We report the discovery of HATS-15 b and HATS-16 b, two massive transiting
extrasolar planets orbiting evolved (∼10 Gyr) main-sequence stars. The
planet HATS-15 b, which is hosted by a G9V star (V=14.8 mag), is a hot
Jupiter with mass of 2.17±0.15MJ and radius of
1.105±0.0.040RJ, and completes its orbit in nearly 1.7 days.
HATS-16 b is a very massive hot Jupiter with mass of 3.27±0.19MJ and radius of 1.30±0.15RJ; it orbits around
its G3 V parent star (V=13.8 mag) in ∼2.7 days. HATS-16 is slightly
active and shows a periodic photometric modulation, implying a rotational
period of 12 days which is unexpectedly short given its isochronal age. This
fast rotation might be the result of the tidal interaction between the star and
its planet.Comment: 16 pages, 8 figures, submitted to PAS