The star formation history of the Sextans dwarf spheroidal galaxy: a
  true fossil of the pre-reionization era
  We present the star formation history (SFH) of the Sextans dwarf spheroidal
galaxy based on deep archive $B$,$I$ photometry taken with Suprime-Cam at
Subaru telescope focusing our analysis on the inner region of the galaxy, fully
located within the core radius. Within the errors of our SFH we have not
detected any metallicity gradient along the considered radial distance
interval. As a main result of this work we can state that the Sextans dwarf
spheroidal stopped forming stars less than $\sim1.3$ Gyr after Big Bang in
correspondance to the end of the reionization epoch. We have been able to
constrain the duration of the main burst of star formation to $\sim0.6$ Gyr.
From the calculation of the mechanical luminosity released from supernovae
(SNe) during the brief episode of star formation, there are strong indications
that SNe could have played an important role in the fate of Sextans, by
removing almost completely the gas component, so preventing a prolonged star
formation.
