NASAのルーシー画像から、小惑星ディンキネスは驚くほど複雑であることが判明(NASA Lucy Images Reveal Asteroid Dinkinesh to be Surprisingly Complex)

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2024-05-29 NASA

2023年11月1日、NASAのルーシー探査機が小惑星ディンキネシュとその衛星セラムの画像を撮影しました。ディンキネシュには大きな溝と尾根があり、これは内部の強度と複雑な歴史を示しています。また、衛星セラムは接触二重星で、両者が形成される過程で衝突や破壊が起こったと考えられます。研究者たちは、ディンキネシュが回転のストレスにより変形し、その過程で破片が衛星となったと推測しています。これらの観測結果は、小惑星の強度と内部構造の理解に重要です。

<関連情報>

小惑星ディンキネッシュ(152830)の接触連星衛星 A contact binary satellite of the asteroid (152830) Dinkinesh

Harold F. Levison,Simone Marchi,Keith S. Noll,John R. Spencer,Thomas S. Statler,James F. Bell III,Edward B. Bierhaus,Richard Binzel,William F. Bottke,Daniel Britt,Michael E. Brown,Marc W. Buie,Philip R. Christensen,Neil Dello Russo,Joshua P. Emery,William M. Grundy,Matthias Hahn,Victoria E. Hamilton,Carly Howett,Hannah Kaplan,Katherine Kretke,Tod R. Lauer,Claudia Manzoni,Raphael Marschall,… Yifan Zhao
Nature  Published:29 May 2024
DOI:https://doi.org/10.1038/s41586-024-07378-0

NASAのルーシー画像から、小惑星ディンキネスは驚くほど複雑であることが判明(NASA Lucy Images Reveal Asteroid Dinkinesh to be Surprisingly Complex)

Abstract

Asteroids with diameters less than about 5 km have complex histories because they are small enough for radiative torques (that is, YORP, short for the Yarkovsky–O’Keefe–Radzievskii–Paddack effect)1 to be a notable factor in their evolution2. (152830) Dinkinesh is a small asteroid orbiting the Sun near the inner edge of the main asteroid belt with a heliocentric semimajor axis of 2.19 AU; its S-type spectrum3,4 is typical of bodies in this part of the main belt5. Here we report observations by the Lucy spacecraft6,7 as it passed within 431 km of Dinkinesh. Lucy revealed Dinkinesh, which has an effective diameter of only 720 m, to be unexpectedly complex. Of particular note is the presence of a prominent longitudinal trough overlain by a substantial equatorial ridge and the discovery of the first confirmed contact binary satellite, now named (152830) Dinkinesh I Selam. Selam consists of two near-equal-sized lobes with diameters of 210 m and 230 m. It orbits Dinkinesh at a distance of 3.1 km with an orbital period of about 52.7 h and is tidally locked. The dynamical state, angular momentum and geomorphologic observations of the system lead us to infer that the ridge and trough of Dinkinesh are probably the result of mass failure resulting from spin-up by YORP followed by the partial reaccretion of the shed material. Selam probably accreted from material shed by this event.

1701物理及び化学
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