Backyard Worlds: Planet 9 Search for Extreme T Subdwarfs

Presentation #208.06 in the session “Stars I”.

by A. Meisner, A. Schneider, A. Burgasser, F. Marocco, J. Faherty, J. Kirkpatrick, M. Kuchner, D. Caselden, J. Gagne, C. Theissen, R. Gerasimov, C. Aganze, C. Hsu, S. Casewell, D. Bardalez Gagliuffi, S. Logsdon, J. Wisniewski, K. Allers, M. Allen, N. Stevnbak Andersen, S. Goodman, L. Gramaize, D. W. Martin, and A. Sainio

Published onJun 18, 2021

The Backyard Worlds: Planet 9 citizen science project recently presented the discoveries of WISEA J041451.67-585456.7 and WISEAJ181006.18-101000.5, which appear to be the first examples of extreme T-type subdwarfs (esdTs; metallicity ≤ -1 dex, Teff ≲ 1400 K). Here we report on our continuing efforts to pinpoint additional members of the newly identified esdT population, based on large proper motions and infrared photometry. Because Backyard Worlds primarily discovers new members of the solar neighborhood via their large proper motions, it is well-positioned to uncover objects like esdTs with anomalous colors that would be missed by traditional color-based brown dwarf queries.