HATS-39b, HATS-40b, HATS-41b, and HATS-42b: three inflated hot Jupiters and a super-Jupiter transiting F stars

We report the discovery of four transiting hot Jupiters from the HATSouth survey: HATS-39b, HATS-40b, HATS-41b, and HATS-42b. These discoveries add to the growing number of transiting planets orbiting moderately bright (12.5 ≲ V ≲ 13.7) F dwarf stars on short (2-5 d) periods. The planets have similar radii, ranging from 1.33^{+0.29}_{-0.20} R_J for HATS-41b to 1.58^{+0.16}_{-0.12} R_J for HATS-40b. Their masses and bulk densities, however, span more than an order of magnitude. HATS-39b has a mass of 0.63 ± 0.13 M_J, and an inflated radius of 1.57 ± 0.12 R_J, making it a good target for future transmission spectroscopic studies. HATS-41b is a very massive 9.7 ± 1.6 M_J planet and one of only a few hot Jupiters found to date with a mass over 5 M_J. This planet orbits the highest metallicity star ([Fe/H] = 0.470 ± 0.010) known to host a transiting planet and is also likely on an eccentric orbit. The high mass, coupled with a relatively young age (1.34^{+0.31}_{-0.51} Gyr) for the host star, is a factor that may explain why this planet's orbit has not yet circularized.