scholarly journals Chemical and physical properties of interstellar dust

2011 ◽  
Vol 7 (S284) ◽  
pp. 72-81 ◽  
Author(s):  
A. G. G. M. Tielens
Keyword(s):  
Interstellar Dust ◽  
Amorphous Materials ◽  
Dust Formation ◽  
Complex Interplay ◽  
Astronomical Observations ◽  
Accretion Process ◽  
Supernova Explosions ◽  
Stellar Sources ◽  
Elemental Depletion ◽  
Intercloud Medium

AbstractThe characteristics of interstellar dust reflect a complex interplay between stellar injection of stardust, destruction in the ISM, and regrowth in clouds. Astronomical observations and analysis of stardust isolated from meteorites have revealed a highly diverse interstellar and circumstellar grain inventory, including both amorphous materials and highly crystalline compounds (silicates and carbon). This review summarizes this dust budget and inventory. Interstellar dust is highly processed during its sojourn from its birthsite (stellar ejecta) to its incorporation into protoplanetary systems. Processing by strong shocks due to supernova explosions is particularly important. Sputtering by impacting gas ions in shocks in the intercloud medium of the ISM is counteracted by accretion in cloud phases and their balance sets the observed, interstellar, elemental depletion patterns. Astronomical and meteoritical-stardust evidence for these processes is reviewed and it is concluded that dust formation in the ISM is very rapid. Not surprisingly, the characteristics of interstellar dust are expected to vary widely reflecting local stellar sources, the effects of SNe processing, and the interstellar accretion process.

scholarly journals Thermal emission from the amorphous dust: An alternative possibility of the origin of the anomalous microwave emission

2019 ◽  
Vol 72 (1) ◽  
Author(s):  
Masashi Nashimoto ◽  
Makoto Hattori ◽  
Ricardo Génova-Santos ◽  
Frédérick Poidevin
Keyword(s):  
Interstellar Dust ◽  
Amorphous Materials ◽  
Thermal Emission ◽  
Far Infrared ◽  
Alternative Interpretation ◽  
Microwave Emission ◽  
Spectral Energy ◽  
Radiative Processes ◽  
Resonance Emission ◽  
Amorphous Silicate

Abstract Complete studies of the radiative processes of thermal emission from the amorphous dust from microwave through far-infrared wavebands are presented by taking into account, self-consistently for the first time, the standard two-level systems (TLS) model of amorphous materials. The observed spectral energy distributions (SEDs) for the Perseus molecular cloud (MC) and W 43 from microwave through far-infrared are fitted with the SEDs calculated with the TLS model of amorphous silicate. We have found that the model SEDs reproduce the observed properties of the anomalous microwave emission (AME) well. The present result suggests an alternative interpretation for the AME being carried by the resonance emission of the TLS of amorphous materials without introducing new species. Simultaneous fitting of the intensity and polarization SEDs for the Perseus MC and W 43 are also performed. The amorphous model reproduces the overall observed feature of the intensity and polarization SEDs of the Perseus MC and W 43. However, the model’s predicted polarization fraction of the AME is slightly higher than the QUIJOTE upper limits in several frequency bands. A possible improvement of our model to resolve this problem is proposed. Our model predicts that interstellar dust is amorphous materials with very different physical characteristics compared with terrestrial amorphous materials.

scholarly journals The origin of Galactic cosmic rays as revealed by their composition

2021 ◽  
Vol 508 (1) ◽  
pp. 1321-1345
Author(s):  
Vincent Tatischeff ◽  
John C Raymond ◽  
Jean Duprat ◽  
Stefano Gabici ◽  
Sarah Recchia
Keyword(s):  
Cosmic Rays ◽  
Interstellar Medium ◽  
Interstellar Dust ◽  
Massive Star ◽  
Gamma Ray ◽  
Galactic Cosmic Rays ◽  
Shock Acceleration ◽  
Ionization State ◽  
Hot Plasma ◽  
Supernova Explosions

