Large-scale changes of the cloud coverage in the ϵ Indi Ba and Bb system
Monthly Notices of the Royal Astronomical Society, vol. 495, pp. 3881–3899
Abstract
ABSTRACT We present the results of 14 nights of I-band photometric monitoring of the nearby brown dwarf binary, ϵ Indi Ba and Bb. Observations were acquired over 2 months, with a total of close to 42 h of coverage at a typically high cadence of 1.4 min. At a separation of just 0.7 arcsec, we do not resolve the individual components, and so effectively treat the binary as if it were a single object. However, ϵ Indi Ba (spectral type T1) is the brightest known T-type brown dwarf, and is expected to dominate the photometric signal. We typically find no strong variability associated with the target during each individual night of observing, but see significant changes in mean brightness – by as much as 0.10 mag – over the 2 months of the campaign. This strong variation is apparent on a time-scale of at least 2 d. We detect no clear periodic signature, which suggests that we may be observing the T1 brown dwarf almost pole-on, and the days-long variability in mean brightness is caused by changes in the large-scale structure of the cloud coverage. Dynamic clouds will very likely produce lightning, and complementary high-cadence V-band and H α images were acquired to search for the emission signatures associated with stochastic ‘strikes’. We report no positive detections for the target in either of these passbands.
Authors 24
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University of St Andrews · Space Research Organisation Netherlands
Affiliation as printed
Centre for Exoplanet Science, University of St Andrews, North Haugh KY16 9SS, UK
SRON Netherlands Institute for Space Research, Sorbonnelaan 2, NL-3584 CA Utrecht, the Netherlands
SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh KY16 9SS, UK
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Affiliation as printed
Centre for Exoplanet Science, University of St Andrews, North Haugh KY16 9SS, UK
SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh KY16 9SS, UK
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Affiliation as printed
Centre for Exoplanet Science, University of St Andrews, North Haugh KY16 9SS, UK
SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh KY16 9SS, UK
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Affiliation as printed
Centre for Exoplanet Science, University of St Andrews, North Haugh KY16 9SS, UK
SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh KY16 9SS, UK
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Affiliation as printed
Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg (ZAH), D-69120 Heidelberg, Germany
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Affiliation as printed
Niels Bohr Institute and Centre for Star and Planet Formation, University of Copenhagen, Øster Voldgade 5, DK-1350 Copenhagen, Denmark
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Affiliation as printed
Unidad de Astronomía, Universidad de Antofagasta, Av. Angamos 601, Antofagasta, Chile
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Isfahan University of Technology
Affiliation as printed
Department of Physics, Isfahan University of Technology, Isfahan 84156-83111, Iran
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Affiliation as printed
Centre for Electronic Imaging, Department of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK
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Royal Observatory · University of Edinburgh
Affiliation as printed
Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ, UK
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University of Salerno · Istituto Nazionale di Fisica Nucleare, Sezione di Napoli
Affiliation as printed
Dipartimento di Fisica ‘E.R. Caianiello’, Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano, Italy
Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, 80126 Napoli, Italy
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Affiliation as printed
Faculty of Mathematics, Informatics and Natural Sciences, Department of Earth Sciences, Meteorological Institute,Universität Hamburg, Bundesstraße 55, D-20146 Hamburg, Germany
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Affiliation as printed
SUPA, School of Science and Engineering, University of Dundee, Nethergate, Dundee DD1 4HN, UK
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University of St Andrews · San Sebastián University
Affiliation as printed
Centre for Exoplanet Science, University of St Andrews, North Haugh KY16 9SS, UK
Facultad de Economía y Negocios, Universidad San Sebastian, General Lagos 1163, Valdivia 5110693, Chile
Facultad de Ingeniería y Tecnología, Universidad San Sebastian, General Lagos 1163, Valdivia 5110693, Chile
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University of Copenhagen · Nagoya University
Affiliation as printed
Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
Niels Bohr Institute and Centre for Star and Planet Formation, University of Copenhagen, Øster Voldgade 5, DK-1350 Copenhagen, Denmark
Niels Bohr International Academy, The Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen, Denmark
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Affiliation as printed
Instituto de Astronomia y Ciencias Planetarias de Atacama, Universidad de Atacama, Copayapu 485, Copiapo, Chile
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Max Planck Institute for Astronomy
Affiliation as printed
Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany
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Affiliation as printed
Department of Astronomy and Space Science,Chungnam National University, 34134 Daejeon, Republic of Korea
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Affiliation as printed
Centre for Astrophysics and Planetary Science, The University of Kent, Canterbury CT2 7NH, UK
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University of Rome Tor Vergata · Osservatorio Astrofisico di Torino · Max Planck Institute for Astronomy · International Institute for Advanced Scientific Studies "Eduardo R. Caianiello"
Affiliation as printed
Department of Physics, University of Rome ‘Tor Vergata’, Via della Ricerca Scientifica 1, I-00133 Rome, Italy
INAF – Osservatorio Astrofisico di Torino, via Osservatorio 20, I-10025 Pino Torinese, Italy
International Institute for Advanced Scientific Studies (IIASS), Via G. Pellegrino 19, I-84019 Vietri sul Mare (SA), Italy
Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany
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Sharif University of Technology
Affiliation as printed
Department of Physics, Sharif University of Technology, Azadi Ave, 11155-9161 Tehran, Iran
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Las Cumbres Observatory Global Telescope Network · University of California, Santa Barbara
Affiliation as printed
Department of Physics, University of California, Santa Barbara, CA 93106-9530, USA
Las Cumbres Observatory Global Telescope, 6740 Cortona Dr., Suite 102, Goleta, CA 93111, USA
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Affiliation as printed
Astrophysics Group, Keele University, Staffordshire ST5 5BG, UK
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Affiliation as printed
Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
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