Please use this identifier to cite or link to this item: http://hdl.handle.net/2381/40365
Title: Emission lines in the atmosphere of the irradiated brown dwarf WD0137−349B
Authors: Longstaff, E. S.
Casewell, Sarah L.
Wynn, G. A.
Maxted, P. F. L.
Helling, C.
First Published: 15-Jul-2017
Publisher: Oxford University Press on behalf of the Royal Astronomical Society
Citation: Monthly Notices of the Royal Astronomical Society, 2017, 471 (2), pp. 1728-1736
Abstract: We present new optical and near-infrared spectra of WD0137-349; a close white dwarf - brown dwarf non-interacting binary system with a period of $\approx$114 minutes. We have confirmed the presence of H$\alpha$ emission and discovered He, Na, Mg, Si, K, Ca, Ti, and Fe emission lines originating from the brown dwarf atmosphere. This is the first brown dwarf atmosphere to have been observed to exhibit metal emission lines as a direct result of intense irradiation. The equivalent widths of many of these lines show a significant difference between the day and night sides of the brown dwarf. This is likely an indication that efficient heat redistribution may not be happening on this object, in agreement with models of hot Jupiter atmospheres. The H$\alpha$ line strength variation shows a strong phase dependency as does the width. We have simulated the Ca II emission lines using a model that includes the brown dwarf Roche geometry and limb darkening and we estimate the mass ratio of the system to be 0.135$\pm$0.004. We also apply a gas-phase equilibrium code using a prescribed drift-phoenix model to examine how the chemical composition of the brown dwarf upper atmosphere would change given an outward temperature increase, and discuss the possibility that this would induce a chromosphere above the brown dwarf atmosphere.
DOI Link: 10.1093/mnras/stx1786
ISSN: 0035-8711
eISSN: 1365-2966
Links: https://academic.oup.com/mnras/article-lookup/doi/10.1093/mnras/stx1786
http://hdl.handle.net/2381/40365
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © The Author(s) 2017. Deposited with reference to the publisher’s open access archiving policy.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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