The SuperWASP Cameras are wide-field imaging systems sited at the Observatorio del Roque de los Muchachos on the island of La Palma in the Canary Islands, and the Sutherland Station of the South African Astronomical Observatory. Each instrument has a field of view of some ~482 square degrees with an angular scale of 13.7 arcsec per pixel, and is capable of delivering photometry with accuracy better than 1% for objects having V ~ 7.0 - 11.5. Lower quality data for objects brighter than V ~15.0 are stored in the project archive. The systems, while designed to monitor fields with high cadence, are capable of surveying the entire visible sky every 40 minutes. Depending on the observational strategy, the data rate can be up to 100GB per night. We have produced a robust, largely automatic reduction pipeline and advanced archive which are used to serve the data products to the consortium members. The main science aim of these systems is to search for bright transiting exo-planets systems suitable for spectroscopic followup observations. The first 6 month season of SuperWASP-North observations produced lightcurves of ~6.7 million objects with 12.9 billion data points.Comment: 42 pages, 2 plates, 5 figures PASP in pres

The death of massive stars produces a variety of supernovae, which are linked to the structure of the exploding stars. The detection of several precursor stars of type II supernovae has been reported (see, for example, ref. 3), but we do not yet have direct information on the progenitors of the hydrogen-deficient type Ib and Ic supernovae. Here we report that the peculiar type Ib supernova SN 2006jc is spatially coincident with a bright optical transient that occurred in 2004. Spectroscopic and photometric monitoring of the supernova leads us to suggest that the progenitor was a carbon-oxygen Wolf-Rayet star embedded within a helium-rich circumstellar medium. There are different possible explanations for this pre-explosion transient. It appears similar to the giant outbursts of luminous blue variable stars (LBVs) of 60-100 solar masses, but the progenitor of SN 2006jc was helium- and hydrogen-deficient (unlike LBVs). An LBV-like outburst of a Wolf-Rayet star could be invoked, but this would be the first observational evidence of such a phenomenon. Alternatively, a massive binary system composed of an LBV that erupted in 2004, and a Wolf-Rayet star exploding as SN 2006jc, could explain the observations.

The flow of energy through the solar atmosphere and the heating of the Sun's outer regions are still not understood. Here, we report the detection of oscillatory phenomena associated with a large bright-point group that is 430,000 square kilometers in area and located near the solar disk center. Wavelet analysis reveals full-width half-maximum oscillations with periodicities ranging from 126 to 700 seconds originating above the bright point and significance levels exceeding 99%. These oscillations, 2.6 kilometers per second in amplitude, are coupled with chromospheric line-of-sight Doppler velocities with an average blue shift of 23 kilometers per second. A lack of cospatial intensity oscillations and transversal displacements rules out the presence of magneto-acoustic wave modes. The oscillations are a signature of Alfvén waves produced by a torsional twist of ±22 degrees. A phase shift of 180 degrees across the diameter of the bright point suggests that these torsional Alfvén oscillations are induced globally throughout the entire brightening. The energy flux associated with this wave mode is sufficient to heat the solar corona.

We report the discovery of WASP‐3b, the third transiting exoplanet to be discovered by the WASP and SOPHIE collaboration. WASP‐3b transits its host star USNO‐B1.0 1256−0285133 every 1.846 834 ± 0.000 002 d. Our high‐precision radial velocity measurements present a variation with amplitude characteristic of a planetary‐mass companion and in phase with the light curve. Adaptive optics imaging shows no evidence for nearby stellar companions, and line‐bisector analysis excludes faint, unresolved binarity and stellar activity as the cause of the radial velocity variations. We make a preliminary spectroscopic analysis of the host star and find it to have Teff= 6400 ± 100 K and log  g= 4.25 ± 0.05 which suggests it is most likely an unevolved main‐sequence star of spectral type F7‐8V. Our simultaneous modelling of the transit photometry and reflex motion of the host leads us to derive a mass of 1.76+0.08−0.14MJ and radius 1.31+0.07−0.14RJ for WASP‐3b. The proximity and relative temperature of the host star suggests that WASP‐3b is one of the hottest exoplanets known, and thus has the potential to place stringent constraints on exoplanet atmospheric models.

