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The changing phases of extrasolar planet CoRoT-1b

Abstract

Hot Jupiters are a class of extrasolar planet that orbit their parent stars at very short distances. They are expected to be tidally locked, which can lead to a large temperature difference between their daysides and nightsides. Infrared observations of eclipsing systems have yielded dayside temperatures for a number of transiting planets1,2,3,4,5. The day–night contrast of the transiting extrasolar planet HD 189733b was ‘mapped’ using infrared observations6,7. It is expected that the contrast between the daysides and nightsides of hot Jupiters is much higher at visual wavelengths, shorter than that of the peak emission, and could be further enhanced by reflected stellar light. Here we report the analysis of optical photometric data8 obtained over 36 planetary orbits of the transiting hot Jupiter CoRoT-1b. The data are consistent with the nightside hemisphere of the planet being entirely black, with the dayside flux dominating the optical phase curve. This means that at optical wavelengths the planet’s phase variation is just as we see it for the interior planets in the Solar System. The data allow for only a small fraction of reflected light, corresponding to a geometric albedo of <0.20.

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Figure 1: Optical phase variation for CoRoT-1b centred on the planetary eclipse.
Figure 2: The optical planet–star contrast compared with models.

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Acknowledgements

We thank the CoRoT team for making the CoRoT data, which forms the basis of this study, publicly available in a high-quality and comprehensible way. The CoRoT space mission, launched on 27 December 2006, was developed and is operated by the Centre National D’Études Spatial, with participation of the science programmes of the European Space Agency, the European Space Research and Technology Centre and the Research and Scientific Support Department, Austria, Belgium, Brazil, Germany and Spain. We thank R. Le Poole for discussions.

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Correspondence to Ignas A. G. Snellen.

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This file contains Supplementary Methods and Data, Supplementary References Supplementary Table 1and Supplementary Figures 1-11 with Legends. (PDF 522 kb)

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Snellen, I., de Mooij, E. & Albrecht, S. The changing phases of extrasolar planet CoRoT-1b. Nature 459, 543–545 (2009). https://doi.org/10.1038/nature08045

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