department of science and technology under grant number 226Z7604G;the science research grants from the China Manned Space Project。

摘　　要：Using 9943 OB-type stars from LAMOST DR7 in the solar neighborhood,we fit the vertical stellar density profile with the model including a single exponential distribution at different positions(R,Φ).The distributions of the scale heights and scale length show that the young disk traced by the OB-type stars is not axisymmetric.The scale length decreases versus the azimuthal angleΦ,i.e.,from.■kpc withΦ=-3°to■kpc withΦ=9°.Meanwhile we find signal of non-symmetry in the distribution of the scale height of the north and south of the disk plane.The scale height in the north side shows signal of flaring of the disk,while that of the south disk stays almost constant around h_(s)=130 pc.The distribution of the displaceeent of the disk plane Z_(0)also shows variance versus the azimuthal angleΦ,which displays significant differences with the warp model constrained by the Cepheid stars.We also test different values for the position of the Sun,and the distance between the Sun and the Galactic center affects the scale heights and the displacement of the disk significantly,but that does not change our conclusion that the disk is not axisymmetric.

关 键 词：Galaxy:disk galaxies:spiral stars:early-type stars:massive 

分 类 号：P152[天文地球—天文学]