techniques: photometric; stars: individual: α Centauri B
Abstract :
[en] 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.
Seager, Sara; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA
Gilliland, Ronald; Department of Astronomy, and Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA
Chaplin, William J.; School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK ; Stellar Astrophysics Centre (SAC), Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
Proffitt, Charles; Science Programs, Computer Sciences Corporation, 3700 San Martin Drive, Baltimore, MD 21218, USA ; Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
Gillon, Michaël ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Günther, Maximilian N.; Astrophysics Group, Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
Benneke, Björn; Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
Dumusque, Xavier; Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
Lovis, Christophe; Observatoire Astronomique de l'Université de Genève, 51 chemin des Maillettes, CH-1290 Versoix, Switzerland
Pepe, Francesco; Observatoire Astronomique de l'Université de Genève, 51 chemin des Maillettes, CH-1290 Versoix, Switzerland
Ségransan, Damien; Observatoire Astronomique de l'Université de Genève, 51 chemin des Maillettes, CH-1290 Versoix, Switzerland
Triaud, Amaury; Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
Udry, Stéphane; Observatoire Astronomique de l'Université de Genève, 51 chemin des Maillettes, CH-1290 Versoix, Switzerland)
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