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planets and satellites: detection
planets and satellites:
individual: HATS-54b
HATS-55b
HATS-56b
HATS-57b
HATS-58b
Astrophysics - Earth and Planetary Astrophysics
Abstract:
We report the discovery by the HATSouth project of five new transiting hot Jupiters (HATS-54b through HATS-58Ab). HATS-54b, HATS-55b, and HATS- 58Ab are prototypical short-period (P = 2.5─4.2 days, R p ∼ 1.1─1.2 {R}{{J}}) hot Jupiters that span effective temperatures from 1350 to 1750 K, putting them in the proposed region of maximum radius inflation efficiency. The HATS-58 system is composed of two stars, HATS-58A and HATS-58B, which are detected thanks to Gaia DR2 data and which we account for in the joint modeling of the available data—with this, we are led to conclude that the hot Jupiter orbits the brighter HATS-58A star. HATS-57b is a short-period (2.35 day), massive (3.15 {M}{{J}}), 1.14 {R}{{J}}, dense (2.65+/- 0.21 {{g}} {cm}}-3) hot Jupiter orbiting a very active star (2% peak-to-peak flux variability). Finally, HATS-56b is a short-period (4.32 day), highly inflated hot Jupiter (1.7 {R}{{J}}, 0.6 {M}{{J}}), which is an excellent target for future atmospheric follow-up, especially considering the relatively bright nature (V = 11.6) of its F dwarf host star. This latter exoplanet has another very interesting feature: the radial velocities show a significant quadratic trend. If we interpret this quadratic trend as arising from the pull of an additional planet in the system, we obtain a period of {P}c={815}-143+253 days for the possible planet HATS-56c, and a minimum mass of {M}c\sin {i}c =5.11+/- 0.94 {M}{{J}}. The candidate planet HATS-56c would have a zero-albedo equilibrium temperature of T eq = 332 ± 50 K, and thus would be orbiting close to the habitable zone of HATS-56. Further radial-velocity follow-up, especially over the next two years, is needed to confirm the nature of HATS-56c. 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.
