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NLTT5306B: an inflated, weakly irradiated brown dwarf

Casewell, S. L. and Debes, J. and Braker, I. P. and Cushing, M. C. and Mace, G. and Marley, M. S. and Kirkpatrick, J. Davy (2020) NLTT5306B: an inflated, weakly irradiated brown dwarf. Monthly Notices of the Royal Astronomical Society, 499 (4). pp. 5318-5324. ISSN 0035-8711. doi:10.1093/mnras/staa3184.

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We present Spitzer observations at 3.6 and 4.5 µm and a near-infrared IRTF SpeX spectrum of the irradiated brown dwarf NLTT5306B. We determine that the brown dwarf has a spectral type of L5 and is likely inflated, despite the low effective temperature of the white dwarf primary star. We calculate brightness temperatures in the Spitzer wavebands for both the model radius, and Roche Lobe radius of the brown dwarf, and conclude that there is very little day–night side temperature difference. We discuss various mechanisms by which NLTT5306B may be inflated, and determine that while low-mass brown dwarfs (M < 35 M_(Jup)) are easily inflated by irradiation from their host star, very few higher mass brown dwarfs are inflated. The higher mass brown dwarfs that are inflated may be inflated by magnetic interactions or may have thicker clouds.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemIRTF telescope archive ItemSpitzer telescope archive
Casewell, S. L.0000-0003-2478-0120
Debes, J.0000-0002-1783-8817
Braker, I. P.0000-0003-2783-1800
Cushing, M. C.0000-0001-7780-3352
Mace, G.0000-0001-7875-6391
Marley, M. S.0000-0002-5251-2943
Kirkpatrick, J. Davy0000-0003-4269-260X
Additional Information:© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2020 October 12. Received 2020 October 12; in original form 2020 July 17. We thank Pierre Bergeron for kindly providing data from Holberg & Bergeron (2006) in the Spitzer bandpasses, and Katelyn Allers for providing her spectral indices code. We also thank Richard Alexander for useful discussions regarding circumbinary discs. SLC acknowledges support from an STFC Ernest Rutherford Fellowship (ST/R003726/1). These data were taken by a visiting Astronomer at the Infrared Telescope Facility, which is operated by the University of Hawaii under contract NNH14CK55B with the National Aeronautics and Space Administration. This work is also based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. We have used the SPLAT routines as part of this work. SPLAT is an experimental, collaborative project of research students in the UCSD Cool Star Lab, aimed at teaching students how to do research by building their own analysis tools. Contributors to SPLAT have included Christian Aganze, Jessica Birky, Daniella Bardalez Gagliuffi, Adam Burgasser (PI), Caleb Choban, Andrew Davis, Ivanna Escala, Joshua Hazlett, Carolina Herrara Hernandez, Elizabeth Moreno Hilario, Aishwarya Iyer, Yuhui Jin, Mike Lopez, Dorsa Majidi, Diego Octavio Talavera Maya, Alex Mendez, Gretel Mercado, Niana Mohammed, Johnny Parra, Maitrayee Sahi, Adrian Suarez, Melisa Tallis, Tomoki Tamiya, Chris Theissen, and Russell van Linge. The SPLAT project is supported by the National Aeronautics and Space Administration under Grant No.NNX15AI75G. DATA AVAILABILITY STATEMENT. The data underlying this article are available in the relevant telescope archives, IRTF and Spitzer, and can be accessed at and using the object name, co-ordinates or programme number given in the text. The data will be shared on reasonable request to the corresponding author.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)ST/R003726/1
Subject Keywords:binaries: close, brown dwarfs, white dwarfs
Issue or Number:4
Record Number:CaltechAUTHORS:20210114-143038321
Persistent URL:
Official Citation:S L Casewell, J Debes, I P Braker, M C Cushing, G Mace, M S Marley, J Davy Kirkpatrick, NLTT5306B: an inflated, weakly irradiated brown dwarf, Monthly Notices of the Royal Astronomical Society, Volume 499, Issue 4, December 2020, Pages 5318–5324,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107490
Deposited By: George Porter
Deposited On:14 Jan 2021 23:43
Last Modified:16 Nov 2021 19:03

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