We report on the latest discovery of the HATNet project ; a very hot giant planet orbiting a bright ( V = 10.5 ) star with a small semi-major axis of a = 0.0377 \pm 0.0005 AU .
Ephemeris for the system is P = 2.2047299 \pm 0.0000040 days , mid-transit time E = 2 , 453 , 790.2593 \pm 0.0010 ( BJD ) .
Based on the available spectroscopic data on the host star and photometry of the system , the planet has a mass of M _ { p } = 1.78 ^ { +0.08 } _ { -0.05 } M _ { Jup } and radius of R _ { p } = 1.36 ^ { +0.20 } _ { -0.09 } R _ { Jup } .
The parent star is a slightly evolved F6 star with M _ { \star } = 1.47 ^ { +0.08 } _ { -0.05 } M _ { \sun } , R _ { \star } = 1.84 ^ { +0.23 } _ { -0.11 } R _ { \sun } , T _ { eff } = 6350 \pm 80 K , and metallicity [ \mathrm { Fe / H } ] = +0.26 \pm 0.08 .
The relatively hot and large host star , combined with the close orbit of the planet , yield a very high planetary irradiance of ( 4.71 ^ { +1.44 } _ { -0.05 } ) \times 10 ^ { 9 } erg cm ^ { -2 } s ^ { -1 } , which places the planet near the top of the pM class of irradiated planets as defined by Fortney et al .
( 17 ) .
If as predicted by Fortney et al .
( 17 ) the planet re-radiates its absorbed energy before distributing it to the night side , the day-side temperature should be about ( 2730 ^ { +150 } _ { -100 } ) K. Because the host star is quite bright , measurement of the secondary eclipse should be feasible for ground-based telescopes , providing a good opportunity to compare the predictions of current hot Jupiter atmospheric models with the observations .
Moreover , the host star falls in the field of the upcoming Kepler mission ; hence extensive space-borne follow-up , including not only primary transit and secondary eclipse observations but also asteroseismology , will be possible .