ABSTRACT Galactic cosmic rays (GCRs) are thought to be accelerated in strong shocks induced by massive star winds and supernova explosions sweeping across the interstellar medium. But the phase of the interstellar medium from which the CRs are extracted has remained elusive until now. Here, we study in detail the GCR source composition deduced from recent measurements by the AMS-02, Voyager 1, and SuperTIGER experiments to obtain information on the composition, ionization state, and dust content of the GCR source reservoirs. We show that the volatile elements of the CR material are mainly accelerated from a plasma of temperature ≳ 2 MK, which is typical of the hot medium found in Galactic superbubbles energized by the activity of massive star winds and supernova explosions. Another GCR component, which is responsible for the overabundance of 22Ne, most likely arises from acceleration of massive star winds in their termination shocks. From the CR-related gamma-ray luminosity of the Milky Way, we estimate that the ion acceleration efficiency in both supernova shocks and wind termination shocks is of the order of 10−5. The GCR source composition also shows evidence for a preferential acceleration of refractory elements contained in interstellar dust. We suggest that the GCR refractories are also produced in superbubbles, from shock acceleration and subsequent sputtering of dust grains continuously incorporated into the hot plasma through thermal evaporation of embedded molecular clouds. Our model explains well the measured abundances of all primary and mostly primary CRs from H to Zr, including the overabundance of 22Ne.

scholarly journals Interstellar Dust in the LMC

1984 ◽  
Vol 108 ◽  
pp. 403-404
Author(s):  
Geoffrey C. Clayton ◽  
Peter G. Martin
Keyword(s):  
Interstellar Dust ◽  
Magellanic Clouds ◽  
Dust Formation ◽  
Infrared Photometry ◽  
The Galaxy ◽  
Ultraviolet Extinction ◽  
Formation Efficiency

New IUE observations confirm the differences between the Galactic and LMC ultraviolet extinction curves and show some evidence for variations within the LMC. Visual and infrared photometry and polarimetry show that the anomalous properties of the LMC dust do not extend to longer wavelengths. Despite the much different dust to gas ratios in the Galaxy and the Magellanic clouds, the dust formation efficiency is similar when the abundances are included.

scholarly journals Investigation of dust formation in fusion reactors by pulsed plasma accelerator

2017 ◽  
Vol 35 (4) ◽  
pp. 741-749 ◽  
Author(s):  
M.K. Dosbolayev ◽  
A.U. Utegenov ◽  
A.B. Tazhen ◽  
T.S. Ramazanov
Keyword(s):  
Plasma Flow ◽  
High Speed ◽  
Amorphous Materials ◽  
Target Surface ◽  
Plasma Accelerator ◽  
Dust Formation ◽  
Pulsed Plasma ◽  
Graphite Target ◽  
Plasma Beam ◽  
Fractal Surfaces

AbstractIn this paper, the results of an experimental investigation of dust formation in a pulsed plasma accelerator, which is formed due to the interaction of a pulsed plasma flow with the candidate material of the thermonuclear reactor, are presented. Dynamic and optical properties of a pulsed plasma flow are considered. The results of the synergetic analysis by the Raman spectrometer of the target surface after irradiation with plasma are also presented. It was revealed that after interaction with the plasma, the surface of the graphite target becomes amorphous. Materials with fractal surfaces, similar to the materials formed in tokamaks under the action of erosion, were obtained experimentally. Using a high-speed camera Phantom v2512 video shooting of the plasma beam was carried out, during which it was revealed that the pulsed plasma beam has a speed of about 23 km/s.

A Candidate Analog for Carbonaceous Interstellar Dust: Formation by Reactive Plasma Polymerization

2005 ◽  
Vol 623 (1) ◽  
pp. 242-251 ◽  
Author(s):  
E. Kovačević ◽  
I. Stefanović ◽  
J. Berndt ◽  
Y. J. Pendleton ◽  
J. Winter
Keyword(s):  
Plasma Polymerization ◽  
Interstellar Dust ◽  
Dust Formation ◽  
Reactive Plasma

scholarly journals Low-temperature MIR to submillimeter mass absorption coefficient of interstellar dust analogues

2017 ◽  
Vol 606 ◽  
pp. A50 ◽  
Author(s):  
K. Demyk ◽  
C. Meny ◽  
H. Leroux ◽  
C. Depecker ◽  
J.-B. Brubach ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Interstellar Dust ◽  
Amorphous Materials ◽  
Sol Gel ◽  
Cosmic Dust ◽  
Mass Absorption Coefficient ◽  
Clear Trend ◽  
Mass Absorption ◽  
Amorphous Silicate ◽  
Grain Temperature