We present model calculations of ionization fractions for elements in the warm (T ∼ 10 4 K), low-density photoionized interstellar medium (WIM) of the Milky Way. We model the WIM as a combination of overlapping low-excitation H II regions having n(H + )/n(H) ∼ > 0.8. Our adopted standard model incorporates an intrinsic elemental abundance pattern similar to that found for warm neutral clouds in the Galaxy and includes the effects of interstellar dust grains. The radiation field is characterized by an ionizing spectrum of a star with T ef f ≈ 35, 000 K and an ionization parameter log (q) ≈ −4.0. The emergent emission line strengths are in agreement with the observed ratios of [S II]/Hα, [N II]/Hα, [S II]/[N II], [O I]/Hα, [O III]/Hα, and He I/Hα in the Galactic WIM.Although the forbidden emission-line intensities depend strongly upon the input model parameters, the ionization fractions of the 20 elements studied in this work are robust over a wide range of physical conditions considered in the models. These ionization fractions have direct relevance to absorption-line determinations of the elemental abundances in the warm neutral and ionized gases in the Milky Way and other late-type galaxies. We demonstrate a method for estimating the WIM contributions to the observed column densities of singly and doubly ionized atoms used to derive abundances in the warm neutral gas. We apply this approach to study the gas-phase abundances of the warm interstellar clouds toward the halo star HD 93521.

We present comprehensive photometric and spectroscopic observations of the faint transient SN 2008S discovered in the nearby galaxy NGC 6946. SN 2008S exhibited slow photometric evolution and almost no spectral variability during the first nine months, implying a long photon diffusion time and a high-density circumstellar medium. Its bolometric luminosity ( 10 41 erg s −1 at peak) is low with respect to most core-collapse supernovae but is comparable to the faintest Type II-P events. Our quasi-bolometric light curve extends to 300 d and shows a tail phase decay rate consistent with that of 56 Co. We propose that this is evidence for an explosion and formation of 56 Ni (0.0014 ± 0.0003 M ). Spectra of SN 2008S show intense emission lines of Hα, [Ca II] doublet and Ca II near-infrared (NIR) triplet, all without obvious P-Cygni absorption troughs. The large mid-infrared (MIR) flux detected shortly after explosion can be explained by a light echo from pre-existing dust. The late NIR flux excess is plausibly due to a combination of warm newly formed ejecta dust together with shock-heated dust in the circumstellar environment. We reassess the progenitor object detected previously in Spitzer archive images, supplementing this discussion with a model of the MIR spectral energy distribution. This supports the idea of a dusty, optically thick shell around SN 2008S with an inner radius of nearly 90 AU and outer radius of 450 AU, and an inferred heating source

Impulsively generated short‐period fast magneto‐acoustic wave trains, guided by solar and stellar coronal loops, are numerically modelled. In the developed stage of the evolution, the wave trains have a characteristic quasi‐periodic signature. The quasi‐periodicity results from the geometrical dispersion of the guided fast modes, determined by the transverse profile of the loop. A typical feature of the signature is a tadpole wavelet spectrum: a narrow‐spectrum tail precedes a broad‐band head. The instantaneous period of the oscillations in the wave train decreases gradually with time. The period and the spectral amplitude evolution are shown to be determined by the steepness of the transverse density profile and the density contrast ratio in the loop. The propagating wave trains recently discovered with the Solar Eclipse Coronal Imaging System (SECIS) instrument are noted to have similar wavelet spectral features, which strengthens the interpretation of SECIS results as guided fast wave trains.

We present a fast and efficient hybrid algorithm for selecting exoplanetary candidates from wide-field transit surveys. Our method is based on the widely used SysRem and Box LeastSquares (BLS) algorithms. Patterns of systematic error that are common to all stars on the frame are mapped and eliminated using the SysRem algorithm. The remaining systematic errors caused by spatially localized flat-fielding and other errors are quantified using a boxcarsmoothing method. We show that the dimensions of the search-parameter space can be reduced greatly by carrying out an initial BLS search on a coarse grid of reduced dimensions, followed by Newton-Raphson refinement of the transit parameters in the vicinity of the most significant solutions. We illustrate the method's operation by applying it to data from one field of the SuperWASP survey, comprising 2300 observations of 7840 stars brighter than V = 13.0. We identify 11 likely transit candidates. We reject stars that exhibit significant ellipsoidal variations caused indicative of a stellar-mass companion. We use colours and proper motions from the Two Micron All Sky Survey and USNO-B1.0 surveys to estimate the stellar parameters and the companion radius. We find that two stars showing unambiguous transit signals pass all these tests, and so qualify for detailed high-resolution spectroscopic follow-up.