Lunch talk on Sept. 26th, 2018: Galactic Mass and Anisotropy Profiles with Halo Stars from LAMOST and Gaia

Speaker: Sarah Ann Bird (NAOC)

Venue: Gewu 4410

Time: 12:30 PM, Wednesday, 26th September, 2018

Abstract: A major uncertainty in the determination of the mass profile of the Milky Way using stellar kinematics has been 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 spectra of over 16,000 Galactic halo K giant and blue horizontal branch stars from LAMOST and SDSS, combined with proper motions from Gaia DR2, to measure beta(r) over a wide range of Galactocentric distances r from 5 to 80 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.

Personal Information: http://www.sarahbird.billbird.com/

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