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WISEA J041451.67–585456.7 and WISEA J181006.18–101000.5: The First Extreme T-type Subdwarfs?

Schneider, Adam C. and Burgasser, Adam J. and Gerasimov, Roman and Marocco, Federico and Gagné, Jonathan and Goodman, Sam and Beaulieu, Paul and Pendrill, William and Rothermich, Austin and Sainio, Arttu and Kuchner, Marc J. and Caselden, Dan and Meisner, Aaron M. and Faherty, Jacqueline K. and Mamajek, Eric E. and Hsu, Chih-Chun and Greco, Jennifer J. and Cushing, Michael C. and Kirkpatrick, J. Davy and Bardalez-Gagliuffi, Daniella C. and Logsdon, Sarah E. and Allers, Katelyn and Debes, John H. (2020) WISEA J041451.67–585456.7 and WISEA J181006.18–101000.5: The First Extreme T-type Subdwarfs? Astrophysical Journal, 898 (1). Art. No. 77. ISSN 1538-4357. doi:10.3847/1538-4357/ab9a40.

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We present the discoveries of WISEA J041451.67−585456.7 and WISEA J181006.18−101000.5, two low-temperature (1200–1400 K), high proper motion T-type subdwarfs. Both objects were discovered via their high proper motion (>0".5 yr⁻¹); WISEA J181006.18−101000.5 as part of the NEOWISE proper motion survey and WISEA J041451.67−585456.7 as part of the citizen science project Backyard Worlds; Planet 9. We have confirmed both as brown dwarfs with follow-up near-infrared spectroscopy. Their spectra and near-infrared colors are unique among known brown dwarfs, with some colors consistent with L-type brown dwarfs and other colors resembling those of the latest-type T dwarfs. While no forward model consistently reproduces the features seen in their near-infrared spectra, the closest matches suggest very low metallicities ([Fe/H] ⩽ −1), making these objects likely the first examples of extreme subdwarfs of the T spectral class (esdT). WISEA J041451.67−585456.7 and WISEA J181006.18−101000.5 are found to be part of a small population of objects that occupy the "substellar transition zone," and have the lowest masses and effective temperatures of all objects in this group.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Schneider, Adam C.0000-0002-6294-5937
Burgasser, Adam J.0000-0002-6523-9536
Marocco, Federico0000-0001-7519-1700
Gagné, Jonathan0000-0002-2592-9612
Goodman, Sam0000-0003-2236-2320
Rothermich, Austin0000-0003-4083-9962
Kuchner, Marc J.0000-0002-2387-5489
Caselden, Dan0000-0001-7896-5791
Meisner, Aaron M.0000-0002-1125-7384
Faherty, Jacqueline K.0000-0001-6251-0573
Mamajek, Eric E.0000-0003-2008-1488
Hsu, Chih-Chun0000-0002-5370-7494
Greco, Jennifer J.0000-0002-4649-1568
Cushing, Michael C.0000-0001-7780-3352
Kirkpatrick, J. Davy0000-0003-4269-260X
Bardalez-Gagliuffi, Daniella C.0000-0001-8170-7072
Logsdon, Sarah E.0000-0002-9632-9382
Allers, Katelyn0000-0003-0580-7244
Debes, John H.0000-0002-1783-8817
Additional Information:© 2020. The American Astronomical Society. Received 2020 April 16; revised 2020 May 19; accepted 2020 June 4; published 2020 July 24. This research was supported by NASA Astrophysics Data Analysis Program grant NNH17AE75I. The Backyard Worlds: Planet 9 team would like to thank the many Zooniverse volunteers who have participated in this project, from providing feedback during the beta review stage to classifying flipbooks to contributing to the discussions on TALK. This work used the Extreme Science and Engineering Discovery Environment (XSEDE) Comet cluster at the San Diego Supercomputer Center (program AST190045). XSEDE is supported by National Science Foundation grant number ACI-1548562 (Towns et al. 2014). 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, and NEOWISE, which is a project of the Jet Propulsion Laboratory/California Institute of Technology. WISE and NEOWISE are funded by the National Aeronautics and Space Administration. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:T subdwarfs ; Brown dwarfs ; Subdwarf stars ; T dwarfs
Issue or Number:1
Record Number:CaltechAUTHORS:20200724-100654510
Persistent URL:
Official Citation:Adam C. Schneider et al 2020 ApJ 898 77
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104565
Deposited By: George Porter
Deposited On:24 Jul 2020 17:52
Last Modified:16 Nov 2021 18:32

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