WISEA J041451.67-585456.7 and WISEA J181006.18-101000.5: The First Extreme T-type Subdwarfs?
Autor: | Schneider, Adam C., Burgasser, Adam J., Gerasimov, Roman, Marocco, Federico, Gagne, Jonathan, Goodman, Sam, Beaulieu, Paul, Pendrill, William, Rothermich, Austin, Sainio, Arttu, Kuchner, Marc J., Caselden, Dan, Meisner, Aaron M., Faherty, Jacqueline K., Mamajek, Eric E., Hsu, Chih-Chun, Greco, Jennifer J., Cushing, Michael C., Kirkpatrick, J. Davy, Gagliuffi, Daniella Bardalez, Logsdon, Sarah E., Allers, Katelyn, Debes, John H., Worlds, The Backyard, Collaboration, Planet 9 |
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Rok vydání: | 2020 |
Předmět: |
Proper motion
010504 meteorology & atmospheric sciences Metallicity Population Brown dwarf FOS: Physical sciences Astrophysics Stellar classification 01 natural sciences Spectral line Planet 0103 physical sciences education 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) 0105 earth and related environmental sciences Physics Earth and Planetary Astrophysics (astro-ph.EP) education.field_of_study Astronomy and Astrophysics Astrophysics - Astrophysics of Galaxies Stars Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Astrophysics - Earth and Planetary Astrophysics |
DOI: | 10.48550/arxiv.2007.03836 |
Popis: | We present the discoveries of WISEA J041451.67-585456.7 and WISEA J181006.18-101000.5, two low-temperature (1200$-$1400 K), high proper motion T-type subdwarfs. Both objects were discovered via their high proper motion ($>$0.5 arcsec yr$^{-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 amongst 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] $\leq$ -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. Accepted for publication in the Astrophysical Journal |
Databáze: | OpenAIRE |
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