HATS-11b and HATS-12b: Two transiting Hot Jupiters orbiting sub-solar metallicity stars selected for the K2 Campaign 7

TL;DR

This paper reports the discovery and characterization of two transiting hot Jupiters orbiting sub-solar metallicity, evolved stars, identified through the HATSouth survey and observed in K2 Campaign 7, highlighting their unique stellar properties.

Contribution

The study presents the discovery of two new hot Jupiters around sub-solar metallicity, evolved stars, with detailed stellar and planetary parameters, expanding the known diversity of exoplanet host stars.

Findings

HATS-11b is a 0.85 M_J, 1.51 R_J planet orbiting a sub-solar metallicity star.

HATS-12b is a 2.38 M_J, 1.35 R_J planet orbiting a slightly evolved star.

Both host stars are among the most metal-poor and evolved stars known to host hot Jupiters.

Abstract

We report the discovery of two transiting extrasolar planets from the HATSouth survey. HATS-11, a V=14.1 G0-star shows a periodic 12.9 mmag dip in its light curve every 3.6192 days and a radial velocity variation consistent with a Keplerian orbit. HATS-11 has a mass of 1.000 $\pm$ 0.060 M$_{\odot}$, a radius of 1.444 $\pm$ 0.057 M$_{\odot}$ and an effective temperature of 6060 $\pm$ 150 K, while its companion is a 0.85 $\pm$ 0.12 M$_J$, 1.510 $\pm$ 0.078 R$_J$ planet in a circular orbit. HATS-12 shows a periodic 5.1 mmag flux decrease every 3.1428 days and Keplerian RV variations around a V=12.8 F-star. HATS-12 has a mass of 1.489 $\pm$ 0.071 M$_{\odot}$, a radius of 2.21 $\pm$ 0.21 R$_{\odot}$, and an effective temperature of 6408 $\pm$ 75 K. For HATS-12, our measurements indicate that this is a 2.38 $\pm$ 0.11 M$_J$, 1.35 $\pm$ 0.17 R$_J$ planet in a circular orbit. Both host stars show sub-solar metallicity of -0.390 $\pm$ 0.060 dex and -0.100 $\pm$ 0.040 dex, respectively and are (slightly) evolved stars. In fact, HATS-11 is amongst the most metal-poor and, HATS-12 is amongst the most evolved stars hosting a hot Jupiter planet. Importantly, HATS-11 and HATS-12 have been observed in long cadence by Kepler as part of K2 campaign 7 (EPIC216414930 and EPIC218131080 respectively).