POLARIZED REFLECTED LIGHT FROM THE EXOPLANET HD189733b: FIRST MULTICOLOR OBSERVATIONS AND CONFIRMATION OF DETECTION

Journal Article · Thu Feb 10 00:00:00 EST 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/728/1/L6· OSTI ID:21560514

Berdyugina, S V ^[1]; Berdyugin, A V; Piirola, V ^[2]

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1. Kiepenheuer Institut fuer Sonnenphysik, Schoeneckstrasse 6, D-79104 Freiburg (Germany)
2. Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Vaeisaelaentie 20, FIN-21500 Piikkioe (Finland)

We report the first multicolor polarimetric measurements (UBV bands) for the hot Jupiter HD189733b and confirm our previously reported detection of polarization in the B band. The wavelength dependence of polarization indicates the dominance of Rayleigh scattering with a peak in the blue B and U bands of {approx}10{sup -4} {+-} 10{sup -5} and at least a factor of two lower signal in the V band. The Rayleigh-like wavelength dependence, also detected in the transmitted light during transits, implies a rapid decrease of the polarization signal toward longer wavelengths. Therefore, the nondetection by Wiktorowicz, based on a measurement integrated within a broad passband covering the V band and partly covering the B and R bands, is inconclusive and consistent with our detection in B. We discuss possible sources of the polarization and demonstrate that effects of incomplete cancellation of stellar limb polarization due to starspots or tidal perturbations are negligible as compared with scattering polarization in the planetary atmosphere. We compare the observations with a Rayleigh-Lambert model and determine effective radii and geometrical albedos for different wavelengths. We find a close similarity of the wavelength-dependent geometrical albedo with that of the Neptune atmosphere, which is known to be strongly influenced by Rayleigh and Raman scattering. Our result establishes polarimetry as a reliable means for directly studying exoplanetary atmospheres.

• OSTI ID: 21560514
• Journal Information: Astrophysical Journal Letters, Vol. 728, Issue 1; Other Information: DOI: 10.1088/2041-8205/728/1/L6; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
DETECTION
FREQUENCY DEPENDENCE
JUPITER PLANET
NEPTUNE PLANET
PLANETARY ATMOSPHERES
POLARIMETRY
POLARIZATION
RAMAN EFFECT
RAYLEIGH SCATTERING
STARSPOTS
VISIBLE RADIATION
WAVELENGTHS
ATMOSPHERES
COHERENT SCATTERING
ELECTROMAGNETIC RADIATION
PLANETS
RADIATIONS
SCATTERING
STELLAR ACTIVITY