|Redefine the Mass of the Milky Way|
CAS National Observatory, in collaboration with Max-Planck-Institute for Astronomy, has
for the first time calculated the mass of the Milky Way to be 1011M⊙, indicating a slimmer
Milky Way. Researchers selected some 2500 Blue Horizontal-Branch (BHB) halo stars
drawn from SDSS-II dataset, the largest in number and widest in distribution (5-60 kpc).
BHBs can be measured in an accurate manner, as they are mostly in an evolutionary stage
to become a star, desirable for studying the Milky Way's halo. Chinese and German
scientists have worked out the latest mass of the Milky Way based on kinematics of BHBs.
The finding, with XUE Xiang-Xiang of the CAS National Observatory as the first author, was
published in the recent issue of Astrophysical Journal.
With a large array of halo stars, one can calculate the mass of the Milky Way in an accurate
manner, and study the structure of the Milky Way's halo, in an attempt to understand the
forming process of the system. China's LAMOST that will soon be put into operation is able
to produce the most spectrums in the world, and is expected to work out start spectrums
with an improved quality. A high quality spectrum is very useful for raising the speed of star
viewing and accuracy of atmospheric parameters, making collecting more and better halo
samples possible. China's LAMOST can also be employed to study the structure and
formation of the Milky Way.