The Flare and Warp of the Young Stellar Disk Traced with LAMOST DR5 OB-type Stars - Archive ouverte HAL Access content directly
Journal Articles The Astrophysical Journal Year : 2021

The Flare and Warp of the Young Stellar Disk Traced with LAMOST DR5 OB-type Stars

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1
Yang Yu
  • Function : Author
Wen-Yuan Cui
  • Function : Author
Lin-Lin Li
  • Function : Author
Chao Liu
  • Function : Author
Bo Zhang
  • Function : Author
Hao Tian
  • Function : Author
Zhen-Yan Huo
  • Function : Author
Jie Ju
  • Function : Author
Zhi-Cun Liu
  • Function : Author
Fang Wen
  • Function : Author
Shuai Feng
  • Function : Author

Abstract

We present an analysis of the spatial density structure for the outer disk from 8-14 kpc with the LAMOST DR5 13,534 OB-type stars and observe similar flaring on the north and south sides of the disk, implying that the flaring structure is symmetrical about the Galactic plane, for which the scale height at different Galactocentric distances is from 0.14 to 0.5 kpc. By using the average slope to characterize the flaring strength, we find that the thickness of the OB stellar disk is similar but that flaring is slightly stronger compared to the thin disk as traced by red giant branch stars, possibly implying that secular evolution is not the main contributor to the flaring but rather perturbation scenarios such as interactions with passing dwarf galaxies could be possible. When comparing the scale height of the OB stellar disk on the north and south sides with the gas disk, the former one is slightly thicker than the latter one by ≍33 and 9 pc, meaning that one could tentatively use young OB-type stars to trace the gas properties. Meanwhile, we determine that the radial scale length of the young OB stellar disk is 1.17 ± 0.05 kpc, which is shorter than that of the gas disk, confirming that the gas disk is more extended than the stellar disk. What is more, by considering the midplane displacements (Z 0) in our density model we find that almost all values of Z 0 are within 100 pc, with an increasing trend as Galactocentric distance increases.

Dates and versions

insu-03720851 , version 1 (12-07-2022)

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Yang Yu, Hai-Feng Wang, Wen-Yuan Cui, Lin-Lin Li, Chao Liu, et al.. The Flare and Warp of the Young Stellar Disk Traced with LAMOST DR5 OB-type Stars. The Astrophysical Journal, 2021, 922, ⟨10.3847/1538-4357/ac1e91⟩. ⟨insu-03720851⟩
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