Journal Article

Photometric characterization of exoplanets using angular and spectral differential imaging

A. Vigan, C. Moutou, M. Langlois, F. Allard, A. Boccaletti, M. Carbillet, D. Mouillet and I. Smith

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 407, issue 1, pages 71-82
Published in print September 2010 | ISSN: 0035-8711
Published online August 2010 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.16916.x
Photometric characterization of exoplanets using angular and spectral differential imaging

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In recent years, there has been intensive research into the direct detection of exoplanets. Data obtained in the future with high-contrast imaging instruments, optimized for the direct detection of giant planets, may be strongly limited by speckle noise. Specific observing strategies and data analysis methods, such as angular and spectral differential imaging, are required to attenuate the noise level and possibly to detect the flux of faint planets. Even though these methods are very efficient at suppressing the speckles, the photometry of faint planets is dominated by the speckle residuals. The determination of the effective temperature and surface gravity of the detected planets from photometric measurements in different bands is then limited by the photometric error on the planet flux. In this paper, we investigate this photometric error and the consequences on the determination of the physical parameters of the detected planets. We perform detailed end-to-end simulation with the caos-based software package for spectro-polarimetric high-contrast exoplanet research (SPHERE) to obtain realistic data representing typical observing sequences in the Y, J, H and Ks bands with a high-contrast imager. The simulated data are used to measure the photometric accuracy as a function of contrast for planets detected with angular and spectral+angular differential methods. We apply this empirical accuracy to study the characterization capabilities of a high-contrast differential imager. We show that the expected photometric performances will allow the detection and characterization of exoplanets down to a Jupiter mass at angular separations of 1.0 and 0.2 arcsec, respectively, around high-mass and low-mass stars with two observations in different filter pairs. We also show that the determination of the physical parameters of the planets from photometric measurements in different filter pairs is essentially limited by the error on the determination of the surface gravity.

Keywords: methods: data analysis; techniques: high angular resolution; techniques: photometric; infrared: planetary systems

Journal Article.  8419 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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