Radial velocity eclipse mapping of exoplanets

Abstract

Planetary rotation rates and obliquities provide information regarding the history of planet formation, but have not yet been measured for evolved extrasolar planets. Here we investigate the theoretical and observational perspective of the Rossiter-McLauglin effect during secondary eclipse (RMse) ingress and egress for transiting exoplanets. Near secondary eclipse, when the planet passes behind the parent star, the star sequentially obscures light from the approaching and receding parts of the rotating planetary surface. The temporal block of light emerging from the approaching (blue-shifted) or receding (red-shifted) parts of the planet causes a temporal distortion in the planet's spectral line profiles resulting in an anomaly in the planet's radial velocity curve. We demonstrate that the shape and the ratio of the ingress-to-egress radial velocity amplitudes depends on the planetary rotational rate, axial tilt and impact factor (i.e. sky-projected planet spin-orbital alignment). In addition, line asymmetries originating from different layers in the atmosphere of the planet could provide information regarding zonal atmospheric winds and constraints on the hot spot shape for giant irradiated exoplanets. The effect is expected to be most-pronounced at near-infrared wavelengths, where the planet-to-star contrasts are large. We create synthetic near-infrared, high-dispersion spectroscopic data and demonstrate how the sky-projected spin axis orientation and equatorial velocity of the planet can be estimated. We conclude that the RMse effect could be a powerful method to measure exoplanet spins.

7 pages, 3 figures, 1 table, accepted for publication in ApJ on 2015 June 12

References in corpus (8)

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Cited by in corpus (10)

• The atmospheric circulation of a nine-hot Jupiter sample: Probing circulation and chemistry over a wide phase space
• The Rossiter-McLaughlin effect in Exoplanet Research
• Constraining mornings & evenings on distant worlds: a new semi-analytical approach and prospects with transmission spectroscopy
• Inferring Planetary Obliquity Using Rotational & Orbital Photometry
• Insights into planet formation from debris disks: II. Giant impacts in extrasolar planetary systems
• Frequency Modulation of Directly Imaged Exoplanets: Geometric Effect as a Probe of Planetary Obliquity
• Models of Warm Jupiter Atmospheres: Observable Signatures of Obliquity
• How to Characterize the Atmosphere of a Transiting Exoplanet
• Evolution of the Planetary Obliquity: The Eccentric Kozai-Lidov Mechanism Coupled with Tide
• A Comprehensive Analysis of the Panchromatic Transmission Spectrum of the Hot-Saturn WASP-96 b: Nondetection of Haze, Possible Sodium Limb Asymmetry, Stellar Characterization, and Formation History