  Bright-rimmed clouds (BRCs) found in H II regions are probable sites of
triggered star formation due to compression by ionization/shock fronts, and it
is hypothesized that star formation proceeds from the exciting star(s) side
outward of the HII region ("small-scale sequential star formation"). In order
to quantitatively testify this hypothesis we undertook BVIc photometry of four
BRC aggregates. The amounts of interstellar extinction and reddening for each
star have been estimated by using the JHKs photometry. Then we constructed
reddening-corrected V/V-Ic color-magnitude diagrams, where the age of each star
has been derived. All the stars turned out to be a few tenths to a few Myr old.
Although the scatters are large and the numbers of the sample stars are small,
we found a clear trend that the stars inside or in the immediate vicinity of
the bright rim are younger than those outside it in all the four aggregates,
confirming the hypothesis in question.
