Three Thousand Motion-confirmed L and T Dwarf Candidates from the Backyard Worlds: Planet 9 Citizen Science Project

Abstract The Backyard Worlds: Planet 9 citizen science project uses data from the Wide-field Infrared Survey Explorer to detect infrared objects with significant motion. In this work, we present the majority of the L and T dwarf candidates discovered through this effort. For each candidate, we provide proper motion measurements as well as optical, near-infrared, and mid-infrared photometry (when available), photometric spectral types and distance estimates. 3006 new motion-confirmed discoveries are presented in this work, 2357 with L-type photometric spectral types and 649 with T-type photometric spectral types. We also present an additional 80 objects as likely L or T dwarfs based on available photometry, but for which a significant motion measurement could not be obtained. We identify 28 objects in this sample as new comoving companions to higher-mass stars, and an additional nine sources that are candidate binary systems made up of two ultracool dwarfs of L type or later. Follow-up spectroscopic observations will be necessary to confirm spectral types and further characterize the sources discovered through this project. This work presents the largest single sample of motion-confirmed L and T dwarf discoveries to date, which would more than double the number of known L and T dwarfs, if confirmed. We wish to sincerely thank our citizen scientist collaborators for their monumental efforts that have directly impacted this project’s success.

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Publication Details

Journal
The Astronomical Journal
Published
2026-05-11
DOI
https://doi.org/10.3847/1538-3881/ae5b60
Primary Topic
Stellar, planetary, and galactic studies
Type
article
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article

Three Thousand Motion-confirmed L and T Dwarf Candidates from the Backyard Worlds: Planet 9 Citizen Science Project

Jean Marc Gantier, Easton J. Honaker, Nikita V. Voloshin, Dan Caselden et al.
The Astronomical Journal
Stellar, planetary, and galactic studies
article

Three Thousand Motion-confirmed L and T Dwarf Candidates from the Backyard Worlds: Planet 9 Citizen Science Project

Jean Marc Gantier, Easton J. Honaker, Nikita V. Voloshin, Dan Caselden, William Pendrill, Ken Hinckley, Frank Kiwy, Peter A. Jałowiczor, Konstantin Glebov, Vincent Schindler, Manfred Schonau, Leslie K. Hamlet, Zbigniew Wędracki, Sam Deen, Arttu Sainio, Martin Bilsing, Vinod Thakur, Karl Selg-Mann, Nikolaj Stevnbak Andersen, Melina Thévenot, Léopold Gramaize, Christine Sunjoto, Guillaume Colin, Alexandru Dereveanco, N.J. McEwan, Christoph Frank, Ben Pumphrey, Maurizio Ventura, Henry Raway, Stéphane Perlin, Daniella Bardalez Gagliuffi, Kevin Jablonski, Kevin Dixon, Andres Stenner, James Rabe, Mayahuel Torres Guerrero, David Roser, Animesh Roy, Andrea Serio, Marianne N. Michaels, Hugo A. Durantini Luca, Paul Beaulieu, Walter Ruben Robledo, Christopher Tanner, Deiby Flores, Jonathan Gagné, Troy K. Bohling, Alexander McColgan, Naoufel Marzak, David Sirbescu-Stanley, Sarah L. Casewell, Giovanni Colombo, Bruce Baller, Lizzeth Ruiz Arroyo, K Ly, John Bell, Breck Wilhite, Adam C. Schneider, Austin Rothermich, Peter Kasprowitz, Michael Gallmann, Spartacus Zitouni, Thomas P. Bickle, Christopher Fulvi, Jörg Schümann, David W. Martin, Adam J. Burgasser, J. Davy Kirkpatrick, Patrick J. Smith, Jim Walla, Marc J. Kuchner, Federico Marocco, Bailey Weyandt, Aaron M. Meisner, Jacqueline K. Faherty, Martin Kabatnik
article en

Abstract

Abstract The Backyard Worlds: Planet 9 citizen science project uses data from the Wide-field Infrared Survey Explorer to detect infrared objects with significant motion. In this work, we present the majority of the L and T dwarf candidates discovered through this effort. For each candidate, we provide proper motion measurements as well as optical, near-infrared, and mid-infrared photometry (when available), photometric spectral types and distance estimates. 3006 new motion-confirmed discoveries are presented in this work, 2357 with L-type photometric spectral types and 649 with T-type photometric spectral types. We also present an additional 80 objects as likely L or T dwarfs based on available photometry, but for which a significant motion measurement could not be obtained. We identify 28 objects in this sample as new comoving companions to higher-mass stars, and an additional nine sources that are candidate binary systems made up of two ultracool dwarfs of L type or later. Follow-up spectroscopic observations will be necessary to confirm spectral types and further characterize the sources discovered through this project. This work presents the largest single sample of motion-confirmed L and T dwarf discoveries to date, which would more than double the number of known L and T dwarfs, if confirmed. We wish to sincerely thank our citizen scientist collaborators for their monumental efforts that have directly impacted this project’s success.

The Astronomical JournalVol. 171(6)
Adler Planetarium (US), Western Michigan University (US), University of Leicester (GB), Rajshahi University of Engineering and Technology (BD), Amherst College (US), The Open University (GB), University of California San Diego (US), Center for Astrophysics Harvard & Smithsonian (US), NSF NOIRLab (US), Fundação Planetário da Cidade do Rio de Janeiro (BR), United States Naval Observatory (US), Institut für Palliative Care (DE), Planetárium Praha (CZ), Université de Montréal (CA), University of Delaware (US), Netherlands Institute for Radio Astronomy (NL)
Openalex Percentile: Top 6%
Stellar, planetary, and galactic studies
DOIOpen Access PDFOpenAlex
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