The composition and structure of Ceres' interior

Research output: Contribution to journalArticle

Abstract

Results of Ceres' exploration with the Dawn spacecraft are modeled and discussed in terms of rock/organic/elemental composition, density and porosity in the interior, and formation, migration and geological evolution of the body. Carbon-rich surface composition is used to assess phase and elemental composition of the interior. The consistent bulk density and surface composition suggest an abundant organic matter within the body. Ceres is modeled as a chemically uniform mixture of CI-type carbonaceous chondritic rocks and 12–29 vol% of macromolecular organic matter. Water ice, gas hydrates or high porosity (>10%) are not required to explain bulk density. Ceres may not have a partially differentiated interior structure because gravity and shape could be explained by compaction of chemically uniform materials. Gravity data suggest a two-layer structure with an abrupt density change. Gravity may not reflect the current global density distribution in the interior because the implied bulk porosity >9% and grain density > 2380 kg m−3 disagree with organic-rich compositions. In contrast, Ceres' polar flattening indicates mild density gradients that could be explained by two-layer and gradual compaction models. The flattening implies grain density of 2200–2350 kg m−3 that is consistent with the organic-rich interior. Viscosity of warmed rock-organic mixtures at depth could account for the observed relaxation of long wavelength topography. The organic-rich composition together with abundant surface carbonates and NH4-bearing phases suggests Ceres' formation at larger heliocentric distances and later than CI chondrites. Ceres-forming materials could have been more water-rich than parent bodies of CI chondrites and excessive water could have been lost from the body. A majority of Ceres' surface compounds could have formed through water-rock-organic reactions in a middle interior followed by collisional stripping of an upper interior.

Original languageEnglish (US)
Article number113404
JournalIcarus
Volume335
DOIs
StatePublished - Jan 1 2020

Fingerprint

porosity
gravity
chondrite
chondrites
rock
flattening
rocks
bulk density
gravitation
compaction
water
carbonaceous rocks
organic matter
parent body
gas hydrate
stripping
hydrates
spacecraft
viscosity
density distribution

Keywords

  • Asteroid Ceres
  • Composition
  • Geophysics
  • Interiors
  • Organic chemistry

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

The composition and structure of Ceres' interior. / Zolotov, Mikhail.

In: Icarus, Vol. 335, 113404, 01.01.2020.

Research output: Contribution to journalArticle

@article{d1d61e07c70c4dc9a8224115be474c2c,
title = "The composition and structure of Ceres' interior",
abstract = "Results of Ceres' exploration with the Dawn spacecraft are modeled and discussed in terms of rock/organic/elemental composition, density and porosity in the interior, and formation, migration and geological evolution of the body. Carbon-rich surface composition is used to assess phase and elemental composition of the interior. The consistent bulk density and surface composition suggest an abundant organic matter within the body. Ceres is modeled as a chemically uniform mixture of CI-type carbonaceous chondritic rocks and 12–29 vol{\%} of macromolecular organic matter. Water ice, gas hydrates or high porosity (>10{\%}) are not required to explain bulk density. Ceres may not have a partially differentiated interior structure because gravity and shape could be explained by compaction of chemically uniform materials. Gravity data suggest a two-layer structure with an abrupt density change. Gravity may not reflect the current global density distribution in the interior because the implied bulk porosity >9{\%} and grain density > 2380 kg m−3 disagree with organic-rich compositions. In contrast, Ceres' polar flattening indicates mild density gradients that could be explained by two-layer and gradual compaction models. The flattening implies grain density of 2200–2350 kg m−3 that is consistent with the organic-rich interior. Viscosity of warmed rock-organic mixtures at depth could account for the observed relaxation of long wavelength topography. The organic-rich composition together with abundant surface carbonates and NH4-bearing phases suggests Ceres' formation at larger heliocentric distances and later than CI chondrites. Ceres-forming materials could have been more water-rich than parent bodies of CI chondrites and excessive water could have been lost from the body. A majority of Ceres' surface compounds could have formed through water-rock-organic reactions in a middle interior followed by collisional stripping of an upper interior.",
keywords = "Asteroid Ceres, Composition, Geophysics, Interiors, Organic chemistry",
author = "Mikhail Zolotov",
year = "2020",
month = "1",
day = "1",
doi = "10.1016/j.icarus.2019.113404",
language = "English (US)",
volume = "335",
journal = "Icarus",
issn = "0019-1035",
publisher = "Academic Press Inc.",

