Measurement of the Spin-Orbit Alignment in the Exoplanetary System HD 189733

Winn, Joshua N.; Johnson, John Asher; Marcy, Geoffrey W.; Butler, R. Paul; Vogt, Steven S.; Henry, Gregory W.; Roussanova, Anna; Holman, Matthew J.; Enya, Keigo; Narita, Norio; Suto, Yasushi; Turner, Edwin L.

doi:10.1086/510528

Cited by 154 publications

(190 citation statements)

References 31 publications

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“…Therefore, our general result provides further evidence for planet formation in a circumstellar disk, and suggests that the evolution of planetary systems might not lead to excitation of extreme inclinations for planetary orbits relative to the original plane of the disk. Additional evidence from observations of exoplanetary systems for planet formation in a disk and little inclination from the original plane includes the coplanarity of an exoplanet's orbit with a debris disk and the stellar spin -planet orbit alignment of a number of transiting planet systems (Winn et al 2005(Winn et al , 2006Wolf et al 2007;Winn et al 2007;Narita et al 2007;Bouchy et al 2008;Winn et al 2008;Loeillet et al 2008;Johnson et al 2008;Cochran et al 2008), although see Hébrard et al (2008) for one possible exception to this trend.…”

Section: Discussionmentioning

confidence: 99%

The architecture of the GJ 876 planetary system

Bean¹,

Seifahrt²

2009

A&A

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We present a combined analysis of previously published high-precision radial velocities and astrometry for the GJ 876 planetary system using a self-consistent model that accounts for the planet-planet interactions. Assuming the three planets so far identified in the system are coplanar, we find that including the astrometry in the analysis does not result in a best-fit inclination significantly different than that found by Rivera and collaborators from analyzing the radial velocities alone. In this unique case, the planet-planet interactions are of such significance that the radial velocity data set is more sensitive to the inclination of the system through the dependence of the interactions on the true masses of the two gas giant planets in the system (planets b and c). The astrometry does allow determination of the absolute orbital inclination (i.e. distinguishing between i and 180 − i) and longitude of the ascending node for planet b, which allows us to quantify the mutual inclination angle between its orbit and planet c's orbit when combined with the dynamical considerations. We find that the planets have a mutual inclination Φ bc = 5.0 • +3.9 • −2.3 • . This result constitutes the first determination of the degree of coplanarity in an exoplanetary system around a normal star. That we find the two planets' orbits are nearly coplanar, like the orbits of the Solar System planets, indicates that the planets likely formed in a circumstellar disk, and that their subsequent dynamical evolution into a 2:1 mean motion resonance only led to excitation of a small mutual inclination. This investigation demonstrates how the degree of coplanarity for other exoplanetary systems could also be established using data obtained from existing facilities.

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Section: Discussionmentioning

confidence: 99%

The architecture of the GJ 876 planetary system

Bean¹,

Seifahrt²

2009

A&A

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“…Therefore, we analysed HD 189733's out-of-transit RV data (Winn et al 2006;Boisse et al 2009) while using priors on independent system parameters; (R p /R ) 2 , P, W, and b. This enable us to assess the constraint derived solely from the RV data on the eccentricity.…”

Section: Complementary Input Of Hd 189733's Rv Measurementsmentioning

confidence: 99%

Towards consistent mapping of distant worlds: secondary-eclipse scanning of the exoplanet HD 189733b

