Discovery of CWISE J052306.42-015355.4, an Extreme T Subdwarf Candidate

February 2022 • 2022AJ....163...47B

Authors • Brooks, Hunter • Kirkpatrick, J. Davy • Caselden, Dan • Schneider, Adam C. • Meisner, Aaron M. • Faherty, Jacqueline K. • Casewell, S. L. • Kuchner, Marc J. • Kuchner, Marc J. • Backyard Worlds: Planet 9 Collaboration

Abstract • We present the discovery of CWISE J052306.42-015355.4, which was found as a faint, significant proper-motion object (0.″52 ± 0.″08 yr^-1) using machine-learning tools on the unWISE re-processing of time series images from the Wide-field Infrared Survey Explorer. Using the CatWISE2020 W1 and W2 magnitudes along with a J-band detection from the VISTA Hemisphere Survey, the location of CWISE J052306.42-015355.4 on the W1 - W2 versus J - W2 diagram best matches that of other known, or suspected, extreme T subdwarfs. As there is currently very little knowledge concerning extreme T subdwarfs we estimate a rough distance of ≤68 pc, which results in a tangential velocity of ≤167 km s^-1, both of which are tentative. A measured parallax is greatly needed to test these values. We also estimate a metallicity of -1.5 < [M/H] < -0.5 using theoretical predictions.

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• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2022AJ....163...47B
• PDF https://iopscience.iop.org/article/10.3847/1538-3881/ac3a0a/pdf
• PREPRINT http://arxiv.org/abs/2111.08182
• DATA https://irsa.ipac.caltech.edu/bibdata/2022/B/2022AJ....163...47B.html
• ELECTR https://doi.org/10.3847%2F1538-3881%2Fac3a0a