}

TY - JOUR

T1 - The composition and structure of Ceres' interior

AU - Zolotov, Mikhail

PY - 2020/1/1

Y1 - 2020/1/1

N2 - Results of Ceres' exploration with the Dawn spacecraft are modeled and discussed in terms of rock/organic/elemental composition, density and porosity in the interior, and formation, migration and geological evolution of the body. Carbon-rich surface composition is used to assess phase and elemental composition of the interior. The consistent bulk density and surface composition suggest an abundant organic matter within the body. Ceres is modeled as a chemically uniform mixture of CI-type carbonaceous chondritic rocks and 12–29 vol% of macromolecular organic matter. Water ice, gas hydrates or high porosity (>10%) are not required to explain bulk density. Ceres may not have a partially differentiated interior structure because gravity and shape could be explained by compaction of chemically uniform materials. Gravity data suggest a two-layer structure with an abrupt density change. Gravity may not reflect the current global density distribution in the interior because the implied bulk porosity >9% and grain density > 2380 kg m−3 disagree with organic-rich compositions. In contrast, Ceres' polar flattening indicates mild density gradients that could be explained by two-layer and gradual compaction models. The flattening implies grain density of 2200–2350 kg m−3 that is consistent with the organic-rich interior. Viscosity of warmed rock-organic mixtures at depth could account for the observed relaxation of long wavelength topography. The organic-rich composition together with abundant surface carbonates and NH4-bearing phases suggests Ceres' formation at larger heliocentric distances and later than CI chondrites. Ceres-forming materials could have been more water-rich than parent bodies of CI chondrites and excessive water could have been lost from the body. A majority of Ceres' surface compounds could have formed through water-rock-organic reactions in a middle interior followed by collisional stripping of an upper interior.

AB - Results of Ceres' exploration with the Dawn spacecraft are modeled and discussed in terms of rock/organic/elemental composition, density and porosity in the interior, and formation, migration and geological evolution of the body. Carbon-rich surface composition is used to assess phase and elemental composition of the interior. The consistent bulk density and surface composition suggest an abundant organic matter within the body. Ceres is modeled as a chemically uniform mixture of CI-type carbonaceous chondritic rocks and 12–29 vol% of macromolecular organic matter. Water ice, gas hydrates or high porosity (>10%) are not required to explain bulk density. Ceres may not have a partially differentiated interior structure because gravity and shape could be explained by compaction of chemically uniform materials. Gravity data suggest a two-layer structure with an abrupt density change. Gravity may not reflect the current global density distribution in the interior because the implied bulk porosity >9% and grain density > 2380 kg m−3 disagree with organic-rich compositions. In contrast, Ceres' polar flattening indicates mild density gradients that could be explained by two-layer and gradual compaction models. The flattening implies grain density of 2200–2350 kg m−3 that is consistent with the organic-rich interior. Viscosity of warmed rock-organic mixtures at depth could account for the observed relaxation of long wavelength topography. The organic-rich composition together with abundant surface carbonates and NH4-bearing phases suggests Ceres' formation at larger heliocentric distances and later than CI chondrites. Ceres-forming materials could have been more water-rich than parent bodies of CI chondrites and excessive water could have been lost from the body. A majority of Ceres' surface compounds could have formed through water-rock-organic reactions in a middle interior followed by collisional stripping of an upper interior.

KW - Asteroid Ceres

KW - Composition

KW - Geophysics

KW - Interiors

KW - Organic chemistry

UR - http://www.scopus.com/inward/record.url?scp=85072158494&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85072158494&partnerID=8YFLogxK

U2 - 10.1016/j.icarus.2019.113404

DO - 10.1016/j.icarus.2019.113404

M3 - Article

VL - 335

JO - Icarus

JF - Icarus

SN - 0019-1035

M1 - 113404

ER -