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

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 (${\mu }_{\alpha }$, ${\mu }_{\delta }$) = ($-$126$\pm$22, $-$478$\pm$23) and angular separation of 34.2${}^{\prime \prime }$ from APMPM 2036-4936, we calculate a chance alignment probability of $1.15\times 10^{-6}$. 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.

3 pages, 1 figure

References in corpus (3)

• SpeX Spectroscopy of Unresolved Very Low Mass Binaries. II. Identification of Fourteen Candidate Binaries with Late-M/Early-L and T Dwarf Components
• Optical Spectroscopy of 2MASS Color-Selected Ultracool Subdwarfs
• Exploring the age dependent properties of M and L dwarfs using Gaia and SDSS

Cited by in corpus (3)

• A Wide Planetary Mass Companion Discovered Through the Citizen Science Project Backyard Worlds: Planet 9
• CWISE J014611.20-050850.0AB: The Widest Known Brown Dwarf Binary in the Field
• Ross 19B: An Extremely Cold Companion Discovered via the Backyard Worlds: Planet 9 Citizen Science Project