Backyard Worlds: Planet 9 Discovery of an Unusual Low-mass Companion to an M Dwarf at 80 pc
Austin Rothermich, Adam C. Schneider, Jacqueline K. Faherty, Katelyn, Allers, Daniella Bardalez-Gagliuffi, Aaron M. Meisner, Marc Kuchner, J. Davy, Kirkpatrick, Dan Caselden, Paul Beaulieu

TL;DR
This paper reports the discovery of an unusual low-mass companion to an M dwarf star at 80 parsecs, identified through citizen science efforts, with peculiar spectral features and underluminosity suggesting unique properties.
Contribution
The study presents the first identification of a peculiar low-mass companion to an M dwarf via citizen science, highlighting its unusual spectral features and potential for further investigation.
Findings
Discovery of a low-mass companion with proper motion consistent with the primary
Spectral analysis shows a triangular H band indicating peculiarity
The system has a very low chance alignment probability, confirming physical association
Abstract
We present the discovery of CWISE J203546.35-493611.0, a peculiar M8 companion to the M4.5 star APMPM J2036-4936 discovered through the citizen science project Backyard Worlds: Planet 9. Given CWISE J203546.35-493611.0's proper motion (, ) = (12622, 47823) and angular separation of 34.2 from APMPM 2036-4936, we calculate a chance alignment probability of . Both stars in this system appear to be underluminous, and the spectrum obtained for CWISE J203546.35-493611.0 shows a triangular H band. Further study of this system is warranted to understand these peculiarities.
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