Towards a fully consistent Milky Way disc model – II. The local disc model and SDSS data of the NGP region
Towards a fully consistent Milky Way disc model – II. The local disc model and SDSS data of the NGP region
复制标题
迈向完全一致的银河系盘模型-II. NGP区域的本地盘模型和SDSS数据
DOI：
--
复制
发表时间：
2010
期刊：
影响因子：
--
通讯作者：
S. Vidrih
中科院分区：
文献类型：
--
作者：
A. Just;Shuang Gao;S. Vidrih
We have used the self-consistent vertical disc models of the solar neighbourhood presented in Paper I, which are based on different star formation histories (SFRs) and fit the local kinematics of main-sequence stars equally well, to predict star counts towards the North Galactic Pole (NGP). We combined these four different models with the local main sequence in the filter system of the Sloan Digital Sky Survey (SDSS) and predicted the star counts in the NGP field with b > 80°. All models fit the Hess diagrams in the F-K dwarf regime better than ±20 per cent and the star number densities in the solar neighbourhood are consistent with the observed values. The χ 2 analysis shows that model A is clearly preferred with systematic deviations of a few per cent only. The SFR of model A is characterized by a maximum at an age of 10 Gyr and a decline by a factor of 4 to the present-day value of 1.4 M ⊙ pc ―2 Gyc ―1 . The thick disc can be modelled very well by an old isothermal simple stellar population. The density profile can be approximated by a sech αt function. We found a power-law index α t = 1.16 and a scaleheight h t = 800 pc corresponding to a vertical velocity dispersion of σ t = 45.3 kms ―1 . About 6 per cent of the stars in the solar neighbourhood are thick-disc stars.
