EPSC Abstracts
Vol. 18, EPSC-DPS2025-339, 2025, updated on 09 Jul 2025
https://doi.org/10.5194/epsc-dps2025-339
EPSC-DPS Joint Meeting 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
The Doubly Synchronous (120347) Salacia-Actaea System: Results From 16 Years of Photometric Monitoring
Cameron Collyer1,2, Estela Fernández-Valenzuela2, José Luis Ortiz3, Rafael Morales Muñoz3, Nicolás Morales3, Bryan Holler4, Benjamin Proudfoot2, and Flavia Luane Rommel2
Cameron Collyer et al.
  • 1Planetary Sciences Group, Department of Physics, University of Central Florida, 4111 Libra Drive, Orlando, FL 32816, USA (cpcollyerastro@gmail.com)
  • 2Florida Space Institute, University of Central Florida, 12354 Research Parkway, Orlando, FL 32765, USA
  • 3Instituto de Astrofísica de Andalucía Glorieta de la Astronomía s/n, Granada 18008, Spain
  • 4Space Telescope Science Institute, Steven Muller Building, 3700 San Martin Drive Baltimore, MD 21218 Baltimore, MD, USA

Long-baseline photometric monitoring of small bodies in the outer solar system is crucial for accurate constraints on their physical properties such as rotation period, shape, spin pole orientation, surface morphology and interior characteristics. In this work we present the analysis of 16 years of ground and space-based photometric observations of the Salacia-Actaea system, corresponding to a total on-target observing time of ∼165 hr. The photometry is derived from ∼1000 images using the automated Massive prOcessing Of aStronomical imagEs (Moose) - version 2 [M2; 1] software.

Invoking a Lomb-Scargle periodogram analysis on the unresolved photometry, we find a photometric period consistent with the orbital period of Actaea [2]. Using resolved HST photometry we isolate Salacia’s contribution to the derived phase-folded lightcurve. The individual HR-mags of Salacia and Actaea, as well as their effective radii and an approximate model of Salacia’s shape and surface morphology are derived from the HST and ground-based photometry. From this, we find that the Salacia-Actaea system is doubly-synchronous, where Salacia and Actaea both rotate at the mutual orbital period. This is only the third TNO-binary system observationally confirmed to exhibit doubly-synchronous rotation; the Pluto-Charon [3] and Eris-Dysnomia systems [4, 5] are also in this tidal end-state. We will additionally discuss our findings from an investigation of the dynamical evolution of the system resulting from tidal interactions, with implications for the formation of the binary system.

References

[1] Rafael Morales, Nicolás Morales, René Duffard, José Luis Ortiz, Mónica Vara-Lubiano, Flavia Rommel, Mike Kretlow, Pablo Santos-Sanz, Estela Fernández-Valenzuela, Alvaro Alvarez-Candal, and Nicolás Robles. Cataloguing astronomical groundbased images of asteroids and TNOs. In European Planetary Science Congress, pages EPSC2022–652, September 2022. doi: 10.5194/epsc2022-652.

[2] W. M. Grundy, K. S. Noll, H. G. Roe, M. W. Buie, S. B. Porter, A. H. Parker, D. Nesvorný, H. F. Levison, S. D. Benecchi, D. C. Stephens, and C. A. Trujillo. Mutual orbit orientations of transneptunian binaries. Icarus, 334:62–78, December 2019. doi: 10.1016/j.icarus.2019.03.035.

[3] J. W. Christy and R. S. Harrington. The satellite of Pluto. AJ, 83:1005, August 1978. doi: 10.1086/112284.

[4] R. Szakáts, Cs. Kiss, J. L. Ortiz, N. Morales, A. Pál, T. G. Müller, J. Greiner, P. Santos-Sanz, G. Marton, R. Duffard, P. Sági, and E. Forgács-Dajka. Tidally locked rotation of the dwarf planet (136199) Eris discovered via long-term ground-based and space photometry. A&A, 669:L3, January 2023. doi: 10.1051/0004-6361/202245234.

[5] Gary M. Bernstein, Bryan J. Holler, Rosario Navarro-Escamilla, Pedro H. Bernardinelli, T. M. C. Abbott, M. Aguena, S. Allam, O. Alves, F. Andrade-Oliveira, J. Annis, D. Bacon, D. Brooks, D. L. Burke, A. Carnero Rosell, J. Carretero, L. N. da Costa, M. E. S. Pereira, J. De Vicente, S. Desai, P. Doel, A. Drlica-Wagner, S. Everett, I. Ferrero, J. Frieman, J. Garcíıa-Bellido, D. W. Gerdes, D. Gruen, G. Gutierrez, K. Herner, S. R. Hinton, D. L. Hollowood, K. Honscheid, D. J. James, K. Kuehn, N. Kuropatkin, J. L. Marshall, J. Mena-Fernández, R. Miquel, R. L. C. Ogando, A. Pieres, A. A. Plazas Malag´on, M. Raveri, K. Reil, E. Sanchez, I. Sevilla-Noarbe, M. Smith, M. Soares-Santos, E. Suchyta, M. E. C. Swanson, P. Wiseman, and DES Collaboration. Synchronous Rotation in the (136199) Eris-Dysnomia System. PSJ, 4(6):115, June 2023. doi: 10.3847/PSJ/acdd5f.

 

How to cite: Collyer, C., Fernández-Valenzuela, E., Ortiz, J. L., Morales Muñoz, R., Morales, N., Holler, B., Proudfoot, B., and Rommel, F. L.: The Doubly Synchronous (120347) Salacia-Actaea System: Results From 16 Years of Photometric Monitoring, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–12 Sep 2025, EPSC-DPS2025-339, https://doi.org/10.5194/epsc-dps2025-339, 2025.