HATS-25b through HATS-30b: A Half-dozen New Inflated Transiting Hot Jupiters from the HATSouth Survey

We report six new inflated hot Jupiters (HATS-25b through HATS-30b) discovered using the HATSouth global network of automated telescopes. The planets orbit stars with V magnitudes in the range of ∼12-14 and have masses in the largely populated 0.5{M}_J{--}0.7{M}_J region of parameter space but span a wide variety of radii, from 1.17{R}_J to 1.75{R}_J. HATS-25b, HATS-28b, HATS-29b, and HATS-30b are typical inflated hot Jupiters ({R}_p=1.17{--}1.26{R}_J) orbiting G-type stars in short period (P = 3.2-4.6 days) orbits. However, HATS-26b ({R}_p=1.75{R}_J, P=3.3024 days) and HATS-27b ({R}_p=1.50{R}_J, P=4.6370 days) stand out as highly inflated planets orbiting slightly evolved F stars just after and in the turn-off points, respectively, which are among the least dense hot Jupiters, with densities of 0.153 {{g}} {cm}}^-3 and 0.180 {{g}} {cm}}^-3, respectively. All the presented exoplanets but HATS-27b are good targets for future atmospheric characterization studies, while HATS-27b is a prime target for Rossiter—McLaughlin monitoring in order to determine its spin-orbit alignment given the brightness (V = 12.8) and stellar rotational velocity (v\sin i≈ 9.3 km s^-1) of the host star. These discoveries significantly increase the number of inflated hot Jupiters known, contributing to our understanding of the mechanism(s) responsible for hot Jupiter inflation.

The HATSouth network is operated by a collaboration consisting of Princeton University (PU), the Max Planck Institute für Astronomie (MPIA), the Australian National University (ANU), and the Pontificia Universidad Católica de Chile (PUC). The station at Las Campanas Observatory (LCO) of the Carnegie Institute is operated by PU in conjunction with PUC, the station at the High Energy Spectroscopic Survey (H.E.S.S.) site is operated in conjunction with MPIA, and the station at Siding Spring Observatory (SSO) is operated jointly with ANU. Based in part on observations made with the MPG 2.2 m Telescope at the ESO Observatory in La Silla.