M105 is a standard elliptical galaxy , located in the Leo I Group .
We present photometry of the resolved stars in its inner region at R \approx 4 \arcmin \approx 4 R _ { eff } , obtained from F606W and F814W images in the Hubble Space Telescope archive .
We combine this with photometry of the outer region at R \approx 12 \arcmin \approx 12 R _ { eff } from archival imaging data .
Color-magnitude diagrams of the resolved stars in the inner region show a prominent red giant branch ( RGB ) with a large color range , while those of the outer region show better a narrow blue RGB .
The metallicity distribution function ( MDF ) of the RGB stars shows the existence of two distinct subpopulations : a dominant metal-rich population ( with a peak at [ M/H ] \approx 0.0 ) and a much weaker metal-poor population ( with a peak at [ M/H ] \approx - 1.1 ) .
The radial number density profiles of the metal-rich and metal-poor RGB stars are fit well by a Sérsic law with n = 2.75 \pm 0.10 and n = 6.89 \pm 0.94 , and by a single power law ( \sigma \propto R ^ { -3.8 } and \sigma \propto R ^ { -2.6 } ) , respectively .
The MDFs of the inner and outer regions can be described well by accretion gas models of chemical evolution with two components .
These provide strong evidence that there are two distinct stellar halos in this galaxy , metal-poor and red metal-rich halos , consistent with the results based on globular cluster systems in bright early-type galaxies ( Park & Lee 2013 ) .
We discuss the implications of these results with regard to the formation of massive early-type galaxies in the dual halo mode formation scenario .