Year: 2023
Type: article
Abstract: Context. The rotation state of small asteroids is affected in the long term by perturbing torques of gravitational and radiative origin (the YORP effect). The former can be detected by a change in the spin-axis orientation in the inertial space; the latter manifests itself by a quadratic increase in the rotation phase. Aims. Direct observational evidence of the YORP effect is the primary goal of our work. This includes both the YORP detection for new objects and an improvement in the accuracy of previously known detections. Methods. We carried out photometric observations of five near-Earth asteroids: (1862) Apollo, (2100) Ra-Shalom, (85989) 1999 JD6, (138852) 2000 WN10, and (161989) Cacus. Then we applied the light-curve inversion method to all available data to determine the spin state and a convex shape model for each of the five studied asteroids. The YORP effect was modeled as a linear change of the rotation frequency υ ≡ dω/dt. In the case of (2100) Ra-Shalom, the analysis required that the spin-axis precession due to the solar gravitational torque also be included. Results. We obtained two new detections of the YORP effect: (i) υ = (2.9 ± 2.0) × 10−9 rad d−2 for (2100) Ra-Shalom, and (ii) υ = (5.5 ± 0.7) × 10−8 rad d−2 for (138852) 2000 WN10. The analysis of Ra-Shalom also reveals a precession of the spin axis with a precession constant α ~ 3000″ yr−1. This is the first such detection from Earth-bound photometric data. For the other two asteroids, we improved the accuracy of the previously reported YORP detection: (i) υ = (4.94 ± 0.09) × 10−8 rad d−2 for (1862) Apollo, and (ii) υ = (1.86 ± 0.09) × 10−8 rad d−2 for (161989) Cacus. With this value, Apollo has the most precisely determined YORP effect so far. Despite the recent report of a detected YORP effect for (85989) 1999 JD6, we show that the model without YORP cannot be rejected statistically. Therefore, the detection of the YORP effect for this asteroid requires future observations. In several of our targets, the currently available observations do not provide enough constraints on the shape model (even at large scales) to compute the theoretical YORP effect with sufficient precision. Nevertheless, the interpretation of the detected signal as the YORP effect is fairly plausible. The spin-axis precession constant of Ra-Shalom determined from observations matches the theoretically expected value. Conclusions. The total number of asteroids with a YORP detection has increased to 12. In all cases, the rotation frequency increases in time. The analysis of a rich photometric data set of irregularly shaped asteroids may require inclusion of spin-axis precession in future studies.
Source: Astronomy and Astrophysics
Authors: J. Ďurech, D. Vokrouhlický, P. Pravec, Yu. Krugly, D. Polishook, J. Hanuš, F. Marchis, A. Rożek, C. Snodgrass, L. Alegre, Z. Donchev, Sh. A. Ehgamberdiev, P. Fatka, N. M. Gaftonyuk, A. Galád, K. Hornoch, R. Ya. Inasaridze, E. Khalouei, H. Kučáková, P. Kušnirák, J. Oey, D. P. Pray, A. Sergeev, I. Slyusarev
Institutions: Charles University, Czech Academy of Sciences, Czech Academy of Sciences, Astronomical Institute, Adam Mickiewicz University in Poznań, V. N. Karazin Kharkiv National University, Weizmann Institute of Science, Search for Extraterrestrial Intelligence, Royal Observatory, University of Edinburgh, Bulgarian Academy of Sciences, Institute of Astronomy and National Astronomical Observatory, Ulugh Beg Astronomical Institute, Crimean Astrophysical Observatory, Evgeni Kharadze Georgian National Astrophysical Observatory, Samtskhe-Javakheti State University, Seoul National University, Centre National de la Recherche Scientifique, Université Côte d'Azur, Lagrange Laboratory, Observatoire de la Côte d’Azur
Language: English
Topic: Astro and Planetary Science
Subfield: Space and Planetary Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,623
Awards: G1114968101, Physical and dynamical properties of space mission target asteroids, and their evolutionary paths, G434337789, Study of evolutionary paths of asteroids driven by non-gravitational forces with photometric observations, The NEO Rapid Observation, Characterization and Key Simulations, Parametre sklonu, absolútne magnitúdy a smery rotácie V-typov asteroidov
OpenAlex ID: W4389473716