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 semimajor axis of a = 0.0377 ±0.0005 AU. Ephemeris for the system is P = 2.2047299 ±0.0000040 days, midtransit time E = 2,453,790.2593 ±0.0010 (BJD). Based on the available spectroscopic data on the host star and photometry of the system, the planet has a mass of Mp = 1.78-0.05 +0.08 MJ and radius of Rp = 1.36 -0.09+0.020 RJ. The parent star is a slightly evolved F6 star with M*= 1.47-0.05+0.08M ⊙R*, =1.840.11+0.23 R ⊙,Teff = 6350 ±80 K, and metallicity [Fe/H] = +0.26 ±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 -0.05+1.44 × 109 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. If as predicted by Fortney et al. the planet reradiates its absorbed energy before distributing it to the night side, the day-side temperature should be about 273012 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.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
- Planetary systems
- Stars: individual (GSC 03547-01402, HAT-P-7)
- Techniques: spectroscopic