Updated parameters for the transiting exoplanet WASP-3b using RISE, a new fast camera for the Liverpool Telescope

Gibson, Neale P.; Pollacco, D.; Simpson, E. K.; Joshi, Y. C.; Todd, Ian A.; Benn, Chris; Christian, D. J.; Hrudková, M.; Keenan, F. P.; Meaburn, J.; Skillen, I.; Steele, I. A.

doi:10.1051/0004-6361:200811015

Cited by 70 publications

(104 citation statements)

References 18 publications

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“…We then further inflated the error bars using the β approach (e.g. Gillon et al 2006;Gibson et al 2008;Winn et al 2008) to account for any correlated noise. We calculated β values for between 2 and 10 data points for each light curve, and adopted the largest β value.…”

Section: O B S E Rvat I O N S a N D Data R E D U C T I O Nmentioning

confidence: 99%

Erratum: Physical properties, star-spot activity, orbital obliquity and transmission spectrum of the Qatar-2 planetary system from multicolour photometry

Mancini

Southworth

Ciceri

et al. 2016

Mon. Not. R. Astron. Soc.

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We present 17 high-precision light curves of five transits of the planet Qatar-2 b, obtained from four defocused 2 m-class telescopes. Three of the transits were observed simultaneously in the Sloan g r i z passbands using the seven-beam Gamma Ray Burst Optical and Near-Infrared Detector imager on the MPG/ESO 2.2-m telescope. A fourth was observed simultaneously in Gunn grz using the Centro Astronómico Hispano Alemán 2.2-m telescope with Bonn University Simultaneous Camera, and in r using the Cassini 1.52-m telescope. Every light curve shows small anomalies due to the passage of the planetary shadow over a cool spot on the surface of the host star. We fit the light curves with the PRISM+GEMC model to obtain the photometric parameters of the system and the position, size and contrast of each spot. We use these photometric parameters and published spectroscopic measurements to obtain the physical properties of the system to high precision, finding a larger radius and lower density for both star and planet than previously thought. By tracking the change in position of one star-spot between two transit observations, we measure the orbital obliquity of Qatar-2 b to be λ = 4.• 3 ± 4.• 5, strongly indicating an alignment of the stellar spin with the orbit of the planet. We calculate the rotation period and velocity of the cool host star to be 11.5 ± 0.2 d and 3.28 ± 0.04 km s −1 at a colatitude of 74 • . We assemble the planet's transmission spectrum over the 386-976 nm wavelength range and search for variations of the measured radius of Qatar-2 b as a function of wavelength. Our analysis highlights a possible H 2 /He Rayleigh scattering in the blue.

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Section: O B S E Rvat I O N S a N D Data R E D U C T I O Nmentioning

confidence: 99%

Erratum: Physical properties, star-spot activity, orbital obliquity and transmission spectrum of the Qatar-2 planetary system from multicolour photometry

Mancini

Southworth

Ciceri

et al. 2016

Mon. Not. R. Astron. Soc.

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“…We therefore rescaled the error bars as in our previous works (Mancini et al 2013a,b,c), first to give a reduced χ 2 of χ 2 ν = 1 and then using the β approach (e.g. Gillon et al 2006;Winn et al 2008;Gibson et al 2008). …”

Section: Light-curve Analysismentioning

confidence: 99%

Physical properties and transmission spectrum of the WASP-80 planetary system from multi-colour photometry

Mancini

Southworth

Ciceri

et al. 2014

A&A

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WASP-80 is one of only two systems known to contain a hot Jupiter which transits its M-dwarf host star. We present eight light curves of one transit event, obtained simultaneously using two defocussed telescopes. These data were taken through the Bessell I, Sloan g r i z and near-infrared JHK passbands. We use our data to search for opacity-induced changes in the planetary radius, but find that all values agree with each other. Our data are therefore consistent with a flat transmission spectrum to within the observational uncertainties. We also measure an activity index of the host star of log R HK = −4.495, meaning that WASP-80 A shows strong chromospheric activity. The non-detection of starspots implies that, if they exist, they must be small and symmetrically distributed on the stellar surface. We model all available optical transit light curves and obtain improved physical properties and orbital ephemerides for the system.

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“…These are formal statistical uncertainties and do not take into account time-correlated noise. We used the out-oftransit data of each light curve before detrending and applied the "time-averaging" procedure proposed by Pont et al (2006) and used by various authors including Gillon et al (2006), Winn et al (2007Winn et al ( , 2008, Gibson et al (2008), Nikolov et al (2012), Southworth et al (2012a,b) and Mancini et al (2013b) to inflate the photometric errors to more realistic values. In summary, for each band we computed the β-ratio between the standard deviation of the out-of-transit unbinned and binned data with bin sizes similar to the transit ingress/egress duration.…”

Section: Light Curve Analysismentioning

confidence: 99%

Refined physical properties andg′,r′,i′,z′,J, H, Ktransmission spectrum of WASP-23b from the ground

Nikolov

Chen

Fortney

et al. 2013

A&A

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Context. Multi-band observations of planetary transits using the telescope defocus technique may yield high-quality light curves suitable for refining the physical properties of exoplanets even with small or medium size telescopes. Such observations can be used to construct a broad-band transmission spectrum of transiting planets and search for the presence of strong absorbers. Aims. We have thoroughly characterised the orbital ephemeris and physical properties of the transiting planet and host star in the WASP-23b system, constructed a broad-band transmission spectrum of WASP-23 b and performed a comparative analysis with theoretical models of hot Jupiters. Methods. We observed a complete transit of WASP-23 b in seven passbands simultaneously, using the GROND instrument on the MPG/ESO 2.2 m telescope at La Silla Observatory and telescope defocussing. The optical data were taken in the Sloan g , r , i and z passbands. The resulting light curves are of high quality, with a root-mean-square scatter of the residual as low as 330 parts per million (ppm) in the z -band, with a cadence of 90 s. Near-infrared data were obtained in the JHK passbands. We performed a MCMC analysis of our photometry plus existing radial velocity data to refine measurements of the ephemeris and physical properties of the WASP-23 system. We constructed a broad-band transmission spectrum of WASP-23 b and compared it with a theoretical transmission spectrum of a hot Jupiter. Results. We measured the central transit time with a precision ∼8 s. From this and earlier observations we obtain an orbital period of P = 2.9444300 ± 0.0000011 d. Our analysis also yielded a larger radius and mass for the planet (R p = 1.067 +0.045 −0.038 R Jup and M p = 0.917 +0.040 −0.039 M Jup ) compared to previous estimates (R p = 0.962 +0.047 −0.056 R Jup and M p = 0.884 +0.088 −0.094 M Jup ). The derived transmission spectrum is marginally flat, which is not surprising given the limited precision of the measurements for the planetary radius and the poor spectral resolution of the data.

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Updated parameters for the transiting exoplanet WASP-3b using RISE, a new fast camera for the Liverpool Telescope

Cited by 70 publications

References 18 publications

Erratum: Physical properties, star-spot activity, orbital obliquity and transmission spectrum of the Qatar-2 planetary system from multicolour photometry

Erratum: Physical properties, star-spot activity, orbital obliquity and transmission spectrum of the Qatar-2 planetary system from multicolour photometry

Physical properties and transmission spectrum of the WASP-80 planetary system from multi-colour photometry

Refined physical properties andg′,r′,i′,z′,J, H, Ktransmission spectrum of WASP-23b from the ground

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