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Evidence for differentiation of the most primitive small bodies
- Source :
- Astronomy and Astrophysics-A&A, Astronomy and Astrophysics-A&A, EDP Sciences, 2021, (in press), Astronomy and Astrophysics-A&A, 2021, 650, A129 (15pp.). ⟨10.1051/0004-6361/202140342⟩, RUA. Repositorio Institucional de la Universidad de Alicante, Universidad de Alicante (UA), Astronomy and Astrophysics-A&A, EDP Sciences, 2021, 650, A129 (15pp.). ⟨10.1051/0004-6361/202140342⟩, Digital.CSIC. Repositorio Institucional del CSIC, instname
- Publication Year :
- 2021
- Publisher :
- HAL CCSD, 2021.
-
Abstract
- Carri, B., et al.<br />[Context] Dynamical models of Solar System evolution have suggested that the so-called P- and D-type volatile-rich asteroids formed in the outer Solar System beyond Neptune's orbit and may be genetically related to the Jupiter Trojans, comets, and small Kuiper belt objects (KBOs). Indeed, the spectral properties of P- and D-type asteroids resemble that of anhydrous cometary dust. Aims. We aim to gain insights into the above classes of bodies by characterizing the internal structure of a large P- and D-type asteroid. [Methods] We report high-angular-resolution imaging observations of the P-type asteroid (87) Sylvia with the Very Large Telescope Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument. These images were used to reconstruct the 3D shape of Sylvia. Our images together with those obtained in the past with large ground-based telescopes were used to study the dynamics of its two satellites. We also modeled Sylvia's thermal evolution. [Results] The shape of Sylvia appears flattened and elongated (a/b 1.45; a/c 1.84). We derive a volume-equivalent diameter of 271 ± 5 km and a low density of 1378 ± 45 kg m-3. The two satellites orbit Sylvia on circular, equatorial orbits. The oblateness of Sylvia should imply a detectable nodal precession which contrasts with the fully-Keplerian dynamics of its two satellites. This reveals an inhomogeneous internal structure, suggesting that Sylvia is differentiated. [Conclusions] Sylvia's low density and differentiated interior can be explained by partial melting and mass redistribution through water percolation. The outer shell should be composed of material similar to interplanetary dust particles (IDPs) and the core should be similar to aqueously altered IDPs or carbonaceous chondrite meteorites such as the Tagish Lake meteorite. Numerical simulations of the thermal evolution of Sylvia show that for a body of such a size, partial melting was unavoidable due to the decay of long-lived radionuclides. In addition, we show that bodies as small as 130-150 km in diameter should have followed a similar thermal evolution, while smaller objects, such as comets and the KBO Arrokoth, must have remained pristine, which is in agreement with in situ observations of these bodies. NASA Lucy mission target (617) Patroclus (diameter ≈140 km) may, however, be differentiated.<br />This work has been supported by the Czech Science Foundation through grants 20-08218S (J. Hanuš, J. Ďurech) and by the Charles University Research program No. UNCE/SCI/023. The work of TSR was carried out through grant APOSTD/2019/046 by Generalitat Valenciana (Spain). This work was supported by the MINECO (Spanish Ministry of Economy) through grant RTI2018-095076-B-C21 (MINECO/FEDER, UE). This material is partially based upon work supported by the National Science Foundation under Grant No. 1743015.
- Subjects :
- asteroids
Solar System
010504 meteorology & atmospheric sciences
individual: Sylvia [Asteroids]
individual: Sylvia [Minor planets, asteroids]
FOS: Physical sciences
general [Minor planets, asteroids]
Astrophysics
01 natural sciences
Kuiper belt
Jupiter
Interplanetary dust cloud
Neptune
Física Aplicada
0103 physical sciences
111 Mathematics
010303 astronomy & astrophysics
0105 earth and related environmental sciences
Physics
Earth and Planetary Astrophysics (astro-ph.EP)
Nodal precession
Sylvia
Minor planets
Astronomy and Astrophysics
general [Kuiper belt]
113 Computer and information sciences
Asteroids: general
Meteorite
115 Astronomy and space science
13. Climate action
Space and Planetary Science
Asteroid
[SDU]Sciences of the Universe [physics]
Carbonaceous chondrite
Minor plantes
Asteroids: individual: Sylvia
Kuiper belt: general
general [Asteroids]
Astrophysics - Earth and Planetary Astrophysics
Subjects
Details
- Language :
- English
- ISSN :
- 20180950 and 00046361
- Database :
- OpenAIRE
- Journal :
- Astronomy and Astrophysics-A&A, Astronomy and Astrophysics-A&A, EDP Sciences, 2021, (in press), Astronomy and Astrophysics-A&A, 2021, 650, A129 (15pp.). ⟨10.1051/0004-6361/202140342⟩, RUA. Repositorio Institucional de la Universidad de Alicante, Universidad de Alicante (UA), Astronomy and Astrophysics-A&A, EDP Sciences, 2021, 650, A129 (15pp.). ⟨10.1051/0004-6361/202140342⟩, Digital.CSIC. Repositorio Institucional del CSIC, instname
- Accession number :
- edsair.doi.dedup.....aec903693a44de38f7a8bdfa34727e1b