The author here uses his earlier work on RR Lyrae stars in the galactic halo to probe the stellar population of the outer halo and to deduce the mass distribution in the far reaches of the Galaxy. The space densities of RR Lyrae stars are traced out to 33 kpc from the galactic center. When combined with data from other surveys, the run of RR Lyrae star densities covering a very wide range of galactocentric distances is available. The chemical abundances of these probe stars show a very wide spread of metallicity, [Fe/H] from -1.0 to -2.2. However, no net abundance gradient is seen in the far halo. From the radial velocities, the kinematics of these stars has been studied. The mass of the Galaxy within 25 kpc is derived via dynamical arguments to be about 3×10¹¹M_sun;.
No takes yet. Share an insight, caveat, or question.
Abhijit Saha (1985) studied this question.