The star-formation history of low-mass disk galaxies: a case study of
  NGC\,300
  Since NGC300 is a bulge-less, isolated low-mass galaxy and has not
experienced radial migration during its evolution history, it can be treated as
an ideal laboratory to test simple galactic chemical evolution models. By
assuming its disk forms gradually from continuous accretion of primordial gas
and including the gas-outflow process, we construct a simple chemical evolution
model for NGC300 to build a bridge between its SFH and its observed data,
especially the present-day radial profiles and global observed properties
(e.g., cold gas mass, star-formation rate and metallicity). By means of
comparing the model predictions with the corresponding observations, we adopt
the classical $\chi^{2}$ methodology to find out the best combination of free
parameters $a$, $b$ and $b_{\rm out}$. Our results show that, by assuming an
inside-out formation scenario and an appropriate outflow rate, our model
reproduces well most of the present-day observational values, not only the
radial profiles but also the global observational data for the NGC300 disk. Our
results suggest that NGC300 may experience a rapid growth of its disk. Through
comparing the best-fitting model predicted SFH of NGC300 with that of M33, we
find that the mean stellar age of NGC300 is older than that of M33 and there is
a lack of primordial gas infall onto the disk of NGC300 recently. Our results
also imply that the local environment may paly a key role in the secular
evolution of NGC300.
