Title：Galactic Mass and Anisotropy Profile with Halo K-Giant and Blue Horizontal Branch Stars from LAMOST/SDSS and Gaia

　Speaker：Dr. Sarah Bird (Aliyun Fellow, NAOC)

　Abstract：A major uncertainty in the determination of the mass profile of the Milky Way using stellar kinematics is the poorly determined anisotropy parameter, beta = 1 - ( ( (sigma_theta)**2 + (sigma_phi)**2 ) / ( 2 * (sigma_r)**2 ), where sigma_r is the Galactocentric radial velocity dispersion, and sigma_theta and sigma_phi are the tangential components of the velocity dispersion. We use a sample of over 22,000 Galactic halo K giant and blue horizontal branch stars from the ground-based LAMOST and SDSS/SEGUE stellar spectroscopic surveys, combined with proper motions from the space telescope Gaia, to measure beta(r) over a wide range of Galactocentric distances r from 4 to 100 kpc. We investigate the extent to which a much improved knowledge of beta influences the determination of the Galactic mass profile M(r) as a function of r.

　时间：7月14日（星期二）上午10点

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