scholarly journals Cometary dust in Antarctic micrometeorites

2012 ◽  
Vol 8 (S288) ◽  
pp. 123-129 ◽  
Author(s):  
Naoya Imae
Keyword(s):  
Interstellar Dust ◽  
Compositional Analysis ◽  
Interplanetary Dust ◽  
Coarse Grained ◽  
Dust Particles ◽  
Interplanetary Dust Particles ◽  
Interstellar Gas ◽  
Cometary Nuclei ◽  
Fine Grained ◽  
Cometary Dust

AbstractCometary nuclei consist of aggregates of interstellar dust particles less than ~1 μm in diameter and can produce rocky dust particles as a result of the sublimation of ice as comets enter the inner solar system. Samples of fine-grained particles known as chondritic porous interplanetary dust particles (CP-IDPs), possibly from comets, have been collected from the Earth's stratosphere. Owing to their fine-grained texture, these particles were previously thought to be condensates formed directly from interstellar gas. However, coarse-grained chondrule-like objects have recently been observed in samples from comet 81P/Wild 2. The chondrule-like objects are chemically distinct from chondrules in meteoritic chondrites, possessing higher MnO contents (0.5 wt%) in olivine and low-Ca pyroxene. In this study, we analyzed AMM samples by secondary electron microscopy and backscattered electron images for textural observations and compositional analysis. We identified thirteen AMMs with characteristics similar to those of the 81P/Wild 2 samples, and believe that recognition of these similarities necessitates reassessment of the existing models of chondrule formation.

scholarly journals Physical and Mineralogical Properties of Anhydrous Interplanetary Dust Particles in the Analytical Electron Microscope

1991 ◽  
Vol 126 ◽  
pp. 63-70
Author(s):  
J. P. Bradley
Keyword(s):  
Carbonaceous Material ◽  
Interplanetary Dust ◽  
Coarse Grained ◽  
Dust Particles ◽  
Interplanetary Dust Particles ◽  
Electron Microscopic ◽  
Atmospheric Entry ◽  
Fine Grained ◽  
Microscopic Studies ◽  
Solar Flare Tracks

AbstractThe fine grained mineralogy and petrography of anhydrous “pyroxene” and “olivine” classes of chondritic interplanetary dust have been investigated by numerous electron microscopic studies. The “pyroxene” interplanetary dust particles (IDPs) are porous, unequilibrated assemblages of mineral grains, metal, glass, and carbonaceous material. They contain enstatite whiskers, FeNi carbides, and high-Mn olivines and pyroxenes, all of which are likely to be well preserved products of nebular gas reactions. Solar flare tracks are prominent in most “pyroxene” IDPs, indicating that they were not strongly heated during atmospheric entry. The “olivine” IDPs are coarse grained, equilibrated mineral assemblages that have probably experienced strong heating. Since most “olivine” IDPs do not contain tracks, it is possible that this heating occurred during atmospheric entry.

scholarly journals Dust of comet 67P/Churyumov-Gerasimenko collected by Rosetta/MIDAS: classification and extension to the nanometer scale

2019 ◽  
Vol 630 ◽  
pp. A26 ◽  
Author(s):  
T. Mannel ◽  
M. S. Bentley ◽  
P. D. Boakes ◽  
H. Jeszenszky ◽  
P. Ehrenfreund ◽  
...  
Keyword(s):  
Interplanetary Dust ◽  
Dust Particles ◽  
Nanometer Scale ◽  
Early Solar System ◽  
Interplanetary Dust Particles ◽  
Surface Features ◽  
Cometary Dust ◽  
Log Normal ◽  
Resolution Of Imaging ◽  
Comet 67P