Context. To model the cold dust emission observed in the diffuse interstellar medium, in dense molecular clouds or in cold clumps that could eventually form new stars, it is mandatory to know the physical and spectroscopic properties of this dust and to understand its emission. Aims. This work is a continuation of previous studies aiming at providing astronomers with spectroscopic data of realistic cosmic dust analogues for the interpretation of observations. The aim of the present work is to extend the range of studied analogues to iron-rich silicate dust analogues. Methods. Ferromagnesium amorphous silicate dust analogues were produced by a sol-gel method with a mean composition close to Mg1−xFexSiO3 with x = 0.1, 0.2, 0.3, 0.4. Part of each sample was annealed at 500 °C for two hours in a reducing atmosphere to modify the oxidation state of iron. We have measured the mass absorption coefficient (MAC) of these eight ferromagnesium amorphous silicate dust analogues in the spectral domain 30−1000 μm for grain temperature in the range 10−300 K and at room temperature in the 5−40 μm range. Results. The MAC of ferromagnesium samples behaves in the same way as the MAC of pure Mg-rich amorphous silicate samples. In the 30−300 K range, the MAC increases with increasing grain temperature whereas in the range 10−30 K, we do not see any change of the MAC. The MAC cannot be described by a single power law in λ− β. The MAC of the samples does not show any clear trend with the iron content. However the annealing process has, on average, an effect on the MAC that we explain by the evolution of the structure of the samples induced by the processing. The MAC of all the samples is much higher than the MAC calculated by dust models. Conclusions. The complex behavior of the MAC of amorphous silicates with wavelength and temperature is observed whatever the exact silicate composition (Mg vs. Fe amount). It is a universal characteristic of amorphous materials, and therefore of amorphous cosmic silicates, that should be taken into account in astronomical modeling. The enhanced MAC of the measured samples compared to the MAC calculated for cosmic dust model implies that dust masses are overestimated by the models.

scholarly journals Signatures of diffuse interstellar gas in the Galaxy Evolution Explorer all-sky survey

2019 ◽  
Vol 631 ◽  
pp. A59
Author(s):  
Marcelo Armengot ◽  
Ana I. Gómez de Castro
Keyword(s):  
Galaxy Evolution ◽  
Interstellar Dust ◽  
Blind Detection ◽  
Interstellar Gas ◽  
Star Forming ◽  
Star Forming Regions ◽  
Interstellar Dust Grains ◽  
Sky Survey ◽  
The Galaxy ◽  
Stellar Sources

Context. The all-sky survey run by the Galaxy Evolution Explorer (GALEX AIS) mapped about 85% of the Galaxy at ultraviolet (UV) wavelengths and detected the diffuse UV background produced by the scattering of the radiation from OBA stars by interstellar dust grains. Against this background, diffuse weak structures were detected as well as the UV counterparts to nebulae and molecular clouds. Aims. To make full profit of the survey, unsupervised and semi-supervised procedures need to be implemented. The main objective of this work is to implement and analyze the results of the method developed by us for the blind detection of ISM features in the GALEX AIS. Methods. Most ISM features are detected at very low signal levels (dark filaments, globules) against the already faint UV background. We have defined an index, the UV background fluctuations index (or UBF index), to identify areas of the sky where these fluctuations are detected. The algorithm is applied to the images obtained in the far-UV (1344–1786 Å) band since this is less polluted by stellar sources, facilitating the automated detection. Results. The UBF index is shown to be sensitive to the main star forming regions within the Gould’s Belt, and to some prominent loops like Loop I or the Eridanus and Monogem areas. The catalog with the UBF index values is made available online to the community.

scholarly journals Stardust in the Laboratory

2008 ◽  
Vol 25 (1) ◽  
pp. 7-17 ◽  
Author(s):  
Ernst Zinner
Keyword(s):  
Interplanetary Dust ◽  
Asymptotic Giant Branch ◽  
Dust Particles ◽  
Red Giants ◽  
Agb Stars ◽  
Interplanetary Dust Particles ◽  
Mixing Processes ◽  
Isotopic Compositions ◽  
Supernova Explosions ◽  
Stellar Sources

