Abstract
Our current understanding of the star formation histories of
spheroidal galaxies is re-viewed, in the context of recent
observational studies of their ultraviolet (UV) properties.
Combination of UV and optical spectro-photometric data indicates that
the bulk of the stellar mass in this forms at high redshift (z > 2),
possibly over short timescales (< 1 Gyr). Nevertheless, spheroids of
all luminosities form stars over the lifetime of the Universe, with
most luminous (-23 < M(V ) < -21) systems forming 10-15% of their
stellar mass after z = 1 (with a scatter to higher value), while their
less luminous (M(V ) > -21) counterparts form 30-60% of their mass in
the same redshift range. The intensity of recent star formation and
the bulk of the UV colour distribution is consistent with what might
be expected from minor mergers (mass ratios < 1:6) in an LCDM
cosmology.