Hubble Space Telescope search for the transit of the Earth-mass exoplanet Centauri B b

• Main Authors: Demory, B.-O (Author), Ehrenreich, D. (Author), Queloz, D. (Author), Gilliland, R. (Author), Chaplin, W. J. (Author), Proffitt, C. (Author), Gillon, M. (Author), Gunther, M. N. (Author), Benneke, B. (Author), Dumusque, X. (Author), Lovis, C. (Author), Pepe, F. (Author), Segransan, D. (Author), Udry, S. (Author), Seager, Sara (Contributor), Triaud, Amaury (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences (Contributor), Massachusetts Institute of Technology. Department of Physics (Contributor), MIT Kavli Institute for Astrophysics and Space Research (Contributor)
• Format: Article
• Language: English
• Published: Oxford University Press, 2017-01-19T21:52:00Z.
• Subjects: Article
• Online Access: Get fulltext

 Results from exoplanet surveys indicate that small planets (super-Earth size and below) are abundant in our Galaxy. However, little is known about their interiors and atmospheres. There is therefore a need to find small planets transiting bright stars, which would enable a detailed characterization of this population of objects. We present the results of a search for the transit of the Earth-mass exoplanet α Centauri B b with the Hubble Space Telescope (HST). We observed α Centauri B twice in 2013 and 2014 for a total of 40 h. We achieve a precision of 115 ppm per 6-s exposure time in a highly saturated regime, which is found to be consistent across HST orbits. We rule out the transiting nature of α Centauri B b with the orbital parameters published in the literature at 96.6 per cent confidence. We find in our data a single transit-like event that could be associated with another Earth-sized planet in the system, on a longer period orbit. Our programme demonstrates the ability of HST to obtain consistent, high-precision photometry of saturated stars over 26 h of continuous observations.