We present Hubble Space Telescope photometry of young stars in NGC 5102 , a nearby gas-rich post-starburst S0 galaxy with a bright young stellar nucleus .
We use the IAC-pop/MinnIAC algorithm to derive the recent star formation history in three fields in the bulge and disk of NGC 5102 .
In the disk fields , the recent star formation rate has declined monotonically and is now barely detectable , but a starburst is still in progress in the bulge and has added about 2 % to the mass of the bulge over the last 200 Myr .
Other studies of star formation in NGC 5102 indicate that about 20 % of its stellar mass was added over the past Gyr .
If this is correct , then much of the stellar mass of the bulge may have formed over this period .
It seems likely that this star formation was fueled by the accretion of a gas-rich system with H i mass of about 2 \times 10 ^ { 9 } M _ { \odot } Â which has now been almost completely converted into stars .
The large mass of recently formed stars and the blue colours of the bulge suggest that the current starburst , which is now fading , may have made a significant contribution to build the bulge of NGC 5102 .