Density of asteroids

By Benoît Carry. 2012

526 citations recorded by the source corpus.

Abstract The small bodies of our solar system are the remnants of the early stages of planetary formation. A considerable amount of information regarding the processes that occurred during the accretion of the early planetesimals is still present among this population. A review of our current knowledge of the density of small bodies is presented here. Density is indeed a fundamental property for the understanding of their composition and internal structure. Intrinsic physical properties of small bodies are sought by searching for relationships between the dynamical and taxonomic classes, size, and density. Mass and volume estimates for 287 small bodies (asteroids, comets, and transneptunian objects) are collected from the literature. The accuracy and biases affecting the methods used to estimate these quantities are discussed and best-estimates are strictly selected. Bulk densities are subsequently computed and compared with meteorite density, allowing to estimate the macroporosity (i.e., amount of voids) within these bodies. Dwarf-planets apparently have no macroporosity, while smaller bodies ( 400 km ) can have large voids. This trend is apparently correlated with size: C- and S-complex asteroids tend to have larger density with increasing diameter. The average density of each Bus-DeMeo taxonomic classes is computed (DeMeo et al., 2009; Icarus 202). S-complex asteroids are more dense on average than those in the C-complex that in turn have a larger macroporosity, although both complexes partly overlap. Within the C-complex asteroids, B-types stand out in albedo, reflectance spectra, and density, indicating a unique composition and structure. Asteroids in the X-complex span a wide range of densities, suggesting that many compositions are included in the complex. Comets and TNOs have high macroporosity and low density, supporting the current models of internal structures made of icy aggregates. Although the number of density estimates sky-rocketed during last decade from a handful to 287, only a third of the estimates are more precise than 20%. Several lines of investigation to refine this statistic are contemplated, including observations of multiple systems, 3-D shape modeling, and orbital analysis from Gaia astrometry.

Subfields: Astronomy and Astrophysics, Ecology

View Paper: https://www.semanticscholar.org/paper/9270d44f9a4710d09e8eb2624f9c00e2aef6ad8f

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Citations in the corpus

Asteroid family ages (2015, background): “Bennu is a B-type asteroid, thus it is possible to compute its porosity by comparison with the very large asteroid (704) Interamnia which is of the same taxonomic type and has a reasonably well determined bulk density (Carry, 2012).”
The primordial nucleus of comet 67P/Churyumov-Gerasimenko (2015, methodology): “Carry (2012) then used these diameters and measured masses to estimate ρbulk.”
The Compositional Structure of the Asteroid Belt (2015, background): “ternal structures and geophysics of asteroids remain largely unexplored. Additional studies of densities and differentiation processes will play an important role in understanding asteroid interiors (Carry 2012). • Studies of small asteroids (a few km in the Main Belt and a few tens of meters among ”
The taxonomic distribution of asteroids from multi-filter all-sky photometric surveys (2013, methodology): “…and most of the meteorites cluster in a tight range, from 2 to 5 g/cm3 (see Consolmagno and Britt 1998, Consolmagno et al. 2008, Britt and Consolmagno 2003, Macke et al. 2010, 2011, and references therein), with the exception of iron meteorites above 7 g/cm3 (see the summary table in Carry 2012).”
INITIAL PERFORMANCE OF THE NEOWISE REACTIVATION MISSION (2014, unknown): “…energy, to the extent that it can be tied to taxonomic types and compositional information through linkages to either meteoritic parent bodies (e.g. Consolmagno & Britt 1998; Binzel & Xu 1993; Buratti et al. 2013) or direct measurements of asteroid density (e.g. Carry 2012; Merline et al. 2002).”
Formation of planetary debris discs around white dwarfs – I. Tidal disruption of an extremely eccentric asteroid (2014, background): “Due to observational evidence that the vast majority of asteroids have densities which satisfy ρ 1 g cm−3 (table 1 of Carry 2012), we find max [rc (MWD)] ≡ rmaxc (MWD) ≈ 2.73 ( MWD 0.6 M )1/3 R , (3) where we have assumed the maximum value of C and minimum value of ρ.”