[en] The results are presented of a search for chromospheric CaII H and K emission in a sample of 195 subgiant and lower giant-branch stars in the old disc clusters NGC 2204, 2243, 2420, 2506 and Melotte 66. It is argued that in subgiant stars belonging to old (3-8x10⁹ yr) clusters such as these, the presence of CaII emission comparable to that seen in the RS CVn binaries of the solar neighbourhood should be a reliable indicator of abnormally rapid axial rotation brought about by tidal locking in a binary system with an orbital period between 1 and 50 day. The search was carried out using intermediate-dispersion spectroscopy with the multi-object fibres system on the AAT. Radial velocities derived from the spectra are used to determine cluster membership probabilities, and it is found that 138 of the 195 stars surveyed are probably cluster members. (author)

[en] Spectra between 2.00 and 2.45 μm, with a resolution of ∼ 0.01 μ are presented, for a sample of 73 stars. These stars include a supergiant, giants, dwarfs and subdwarfs, and have a range in chemical abundance from about ∼ -2 to + 0.5 dex. (author)

[en] WASP-19b has the shortest orbital period of any known exoplanet, orbiting at only 1.2 times the Roche tidal radius. By observing the Rossiter-McLaughlin effect we show that WASP-19b's orbit is aligned, with λ = 4.⁰6 ± 5.⁰2. Using, in addition, a spectroscopic vsin I and the observed rotation period we conclude that the obliquity, ψ, is less than 20⁰. Further, the eccentricity of the orbit is less than 0.02. We argue that hot Jupiters with orbital periods as short as that of WASP-19b are two orders of magnitude less common than hot Jupiters at the 3-4 day 'pileup'. We discuss the evolution of WASP-19b's orbit and argue that most likely it was first moved to near twice the Roche limit by third-body interactions, and has since spiralled inward to its current location under tidal decay. This is compatible with a stellar tidal-dissipation quality factor, Q'_*, of order 10⁷.

[en] We report the discovery of three new transiting hot Jupiters by WASP-South together with the TRAPPIST photometer and the Euler/CORALIE spectrograph. WASP-74b orbits a star of V = 9.7, making it one of the brighter systems accessible to southern telescopes. It is a 0.95M_Jup planet with a moderately bloated radius of 1.5 $R_{\mathrm{J}\mathrm{u}\mathrm{p}}$ in a 2 day orbit around a slightly evolved F9 star. WASP-83b is a Saturn-mass planet at 0.3 $M_{\mathrm{J}\mathrm{u}\mathrm{p}}$ with a radius of 1.0 $R_{\mathrm{J}\mathrm{u}\mathrm{p}}$. It is in a 5 day orbit around a fainter (V = 12.9) G8 star. WASP-89b is a 6 M_Jup planet in a 3 day orbit with an eccentricity of e = 0.2. It is thus similar to massive, eccentric planets such as XO-3b and HAT-P-2b, except that those planets orbit F stars whereas WASP-89 is a K star. The V = 13.1 host star is magnetically active, showing a rotation period of 20.2 days, while star spots are visible in the transits. There are indications that the planet’s orbit is aligned with the stellar spin. WASP-89 is a good target for an extensive study of transits of star spots.

[en] We report the discovery of a transiting planet orbiting the star TYC 6446-326-1. The star, WASP-22, is a moderately bright (V = 12.0) solar-type star (T_eff = 6000 ± 100 K, [Fe/H] = -0.05 ± 0.08). The light curve of the star obtained with the WASP-South instrument shows periodic transit-like features with a depth of about 1% and a duration of 0.14 days. The presence of a transit-like feature in the light curve is confirmed using z-band photometry obtained with Faulkes Telescope South. High-resolution spectroscopy obtained with the CORALIE and HARPS spectrographs confirms the presence of a planetary mass companion with an orbital period of 3.533 days in a near-circular orbit. From a combined analysis of the spectroscopic and photometric data assuming that the star is a typical main-sequence star we estimate that the planet has a mass M_p = 0.56 ± 0.02M_Jup and a radius R_p = 1.12 ± 0.04R_Jup. In addition, there is a linear trend of 40 m s^-1 yr^-1 in the radial velocities measured over 16 months, from which we infer the presence of a third body with a long-period orbit in this system. The companion may be a low mass M-dwarf, a white dwarf, or a second planet.

[en] We report the discovery of a Saturn-sized planet transiting a V = 11.3, K4 dwarf star every 3.9 days. WASP-29b has a mass of 0.24 ± 0.02 M _Jup and a radius of 0.79 ± 0.05 R _Jup, making it the smallest planet so far discovered by the WASP survey, and the exoplanet most similar in mass and radius to Saturn. The host star WASP-29 has an above-solar metallicity and fits a possible correlation for Saturn-mass planets such that planets with higher-metallicity host stars have higher core masses and thus smaller radii.

[en] We report the discovery of a low-density exoplanet transiting an 11th magnitude star in the Southern hemisphere. WASP-15b, which orbits its host star with a period P = 3.7520656 ± 0.0000028 d, has a mass M _p = 0.542 ± 0.050 M _J and radius R _p = 1.428 ± 0.077 R _J, and is therefore one of the least dense transiting exoplanets so far discovered (ρ_p = 0.247 ± 0.035 g cm^-3). An analysis of the spectrum of the host star shows it to be of spectral type around F5, with an effective temperature T _eff = 6300 ± 100 K and [Fe/H] = -0.17 ± 0.11.

[en] We report the discovery, from WASP and CORALIE, of a transiting exoplanet in a 1.54 day orbit. The host star, WASP-36, is a magnitude V = 12.7, metal-poor G2 dwarf (T_eff = 5959 ± 134 K), with [Fe/H] =–0.26 ± 0.10. We determine the planet to have mass and radius, respectively, 2.30 ± 0.07 and 1.28 ± 0.03 times that of Jupiter. We have eight partial or complete transit light curves, from four different observatories, which allow us to investigate the potential effects on the fitted system parameters of using only a single light curve. We find that the solutions obtained by analyzing each of these light curves independently are consistent with our global fit to all the data, despite the apparent presence of correlated noise in at least two of the light curves.

[en] We report the discovery of a 61-Jupiter-mass brown dwarf (BD), which transits its F8V host star, WASP-30, every 4.16 days. From a range of age indicators we estimate the system age to be 1-2 Gyr. We derive a radius (0.89 ± 0.02 R_Jup) for the companion that is consistent with that predicted (0.914 R_Jup) by a model of a 1 Gyr old, non-irradiated BD with a dusty atmosphere. The location of WASP-30b in the minimum of the mass-radius relation is consistent with the quantitative prediction of Chabrier and Baraffe, thus confirming the theory.

[en] We report on the discovery of a new extremely short period transiting extrasolar planet, WASP-19b. The planet has mass M_pl = 1.15 ± 0.08 M_J , radius R_pl = 1.31 ± 0.06 R_J , and orbital period P = 0.7888399 ± 0.0000008 days. Through spectroscopic analysis, we determine the host star to be a slightly super-solar metallicity ([M/H] = 0.1 ± 0.1 dex) G-dwarf with T_eff = 5500 ± 100 K. In addition, we detect periodic, sinusoidal flux variations in the light curve which are used to derive a rotation period for the star of P_rot = 10.5 ± 0.2 days. The relatively short stellar rotation period suggests that either WASP-19 is somewhat young (∼ 600 Myr old) or tidal interactions between the two bodies have caused the planet to spiral inward over its lifetime resulting in the spin-up of the star. Due to the detection of the rotation period, this system has the potential to place strong constraints on the stellar tidal quality factor, Q'_s, if a more precise age is determined.