Star formation histories and evolution of 35 brightest E+A galaxies from
  SDSS DR5
  We pick out the 35 brightest galaxies from Goto's E+A galaxies catalogue
which are selected from the Sloan Digital Sky Survey Data Release 5. The
spectra of E+As are prominently characterized by the strong Balmer absorption
lines but little [Oii] or H_alpha emission lines. In this work we study the
stellar populations of the sample galaxies by fitting their spectra using
ULySS, which is a robust full spectrum fitting method. We fit each of the
sample with 1-population (a single stellar population-a SSP) and 3-population
(3 SSPs) models, separately. By 1-population fits, we obtain SSP-equivalent
ages and metallicities which correspond to the `luminosity-weighted' averages.
By 3-population fits, we divide components into three groups in age (old
stellar population-OSP, intermediate-age stellar population-ISP, and young
stellar population-YSP), and then get the optimal age, metallicity and
population fractions in both mass and light for OSP, ISP and YSP. During the
fits, both Pegase.HR/Elodie3.1 and Vazdekis/Miles are used as two independent
population models. The two models result in generally consistent conclusions as
follows: for all the sample galaxies, YSPs (< 1Gyr) make important
contributions to the light. However, the dominant contributors to mass are
OSPs. We also reconstruct the smoothing star formation histories (SFHs) by
giving star formation rate (SFR) versus evolutionary age. In addition, we fit
the E+A sample and 34 randomly selected elliptical galaxies with 2-population
(2 SSPs) model. We obtain the equivalent age of old components for each of the
E+A sample and elliptical galaxies. By comparison, the old components of E+As
are statistically much younger than those of ellipticals. From the standpoint
of the stellar population age, this probably provides an evidence for the
proposed evolutionary link from E+As to early-types (E/S0s).
