Low-redshift quasars in the SDSS Stripe 82 II: associated companion
  galaxies and signature of star formation
  We present optical spectroscopy of the close companions of 22 low redshift
(z<0.5) quasars (QSO) selected from a larger sample of QSO in the SDSS Stripe82
region for which both the host galaxy and the large scale environments have
been investigated in our previous work. The new observations extend the number
of QSO studied in our previous paper on close companion galaxies of 12 quasars.
Our analysis here covers all 34 quasars from both this work and the previously
published paper. We find that half of them (15 QSO; $\sim$44%) have at least
one associated galaxy. Many (12 galaxies; $\sim$67%) of the associated
companions exhibit [OII] 3727 A emission line as signature of recent star
formation. The star formation rate (SFR) of these galaxies is modest (median
SFR $\sim$ 4.3 M$_{\odot}$ yr$^{-1}$). For 8 QSO we are also able to detect the
starlight of the host galaxy from which 3 have a typical spectrum of a
post-starburst galaxy. Our results suggest that quasars do not have a strong
influence on the star formation of their companion galaxies.