Context. The properties of the smallest subunits of cometary dust contain information on their origin and clues to the formation of planetesimals and planets. Compared to interplanetary dust particles or particles collected during the Stardust mission, dust collected in the coma of comet 67P/Churyumov-Gerasimenko (67P) during the Rosetta mission provides a resource of minimally altered material with known origin whose structural properties can be used to further the investigation of the early solar system. Aims. The cometary dust particle morphologies found at comet 67P on the micrometer scale are classified, and their structural analysis is extended to the nanometer scale. Methods. We present a novel method for achieving the highest spatial resolution of imaging obtained with the MIDAS Atomic Force Microscope on board Rosetta. 3D topographic images with resolutions down to 8 nm were analyzed to determine the subunit sizes of particles on the nanometer scale. Results. Three morphological classes can be determined: (i) fragile agglomerate particles of sizes larger than about 10 μm comprised of micrometer-sized subunits that may themselves be aggregates and show a moderate packing density on the surface of the particles. (ii) A fragile agglomerate with a size of about a few tens of micrometers comprised of micrometer-sized subunits that are suggested to be aggregates themselves and are arranged in a structure with a fractal dimension lower than two. (iii) Small micrometer-sized particles comprised of subunits in the size range of hundreds of nanometers that show surface features that are again suggested to represent subunits. Their differential size distributions follow a log-normal distribution with means of about 100 nm and standard deviations between 20 and 35 nm. Conclusions. The properties of the dust particles found by MIDAS represent an extension of the dust results of Rosetta to the micro- and nanometer scale. All micrometer-sized particles are hierarchical dust agglomerates of smaller subunits. The arrangement, appearance, and size distribution of the smallest determined surface features are reminiscent of those found in chondritic porous interplanetary dust particles. They represent the smallest directly detected subunits of comet 67P.

scholarly journals Interstellar and Solar System organic matter preserved in interplanetary dust

2015 ◽  
Vol 11 (A29B) ◽  
pp. 426-426
Author(s):  
Scott Messenger ◽  
K. Nakamura-Messenger
Keyword(s):  
Organic Matter ◽  
Solar System ◽  
Carbonaceous Material ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Interplanetary Dust Particles ◽  
Fine Grained ◽  
Mass Fractionation ◽  
Current State ◽  
Short Period

AbstractInterplanetary dust particles (IDPs) collected in the Earths stratosphere derive from collisions among asteroids and by the disruption and outgassing of short-period comets. Chondritic porous (CP) IDPs are among the most primitive Solar System materials. CP-IDPs have been linked to cometary parent bodies by their mineralogy, textures, C-content, and dynamical histories. CP-IDPs are fragile, fine-grained (< um) assemblages of anhydrous amorphous and crystalline silicates, oxides and sulfides bound together by abundant carbonaceous material. Ancient silicate, oxide, and SiC stardust grains exhibiting highly anomalous isotopic compositions are abundant in CP-IDPs, constituting 0.01-1% of the mass of the particles. The organic matter in CP-IDPs is isotopically anomalous, with enrichments in D/H reaching 50x the terrestrial SMOW value and 15N/14N ratios up to 3x terrestrial standard compositions. These anomalies are indicative of low T (10-100 K) mass fractionation in cold molecular cloud or the outermost reaches of the protosolar disk. The organic matter shows distinct morphologies, including sub-um globules, bubbly textures, featureless, and with mineral inclusions. Infrared spectroscopy and mass spectrometry studies of organic matter in IDPs reveals diverse species including aliphatic and aromatic compounds. The organic matter with the highest isotopic anomalies appears to be richer in aliphatic compounds. These materials also bear similarities and differences with primitive, isotopically anomalous organic matter in carbonaceous chondrite meteorites. The diversity of the organic chemistry, morphology, and isotopic properties in IDPs and meteorites reflects variable preservation of interstellar/primordial components and Solar System processing. One unifying feature is the presence of sub-um isotopically anomalous organic globules among all primitive materials, including IDPs, meteorites, and comet Wild-2 samples returned by the Stardust mission. We will present an overview of the current state of understanding of the properties and origins of organic matter in primitive IDPs.

ERE from Graphene Oxide in the ISM. A possible link to IOM?

