  We report on the first measurement of charm-strange meson $D_s^{\pm}$
production at midrapidity in Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 200
GeV from the STAR experiment. The yield ratio between strange ($D_{s}^{\pm}$)
and non-strange ($D^{0}$) open-charm mesons is presented and compared to model
calculations. A significant enhancement, relative to a PYTHIA simulation of
$p$+$p$ collisions, is observed in the $D_{s}^{\pm}/D^0$ yield ratio in Au+Au
collisions over a large range of collision centralities. Model calculations
incorporating abundant strange-quark production in the quark-gluon plasma (QGP)
and coalescence hadronization qualitatively reproduce the data. The
transverse-momentum integrated yield ratio of $D_{s}^{\pm}/D^0$ at midrapidity
is consistent with a prediction from a statistical hadronization model with the
parameters constrained by the yields of light and strange hadrons measured at
the same collision energy. These results suggest that the coalescence of charm
quarks with strange quarks in the QGP plays an important role in $D_{s}^{\pm}$
meson production in heavy-ion collisions.
