A change of the rotation period of asteroid (65803) Didymos caused by the DART impact

Fuente: arXiv
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Auteurs principaux: Durech, Josef, Pravec, Petr, Hirabayashi, Masatoshi, Richardson, Derek C., Agrusa, Harrison, Nakano, Ryota
Format: Preprint
Publié: 2026
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author Durech, Josef
Pravec, Petr
Hirabayashi, Masatoshi
Richardson, Derek C.
Agrusa, Harrison
Nakano, Ryota
author_facet Durech, Josef
Pravec, Petr
Hirabayashi, Masatoshi
Richardson, Derek C.
Agrusa, Harrison
Nakano, Ryota
contents On 26 September 2022, the NASA Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, the secondary component of the binary asteroid (65803)~Didymos. This experiment tested the Kinetic Impactor technology for diverting dangerous asteroids. Due to the impact, the binary system's angular momentum has changed, resulting in a significant change in the orbital period of Dimorphos. Precise values of the pre- and post-impact orbital periods were derived from a large set of photometric light curves measured for the Didymos-Dimorphos system during six apparitions from 2003 to 2023. We used these data to detect a possible change in the rotation period of the primary as a consequence of the impact. We analyzed the binary system's light curves using the binary asteroid light curve decomposition method. We selected parts of the light curves covering orbital phases outside mutual events, which represent the primary rotational light curves. We applied the light curve inversion method to construct a convex shape model of Didymos and determine its rotation period before and after the impact. These two periods were treated as independent free parameters of the modeling. We found a value of 2.2603891 +/- 0.0000002 h for the pre-impact period and 2.260440 +/- 0.000008 h for the post-impact period. Their difference 0.18 +/- 0.03 s is small yet significant, indicating that the rotation of Didymos became slower after the DART impact. The most plausible physical explanation is Didymos's post-impact reshaping, making its shape more oblate.
format Preprint
id arxiv_https___arxiv_org_abs_2601_04793
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A change of the rotation period of asteroid (65803) Didymos caused by the DART impact
Durech, Josef
Pravec, Petr
Hirabayashi, Masatoshi
Richardson, Derek C.
Agrusa, Harrison
Nakano, Ryota
Earth and Planetary Astrophysics
On 26 September 2022, the NASA Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, the secondary component of the binary asteroid (65803)~Didymos. This experiment tested the Kinetic Impactor technology for diverting dangerous asteroids. Due to the impact, the binary system's angular momentum has changed, resulting in a significant change in the orbital period of Dimorphos. Precise values of the pre- and post-impact orbital periods were derived from a large set of photometric light curves measured for the Didymos-Dimorphos system during six apparitions from 2003 to 2023. We used these data to detect a possible change in the rotation period of the primary as a consequence of the impact. We analyzed the binary system's light curves using the binary asteroid light curve decomposition method. We selected parts of the light curves covering orbital phases outside mutual events, which represent the primary rotational light curves. We applied the light curve inversion method to construct a convex shape model of Didymos and determine its rotation period before and after the impact. These two periods were treated as independent free parameters of the modeling. We found a value of 2.2603891 +/- 0.0000002 h for the pre-impact period and 2.260440 +/- 0.000008 h for the post-impact period. Their difference 0.18 +/- 0.03 s is small yet significant, indicating that the rotation of Didymos became slower after the DART impact. The most plausible physical explanation is Didymos's post-impact reshaping, making its shape more oblate.
title A change of the rotation period of asteroid (65803) Didymos caused by the DART impact
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2601.04793