[en] We report the discovery of HATS-1b, a transiting extrasolar planet orbiting the moderately bright V = 12.05 G dwarf star GSC 6652-00186, and the first planet discovered by HATSouth, a global network of autonomous wide-field telescopes. HATS-1b has a period of P ≈ 3.4465 days, mass of M_p ≈ 1.86 M_J, and radius of R_p ≈ 1.30 R_J. The host star has a mass of 0.99 M_☉ and radius of 1.04 R_☉. The discovery light curve of HATS-1b has near-continuous coverage over several multi-day timespans, demonstrating the power of using a global network of telescopes to discover transiting planets.

[en] We report the discovery by the HATSouth network of HATS-18b: a $1.980\pm <!--\; ??\; -->0.077$ $M_{\mathrm{J}}$, ${1.337}_{-<!--\; ???\; -->0.049}^{+0.102}$ $R_{\mathrm{J}}$ planet in a $0.8378$ day orbit, around a solar analog star (mass $1.037\pm <!--\; ??\; -->0.047$ $M_{\odot <!--\; ???\; -->}$ and radius ${1.020}_{-<!--\; ???\; -->0.031}^{+0.057}$ $R_{\odot <!--\; ???\; -->}$) with $V=14.067\pm <!--\; ??\; -->0.040$ mag. The high planet mass, combined with its short orbital period, implies strong tidal coupling between the planetary orbit and the star. In fact, given its inferred age, HATS-18 shows evidence of significant tidal spin up, which together with WASP-19 (a very similar system) allows us to constrain the tidal quality factor for Sun-like stars to be in the range of $6.5\lesssim <!--\; ???\; -->{\mathrm{l}\mathrm{o}\mathrm{g}}_{10}(Q^{\ast <!--\; ???\; -->}/k_2)\lesssim <!--\; ???\; -->7$ even after allowing for extremely pessimistic model uncertainties. In addition, the HATS-18 system is among the best systems (and often the best system) for testing a multitude of star–planet interactions, be they gravitational, magnetic, or radiative, as well as planet formation and migration theories.

[en] 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 M_p = 1.07 M _J, and radius of R_p = 1.38 R _J. Given the radius of the planet, the brightness of the host star, and the stellar rotational velocity (vsin i = 9.0 km s^–1), this system will make an interesting target for future observations to measure the Rossiter-McLaughlin effect and determine its spin-orbit alignment. We detail the low-/medium-resolution reconnaissance spectroscopy that we are now using to deal with large numbers of transiting planet candidates produced by the HATSouth survey. We show that this important step in discovering planets produces log g and T _eff parameters at a precision suitable for efficient candidate vetting, as well as efficiently identifying stellar mass eclipsing binaries with radial velocity semi-amplitudes as low as 1 km s^–1

[en] 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 $1.444\pm <!--\; ??\; -->0.057$ $R_{\odot <!--\; ???\; -->}$ and an effective temperature of $6060\pm <!--\; ??\; -->150$ K, while its companion is a $0.85\pm <!--\; ??\; -->0.12$ $M_{\mathrm{J}}$, $1.510\pm <!--\; ??\; -->0.078$ $R_{\mathrm{J}}$ 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-12b, our measurements indicate that this is a $2.38\pm <!--\; ??\; -->0.11$ $M_{\mathrm{J}}$, $1.35\pm <!--\; ??\; -->0.17$ $R_{\mathrm{J}}$ planet in a circular orbit. Both host stars show subsolar metallicities 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 among the most metal-poor and, HATS-12, with a $\mathrm{l}\mathrm{o}\mathrm{g}{g}_{\star <!--\; ???\; -->}$ of $3.923\pm <!--\; ??\; -->0.065$, is among 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).

