Search

We report the discovery of two transiting Neptunes by the HATSouth survey. The planet HATS-37Ab has a mass of 0.099 +- 0.042 MJ (31.5 +- 13.4 M) and a radius of 0.606 +- 0.016 RJ, and is on a P = 4.3315 day orbit around a V = 12.266 +- 0.030 mag, 0.843-+0.0120.017 M☉ star with a radius of 0.877-+0.0120.019 R☉. We also present evidence that the star HATS-37A has an unresolved stellar companion HATS-37B, with a photometrically estimated mass of 0.654 +- 0.033 M☉. The planet HATS-38b has a mass of 0.074 +- 0.011 MJ (23.5 +- 3.5 M) and a radius of 0.614 +- 0.017 RJ, and is on a P = 4.3750 day orbit around a V = 12.411 +- 0.030 mag, 0.890-+0.0120.016 M☉ star with a radius of 1.105 +- 0.016 R☉. Both systems appear to be old, with isochrone-based ages of 11.46-+1.450.79 Gyr, and 11.89 +- 0.60 Gyr, respectively. Both HATS-37Ab and HATS-38b lie in the Neptune desert and are thus examples of a population with a low occurrence rate. They are also among the lowest-mass planets found from ground-based wide-field surveys to date.

We report the discovery of five new transiting hot-Jupiter planets discovered by the HATSouth survey, HATS-31b through HATS-35b. These planets orbit moderately bright stars with V magnitudes within the range of $11.9$–$14.4$ mag while the planets span a range of masses of $0.88$–$1.22$ ${M}_{{\rm{J}}}$ and have somewhat inflated radii between $1.23$ and $1.64$ ${R}_{{\rm{J}}}$. These planets can be classified as typical hot Jupiters, with HATS-31b and HATS-35b being moderately inflated gas giant planets with radii of $1.64\pm 0.22$ ${R}_{{\rm{J}}}$ and ${1.464}_{-0.044}^{+0.069}$ ${R}_{{\rm{J}}}$, respectively, that can be used to constrain inflation mechanisms. All five systems present a higher Bayesian evidence for a fixed-circular-orbit model than for an eccentric orbit. The orbital periods range from $1.8209993\pm 0.0000016$ day for HATS-35b) to $3.377960\pm 0.000012$ day for HATS-31b. Additionally, HATS-35b orbits a relatively young F star with an age of $2.13\pm 0.51$ Gyr. We discuss the analysis to derive the properties of these systems and compare them in the context of the sample of well-characterized transiting hot Jupiters known to date.

HATS-8b is a low density transiting super-Neptune discovered as part of the HATSouth project. The planet orbits its solar-like G-dwarf host (V = , = K) with a period of days. HATS-8b is the third lowest-mass transiting exoplanet to be discovered from a wide-field ground-based search, and with a mass of it is approximately halfway between the masses of Neptune and Saturn. However, HATS-8b has a radius of , resulting in a bulk density of just . The metallicity of the host star is super-solar ( = ), providing evidence against the idea that low-density exoplanets form from metal-poor environments. The low density and large radius of HATS-8b results in an atmospheric scale height of almost 1000 km, and in addition to this there is an excellent reference star of nearly equal magnitude at just 19″ separation in the sky. These factors make HATS-8b an exciting target for future atmospheric characterization studies, particularly for long-slit transmission spectroscopy.

We report the discovery of two transiting extrasolar planets by the HATSouth survey. HATS-9b orbits an old (10.8 ± 1.5 Gyr) V = 13.3 G dwarf star with a period days. The host star has a mass of 1.03 M⊙, radius of 1.503 R⊙, and effective temperature 5366 ± 70 K. The planetary companion has a mass of 0.837 Mj and radius of 1.065 Rj, yielding a mean density of 0.85g cm-3. HATS-10b orbits a V = 13.1 G dwarf star with a period days. The host star has a mass of 1.1 M⊙, radius of 1.11 R⊙, and effective temperature 5880 ± 120 K. The planetary companion has a mass of 0.53 and radius of 0.97 , yielding a mean density of 0.7 g cm-3. Both planets are compact in comparison with planets receiving similar irradiation from their host stars and lie in the nominal coordinates of Field 7 of K2, but only HATS-9b falls on working silicon. Future characterization of HATS-9b with the exquisite photometric precision of the Kepler telescope may provide measurements of its reflected light signature.

We report the discovery of HATS-5b, a transiting hot Saturn orbiting a G-type star, by the HATSouth survey. HATS-5b has a mass of Mp 0.24 MJ, radius of Rp 0.91 R J, and transits its host star with a period of P 4.7634 days. The radius of HATS-5b is consistent with both theoretical and empirical models. The host star has a V-band magnitude of 12.6, mass of 0.94 M ⊙, and radius of 0.87 R. The relatively high scale height of HATS-5b and the bright, photometrically quiet host star make this planet a favorable target for future transmission spectroscopy follow-up observations. We reexamine the correlations in radius, equilibrium temperature, and metallicity of the close-in gas giants and find hot Jupiter-mass planets to exhibit the strongest dependence between radius and equilibrium temperature. We find no significant dependence in radius and metallicity for the close-in gas giant population.

We report the discovery by the HATSouth survey of HATS-3b, a transiting extrasolar planet orbiting a V = 12.4 F dwarf star. HATS-3b has a period of P = 3.5479 days, mass of Mp = 1.07 M J, and radius of R p = 1.38 R J. Given the radius of the planet, the b

HATSouth is the world's first network of automated and homogeneous telescopes that is capable of year-round 24 hr monitoring of positions over an entire hemisphere of the sky. The primary scientific goal of the network is to discover and characterize a large number of transiting extrasolar planets, reaching out to long periods and down to small planetary radii. HATSouth achieves this by monitoring extended areas on the sky, deriving high precision light curves for a large number of stars, searching for the signature of planetary transits, and confirming planetary candidates with larger telescopes. HATSouth employs six telescope units spread over three prime locations with large longitude separation in the southern hemisphere (Las Campanas Observatory, Chile; HESS site, Namibia; Siding Spring Observatory, Australia). Each of the HATSouth units holds four 0.18 m diameter f=2:8 focal ratio telescope tubes on a common mount producing an 8:2° × 8:2° field of view on the sky, imaged using four 4 K×4 K CCD cameras and Sloan r filters, to give a pixel scale of 3:7″ pixel-1. The HATSouth network is capable of continuously monitoring 128 square arc degrees at celestial positions moderately close to the anti-solar direction. We present the technical details of the network, summarize operations, and present detailed weather statistics for the three sites. Robust operations have meant that on average each of the six HATSouth units has conducted observations on ~500 nights over a 2 years time period, yielding a total of more than 1 million science frames at a 4 minute integration time and observing ~10:65 hr day-1 on average. We describe the scheme of our data transfer and reduction from raw pixel images to trend-filtered light curves and transiting planet candidates. Photometric precision reaches ~6 mmag at 4 minute cadence for the brightest non-saturated stars at r ≈ 10:5. We present detailed transit recovery simulations to determine the expected yield of transiting planets fro