Hubble Space Telescope search for the transit of the earth-mass exoplanet α centauri B b

Brice Olivier Demory, David Ehrenreich, Didier Queloz, Sara Seager, Ronald Gilliland, William J. Chaplin, Charles Proffitt, Michael Gillon, Maximilian N. Günther, Björn Benneke, Xavier Dumusque, Christophe Lovis, Francesco Pepe, Damien Ségransan, Amaury Triaud, Stéphane Udry

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)2043-2051
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - Apr 10 2015

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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