SMDET-1: A Nearby Y-dwarf Candidate

September 2026 • 2026AJ....172..154M

Authors • Meisner, Aaron M. • Caselden, Dan • Marocco, Federico • Kirkpatrick, J. Davy • Gagné, Jonathan • Schneider, Adam C. • Beiler, Samuel A. • Fajardo-Acosta, Sergio B. • Faherty, Jacqueline K. • Metchev, Stanimir A. • Barber, Sam • Kuchner, Marc J. • Bickle, Thomas P. • Rustamkulov, Zafar • The Backyard Worlds: Planet 9 Collaboration

Abstract • We present the discovery of SMDET-1, a red, fast-moving object ( μ≍1.″3 yr⁻¹) identified in time-resolved unblurred Wide-field Infrared Survey Explorer coadds using a pixel-level deep learning methodology called SMDET. Despite being relatively bright at 4.5 μm compared to many other recent WISE-based brown dwarf discoveries (m_[4.5] ≍ 14.6 mag Vega), SMDET-1 had remained overlooked due to its location in a very crowded Galactic plane field (b ≍ 2 .° 25) and contamination from brighter background objects. SMDET-1 is also serendipitously detected at 4.5 μm in late-2012 Spitzer Deep GLIMPSE survey imaging. SMDET-1 is undetected in UKIDSS and Palomar/Wide Field Infrared Camera 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.

Links

• ELECTR https://doi.org/10.3847/1538-3881/ae8e73