The density and porosity of meteorites from the Vatican collection

Britt, D. T.

doi:10.1111/j.1945-5100.1998.tb01308.x

Cited by 186 publications

(164 citation statements)

References 14 publications

(9 reference statements)

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“…We know that small particles, from dust grains to asteroids are porous and may therefore be characterized by small densities (e.g., Consolmagno & Britt 1998;Dominik & Tielens 1997;Kataoka et al 2013). On the other hand, large planetesimals and protoplanets are affected by compression effects and will generally have higher densities.…”

Section: Compact Vs Porous Grains and Planetesimalsmentioning

confidence: 99%

On the filtering and processing of dust by planetesimals

Guillot

Ida

Ormel

2014

A&A

141

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Context. Circumstellar disks are known to contain a significant mass in dust ranging from micron to centimeter size. Meteorites are evidence that individual grains of those sizes were collected and assembled into planetesimals in the young solar system. Aims. We assess the efficiency of dust collection of a swarm of non-drifting planetesimals with radii ranging from 1 to 10 3 km and beyond. Methods. We calculate the collision probability of dust drifting in the disk due to gas drag by planetesimal accounting for several regimes depending on the size of the planetesimal, dust, and orbital distance: the geometric, Safronov, settling, and three-body regimes. We also include a hydrodynamical regime to account for the fact that small grains tend to be carried by the gas flow around planetesimals. Results. We provide expressions for the collision probability of dust by planetesimals and for the filtering efficiency by a swarm of planetesimals. For standard turbulence conditions (i.e., a turbulence parameter α = 10 −2 ), filtering is found to be inefficient, meaning that when crossing a minimum-mass solar nebula (MMSN) belt of planetesimals extending between 0.1 AU and 35 AU most dust particles are eventually accreted by the central star rather than colliding with planetesimals. However, if the disk is weakly turbulent (α = 10 −4 ) filtering becomes efficient in two regimes: (i) when planetesimals are all smaller than about 10 km in size, in which case collisions mostly take place in the geometric regime; and (ii) when planetary embryos larger than about 1000 km in size dominate the distribution, have a scale height smaller than one tenth of the gas scale height, and dust is of millimeter size or larger in which case most collisions take place in the settling regime. These two regimes have very different properties: we find that the local filtering efficiency x filter,MMSN scales with r −7/4 (where r is the orbital distance) in the geometric regime, but with r −1/4 to r 1/4 in the settling regime. This implies that the filtering of dust by small planetesimals should occur close to the central star and with a short spread in orbital distances. On the other hand, the filtering by embryos in the settling regime is expected to be more gradual and determined by the extent of the disk of embryos. Dust particles much smaller than millimeter size tend only to be captured by the smallest planetesimals because they otherwise move on gas streamlines and their collisions take place in the hydrodynamical regime. Conclusions. Our results hint at an inside-out formation of planetesimals in the infant solar system because small planetesimals in the geometrical limit can filter dust much more efficiently close to the central star. However, even a fully-formed belt of planetesimals such as the MMSN only marginally captures inward-drifting dust and this seems to imply that dust in the protosolar disk has been filtered by planetesimals even smaller than 1 km (not included in this study) or that it has been assembled into planetesi...

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Section: Compact Vs Porous Grains and Planetesimalsmentioning

confidence: 99%

On the filtering and processing of dust by planetesimals

Guillot

Ida

Ormel

2014

A&A

141

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“…As Iron is the most cosmochemically abundant element with a bulk density in this range, we presume this is a major component, though the mineralogy is quite unconstrained. These so called "iron" meteoroids have density values most closely matching stonyiron meteorites, which have grain densities around 4820 kg m −3 , and porosities of 6% (Consolmagno & Britt 1998, Table 5). It is possible that these high density (ρ > 4000 kg m −3 ) meteoroids may be related to IDPs with sulfide inclusions, described by Love et al (1994).…”

Section: Interpretation Of Meteoroid Physical Propertiesmentioning

confidence: 99%

“…A second population with average bulk density around 3000 kg m −3 we interpret to be similar in structure to chondrites based on similarity of these density values to the measured bulk density of recovered chondritic meteorites (cf. Consolmagno & Britt 1998). This population has orbits which are like Jupiter-family comets (JFC) and also span Apollo-type orbits, suggestive of a main asteroid belt origin.…”

Section: Origin Of Our Meteoroidsmentioning

confidence: 99%

Bulk density of small meteoroids

Kikwaya

Campbell-Brown

Brown

2011

A&A

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Aims. Here we report on precise metric and photometric observations of 107 optical meteors, which were simultaneously recorded at multiple stations using three different intensified video camera systems. The purpose is to estimate bulk meteoroid density, link small meteoroids to their parent bodies based on dynamical and physical density values expected for different small body populations, to better understand and explain the dynamical evolution of meteoroids after release from their parent bodies. Methods. The video systems used had image sizes ranging from 640 × 480 to 1360 × 1036 pixels, with pixel scales from 0.01 • per pixel to 0.05 • per pixel, and limiting meteor magnitudes ranging from M v = +2.5 to +6.0. We find that 78% of our sample show noticeable deceleration, allowing more robust constraints to be placed on density estimates. The density of each meteoroid is estimated by simultaneously fitting the observed deceleration and lightcurve using a model based on thermal fragmentation, conservation of energy and momentum. The entire phase space of the model free parameters is explored for each event to find ranges of parameters which fit the observations within the measurement uncertainty. Results. (a) We have analysed our data by first associating each of our events with one of the five meteoroid classes. The average density of meteoroids whose orbits are asteroidal and chondritic (AC) is 4200 kg m −3 suggesting an asteroidal parentage, possibly related to the high-iron content population. Meteoroids with orbits belonging to Jupiter family comets (JFCs) have an average density of 3100 ± 300 kg m −3 . This high density is found for all meteoroids with JFC-like orbits and supports the notion that the refractory material reported from the Stardust measurements of 81P/Wild 2 dust is common among the broader JFC population. This high density is also the average bulk density for the 4 meteoroids with orbits belonging to the Ecliptic shower-type class (ES) also related to JFCs. Both categories we suggest are chondritic based on their high bulk density. Meteoroids of HT (Halley type) orbits have a minimum bulk density value of 360 +400 −100 kg m −3 and a maximum value of 1510 +400 −900 kg m −3 . This is consistent with many previous works which suggest bulk cometary meteoroid density is low. SA (Sun-approaching)-type meteoroids show a density spread from 1000 kg m −3 to 4000 kg m −3 , reflecting multiple origins. (b) We found two different meteor showers in our sample: Perseids (10 meteoroids, ∼11% of our sample) with an average bulk density of 620 kg m −3 and Northern Iota Aquariids (4 meteoroids) with an average bulk density of 3200 kg m −3 , consistent with the notion that the NIA derive from 2P/Encke.

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“…The micro porosity is simply assumed to be 0-1.2% [38]. This range is consistent with the iron-nickel meteorites of the Vatican collection with porosities of near zero [39].…”

Section: A13 M-typementioning

confidence: 63%