We construct a sample of nearly 30,000 main-sequence stars with 4500K < Teﬀ < 5000K and stellar ages estimated by the chromospheric activity−age relation. This sample is used to determine the age distribution in the R − Z plane of the Galaxy, where R is the projected Galactocentric distance in the disk midplane and Z is the height above the disk midplane. As |Z| increases, the percentage of old stars becomes larger. It is known that scale-height of Galactic disk increases as R increases, which is called ﬂare. A mild ﬂare from R ∼ 8.0 to 9.0 kpc in stellar age distribution is found. We also ﬁnd that the velocity dispersion increases with age as conﬁrmed by previous studies. Finally we present spiral-shaped structures in Z − υZ phase space in three stellar age bins. The spiral is clearly seen in the age bin of [0, 1] Gyr, which suggests that a vertical perturbation to the disk probably took place within the last ∼ 1.0 Gyr.
Scholarly Commons Citation
Zhang, J., Oswalt, T. D., Zhao, J., Liang, X., Ye, X., & Zhao, G. (2020). Nearly 30,000 Late-Type Main-Sequence Stars with Stellar Age from LAMOST DR5. , (). Retrieved from https://commons.erau.edu/publication/1493