Star formation histories of the LEGUS dwarf galaxies (III): the
  non-bursty nature of 23 star forming dwarf galaxies
  We derive the recent star formation histories of 23 active dwarf galaxies
using HST observations from the Legacy Extragalactic UV Survey (LEGUS). We
apply a color-magnitude diagram fitting technique using two independent sets of
stellar models, PARSEC-COLIBRI and MIST. Despite the non-negligible recent
activity, none of the 23 star forming dwarfs show enhancements in the last 100
Myr larger than three times the 100-Myr-average. The unweighted mean of the
individual SFHs in the last 100 Myr is also consistent with a rather constant
activity, irrespective of the atomic gas fraction. We confirm previous results
that for dwarf galaxies the CMD-based average star formation rates (SFRs) are
generally higher than the FUV-based SFR. For half of the sample, the
60-Myr-average CMD-based SFR is more than two times the FUV SFR. In contrast,
we find remarkable agreement between the 10-Myr-average CMD-based SFR and the
H${\alpha}$-based SFR. Finally, using core helium burning stars of intermediate
mass we study the pattern of star formation spatial progression over the past
60 Myr, and speculate on the possible triggers and connections of the star
formation activity with the environment in which these galaxies live.
Approximately half of our galaxies show spatial progression of star formation
in the last 60 Myr, and/or very recent diffuse and off-center activity compared
to RGB stars.
