We present a summary of our recent work on the vertical distribution of the resolved stellar populations in six low mass , edge-on , spiral galaxies observed with the Hubble Space Telescope Advanced Camera for Surveys ( HST/ACS ) .
In each galaxy we find evidence for an extraplanar stellar component extending up to 15 scale heights ( \sim 3.5 kpc ) above the plane .
We analyze the vertical distribution as a function of stellar age by tracking changes in the color-magnitude diagram .
The young stellar component ( < 10 ^ { 8 } yrs ) is found to have a scale height larger than the young component in the Milky Way , suggesting that stars in these low mass galaxies form in a thicker disk .
We also find that the scale height of a stellar population increases with age , with young main sequence stars , intermediate age asymptotic giant branch stars , and old red giant branch stars having succesively larger scale heights in each galaxy .
This systematic trend indicates that disk heating must play some role in producing the extraplanar stars .
We constrain the rate of disk heating using the observed trend between scale height and stellar age , and find that the observed heating rates are dramatically smaller than in the Milky Way .
The color distributions of the red giant branch ( RGB ) stars well above the midplane indicate that the extended stellar components we see are moderately metal-poor , with peak metallicities of [ Fe/H ] \sim -1 and with little or no metallicity gradient with height .
The lack of metallicity gradient can be explained if a majority of extraplanar RGB stars were formed at early times and are not dominated by a younger heated population .
Our observations suggest that , like the Milky Way , low mass disk galaxies also have multiple stellar components .
We examine our results in light of disk heating and merger scenarios and conclude that both mechanisms likely played a role in forming the disks of our sample galaxies .