  We present the results of a study of the stellar population in a region of 30
pc radius around SN1987A, based on an analysis of multi-band HST-WFPC2 images.
  The effective temperature, radius and, possibly, reddening of each star were
determined for 21,955 stars by fitting the measured broad band magnitudes to
the ones calculated with model atmospheres. In addition, we have identified all
stars with Halpha equivalent widths in excess of 8 A, amounting to a total of
492 stars.
  An inspection to the HR diagram reveals the presence of several generations
of young stars, with ages between 1 and 150 Myrs, superposed on a much older
field population (0.6-6 Gyrs). A substantial fraction of young stars have ages
around 12 Myrs which is the stellar generation coeval to SN 1987A progenitor.
The youngest stars in the field appear to be strong-line T Tauri stars. This
constitute the first positive detection of low mass (about 1-2 Mo) Pre Main
Sequence (PMS) stars outside the Milky Way. Their positions in the HR diagram
appear to require that star formation in the LMC occurs with accretion rates
about 10 times higher than in the Milky Way, i.e. ~10^{-4} Mo/yr.
  SN1987A appears to belong to a loose, young cluster 12+/-2 Myrs old, in which
the slope of the present mass function is almost identical to Salpeter's for
masses above 3 Mo, but becomes much flatter for lower masses. On a large scale,
we find that the spatial distribution of massive stars and low-mass PMS stars
are conclusively different. This results casts doubts on the validity of an IMF
concept on a small scale (say, less than 10 pc). A preliminary analysis, done
for the whole field as a single entity, shows that the IMF slope for the young
population present over the entire region is steeper than Gamma ~ -1.7.
