Hitchcock, JA, Helling, C, Scholz, A, Hodosan, G, Dominik, M, Hundertmark, M, Jørgensen, UG, Longa-Peña, P, Sajadian, S, Skottfelt, J, Snodgrass, C, Bozza, V, Burgdorf, MJ, Campbell-White, J, Jaimes, RF, Fujii, YI, Haikala, LK, Henning, T, Hinse, TC, Lowry, S, Mancini, L, Rahvar, S, Rabus, M, Southworth, J and von Essen, C (2020) Large-scale changes of the cloud coverage in the ε Indi Ba,Bb system. Monthly Notices of the Royal Astronomical Society, 495 (4). pp. 3881-3899. ISSN 0035-8711

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We present the results of 14 nights of I-band photometric monitoring of the nearby brown dwarf binary, ε Indi Ba,Bb. Observations were acquired over 2 months, and total close to 42 hours of coverage at a typically high cadence of 1.4 minutes. At a separation of just 0.7″, 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 magnitudes - over the 2 months of the campaign. This strong variation is apparent on a timescale of at least 2 days. We detect no clear periodic signature, which suggests 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 Hα 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.

Item Type: Article
Additional Information: This article has been accepted for publication in the Monthly Notices of the Royal Astronomical Society © 2020, published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: techniques: photometric, brown dwarfs, stars: individual: ϵ Indi Ba and Bb
Subjects: Q Science > QB Astronomy > QB460 Astrophysics
Q Science > QB Astronomy > QB799 Stars
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Depositing User: Symplectic
Date Deposited: 28 May 2020 10:48
Last Modified: 23 Jul 2020 11:02
URI: https://eprints.keele.ac.uk/id/eprint/8070

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