Using polarimetry to detect and characterize Jupiter-like extrasolar planets

¹ Astronomical Institute “Anton Pannekoek”, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands e-mail: dstam@science.uva.nl
² Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200B, 3001 Heverlee, Belgium

Received: 14 April 2004
Accepted: 9 August 2004

Abstract

Using numerical simulations of flux and polarization spectra of visible to near-infrared starlight reflected by Jupiter-like extrasolar planets, we show that polarimetry can be used both for the detection and for the characterization of extrasolar planets. Polarimetry is valuable for detection because direct, unscattered starlight is generally unpolarized, while starlight that has been reflected by a planet will generally be polarized. Polarimetry is valuable for planet characterization because the degree of polarization of starlight that has been reflected by a planet depends strongly on the composition and structure of the planetary atmosphere.