Extended gas clouds have been previously detected surrounding the brightest known close-in transiting hot Jupiter exoplanets, HD 209458 b and HD 189733 b; we observed the distant but more extreme ...close-in hot Jupiter system, WASP-12, with Hubble Space Telescope (HST). Near-UV (NUV) transits up to three times deeper than the optical transit of WASP-12 b reveal extensive diffuse gas, extending well beyond the Roche lobe. Our spectra reveal significantly enhanced absorption (greater than 3sigma below the median) at ~200 individual wavelengths on each of two HST visits; 65 of these wavelengths are consistent between the two visits, using a strict criterion for velocity matching that excludes matches with velocity shifts exceeding ~20 km s super(-1). Our Visit 2 NUV light curves show evidence for a stellar flare. We show that some of the possible transit detections in resonance lines of rare elements may be due instead to non-resonant transitions in common species. We present optical observations and update the transit ephemeris.
Building on previous work, a new search of the SuperWASP archive was carried out to identify eclipsing binary systems near the short-period limit. 143 candidate objects were detected with orbital ...periods between 16 000 and 20 000 s, of which 97 are new discoveries. Period changes significant at 1σ or more were detected in 74 of these objects, and in 38 the changes were significant at 3σ or more. The significant period changes observed followed an approximately normal distribution with a half-width at half-maximum of ~0.1 s yr-1. There was no apparent relationship between period length and magnitude or direction of period change. Amongst several interesting individual objects studied, 1SWASP J093010.78+533859.5 is presented as a new doubly eclipsing quadruple system, consisting of a contact binary with a 19 674.575 s period and an Algol-type binary with a 112 799.109 s period, separated by 66.1 AU, being the sixth known system of this type.
ABSTRACT
Phase curves of asteroids are typically considered to depend solely on the scattering properties of airless particulate surfaces and the size of the object being studied. In this study, we ...demonstrate the additional dependence of phase curves on object shape, rotation pole orientation, and viewing geometry over an apparition. Variations in the phase curve of near-Earth asteroid (159402) 1999 AP10 over its apparition from 2020 July to 2021 January are verified to be due to aspect changes over the apparition. This is achieved through shape modelling of the asteroid and simulation of the phase curve over the apparition. We present simulations of asteroid phase curves over a range of geometries to understand the potential magnitude of this aspect effect, and under which circumstances it can begin to dominate in the phase curves. This dependence on aspect may introduce significant additional uncertainty in the properties derived from phase-curve data. We provide and demonstrate software code to estimate the aspect-related uncertainty in near-Earth asteroid phase curves through simulation and model fitting of a randomly generated sample of ellipsoidal asteroid models over the observed viewing geometry. We demonstrate how ignoring this effect may lead to misleading interpretations of the data and underestimation of uncertainties in further studies, such as those in the infrared that use phase curve derived parameters when fitting physical properties of an asteroid.
ABSTRACT
We present the discovery of two new hot Jupiters identified from the Wide-Angle Search for Planets (WASP) survey, WASP-186b and WASP-187b (TOI-1494.01 and TOI-1493.01). Their planetary ...nature was established from SOPHIE spectroscopic observations, and additional photometry was obtained from Transiting Exoplanet Survey Satellite. Stellar parameters for the host stars are derived from spectral line, infrared flux method, and isochrone placement analyses. These parameters are combined with the photometric and radial velocity data in a Markov chain Monte Carlo method to determine the planetary properties. WASP-186b is a massive Jupiter (4.22 ± 0.18 MJ, 1.11 ± 0.03 RJ) orbiting a mid-F star on a 5.03-d eccentric (e = 0.327 ± 0.008) orbit. WASP-187b is a low-density (0.80 ± 0.09 MJ, 1.64 ± 0.05 RJ) planet in a 5.15-d circular orbit around a slightly evolved early F-type star.
The two objects 1SWASP J150822.80−054236.9 and 1SWASP J160156.04+202821.6 were initially detected from their SuperWASP archived light curves as candidate eclipsing binaries with periods close to the ...short-period cut-off of the orbital period distribution of main-sequence binaries, at ~0.2 d. Using spectroscopic data from the Isaac Newton Telescope in La Palma, Canary Islands, we here confirm them as double-lined spectroscopic and eclipsing binaries, in contact configuration. Following modelling of their visual light curves and radial velocity curves, we determine their component and system parameters to precisions between ~2 and 11%. The first system contains components of 1.07 and 0.55 M⊙, with radii of 0.90 and 0.68 R⊙, respectively; its primary exhibits pulsations with a period of 1/6 of the orbital period of the system. The latter contains components of 0.86 and 0.57 M⊙, with radii of 0.75 and 0.63 R⊙, respectively.
Period or amplitude variations in eclipsing binaries may reveal the presence of additional massive bodies in the system, such as circumbinary planets. Here, we have studied twelve previously-known ...eclipsing post-common-envelope binaries for evidence of such light curve variations, on the basis of multi-year observations in the SuperWASP archive. The results for HW Vir provided strong evidence for period changes consistent with those measured by previous studies, and help support a two-planet model for the system. ASAS J102322−3737.0 exhibited plausible evidence for a period increase not previously suggested; while NY Vir, QS Vir and NSVS 14256825 afforded less significant support for period change, providing some confirmation to earlier claims. In other cases, period change was not convincingly observed; for AA Dor and NSVS 07826147, previous findings of constant period were confirmed. This study allows us to present hundreds of new primary eclipse timings for these systems, and further demonstrates the value of wide-field high-cadence surveys like SuperWASP for the investigation of variable stars.
