Near-infrared Spectra of the Inflated Post-common Envelope Brown Dwarf NLTT 5306 B
Abstract
NLTT 5306 is a post-common envelope binary made up of a white dwarf host and brown dwarf companion that has shown evidence of inflation and active mass donation despite not filling its Roche lobe. Two proposed mechanisms for the brown dwarf's inflation are magnetic interactions and a high-metallicity, cloudy atmosphere. We present moderate-resolution (R ≲ 2000) J-band Keck/NIRSPEC observations of this system. These phase-resolved data allow us to constrain differences between atmospheric parameters of the day- and nightside of the brown dwarf. Our day- and nightside effective temperature measurements are consistent, in agreement with the brightness temperatures measurements from Casewell et al. The dayside favors a slightly lower surface gravity, perhaps stemming from the material streaming between the two objects. Finally, our data show a preference for low-metallicity models. This would be expected from the system's old age, but provides direct evidence that a high-metallicity, cloudy brown dwarf atmosphere is not responsible for the witnessed inflation. These results strengthen the case for magnetic interactions leading to inflation of NLTT 5306 B.
Additional Information
© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2022 February 23; revised 2022 April 1; accepted 2022 April 5; published 2022 May 12. We thank Shreyas Vissapragada, Jessica Spake, and Antonija Oklopc̆ić for interesting conversations along the way. We also thank our anonymous reviewer for their helpful feedback on this manuscript. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. The irradiated atmosphere models were calculated as part of program HST-AR-16142. Support for HST-AR-16142 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. S.L.C. acknowledges support from an STFC Ernest Rutherford Fellowship. This work also benefited from a NASA Exoplanet Research Program grant (No. NNX16AI14G; PI: G.A. Blake).Attached Files
Published - Buzard_2022_AJ_163_262.pdf
Accepted Version - 2204.05330.pdf
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Additional details
- Eprint ID
- 114710
- Resolver ID
- CaltechAUTHORS:20220512-561526000
- W. M. Keck Foundation
- NAS5-26555
- NASA
- HST-AR-16142
- NASA
- Science and Technology Facilities Council (STFC)
- NNX16AI14G
- NASA
- Created
-
2022-05-13Created from EPrint's datestamp field
- Updated
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2022-05-13Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences