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Campo Bagatin A, Dell'Oro A, Parro LM, Benavidez PG, Jacobson S, Lucchetti A, Marzari F, Michel P, Pajola M, Vincent JB. Recent collisional history of (65803) Didymos. Nat Commun 2024; 15:3714. [PMID: 38702317 PMCID: PMC11068898 DOI: 10.1038/s41467-024-48094-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 04/17/2024] [Indexed: 05/06/2024] Open
Abstract
The Double Asteroid Redirection Test (DART, NASA) spacecraft revealed that the primary of the (65803) Didymos near-Earth asteroid (NEA) binary system is not exactly the expected spinning top shape observed for other km-size asteroids. Ground based radar observations predicted that such shape was compatible with the uncertainty along the direction of the asteroid spin axis. Indeed, Didymos shows crater and landslide features, and evidence for boulder motion at low equatorial latitudes. Altogether, the primary seems to have undergone sudden structural failure in its recent history, which may even result in the formation of the secondary. The high eccentricity of Didymos sets its aphelion distance inside the inner main belt, where it spends more than 1/3 of its orbital period and it may undergo many more collisions than in the NEA region. In this work, we investigate the collisional environment of this asteroid and estimate the probability of collision with multi-size potential impactors. We analyze the possibility that such impacts produced the surface features observed on Didymos by comparing collisional intervals with estimated times for surface destabilization by the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect. We find that collisional effects dominate over potential local or global deformation due to YORP spin up.
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Affiliation(s)
- Adriano Campo Bagatin
- Instituto de Física Aplicada a las Ciencias y las Tecnologías, Universidad de Alicante, Ctra. de San Vicente del Raspeig, s/n, Sant Vicent del Raspeig, 03690, Alicante, Spain.
- Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, Ctra. de San Vicente del Raspeig, s/n, San Vicente del Raspeig, 03690, Alicante, Spain.
| | - Aldo Dell'Oro
- Osservatorio Astrofisico di Arcetri, INAF, Largo Enrico Fermi, 5, Firenze, I-50125, Italy
| | - Laura M Parro
- Instituto de Física Aplicada a las Ciencias y las Tecnologías, Universidad de Alicante, Ctra. de San Vicente del Raspeig, s/n, Sant Vicent del Raspeig, 03690, Alicante, Spain
- Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, Ctra. de San Vicente del Raspeig, s/n, San Vicente del Raspeig, 03690, Alicante, Spain
| | - Paula G Benavidez
- Instituto de Física Aplicada a las Ciencias y las Tecnologías, Universidad de Alicante, Ctra. de San Vicente del Raspeig, s/n, Sant Vicent del Raspeig, 03690, Alicante, Spain
- Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, Ctra. de San Vicente del Raspeig, s/n, San Vicente del Raspeig, 03690, Alicante, Spain
- European Space Astronomy Centre, European Space Agency, Camino bajo del Castillo S/N, Urbanización Villafranca del Castillo, Villanueva de la Cañada, Madrid, 28692, Spain
| | - Seth Jacobson
- Department of Earth and Environmental Sciences, Michigan State University, 288 Farm Ln. Natural Science Bldg, East Lansing, MI, 48824, USA
| | - Alice Lucchetti
- Astronomical Observatory of Padova, INAF, Vic. Osservatorio 5, Padova, 35122, Italy
| | - Francesco Marzari
- Department of Physics and Astronomy 'Galileo Galilei', Università degli Studi di Padova, via Marzolo 8, Padova, 35131, Italy
| | - Patrick Michel
- Laboratorie Lagrange, Observatoire de la Côte d'Azur - CNRS, Cedex 4, Nice, 03604, France
| | - Maurizio Pajola
- Astronomical Observatory of Padova, INAF, Vic. Osservatorio 5, Padova, 35122, Italy
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Tian J, Zhao HB, Li B. Shape Model and Rotation Acceleration of (1685) Toro and (85989) 1999 JD6 from Optical Observations. RESEARCH IN ASTRONOMY AND ASTROPHYSICS 2022; 22:125004. [DOI: 10.1088/1674-4527/ac977d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Abstract
The Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) effect is a net torque caused by solar radiation directly reflected and thermally re-emitted from the surface of small asteroids and is considered to be crucial in their dynamical evolution. By long-term photometric observations of selected near-Earth asteroids, it is hoped to enlarge asteroid samples with a detected YORP effect to facilitate the development of a theoretical framework. Archived light-curve data are collected and photometric observations are made for (1685) Toro and (85989) 1999 JD6, which enables measurement of their YORP effect by inverting the light curve to fit observations from a convex shape model. For (1685) Toro, a YORP acceleration υ = (3.2 ± 0.3) × 10−9 rad · day−2 (1σ error) is updated, which is consistent with previous YORP detection based on different light-curve data; for (85989) 1999 JD6, it is determined that the sidereal period is 7.667 749 ± 0.000009 hr, the rotation pole direction is located at λ = 232° ± 2°, β = − 59° ± 1°, the acceleration is detected to be υ = (2.4 ± 0.3) × 10−8 rad · day−2 (1σ error) and in addition to obtaining an excellent agreement between the observations and model. YORP should produce both spin-up and spin-down cases. However, including (85989) 1999 JD6, the dω/dt values of 11 near-Earth asteroids are positive totally, which suggests that there is either a bias in the sample of YORP detections or a real feature needs to be explained.
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Fission and reconfiguration of bilobate comets as revealed by 67P/Churyumov-Gerasimenko. Nature 2016; 534:352-5. [PMID: 27281196 DOI: 10.1038/nature17670] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 03/14/2016] [Indexed: 11/08/2022]
Abstract
The solid, central part of a comet--its nucleus--is subject to destructive processes, which cause nuclei to split at a rate of about 0.01 per year per comet. These destructive events are due to a range of possible thermophysical effects; however, the geophysical expressions of these effects are unknown. Separately, over two-thirds of comet nuclei that have been imaged at high resolution show bilobate shapes, including the nucleus of comet 67P/Churyumov-Gerasimenko (67P), visited by the Rosetta spacecraft. Analysis of the Rosetta observations suggests that 67P's components were brought together at low speed after their separate formation. Here, we study the structure and dynamics of 67P's nucleus. We find that sublimation torques have caused the nucleus to spin up in the past to form the large cracks observed on its neck. However, the chaotic evolution of its spin state has so far forestalled its splitting, although it should eventually reach a rapid enough spin rate to do so. Once this occurs, the separated components will be unable to escape each other; they will orbit each other for a time, ultimately undergoing a low-speed merger that will result in a new bilobate configuration. The components of four other imaged bilobate nuclei have volume ratios that are consistent with a similar reconfiguration cycle, pointing to such cycles as a fundamental process in the evolution of short-period comet nuclei. It has been shown that comets were not strong contributors to the so-called late heavy bombardment about 4 billion years ago. The reconfiguration process suggested here would preferentially decimate comet nuclei during migration to the inner solar system, perhaps explaining this lack of a substantial cometary flux.
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