SMDET-1: a Nearby Y Dwarf Candidate

arXiv:2608.00046 · astro-ph.SR, astro-ph.GA · Submitted 2026-07-24 · Read on arXiv

Aaron M. Meisner, Dan Caselden, Federico Marocco, J. Davy Kirkpatrick, Jonathan Gagné, Adam C. Schneider, Samuel A. Beiler, Sergio B. Fajardo-Acosta, Jacqueline K. Faherty, Stanimir A. Metchev, Sam Barber, Marc J. Kuchner, Thomas P. Bickle, Zafar Rustamkulov

for the Backyard Worlds: Planet 9 Collaboration · for the Backyard Worlds: Planet 9 Collaboration · for the Backyard Worlds: Planet 9 Collaboration · for the Backyard Worlds: Planet 9 Collaboration · for the Backyard Worlds: Planet 9 Collaboration · for the Backyard Worlds: Planet 9 Collaboration · for the Backyard Worlds: Planet 9 Collaboration · for the Backyard Worlds: Planet 9 Collaboration · for the Backyard Worlds: Planet 9 Collaboration · for the Backyard Worlds: Planet 9 Collaboration · for the Backyard Worlds: Planet 9 Collaboration · for the Backyard Worlds: Planet 9 Collaboration · for the Backyard Worlds: Planet 9 Collaboration · for the Backyard Worlds: Planet 9 Collaboration

astro-ph.SR, astro-ph.GA

Submitted: 2026-07-24

Comments: corrected author list metadata formatting

License: http://creativecommons.org/licenses/by/4.0/

The gist: We present the discovery of SMDET-1, a red, fast-moving object (mu about 1.3 "/yr) identified in time-resolved unWISE coadds using a pixel-level deep learning methodology called SMDET.

Terminology

Abstract

We present the discovery of SMDET-1, a red, fast-moving object (mu about 1.3 "/yr) identified in time-resolved unWISE coadds using a pixel-level deep learning methodology called SMDET. Despite being relatively bright at 4.5 microns compared to many other recent WISE-based brown dwarf discoveries (m[4.5] about 14.6 mag Vega), SMDET-1 had remained overlooked due to its location in a very crowded Galactic plane field (b about 2.25) and contamination from brighter background objects. SMDET-1 is also serendipitously detected at 4.5 microns in late-2012 Spitzer Deep GLIMPSE survey imaging. SMDET-1 is undetected in UKIDSS and Palomar/WIRC near-infrared imaging, with the strongest constraint on its temperature (T eff < 391 K) arising from its Deep GLIMPSE color limit of m[3.6] - m[4.5] > 2.81 mag, which also implies a very nearby photometric distance < 7.4 pc. The Spitzer color bound corresponds to a Y dwarf phototype. SMDET-1 illustrates the importance of continued searches for nearby brown dwarfs within archival datasets like WISE and Spitzer, as well as the potential of pixel-level deep learning to discover astronomical moving objects that challenge traditional data analysis approaches.

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