2020 ◽  
Author(s):  
Peter Sarre
Keyword(s):  
Graphene Oxide ◽  
Organic Material ◽  
Interstellar Dust ◽  
Emission Spectra ◽  
Optical Emission ◽  
Interplanetary Dust ◽  
Infrared Emission ◽  
Dust Particles ◽  
Interplanetary Dust Particles ◽  
Infrared Space Observatory

&lt;p&gt;Dust particles play a major role in the formation, evolution and chemistry of interstellar clouds, stars, and planetary systems. Commonly identified forms include amorphous and crystalline carbon-rich particles and silicates. Also present in many astrophysical environments are polycyclic aromatic hydrocarbons (PAHs), detected through their infrared emission, and which are essentially small flakes of graphene. Astronomical observations over the past four decades have revealed a widespread unassigned &amp;#8216;extended red emission&amp;#8217; (ERE) feature which is attributed to luminescence of dust grains. A luminescence feature with similar characteristics to ERE has been found in organic material in interplanetary dust particles and carbonaceous chondrites. &amp;#160;&lt;/p&gt; &lt;p&gt;There is a strong similarity between laboratory optical emission spectra of graphene oxide (GO) and ERE, leading to this proposal that emission from GO nanoparticles is the origin of ERE and that heteroatom-containing PAH structures are a significant component of interstellar dust. The proposal is supported by infrared emission features detected by the &lt;em&gt;Infrared Space Observatory (ISO)&lt;/em&gt; and the &lt;em&gt;Spitzer Space Telescope&lt;/em&gt;. &amp;#160;&lt;/p&gt; &lt;p&gt;Insoluble Organic Material (IOM) has a chemical structure with some similarities to graphene oxide. &amp;#160;It is suggested this may contribute to the discussion as to whether IOM has an origin in the interstellar medium or the solar nebula, or some combination.&lt;/p&gt;

scholarly journals Multiple generations of grain aggregation in different environments preceded solar system body formation

2018 ◽  
Vol 115 (26) ◽  
pp. 6608-6613 ◽  
Author(s):  
Hope A. Ishii ◽  
John P. Bradley ◽  
Hans A. Bechtel ◽  
Donald E. Brownlee ◽  
Karen C. Bustillo ◽  
...  
Keyword(s):  
Solar System ◽  
Organic Carbon ◽  
Molecular Cloud ◽  
Interstellar Dust ◽  
Solar Nebula ◽  
Carbon Matrix ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Interplanetary Dust Particles ◽  
System Body

The solar system formed from interstellar dust and gas in a molecular cloud. Astronomical observations show that typical interstellar dust consists of amorphous (a-) silicate and organic carbon. Bona fide physical samples for laboratory studies would yield unprecedented insight about solar system formation, but they were largely destroyed. The most likely repositories of surviving presolar dust are the least altered extraterrestrial materials, interplanetary dust particles (IDPs) with probable cometary origins. Cometary IDPs contain abundant submicrona-silicate grains called GEMS (glass with embedded metal and sulfides), believed to be carbon-free. Some have detectable isotopically anomalousa-silicate components from other stars, proving they are preserved dust inherited from the interstellar medium. However, it is debated whether the majority of GEMS predate the solar system or formed in the solar nebula by condensation of high-temperature (>1,300 K) gas. Here, we map IDP compositions with single nanometer-scale resolution and find that GEMS contain organic carbon. Mapping reveals two generations of grain aggregation, the key process in growth from dust grains to planetesimals, mediated by carbon. GEMS grains, some witha-silicate subgrains mantled by organic carbon, comprise the earliest generation of aggregates. These aggregates (and other grains) are encapsulated in lower-density organic carbon matrix, indicating a second generation of aggregation. Since this organic carbon thermally decomposes above ∼450 K, GEMS cannot have accreted in the hot solar nebula, and formed, instead, in the cold presolar molecular cloud and/or outer protoplanetary disk. We suggest that GEMS are consistent with surviving interstellar dust, condensed in situ, and cycled through multiple molecular clouds.

scholarly journals Synthesis of the morphological description of cometary dust at comet 67P/Churyumov-Gerasimenko

2019 ◽  
Vol 630 ◽  
pp. A24 ◽  
Author(s):  
C. Güttler ◽  
T. Mannel ◽  
A. Rotundi ◽  
S. Merouane ◽  
M. Fulle ◽  
...  
Keyword(s):  
Interplanetary Dust ◽  
Dust Particles ◽  
Morphological Description ◽  
Complex Data ◽  
Particle Structure ◽  
Interplanetary Dust Particles ◽  
Data Set ◽  
Cometary Dust ◽  
Common Framework ◽  
Comet 67P

