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John M C Plane - One of the best experts on this subject based on the ideXlab platform.
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Impacts of Cosmic Dust on Planetary Atmospheres and Surfaces
Space Science Reviews, 2018Co-Authors: John M C Plane, George J. Flynn, Anni Määttänen, John E. Moores, Andrew R. Poppe, Juan Diego Carrillo-sanchez, Constantino ListowskiAbstract:Recent advances in interplanetary Dust modelling provide much improved estimates of the fluxes of Cosmic Dust particles into planetary (and lunar) atmospheres throughout the solar system. Combining the Dust particle size and velocity distributions with new chemical ablation models enables the injection rates of individual elements to be predicted as a function of location and time. This information is essential for understanding a variety of atmospheric impacts, including: the formation of layers of metal atoms and ions; meteoric smoke particles and ice cloud nucleation; perturbations to atmospheric gas-phase chemistry; and the effects of the surface deposition of micrometeorites and Cosmic spherules. There is discussion of impacts on all the planets, as well as on Pluto, Triton and Titan.
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sources of Cosmic Dust in the earth s atmosphere
Geophysical Research Letters, 2016Co-Authors: J D Carrillosanchez, Petr Pokorný, David Nesvorný, Diego Janches, John M C PlaneAbstract:There are four known sources of Dust in the inner solar system: Jupiter Family comets, asteroids, Halley Type comets, and Oort Cloud comets. Here we combine the mass, velocity, and radiant distributions of these Cosmic Dust populations from an astronomical model with a chemical ablation model to estimate the injection rates of Na and Fe into the Earth's upper atmosphere, as well as the flux of Cosmic spherules to the surface. Comparing these parameters to lidar observations of the vertical Na and Fe fluxes above 87.5 km, and the measured Cosmic spherule accretion rate at South Pole, shows that Jupiter Family Comets contribute (80 ± 17)% of the total input mass (43 ± 14 t d−1), in good accord with Cosmic Background Explorer and Planck observations of the zodiacal cloud.
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ablation and chemical alteration of Cosmic Dust particles during entry into the earth s atmosphere
Astrophysical Journal Supplement Series, 2016Co-Authors: N G Rudraswami, Shyam M Prasad, Shirshendu Dey, John M C Plane, Wuhu Feng, J D Carrillosanchez, D FernandesAbstract:Most Dust-sized Cosmic particles undergo ablation and chemical alteration during atmospheric entry, which alters their original properties. A comprehensive understanding of this process is essential in order to decipher their pre-entry characteristics. The purpose of the study is to illustrate the process of vaporization of different elements for various entry parameters. The numerical results for particles of various sizes and various zenith angles are treated in order to understand the changes in chemical composition that the particles undergo as they enter the atmosphere. Particles with large sizes (> few hundred μm) and high entry velocities (>16 km s−1) experience less time at peak temperatures compared to those that have lower velocities. Model calculations suggest that particles can survive with an entry velocity of 11 km s−1 and zenith angles (ZA) of 30°–90°, which accounts for ~66% of the region where particles retain their identities. Our results suggest that the changes in chemical composition of MgO, SiO2, and FeO are not significant for an entry velocity of 11 km s−1 and sizes <300 μm, but the changes in these compositions become significant beyond this size, where FeO is lost to a major extent. However, at 16 km s−1 the changes in MgO, SiO2, and FeO are very intense, which is also reflected in Mg/Si, Fe/Si, Ca/Si, and Al/Si ratios, even for particles with a size of 100 μm. Beyond 400 μm particle sizes at 16 km s−1, most of the major elements are vaporized, leaving the refractory elements, Al and Ca, suspended in the troposphere.