Wit

Gillon

Demory

et al. 2012

A&A

141

163

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Context. Mapping distant worlds is the next frontier for exoplanet infrared (IR) photometry studies. Ultimately, constraining spatial and temporal properties of an exoplanet atmosphere (e.g., its temperature) will provide further insight into its physics. For tidallylocked hot Jupiters that transit and are eclipsed by their host star, the first steps are now possible. Aims. Our aim is to constrain an exoplanet's (1) shape, (2) brightness distribution (BD) and (3) system parameters from its phase curve and eclipse measurements. In particular, we rely on the secondary-eclipse scanning which is obtained while an exoplanet is gradually masked by its host star. Methods. We use archived Spitzer/IRAC 8-µm data of HD 189733 (six transits, eight secondary eclipses, and a phase curve) in a global Markov chain Monte Carlo (MCMC) procedure for mitigating systematics. We also include HD 189733's out-of-transit radial velocity (RV) measurements to assess their incidence on the inferences obtained solely from the photometry. Results. We find a 6σ deviation from the expected occultation of a uniformly-bright disk. This deviation emerges mainly from a large-scale hot spot in HD 189733b's atmosphere, not from HD 189733b's shape. We indicate that the correlation of the exoplanet orbital eccentricity, e, and BD ("uniform time offset") does also depend on the stellar density, ρ , and the exoplanet impact parameter, b ("e-b-ρ -BD correlation"). For HD 189733b, we find that relaxing the eccentricity constraint and using more complex BDs lead to lower stellar/planetary densities and a more localized and latitudinally-shifted hot spot. We, therefore, show that the light curve of an exoplanet does not constrain uniquely its brightness peak localization. Finally, we obtain an improved constraint on the upper limit of HD 189733b's orbital eccentricity, e ≤ 0.011 (95% confidence), when including HD 189733's RV measurements. Conclusions. Reanalysis of archived HD 189733's data constrains HD 189733b's shape and BD at 8 µm. Our study provides new insights into the analysis of exoplanet light curves and a proper framework for future eclipse-scanning observations. In particular, observations of the same exoplanet at different wavelengths could improve the constraints on HD 189733's system parameters while ultimately yielding a large-scale time-dependent 3D map of HD 189733b's atmosphere. Finally, we discuss the perspective of extending our method to observations in the visible (e.g., Kepler data), in particular to better understand exoplanet albedos.

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“…They included these into their analysis of the line-spread function and produced semiempirical corrections to the model radial velocities. However, their method does not account for the problem entirely as their analysis of HD 189733b shows a clear pattern of correlated residuals in the radial velocities during transit (Winn et al 2006). A similar pattern in the radial velocity residuals of HD 189733b was found by Triaud et al (2009) who discuss their cause in detail.…”

Section: Introductionmentioning

confidence: 77%

“…In more recent studies Winn et al (2005Winn et al ( , 2006Winn et al ( , 2007 tried to account for this by building models of the out of transit line profile and the light blocked by the planet. They included these into their analysis of the line-spread function and produced semiempirical corrections to the model radial velocities.…”

Section: Introductionmentioning

confidence: 99%

The Doppler shadow of WASP-3b

Miller

Cameron

Simpson

et al. 2010

A&A

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Context. Hot-Jupiter planets must form at large separations from their host stars where the temperatures are cool enough for their cores to condense. They then migrate inwards to their current observed orbital separations. Different theories of how this migration occurs lead to varying distributions of orbital eccentricity and the alignment between the rotation axis of the star and the orbital axis of the planet. Aims. The spin-orbit alignment of a transiting system is revealed via the Rossiter-McLaughlin effect, which is the anomaly present in the radial velocity measurements of the rotating star during transit due to the planet blocking some of the starlight. In this paper we aim to measure the spin-orbit alignment of the WASP-3 system via a new way of analysing the Rossiter-McLaughlin observations. Methods. We apply a new tomographic method for analysing the time variable asymmetry of stellar line profiles caused by the Rossiter-McLaughlin effect. This new method eliminates the systematic error inherent in previous methods used to analyse the effect. Results. We find a value for the projected stellar spin rate of v sin i = 13.9 ± 0.03 km s −1 which is in agreement with previous measurements but has a much higher precision. The system is found to be well aligned, with λ = 5 +6 −5• which favours an evolutionary history for WASP-3b involving migration through tidal interactions with a protoplanetary disc. From comparison with isochrones we put an upper limit on the age of the star of 2 Gyr.

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Measurement of the Spin-Orbit Alignment in the Exoplanetary System HD 189733

Cited by 154 publications

References 31 publications

The architecture of the GJ 876 planetary system

The architecture of the GJ 876 planetary system

Towards consistent mapping of distant worlds: secondary-eclipse scanning of the exoplanet HD 189733b

The Doppler shadow of WASP-3b

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