Isolating the young stellar population in the outer disk of NGC 300
  The recent star formation history (SFH) in the outer disk of NGC 300 is
presented through the analysis of color magnitude diagrams (CMDs). We analyze
resolved stellar photometry by creating CMDs from four Hubble Space Telescope
fields containing a combination of images from the Advanced Camera for Surveys
and the UVIS imager aboard the Wide Field Camera 3. From the best models of
these CMDs, we derive the SFH in order to extract the young stellar component
for the past 200 Myrs. We find that the young stellar disk of NGC 300 is
unbroken out to at least ${\sim}$8 scale lengths (including an upper limit out
to ${\sim}$10 scale lengths) with $r{_s}$ = 1.4 ${\pm}$ 0.1 kpc, which is
similar to the total stellar surface brightness profile. This unbroken profile
suggests that NGC 300 is undisturbed, similar to the isolated disk galaxy NGC
2403. We compare the environments of NGC 300, NGC 2403, and M33 along with the
properties of the gas and stellar disks. We find that the disturbed HI outer
disk morphology is not accompanied by a break in the young stellar disk. This
may indicate that processes which affect the outer HI morphology may not leave
an imprint on the young stellar disk.