Before Rosetta, the space missions Giotto and Stardust shaped our view on cometary dust, supported by plentiful data from Earth based observations and interplanetary dust particles collected in the Earth’s atmosphere. The Rosetta mission at comet 67P/Churyumov-Gerasimenko was equipped with a multitude of instruments designed to study cometary dust. While an abundant amount of data was presented in several individual papers, many focused on a dedicated measurement or topic. Different instruments, methods, and data sources provide different measurement parameters and potentially introduce different biases. This can be an advantage if the complementary aspect of such a complex data set can be exploited. However, it also poses a challenge in the comparison of results in the first place. The aim of this work therefore is to summarize dust results from Rosetta and before. We establish a simple classification as a common framework for intercomparison. This classification is based on the dust particle structure, porosity, and strength and also on its size. Depending on the instrumentation, these are not direct measurement parameters, but we chose them because they were the most reliable for deriving our model. The proposed classification has proved helpful in the Rosetta dust community, and we offer it here also for a broader context. In this manner, we hope to better identify synergies between different instruments and methods in the future.

scholarly journals The Contribution of Kuiper Belt Dust Grains to the Inner Solar System

1996 ◽  
Vol 150 ◽  
pp. 163-166
Author(s):  
Jer-Chyi Liou ◽  
Herbert A. Zook ◽  
Stanley F. Dermott
Keyword(s):  
Solar System ◽  
Interstellar Dust ◽  
Numerical Study ◽  
Kuiper Belt ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Dust Grains ◽  
Zodiacal Light ◽  
Interplanetary Dust Particles ◽  
The Earth

AbstractThe recent discovery of the so-called Kuiper belt objects has prompted the idea that these objects produce dust grains that may contribute significantly to the interplanetary dust population at 1 AU. We have completed a numerical study of the orbital evolution of dust grains, of diameters 1 to 9 μm, that originate in the region of the Kuiper belt. Our results show that about 80% of the grains are ejected from the Solar System by the giant planets while the remaining 20% of the grains evolve all the way to the Sun. Surprisingly, these dust grains have small orbital eccentricities and inclinations when they cross the orbit of the Earth. This makes them behave more like asteroidal than cometary-type dust particles. This also enhances their chances to be captured by the Earth and makes them a possible source of the collected interplanetary dust particles (IDPs); in particular, they represent a possible source that brings primitive/organic materials from the outer Solar System to the Earth.When collisions with interstellar dust grains are considered, however, Kuiper belt dust grains larger than about 9 μm appear likely to be collisionally shattered before they can evolve to the inner part of the Solar System. Therefore, Kuiper belt dust grains may not, as they are expected to be small, contribute significantly to the zodiacal light.

scholarly journals Dust in Dense Clouds

1989 ◽  
Vol 135 ◽  
pp. 239-262 ◽  
Author(s):  
A. G. G. M. Tielens
Keyword(s):  
Grain Size ◽  
Molecular Clouds ◽  
Interstellar Dust ◽  
Theoretical Models ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Theoretical Studies ◽  
Interplanetary Dust Particles ◽  
Ir Reflection ◽  
Grain Surface

Recent observational and theoretical studies of dust in dense clouds are reviewed with an emphasis on the growth of dust grains through accretion and coagulation. IR reflection nebulae around protostellar objects are useful probes of grain sizes in dense clouds. For example, detailed studies of the IR reflection nebula surrounding OMC 2-IRS 1 show that the (scattering) grains are much larger (Ã 5000 å) than in the diffuse interstellar medium. Likewise, the presence of a weak shoulder at 2.95 μm on the 3.08 μm feature in BN indicates the importance of scattering by icy grains and implies a very similar increase in the grain size.Theoretical studies of grain surface chemistry predict the possible presence of three distinctly different grain mantle components in dense clouds depending on the physical conditions in the gas phase. These are: 1) A hydrogenated mantle dominated by H2O and CH3OH; 2) An inert grain mantle dominated by CO and O2; and 3) An oxidized grain mantle dominated by CO2. Although the importance of H2O dominated grain mantles was known for 10 yrs, the presence of CH3OH was only recently confirmed. Furthermore, recent studies of the solid CO band have revealed the presence of at least two distinctly different interstellar grain mantle components along the line of sights towards most stars: One dominated by polar and one by non-polar molecules. Although specific identification of the molecules mixed in with the CO in these components is difficult, it is quite possible that the former component is dominated by H2O and the latter by CO itself, as suggested by theoretical models. Finally, the photochemical evolution of icy grain mantles is briefly reviewed and it is suggested that the resulting complex molecular mantles may evolve into amorphous carbon mantles in the diffuse ISM.Grain-grain collisions can lead to large modifications of the interstellar grain size distribution. At high velocities (v ≳ 1 kms−1) shattering into many small fragments will be important, while at low velocities (v ≲ 10 ms−1) coagulation dominates. Both processes can play a role in dense molecular clouds. The sticking of grains at low velocities is discussed in some detail and it is concluded that coagulation in molecular clouds is only important if the colliding grains are covered by icy grain mantles.Thus, a model for interstellar dust is proposed in which small (≲ 500 å) silicate and carbonaceous grains are “glued” together in large (Ã 3000å), open conglomerates by a polymerized, all enveloping grain mantle. This structure resembles that of certain interplanetary dust particles collected in the upper stratosphere.