[en] We report the discovery by the HATSouth network of HATS-7b, a transiting Super-Neptune with a mass of 0.120 ± 0.012 $M_{\mathrm{J}}$, a radius of ${0.563}_{-<!--\; ???\; -->0.034}^{+0.046}$ $R_{\mathrm{J}}$, and an orbital period of 3.1853 days. The host star is a moderately bright ($V=13.340\pm <!--\; ??\; -->0.010$ mag, $K_S=10.976\pm <!--\; ??\; -->0.026$ mag) K dwarf star with a mass of 0.849 ± 0.027 $M_{\odot <!--\; ???\; -->}$, a radius of ${0.815}_{-<!--\; ???\; -->0.035}^{+0.049}$ $R_{\odot <!--\; ???\; -->}$, and a metallicity of $[\mathrm{F}\mathrm{e}/\mathrm{H}]$ $=+0.250\pm <!--\; ??\; -->\mathrm{0.080.}$ The star is photometrically quiet to within the precision of the HATSouth measurements, has low RV jitter, and shows no evidence for chromospheric activity in its spectrum. HATS-7b is the second smallest radius planet discovered by a wide-field ground-based transit survey, and one of only a handful of Neptune-size planets with mass and radius determined to 10% precision. Theoretical modeling of HATS-7b yields a hydrogen–helium fraction of 18 ± 4% (rock-iron core and H₂–He envelope), or 9 ± 4% (ice core and H₂–He envelope), i.e., it has a composition broadly similar to that of Uranus and Neptune, and very different from that of Saturn, which has 75% of its mass in H₂–He. Based on a sample of transiting exoplanets with accurately (<20%) determined parameters, we establish approximate power-law relations for the envelopes of the mass–density distribution of exoplanets. HATS-7b, which, together with the recently discovered HATS-8b, is one of the first two transiting super-Neptunes discovered in the Southern sky, is a prime target for additional follow-up observations with Southern hemisphere facilities to characterize the atmospheres of Super-Neptunes (which we define as objects with mass greater than that of Neptune, and smaller than halfway between that of Neptune and Saturn, i.e., $0.054M_{\mathrm{J}}<<!--\; <\; -->M_{\mathrm{p}}<<!--\; <\; -->0.18M_{\mathrm{J}}$).

[en] We report the discovery by the HATSouth survey of HATS-4b, an extrasolar planet transiting a V = 13.46 mag G star. HATS-4b has a period of P ≈ 2.5167 days, mass of M_p ≈ 1.32 M _Jup, radius of R_p ≈ 1.02 R _Jup, and density of ρ _p = 1.55 ± 0.16 g cm^–3 ≈1.24 ρ_Jup. The host star has a mass of 1.00 M _☉, a radius of 0.92 R _☉, and a very high metallicity [Fe/H]=0.43 ± 0.08. HATS-4b is among the densest known planets with masses between 1 and 2 M _J and is thus likely to have a significant content of heavy elements of the order of 75 M _⊕. In this paper we present the data reduction, radial velocity measurements, and stellar classification techniques adopted by the HATSouth survey for the CORALIE spectrograph. We also detail a technique for simultaneously estimating vsin i and macroturbulence using high resolution spectra.

[en] We report the discovery by the HATSouth survey of HATS-6b, an extrasolar planet transiting a V = 15.2 mag, i = 13.7 mag M1V star with a mass of 0.57 $M_{\odot <!--\; ???\; -->}$ and a radius of 0.57 $R_{\odot <!--\; ???\; -->}$. HATS-6b has a period of P = 3.3253 d, mass of $M_p$ = 0.32 $M_J$, radius of $R_p$ = 1.00 $R_J$, and zero-albedo equilibrium temperature of $T_{\mathrm{e}\mathrm{q}}$ = 712.8 ± 5.1 K. HATS-6 is one of the lowest mass stars known to host a close-in gas giant planet, and its transits are among the deepest of any known transiting planet system. We discuss the follow-up opportunities afforded by this system, noting that despite the faintness of the host star, it is expected to have the highest K-band S/N transmission spectrum among known gas giant planets with $T_{\mathrm{e}\mathrm{q}}<<!--\; <\; -->750$ K. In order to characterize the star we present a new set of empirical relations between the density, radius, mass, bolometric magnitude, and V-, J-, H- and K-band bolometric corrections for main sequence stars with $M<<!--\; <\; -->0.80$ $M_{\odot <!--\; ???\; -->}$, or spectral types later than K5. These relations are calibrated using eclipsing binary components as well as members of resolved binary systems. We account for intrinsic scatter in the relations in a self-consistent manner. We show that from the transit-based stellar density alone it is possible to measure the mass and radius of a ∼0.6 $M_{\odot <!--\; ???\; -->}$ star to ∼7 and ∼2% precision, respectively. Incorporating additional information, such as the $V-<!--\; ???\; -->K$ color, or an absolute magnitude, allows the precision to be improved by up to a factor of two.