AbstractPrimitive meteorites and interplanetary dust particles contain small grains that originated in stellar outflows and supernova explosions. These μm- and sub-μm-sized presolar grains can be isolated and studied for their isotopic compositions in the laboratory. They are recognised as stardust by their isotopic compositions, which are completely different from those of the Solar System. They provide new information on stellar evolution, nucleosynthesis, mixing processes in asymptotic giant branch (AGB) stars and supernovae, and Galactic chemical evolution. Red giants, AGB stars, Type II supernovae and possibly novae have been identified as stellar sources of the grains. Of the eight nuclear processes proposed by Burbidge et al. (1957), signatures of all except the r-process can be found in presolar dust grains.

scholarly journals 2D Chemodynamical Simulations of Low-Mass Galaxies

1998 ◽  
Vol 11 (1) ◽  
pp. 139-140
Author(s):  
G. Hensler ◽  
A. Rieschick
Keyword(s):  
Interstellar Medium ◽  
Dynamical Behaviour ◽  
Gravitational Energy ◽  
Disk Galaxies ◽  
Gas Phases ◽  
Supernova Explosions ◽  
Low Mass ◽  
Gas Interactions ◽  
Multi Phase ◽  
Intercloud Medium

Because of their low gravitational energy, low-mass galaxies are seriously affected by energetical processes in their interstellar medium, such as supernova explosions, or by gravitational perturbations, e.g., by neighbouring galaxies. This can reasonably explain their variety of morphological types. If the evolutionary timescales of galaxies are predominantly determined by internal processes, the multi-phase character as well as star-gas interactions and phase transitions have to be taken into account. For this purpose we have developed a numerical treatment of the dynamical behaviour of gas and stars, which also accounts for the metal dependence of some processes and which can trace the chemical evolution for different elements. This so-called chemodynamical treatment is described in detail in Theis et al. (1992) and Samland et al. (1997). It considers three stellar components and devides the gas into clouds (CM, with a mass spectrum) and a hot intercloud medium (ICM). Since the element enhancement of the interstellar medium is produced by different processes with different lifetimes of their progenitors, O, Fe, and N are used as tracer elements to represent supernovae type II (SNell), type la (SNela), and planetary nebulae (PNe) contributions. While supernovae form the ICM, PNe only attribute to the CM so that only mixing effects of both gas phases can alter abundance ratios. Due to limited computer capacities the first chemodynamical simulations of dwarf galaxies could be performed only one-dimensionally so far (see e.g., Hensler et al. 1993, 1998). The recently developed two-dimensional chemodynamical code CoDEx (Samland 1994) was first applied to massive disk galaxies and produced models of which a particular one could represent various chemical and structural observations of the Milky Way with striking agreement (Samland et al. 1997).

scholarly journals Aliphatic hydrocarbon content of interstellar dust

2019 ◽  
Vol 15 (S350) ◽  
pp. 241-244
Author(s):  
T. W. Schmidt ◽  
B. Günay ◽  
M. G. Burton ◽  
A. Rawal
Keyword(s):  
Absorption Coefficient ◽  
Column Density ◽  
Interstellar Dust ◽  
Aliphatic Hydrocarbon ◽  
Line Of Sight ◽  
Absorption Feature ◽  
Astronomical Observations ◽  
Hydrocarbon Content ◽  
Aliphatic Carbon ◽  
C Nmr

AbstractThe mid-IR spectrum of the interstellar medium contains both aromatic and aliphatic hydrocarbon features. These are generally attributed to carbonaceous dust. The aliphatic component is of particular interest because it produces a significant 3.4 μm absorption feature. The optical depth of this feature is related to the number and type of aliphatic carbon C–H bonds in the line of sight. It is possible to estimate the column density of aliphatic carbon from quantitative analysis of the 3.4 μm interstellar feature, providing that the absorption coefficient of interstellar aliphatic hydrocarbon is known. We produced interstellar dust analogues with spectra closely matching astronomical observations. Using a combination of FTIR and 13C NMR spectroscopy, we determined an integrated absorption coefficient of the aliphatic component. The results thus obtained permit direct calibration of astronomical observations, providing rigorous estimates of the amount of aliphatic carbon in the ISM.

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