  New CCD photometric light curves of short period (P=0.285d) eclipsing binary
RW Dor are presented. The observations performed with the PROMPT-8 robotic
telescope at CTIO in Chile from March 2015 to March 2017. The other eclipse
timings were obtained from the 2.15-m JS telescope at CASLEO, San Juan,
Argentina in December 2011. By light-curve analysis, it is found that RW Dor is
a W-type shallow contact binary with a fill-out factor $f \sim 11\%$ and high
mass ratio $q \sim 1.587$ (1/q = 0.63), where the hotter component is the less
massive one ($M_1 \sim 0.52M_{\odot}$ and $M_2 \sim 0.82M_{\odot}$). For
orbital period investigation, the new fifteen eclipse times and those in
previous published were compiled. Based on $O-C$ analysis with very weak
evidence suggests that a long-term period decrease with a rate of
$\mathrm{d}P/\mathrm{d}t = -9.61\times10^{-9}$ d $\textrm{yr}^{-1}$ is
superimposed on a cyclic variation ($A_3$ = 0.0054 days and $P_3$ = 49.9 yrs).
The long-term period decrease can be interpreted as mass transfer from the more
massive component to the less massive one or combine with the angular momentum
loss (AML) via magnetic braking. In addition, with the marginal contact phase,
high mass ratio (1/q $>$ 0.4) and the long-term period decrease, all suggest
that RW Dor is a newly formed contact binary via a Case A mass transfer and it
will evolve into a deeper normal contact binary. If the cyclic change is
correct, the light-travel time effect via the presence of a cool third body
will be more plausible to explain for this.
