Asteroid modelling by starlight diffraction: The shape of Dimorphos, the satellite of (65803) Didymos
Abstract
Context. The DART spacecraft impacted Dimorphos, the satellite of (65803) Didymos, in September 2022. Evidence of crater formation and possible global reshaping has been obtained indirectly from spacecraft and ground-based data. Aims. Since the impact, several stellar occultations by Didymos have been observed, but only one in particular, on January 21, 2023, can provide useful constraints on the size and shape of Dimorphos. Methods. We modelled the diffraction signatures recorded on multiple occultation chords to constrain the projected shape and size of Dimorphos, assuming an ellipsoidal model. This is the first time diffraction observed simultaneously on several chords of a single event has been used for such a purpose. Results. The projected shape at the epoch of the event is well constrained and consistent with recent post-DART determinations. When extended to a full three-dimensional ellipsoidal solution, the result remains compatible with previous studies, suggesting an equatorially elongated post-impact shape.
Related
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BibTeX
@article{tanga2026asteroid,
title = {{Asteroid modelling by starlight diffraction: The shape of Dimorphos, the satellite of (65803) Didymos}},
author = {P Tanga and K Tsiganis and D Souami and R Anderson and E Barbotin and A Cazaux and F Colas and J Hanuš and F Marchis and J-L Dauvergne and G Langin and A Leroy and B Lott and A Manna and L Rousselot and A Siakas and S Sposetti and Ch H Vigna and F Weber and A Wünche},
journal = {Astronomy \& Astrophysics - A\&A},
year = {2026},
month = oct,
doi = {10.1051/0004-6361/202659734},
url = {https://hal-obspm.ccsd.cnrs.fr/obspm-05805965v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Asteroid modelling by starlight diffraction: The shape of Dimorphos, the satellite of (65803) Didymos
AU - P Tanga
AU - K Tsiganis
AU - D Souami
AU - R Anderson
AU - E Barbotin
AU - A Cazaux
AU - F Colas
AU - J Hanuš
AU - F Marchis
AU - J-L Dauvergne
AU - G Langin
AU - A Leroy
AU - B Lott
AU - A Manna
AU - L Rousselot
AU - A Siakas
AU - S Sposetti
AU - Ch H Vigna
AU - F Weber
AU - A Wünche
PY - 2026
DA - 2026/10/19
JO - Astronomy & Astrophysics - A&A
DO - 10.1051/0004-6361/202659734
UR - https://hal-obspm.ccsd.cnrs.fr/obspm-05805965v1
AB - Context. The DART spacecraft impacted Dimorphos, the satellite of (65803) Didymos, in September 2022. Evidence of crater formation and possible global reshaping has been obtained indirectly from spacecraft and ground-based data. Aims. Since the impact, several stellar occultations by Didymos have been observed, but only one in particular, on January 21, 2023, can provide useful constraints on the size and shape of Dimorphos. Methods. We modelled the diffraction signatures recorded on multiple occultation chords to constrain the projected shape and size of Dimorphos, assuming an ellipsoidal model. This is the first time diffraction observed simultaneously on several chords of a single event has been used for such a purpose. Results. The projected shape at the epoch of the event is well constrained and consistent with recent post-DART determinations. When extended to a full three-dimensional ellipsoidal solution, the result remains compatible with previous studies, suggesting an equatorially elongated post-impact shape.
SN - 0004-6361
SN - 1432-0746
ER -