We report the discovery of HAT-P-16b , a transiting extrasolar planet orbiting the V = 10.8 mag F8 dwarf GSC 2792-01700 , with a period P = 2.775960 \pm 0.000003 d , transit epoch T _ { c } = 2455027.59293 \pm 0.00031 ( BJD All BJD values given in this paper are UTC-based ( e.g . Torres et al .
( 45 ) ) ) , and transit duration 0.1276 \pm 0.0013 d. The host star has a mass of 1.22 \pm 0.04 M _ { \sun } , radius of 1.24 \pm 0.05 R _ { \sun } , effective temperature 6158 \pm 80 K , and metallicity [ Fe / H ] = +0.17 \pm 0.08 .
The planetary companion has a mass of 4.193 \pm 0.094 M _ { J } , and radius of 1.289 \pm 0.066 R _ { J } yielding a mean density of 2.42 \pm 0.35 g cm ^ { -3 } .
Comparing these observed characteristics with recent theoretical models , we find that HAT-P-16b is consistent with a 1 Gyr H/He-dominated gas giant planet .
HAT-P-16b resides in a sparsely populated region of the mass–radius diagram and has a non-zero eccentricity of e = 0.036 with a significance of 10 \sigma .