scholarly journals 21. Light of the Night Sky / Lumière du Ciel Nocturne

1997 ◽  
Vol 23 (1) ◽  
pp. 231-236
Author(s):  
Christoph Leinert
Keyword(s):  
Interstellar Dust ◽  
Thermal Emission ◽  
Scattered Light ◽  
Diffuse Radiation ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Zodiacal Light ◽  
Interplanetary Dust Particles ◽  
Extragalactic Background Light ◽  
Night Sky

The light of the night sky is a difficult to disentangle mixture of tropospherically scattered light, airglow, zodiacal light (including the thermal emission by interplanetary dust particles), unresolved stellar light, diffuse scattering and emission by interstellar dust and gas, and finally an extragalactic component. It has the reputation of being a very traditional field of astronomy, which certainly is true if we look at the long history of the subject. The recent renewed interest in this topic, which continued during this triennium, appears mainly to come from three sources: - first from the impressive results of the IRAS and COBE infrared satellites. They brought to general consciousness the fact that the infrared sky is characterised by strong emission from interplanetary and interstellar dust, and made clear that this emission may interfere with the study of faint interesting sources. - then from the development of sensitive detectors and arrays for essentially all of the wavelength range to be covered in this report, from the Lyman limit to ≈ 300 μm. Now the difficult measurements of the ultraviolet diffuse radiation and of the extragalactic background light in the infrared cosmological windows around 3 μm and 200 μm have become feasible and state of the art projects. - finally, the threat to astronomical observations arising from man-made development and lighting has become important enough to further studies of uncontaminated and contaminated night sky brightnesses. This report will refer mainly to those areas and is meant to highlight noteworthy developments. It was prepared with the help of Drs. Bowyer and Mattila.

scholarly journals Scattering, absorption, and thermal emission by large cometary dust particles: Synoptic numerical solution

2019 ◽  
Vol 631 ◽  
pp. A164 ◽  
Author(s):  
Johannes Markkanen ◽  
Jessica Agarwal
Keyword(s):  
Light Scattering ◽  
Numerical Solution ◽  
Electromagnetic Waves ◽  
Random Media ◽  
Thermal Emission ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Conductive Heat ◽  
Interplanetary Dust Particles ◽  
Cometary Dust

Context. Remote light scattering and thermal infrared observations provide clues about the physical properties of cometary and interplanetary dust particles. Identifying these properties will lead to a better understanding of the formation and evolution of the Solar System. Aims. We present a numerical solution for the radiative and conductive heat transport in a random particulate medium enclosed by an arbitrarily shaped surface. The method will be applied to study thermal properties of cometary dust particles. Methods. The recently introduced incoherent Monte Carlo radiative transfer method developed for scattering, absorption, and propagation of electromagnetic waves in dense discrete random media is extended for radiative heat transfer and thermal emission. The solution is coupled with the conductive Fourier transport equation that is solved with the finite-element method. Results. The proposed method allows the synoptic analysis of light scattering and thermal emission by large cometary dust particles consisting of submicrometer-sized grains. In particular, we show that these particles can sustain significant temperature gradients resulting in the superheating factor phase function observed for the coma of comet 67P/Churyumov–Gerasimenko.

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