We report our investigation of 1SWASP J234401.81−212229.1, a variable with a 18 461.6 s period. After identification in a 2011 search of the SuperWASP archive for main-sequence eclipsing binary ...candidates near the distribution’s short-period limit of ~0.20 d, it was measured to be undergoing rapid period decrease in our earlier work, though later observations supported a cyclic variation in period length. Spectroscopic data obtained in 2012 with the Southern African Large Telescope did not, however, support the interpretation of the object as a normal eclipsing binary. Here, we consider three possible explanations consistent with the data: a single-star oblique rotator model in which variability results from stable cool spots on opposite magnetic poles; a two-star model in which the secondary is a brown dwarf; and a three-star model involving a low-mass eclipsing binary in a hierarchical triple system. We conclude that the latter is the most likely model.
Aims. We set out to compile a catalogue of RRab pulsating variables in the SuperWASP archive and identify candidate Blazhko effect objects within this catalogue. We analysed their light curves and ...power spectra for correlations in their common characteristics to further our understanding of the phenomenon. Methods. Pulsation periods were found for each SWASP RRab object using phase dispersion minimisation techniques. Low frequency periodic signals detected in the CLEAN power spectra of RRab stars were matched with modulation sidebands and combined with pairs of sidebands to produce a list of candidate Blazhko periods. A novel technique was used in an attempt to identify Blazhko effect stars by comparing scatter at different parts of the folded light curve. Pulsation amplitudes were calculated based on phase folded light curves. Results. The SuperWASP RRab catalogue consists of 4963 objects of which 3397 are previously unknown. We discovered 983 distinct candidates for Blazhko effect objects, 613 of these being previously unknown in the literature as RR Lyrae stars, and 894 are previously unknown to be Blazhko effect stars. Correlations were investigated between the scatter of points on the light curve, the periods and amplitudes of the objects’ pulsations, and those of the Blazhko effect. Conclusions. A statistical analysis has been performed on a large population of Blazhko effect stars from the wide-field SuperWASP survey. No correlations were found between the Blazhko period and other parameters including the Blazhko amplitude, although we confirmed a lower rate of occurrence of the Blazhko effect in long pulsation period objects.
Our discovery of 1SWASP J093010.78+533859.5 as a probable doubly eclipsing quadruple system, containing a contact binary with P ~ 0.23 d and a detached binary with P ~ 1.31 d, was announced in 2013. ...Subsequently, Koo and collaborators confirmed the detached binary spectroscopically, and identified a fifth set of static spectral lines at its location, corresponding to an additional non-eclipsing component of the system. Here we present new spectroscopic and photometric observations, allowing confirmation of the contact binary and improved modelling of all four eclipsing components. The detached binary is found to contain components of masses 0.837 ± 0.008 and 0.674 ± 0.007M⊙, with radii of 0.832 ± 0.018 and 0.669 ± 0.018R⊙ and effective temperatures of 5185-20+2 and 4325-15+20 K, respectively; the contact system has masses 0.86 ± 0.02 and 0.341 ± 0.011M⊙, radii of 0.79 ± 0.04 and 0.52 ± 0.05R⊙, respectively, and a common effective temperature of 4700 ± 50 K. The fifth star is of similar temperature and spectral type to the primaries in the two binaries. Long-term photometric observations indicate the presence of a spot on one component of the detached binary, moving at an apparent rate of approximately one rotation every two years. Both binaries have consistent system velocities around −11 to −12 km s-1, which match the average radial velocity of the fifth star; consistent distance estimates for both subsystems of d = 78 ± 3 and d = 73 ± 4 pc are also found, and, with some further assumptions, of d = 83 ± 9 pc for the fifth star. These findings strongly support the claim that both binaries – and very probably all five stars – are gravitationally bound in a single system. The consistent angles of inclination found for the two binaries (88.2 ± 0.3°and 86 ± 4°) may also indicate that they originally formed by fragmentation (around 9–10 Gyr ago) from a single protostellar disk, and subsequently remained in the same orbital plane.
SuperWASP light curves for 53 W UMa-type eclipsing binary (EB) candidates, identified in previous work as being close to the contact binary short-period limit, were studied for evidence of period ...change. The orbital periods of most of the stars were confirmed, and period decrease, significant at more than 5σ, was observed in three objects: 1SWASP J174310.98+432709.6 (−0.055 ± 0.003 s yr-1), 1SWASP J133105.91+121538.0 (−0.075 ± 0.013 s yr-1) and 1SWASP J234401.81−212229.1 (−0.313 ± 0.019 s yr-1). The magnitudes of the observed period changes cannot be explained by magnetic braking or gravitational radiation effects, and are most likely primarily due to unstable mass transfer from primary to secondary components, possibly accompanied by unstable mass and angular momentum loss from the systems. If these period decreases persist, the systems could merge on a relatively short timescale.
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