What the study found: The study reports three Milky Way satellite candidates: Carina IV, Phoenix III, and DELVE 7. All three are described as extremely faint systems with old, metal-poor stellar populations.
Why the authors say this matters: The authors state that Phoenix III is the faintest known satellite in the extreme outer stellar halo, and DELVE 7 is the faintest known satellite beyond 20 kpc. They also note that Carina IV and Phoenix III have sizes consistent with dwarf galaxies, while DELVE 7 may instead be a star cluster, though its nature is still unclear.
What the researchers tested: The candidates were identified in the third data release of the DECam Local Volume Exploration survey (DELVE) by cross-matching the results of two independent search algorithms. The study also used Gaia proper motions for Carina IV and DECam CaHK photometry to examine its member stars.
What worked and what didn't: Carina IV and Phoenix III were found to have half-light radii consistent with known dwarf galaxies. Carina IV's Gaia proper motions suggest it is unlikely to be associated with the Large Magellanic Cloud, and DECam CaHK photometry shows its member stars are metal poor. DELVE 7 is very compact and appears more likely to be a star cluster, but its nature remains ambiguous without spectroscopic follow-up.
What to keep in mind: The abstract does not describe spectroscopy for DELVE 7, and the authors say spectroscopic follow-up is needed to resolve its nature. No other limitations are described in the available summary.
Key points
- Three Milky Way satellite candidates were reported: Carina IV, Phoenix III, and DELVE 7.
- All three systems are described as extremely faint and metal-poor, with old stellar populations.
- Carina IV and Phoenix III have half-light radii consistent with dwarf galaxies.
- DELVE 7 is very compact and may be a star cluster rather than a dwarf galaxy.
- The authors say Phoenix III is the faintest known satellite in the extreme outer stellar halo, and DELVE 7 is the faintest known satellite beyond 20 kpc.
Disclosure
- Research title:
- Three ultra-faint Milky Way satellite candidates were discovered
- Authors:
- Chin Yi Tan, W. Cerny, Andrew B. Pace, J. A. Sharp, K Overdeck, A. Drlica-Wagner, J. D. Simon, Burçı̇n Mutlu-Pakdı̇l, D. J. Sand, A. M. Senkevich, Denis Erkal, P. S. Ferguson, F. Sobreira, Kaia R. Atzberger, Jeffrey L. Carlin, Anirudh Chiti, Denija Crnojević, Alexander P. Ji, L. C. Johnson, T. S. Li, Guilherme Limberg, C. E. Martínez-Vázquez, G. E. Medina, Vinicius M. Placco, A. H. Riley, Erik Tollerud, A. K. Vivas, T. M. C. Abbott, M Aguena, O. Alves, D. Bacon, S. Bocquet, D. Brooks, D. L. Burke, R Camilleri, J. A. Carballo-Bello, A Carnero Rosell, J. Carretero, Ting-Yun Cheng, Yumi Choi, L. N. da Costa, M. E. S. Pereira, T. M. Davis, J. De Vicente, S. Desai, P Doel, S. Everett, B. Flaugher, J. Frieman, J García-Bellido, D. Gruen, G. Gutierrez, S. R. Hinton, D.L Hollowood, D. J. James, K. Kuehn, S. Lee, J.L Marshall, J. Mena-Fernández, F. Menanteau, R Miquel, J Myles, M. Navabi, David L. Nidever, N. E. D. Noël, R. L. C. Ogando, A. A. Plazas Malagón, A. Porredon, S Samuroff, E. Sánchez, D Sanchez Cid, I Sevilla-Noarbe, M. Smith, G. S. Stringfellow, E Suchyta, M. E. C. Swanson, V. Vikram, A. R. Walker, A. Zenteno
- Institutions:
- University of Chicago, Simons Foundation, Yale University, McCormick (United States), University of Virginia, Fermi National Accelerator Laboratory, Carnegie Institution for Science, Carnegie Observatories, Dartmouth College, University of Surrey, Institute of Astronomy, Universidade Estadual de Campinas (UNICAMP), Laboratório Interinstitucional de e-Astronomia, University of Tampa, Northwestern University, University of Toronto, Gemini North Observatory, Community Science and Data Center, NSF NOIRLab, Lund University, Durham University, Space Telescope Science Institute, Université Bourgogne Franche-Comté, Cerro Tololo Inter-American Observatory, Trieste Astronomical Observatory, University of Michigan, University of Portsmouth, LMU Klinikum, Ludwig-Maximilians-Universität München, University College London, SLAC National Accelerator Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, The University of Queensland, University of Tarapacá, Universidad de La Laguna, Instituto de Astrofísica de Canarias, Institute for High Energy Physics, University of Groningen, Universität Hamburg, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Indian Institute of Technology Hyderabad, California Institute of Technology, Universidad Autónoma de Madrid, Center for Astrophysics Harvard & Smithsonian, Lowell Observatory, Australian Astronomical Observatory, Macquarie University, Jet Propulsion Laboratory, Mitchell Institute, Texas A&M University, Centre National de la Recherche Scientifique, Institut National de Physique Nucléaire et de Physique des Particules, Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble Alpes, University of Illinois Urbana-Champaign, National Center for Supercomputing Applications, Institució Catalana de Recerca i Estudis Avançats, Princeton University, Montana State University, Valongo Observatory, National Observatory, Centro de Tecnologia da Informação Renato Archer, Ruhr University Bochum, Northeastern University, University of Zurich, Lancaster University, Laboratory for Atmospheric and Space Physics, Oak Ridge National Laboratory, Central University of Kerala
- Publication date:
- 2026-03-11
- OpenAlex record:
- View
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