[en] 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 = $14.03\pm <!--\; ??\; -->0.10$, $T_{\mathrm{e}\mathrm{f}\mathrm{f}}$ = $5679\pm <!--\; ??\; -->50$ K) with a period of $3.5839$ 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 $0.138\pm <!--\; ??\; -->0.019$ $M_{\mathrm{J}}$ it is approximately halfway between the masses of Neptune and Saturn. However, HATS-8b has a radius of ${0.873}_{-<!--\; ???\; -->0.075}^{+0.123}$ $R_{\mathrm{J}}$, resulting in a bulk density of just $0.259\pm <!--\; ??\; -->0.091$ $\mathrm{g}{\mathrm{c}\mathrm{m}}^{-<!--\; ???\; -->3}$. The metallicity of the host star is super-solar ($[\mathrm{F}\mathrm{e}/\mathrm{H}]$ = $0.210\pm <!--\; ??\; -->0.080$), 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.

[en] 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 $0.5M_J\text{--}0.7M_J$ region of parameter space but span a wide variety of radii, from $1.17R_J$ to $1.75R_J$. HATS-25b, HATS-28b, HATS-29b, and HATS-30b are typical inflated hot Jupiters ($R_p=1.17\text{--}1.26R_J$) orbiting G–type stars in short period (P = 3.2-4.6 days) orbits. However, HATS-26b ($R_p=1.75R_J$, $P=3.3024$ days) and HATS-27b ($R_p=1.50R_J$, $P=4.6370$ 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 $\mathrm{g}{\mathrm{c}\mathrm{m}}^{-<!--\; ???\; -->3}$ and 0.180 $\mathrm{g}{\mathrm{c}\mathrm{m}}^{-<!--\; ???\; -->3}$, 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 ($v\sin <!--\; ???\; -->i\approx <!--\; ???\; -->9.3$ 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.

[en] 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 $P\approx <!--\; ???\; -->1.9153$ days. The host star has a mass of 1.03 $M_{\odot <!--\; ???\; -->}$, radius of 1.503 $R_{\odot <!--\; ???\; -->}$ , and effective temperature 5366 ± 70 K. The planetary companion has a mass of 0.837 $M_{\mathrm{J}}$ and radius of 1.065 $R_{\mathrm{J}}$, yielding a mean density of 0.85 $\mathrm{g}{\mathrm{c}\mathrm{m}}^{-<!--\; ???\; -->3}$. HATS-10b orbits a V = 13.1 G dwarf star with a period $P\approx <!--\; ???\; -->3.3128$ days. The host star has a mass of 1.1 $M_{\odot <!--\; ???\; -->}$, radius of 1.11 $R_{\odot <!--\; ???\; -->}$ , and effective temperature 5880 ± 120 K. The planetary companion has a mass of 0.53 $M_{\mathrm{J}}$ and radius of 0.97 $R_{\mathrm{J}}$, yielding a mean density of 0.7 $\mathrm{g}{\mathrm{c}\mathrm{m}}^{-<!--\; ???\; -->3}$. 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.