The Astromineralogy of Interplanetary Dust Particles

Bradley, J. P.

doi:10.1007/3-540-45840-9_6

Cited by 33 publications

(37 citation statements)

References 52 publications

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“…Together, this aggregation on scales from a few nanometers to tens of micrometers probably corresponds to that seen in numerous electron microscope studies of chondritic porous (CP) IDPs, e.g., Fig. 1 of Bradley (2003), the cluster and aggregate IDP discussed at length by Rietmeijer (1998), and may be akin to the structures inferred from spectroscopic remote sensing of dust (e.g., Greenberg and Gustafson 1981). As it is suspected that porous aggregates break up on entering aerogel to form the "bulbous" tracks described by Hörz et al (2006), it seems that Al foil impacts provide the best record of the abundance and size of fine dust aggregates from comet Wild 2.…”

Section: Implications For the Structure And Composition Of Wild 2 Dussupporting

confidence: 68%

Dust from comet Wild 2: Interpreting particle size, shape, structure, and composition from impact features on the Stardust aluminum foils

Kearsley

Borg

Graham

et al. 2008

Meteorit & Planetary Scien

120

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Abstract-Aluminum foils of the Stardust cometary dust collector are peppered with impact features of a wide range of sizes and shapes. By comparison to laboratory shots of known particle dimensions and density, using the same velocity and incidence geometry as the Stardust Wild 2 encounter, we can derive size and mass of the cometary dust grains. Using scanning electron microscopy (SEM) of foil samples (both flown on the mission and impacted in the laboratory) we have recognized a range of impact feature shapes from which we interpret particle density and internal structure. We have documented composition of crater residues, including stoichiometric material in 3 of 7 larger craters, by energy dispersive X-ray microanalysis. Wild 2 dust grains include coarse (>10 μm) mafic silicate grains, some dominated by a single mineral species of density around 3-4 g cm −3 (such as olivine). Other grains were porous, low-density aggregates from a few nanometers to 100 μm, with an overall density that may be lower than 1 g cm −3 , containing mixtures of silicates and sulfides and possibly both alkali-rich and mafic glass. The mineral assemblage is very similar to the most common species reported from aerogel tracks. In one large aggregate crater, the combined diverse residue composition is similar to CI chondrites. The foils are a unique collecting substrate, revealing that the most abundant Wild 2 dust grains were of sub-micrometer size and of complex internal structure. Impact residues in Stardust foil craters will be a valuable resource for future analyses of cometary dust.

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Section: Implications For the Structure And Composition Of Wild 2 Dussupporting

confidence: 68%

Dust from comet Wild 2: Interpreting particle size, shape, structure, and composition from impact features on the Stardust aluminum foils

Kearsley

Borg

Graham

et al. 2008

Meteorit & Planetary Scien

120

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“…The lack of SiO 2 suggests that the dust may be second generation, which might further hint at the presence of a planet disturbing the orbits of smaller bodies, causing them to collide with each other. The large resemblance of the dust around HD 113766 to that found in comets and interplanetary dust particles in our own solar system (IDP; Bradley 2003) suggests that we might see the early stages of our solar system by observing this object.…”

Section: Discussionmentioning

confidence: 71%

Mid-IR observations of circumstellar disks

Schütz¹,

Meeus

Sterzik

2005

A&A

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Abstract. We present spectral energy distributions and new N-band photometry and spectroscopy for a sample of six main sequence stars and one post-MS object using the ESO TIMMI2 camera at La Silla observatory (Chile). All objects are thought to possess circumstellar material and for the majority of the targets this is their first N-band spectroscopic observation. The emission spectra (observed in three cases), modelled with a mixture of silicates consisting of different grain sizes and composition, confirm the suspected presence of disks around these targets. The most important discovery is that HD 113766, a young Vega-type star, is host to highly processed dust which is probably second generation. It is the first time a Vega-type star with such highly evolved dust has been observed. Silicate emission of basically unevolved dust is seen in case of the post-MS object HD 41511 and the Vega-type star HD 172555. In addition, to study the cold dust, we observed a subsample at 1200 µm with the bolometer array SIMBA at the SEST in La Silla but we only got upper limits for those five objects. This shows that these Vega-type stars have a smaller amount of dust than their precursors, the T Tauri and Herbig Ae/Be stars.

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“…Its prominent bands are observed in many spectra of accretion disks around young stars and in the outflows A68, page 6 of 10 of AGB stars (Henning 2003a,b). Olivine also occurs in our solar system in the form of cometary dust (Hanner 2003), as interplanetary dust particles (Bradley 2003), and on planetary surfaces (e.g. Hartmann 2005).…”

Section: Olivinementioning

confidence: 99%

Near-infrared absorption properties of oxygen-rich stardust analogs

Zeidler¹,

Posch²,

Mutschke³

et al. 2010

A&A

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Context. Several astrophysically relevant solid oxides and silicates have extremely small opacities in the visual and near-infrared in their pure forms. Datasets for the opacities and for the imaginary part k of their complex indices of refraction are hardly available in these wavelength ranges. Aims. We aimed at determining k for spinel, rutile, anatase, and olivine, especially in the near-infrared region. Our measurements were made with impurity-containing, natural, and synthetic stardust analogs. Methods. Two experimental methods were used: preparing small sections of natural minerals and synthesizing melt droplets under the electric arc furnace. In both cases, the aborption properties of the samples were measured by transmission spectroscopy. Results. For spinel (MgAl 2 O 4 ), anatase, rutile (both TiO 2 ), and olivine ((Mg,Fe) 2 SiO 4 ), the optical constants have been extended to the visual and near-infrared. We highlight that the individual values of k(λ) and the absorption cross section Q abs (λ) depend strongly on the content in transition metals like iron. Based on our measurements, we infer that k values below 10 −5 are very rare in natural minerals including stardust grains, if they occur at all. Conclusions. Data for k and Q abs (λ) are important for various physical properties of stardust grains such as temperature and radiation pressure. With increasing Q abs (λ) due to impurities, the equilibrium temperature of small grains in circumstellar shells increases as well. We discuss why and to what extent this is the case.

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The Astromineralogy of Interplanetary Dust Particles

Cited by 33 publications

References 52 publications

Dust from comet Wild 2: Interpreting particle size, shape, structure, and composition from impact features on the Stardust aluminum foils

Dust from comet Wild 2: Interpreting particle size, shape, structure, and composition from impact features on the Stardust aluminum foils

Mid-IR observations of circumstellar disks

Near-infrared absorption properties of oxygen-rich stardust analogs

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