A lower radius and mass for the transiting extrasolar planet HAT-P-8 b

Mancini, L.; Southworth, J.; Ciceri, S.; Fortney, Jonathan J.; Morley, Caroline; Dittmann, Jason; Tregloan-Reed, J.; Bruni, I.; Barbieri, M.; Evans, D. F.; D’Ago, G.; Nikolov, Nikolay; Henning, Th.

doi:10.1051/0004-6361/201220291

Cited by 54 publications

(38 citation statements)

References 58 publications

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“…Based on our experience with a similar situation in previous studies (e.g. Southworth et al 2012a,b;Mancini et al 2013a,c), we conservatively do not interpret the large χ 2 ν values as a sign of transit timing variations, but as an underestimation of the uncertainties in the various T 0 measurements.…”

Section: New Orbital Ephemerissupporting

confidence: 56%

“…We have so far refined the measured parameters of several TEP systems (e.g. Southworth et al 2011;Mancini et al 2013aMancini et al , 2014c, studied starspot crossing events (Mancini et al 2013c(Mancini et al , 2014b, and probed opacity-induced variations of measured planetary radius with wavelength (e.g. Southworth et al 2012b;Mancini et al 2013bMancini et al ,c, 2014bNikolov et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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Physical properties of the HAT-P-23 and WASP-48 planetary systems from multi-colour photometry

Ciceri

Mancini

Southworth

et al. 2015

A&A

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Context. Accurate and repeated photometric follow-up observations of planetary transit events are important to precisely characterize the physical properties of exoplanets. A good knowledge of the main characteristics of the exoplanets is fundamental in order to trace their origin and evolution. Multi-band photometric observations play an important role in this process. Aims. By using new photometric data, we computed precise estimates of the physical properties of two transiting planetary systems at equilibrium temperatures of ∼2000 K. Methods. We present new broadband, multi-colour photometric observations obtained using three small class telescopes and the telescope-defocussing technique. In particular we obtained 11 and 10 light curves covering 8 and 7 transits of HAT-P-23 and WASP-48, respectively. For each of the two targets, one transit event was simultaneously observed through four optical filters. One transit of WASP-48 b was monitored with two telescopes from the same observatory. The physical parameters of the systems were obtained by fitting the transit light curves with jktebop and from published spectroscopic measurements.Results. We have revised the physical parameters of the two planetary systems, finding a smaller radius for both HAT-P-23 b and WASP-48 b, R b = 1.224 ± 0.037 R Jup and R b = 1.396 ± 0.051 R Jup , respectively, than those measured in the discovery papers (R b = 1.368 ± 0.090 R Jup and R b = 1.67 ± 0.10 R Jup ). The density of the two planets are higher than those previously published (ρ b ∼ 1.1 and ∼0.3 ρ jup for HAT-P-23 and WASP-48, respectively) hence the two hot Jupiters are no longer located in a parameter space region of highly inflated planets. An analysis of the variation of the planet's measured radius as a function of optical wavelength reveals flat transmission spectra within the experimental uncertainties. We also confirm the presence of the eclipsing contact binary NSVS-3071474 in the same field of view of WASP-48, for which we refine the value of the period to be 0.459 d.

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Section: New Orbital Ephemerissupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Physical properties of the HAT-P-23 and WASP-48 planetary systems from multi-colour photometry

Ciceri

Mancini

Southworth

et al. 2015

A&A

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“…This telescope was already successfully utilised to follow up several transiting planets (Southworth et al 2010(Southworth et al , 2012aMancini et al 2013). It is equipped with the Bologna Faint Object Spectrograph & Camera (BFOSC), an instrument built to allow the acquisition of both images and spectra with a simple configuration change.…”

Section: Cassini Telescopementioning

confidence: 99%

Multi-site campaign for transit timing variations of WASP-12 b: possible detection of a long-period signal of planetary origin

Maciejewski

Dimitrov

Seeliger³

et al. 2013

A&A

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Aims. The transiting planet WASP-12 b was identified as a potential target for transit-timing studies because a departure from a linear ephemeris has been reported in the literature. Such deviations could be caused by an additional planet in the system. We attempt to confirm the claimed variations in transit timing and interpret their origin. Methods. We organised a multi-site campaign to observe transits by WASP-12 b in three observing seasons, using 0.5-2.6-metre telescopes. Results. We obtained 61 transit light curves, many of them with sub-millimagnitude precision. The simultaneous analysis of the best-quality datasets allowed us to obtain refined system parameters, which agree with values reported in previous studies. The residuals versus a linear ephemeris reveal a possible periodic signal that may be approximated by a sinusoid with an amplitude of 0.00068 ± 0.00013 d and period of 500 ± 20 orbital periods of WASP-12 b. The joint analysis of timing data and published radial velocity measurements results in a two-planet model that explains observations better than do single-planet scenarios. We hypothesise that WASP-12 b might not be the only planet in the system, and there might be the additional 0.1 M Jup body on a 3.6-d eccentric orbit. A dynamical analysis indicates that the proposed two-planet system is stable on long timescales.

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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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A lower radius and mass for the transiting extrasolar planet HAT-P-8 b

Cited by 54 publications

References 58 publications

Physical properties of the HAT-P-23 and WASP-48 planetary systems from multi-colour photometry

Physical properties of the HAT-P-23 and WASP-48 planetary systems from multi-colour photometry

Multi-site campaign for transit timing variations of WASP-12 b: possible detection of a long-period signal of planetary origin

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

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