1,2,1,1,- 1LTE, Observatoire de Paris, Université PSL, 61 Avenue de l’Observatoire, 75014 Paris, FRANCE
- 2V.N. Karazin Kharkiv National University, Institute of Astronomy, 35 Sumska Str., 61022 Kharkiv, UKRAINE
- *A full list of authors appears at the end of the abstract
Introduction: The Gaia space mission of ESA has collected extremely precise data on the astrometry of asteroids. These data can be used to measure the periodic oscillation of the photocenter of binary asteroids and thus to discover their binarity [1]. Using this method for the Gaia DR3 catalogue, Liberato et al. [2] has so far discovered hundreds of candidates in binaries (the so-called Gaiamoons), and most of them are expected to be confirmed in the following years.
Observations: We have implemented the observation program of Gaia binary asteroids to reveal their binary nature and determine their physical parameters using precise photometry. For this purpose, we cooperate with different observatories in France, Slovakia, Bulgaria, Georgia, Uzbekistan, Kazakhstan, Taiwan, and Chile. The observatories are distributed across different locations, allowing observations to continue even when weather conditions are poor at some sites. In addition, their coverage across multiple longitudes makes it possible to obtain long, continuous lightcurves, which are essential for the reliable interpretation of the photometric data. The observations are carried out with 0.6 - 2 m telescopes. If possible, the predicted timing of mutual events in the Gaiamoons binary system is used to plan photometric observations. Thus, we expect to obtain photometric lightcurves with the occultation/eclipse events, which could confirm binarity and improve the parameters of mutual orbits.
Results and prospects: We present the results of our photometric observations of the Gaiamoons binary candidates, which fall into two categories: known binary asteroids — (87) Sylvia, (90) Antiope, (121) Hermione, (317) Roxane, (542) Susanna, and (4337) Arecibo — and asteroids suspected of being binary systems — (605) Juvisia, (712) Boliviana, (1127) Mimi, (1967) Menzel, and (4209) Briggs. In addition, we include in the analysis the photometric data for Gaiamoons binary asteroids obtained from various sky survey data, including TESS and others. In particular, using photometric data from the TESS survey, we confirmed the predicted occultation/eclipse events in the well-known binary asteroid (22) Kalliope [3].
The obtained observations are supposed to be used to conduct numerical modeling of the binary systems using the astrometric and photometric data. Our numerical code generalizes our previously devised algorithm for shape modeling of contact-binary asteroids [4]. It represents a model of a binary system as two ellipsoid-shaped objects orbiting each other. By comparing simulated brightness and position of the photocenter of the binary system with real observations, we estimate the most likely shapes, sizes, masses, and densities of the asteroid components, together with uncertainties of these values.
Acknowledgments: The Kharkiv team is thankful to Ukrainian soldiers who defend our lives and freedom against russian aggression. YK thanks the French PAUSE program for its support of scientists at risk.
References
[1] Pravec, P., & Scheirich, P. 2012, Planet. Space Sci., 73, 56
[2] Liberato L., Tanga P., Mary D., et al., A&A, 2024, 688, A50.
[3] Emelyanov, N. V., Kovalev, M. Y., & Varfolomeev, M. I. 2023, MNRAS, 522,165
[4] Krugly Y., Golubov O., Kyrylenko I., et al., A&A, 2025, 702, A170
William Thuillot (1), Melaine Saillenfest (1), Kevin Baillie (1), Josselin Desmars (1), Ihor Kyrylenko (2), Oleksiy Golubov (2), Alexey Sergeyev (2), Luana Liberato (3: Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, FRANCE), Paolo Tanga (3), Raguli Inasaridze (4: E. Kharadze Georgian National Astrophysical Observatory, Abastumani, GEORGIA), Vova Ayvazian (4), Vasili Zhuzhunadze (4), Zahary Donchev (5: Institute of Astronomy and NAO, Bulgarian Academy of Sciences, Sofia, BULGARIA), Andon Kostov (5), Vladimir Kouprianov (6: University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA), Joshua Haislip (6), Dan Reichart (6), Kamoliddin Ergashev (7:Ulugh Beg Astronomical Institute, Tashkent, UZBEKISTAN), František Dinnbier (8: Center of Astronomy and Gravitation and Department of Earth Sciences, National Taiwan Normal University, TAIWAN), Yueh-Ning Lee (8), and Inna Reva (9: Fesenkov Astrophysical Institute, Almaty, KAZAKHSTAN)
How to cite: Kruhlyi, Y., Hestroffer, D., and Liu, Z. and the Gaiamoons photometry: Gaia Binary Asteroids: Lightcurve Photometry and Modelling, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-1126, https://doi.org/10.5194/epsc2026-1126, 2026.
