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 ∼ 1.3 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 ∼ 0.6 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.

We present the star formation history (SFH) of the Sculptor dwarf spheroidal galaxy based on deep g,r photometry taken with DECam at the Blanco telescope, focusing our analysis on the central region of the galaxy extended up to ∼ 3 core radii. We have investigated how the SFH changes radially, subdividing the sampled area into four regions, and have detected a clear trend of star formation. All the SFHs show a single episode of star formation, with the innermost region presenting a longer period of star formation of ∼ 1.5 Gyr and for the outermost region the main period of star formation is confined to ∼ 0.5 Gyr. We observe a gradient in the mean age which is found to increase going towards the outer regions. These results suggest that Sculptor continued forming stars after the reionization epoch in its central part, while in the peripheral region the majority of stars probably formed during the reionization epoch and soon after its end. From our analysis Sculptor can not be considered strictly as a fossil of the reionization epoch.

We report the discovery of an optical Einstein Ring in the Sculptor constellation, IAC J010127-334319, in the vicinity of the Sculptor Dwarf Spheroidal Galaxy. It is an almost complete ring (∼ 300 • ) with a diameter of ∼ 4.5 arcsec. The discovery was made serendipitously from inspecting Dark Energy Camera (DECam) archive imaging data. Confirmation of the object nature has been obtained by deriving spectroscopic redshifts for both components, lens and source, from observations at the 10.4 m Gran Telescopio CANARIAS (GTC) with the spectrograph OSIRIS. The lens, a massive early-type galaxy, has a redshift of z = 0.581 while the source is a starburst galaxy with redshift of z = 1.165. The total enclosed mass that produces the lensing effect has been estimated to be M tot = (1.86 ± 0.23) · 10 12 M ⊙ .