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Backyard Worlds: Planet 9 Discovery of an Unusual Low-mass Companion to an M Dwarf at 80 pc

Rothermich, Austin and Schneider, Adam C. and Faherty, Jacqueline K. and Allers, Katelyn and Bardalez-Gagliuffi, Daniella and Meisner, Aaron M. and Kuchner, Marc and Kirkpatrick, J. Davy and Caselden, Dan and Beaulieu, Paul (2021) Backyard Worlds: Planet 9 Discovery of an Unusual Low-mass Companion to an M Dwarf at 80 pc. Research Notes of the AAS, 5 (1). Art. No. 18. ISSN 2515-5172. doi:10.3847/2515-5172/abdf46.

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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 (μ α , μ δ ) = (−126 ± 22, −478 ± 23) and angular separation of 34.”2 from APMPM 2036−4936, we calculate a chance alignment probability of 1.15 × 10⁻⁶. 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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Rothermich, Austin0000-0003-4083-9962
Schneider, Adam C.0000-0002-6294-5937
Faherty, Jacqueline K.0000-0001-6251-0573
Allers, Katelyn0000-0003-0580-7244
Bardalez-Gagliuffi, Daniella0000-0001-8170-7072
Meisner, Aaron M.0000-0002-1125-7384
Kuchner, Marc0000-0002-2387-5489
Kirkpatrick, J. Davy0000-0003-4269-260X
Caselden, Dan0000-0001-7896-5791
Additional Information:© 2021 The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 January 20; Accepted 2021 January 22; Published 2021 January 27. This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Gaia Multilateral AgreementUNSPECIFIED
Subject Keywords:Low mass stars ; Binary stars
Issue or Number:1
Record Number:CaltechAUTHORS:20210128-090208916
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107782
Deposited By: Tony Diaz
Deposited On:28 Jan 2021 17:33
Last Modified:16 Nov 2021 19:06

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