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uptake of acetylene on Cosmic Dust and production of benzene in titan s atmosphere
Icarus, 2016Co-Authors: Victoria Frankland, Alexander D James, Juan Diego Carrillo Sanchez, T P Mangan, Karen Willacy, A R Poppe, John M C PlaneAbstract:A low-temperature flow tube and ultra-high vacuum apparatus were used to explore the uptake and heterogeneous chemistry of acetylene (C2H2) on Cosmic Dust analogues over the temperature range encountered in Titan's atmosphere below 600 km. The uptake coefficient, γ, was measured at 181 K to be (1.6 ± 0.4) × 10-4, (1.9 ± 0.4) × 10−4 and (1.5 ± 0.4) × 10−4 for the uptake of C2H2 on Mg2SiO4, MgFeSiO4 and Fe2SiO4, respectively, indicating that γ is independent of Mg or Fe active sites. The uptake of C2H2 was also measured on SiO2 and SiC as analogues for meteoric smoke particles in Titan's atmosphere, but was found to be below the detection limit (γ < 6 × 10−8 and < 4 × 10-7, respectively). The rate of cyclo-trimerization of C2H2 to C6H6 was found to be 2.6 × 10-5 exp(-741/T) s−1, with an uncertainty ranging from ± 27 % at 115 K to ± 49 % at 181 K. A chemical ablation model was used to show that the bulk of Cosmic Dust particles (radius 0.02–10 µm) entering Titan's atmosphere do not ablate (< 1% mass loss through sputtering), thereby providing a significant surface for heterogeneous chemistry. A 1D model of Dust sedimentation shows that the production of C6H6 via uptake of C2H2 on Cosmic Dust, followed by cyclo-trimerization and desorption, is probably competitive with gas-phase production of C6H6 between 80 and 120 km.
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on the size and velocity distribution of Cosmic Dust particles entering the atmosphere
Geophysical Research Letters, 2015Co-Authors: J D Carrillosanchez, John M C Plane, Wuhu Feng, David Nesvorný, Diego JanchesAbstract:The size and velocity distribution of Cosmic Dust particles entering the Earth's atmosphere is uncertain. Here we show that the relative concentrations of metal atoms in the upper mesosphere, and the surface accretion rate of Cosmic spherules, provide sensitive probes of this distribution. Three Cosmic Dust models are selected as case studies: two are astronomical models, the first constrained by infrared observations of the Zodiacal Dust Cloud and the second by radar observations of meteor head echoes; the third model is based on measurements made with a spaceborne Dust detector. For each model, a Monte Carlo sampling method combined with a chemical ablation model is used to predict the ablation rates of Na, K, Fe, Mg, and Ca above 60 km and Cosmic spherule production rate. It appears that a significant fraction of the Cosmic Dust consists of small (<5 µg) and slow (<15 km s−1) particles.
Wilfriedsolo Ojo - One of the best experts on this subject based on the ideXlab platform.
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low temperature mir to submillimeter mass absorption coefficient of interstellar Dust analogues ii mg and fe rich amorphous silicates
arXiv: Astrophysics of Galaxies, 2017Co-Authors: K Demyk, Hugues Leroux, C Meny, Christophe Depecker, Jeanblaise Brubach, Pascale Roy, Celine Nayral, Wilfriedsolo OjoAbstract: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. 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. Ferromagnesium amorphous silicate Dust analogues were produced with a mean composition close to $\mathrm{Mg_{1-x}Fe_{x}SiO_3}$ with x = 0.1, 0.2, 0.3, 0.4. Part of each sample was annealed at 500$^{\circ}$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 ferromagnesium amorphous silicate Dust analogues in the spectral domain 30 - 1000 $\mu$m for grain temperature in the range 10 - 300 K and at room temperature in the 5 - 40 $\mu$m range. 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 ${\lambda}^{-\beta}$. The MAC of all the samples is much higher than the MAC calculated by Dust models. 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.
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low temperature mir to submillimeter mass absorption coefficient of interstellar Dust analogues i mg rich glassy silicates
Astronomy and Astrophysics, 2017Co-Authors: K Demyk, Hugues Leroux, C Meny, G N Papatheodorou, M J Toplis, Christophe Depecker, Jeanblaise Brubach, Pascale Roy, Celine Nayral, Wilfriedsolo OjoAbstract:Context. The submillimeter spectral domain has been extensively explored by the Herschel and Planck satellites and is now reachable from the ground with ALMA. A wealth of data, revealing cold Dust thermal emission, is available for astronomical environments ranging from interstellar clouds, cold clumps, circumstellar envelops, and protoplanetary disks. The interpretation of these observations relies on the understanding and modeling of cold Dust emission and on the knowledge of the Dust optical properties. Aims. The aim of this work is to provide astronomers with a set of spectroscopic data of realistic interstellar Dust analogues that can be used to interpret the observations. It pursues the experimental effort aimed at characterizing the spectroscopic properties of interstellar Dust analogues at low temperature in the mid-infrared (MIR) to millimeter spectral domain. Compared to previous studies, it extends the range of studied Dust analogues in terms of composition and of structure of the material. Methods. Glassy silicates of mean composition (1− x )MgO – x SiO 2 with x = 0.35 (close to forsterite, Mg 2 SiO 4 ), 0.50 (close to enstatite, MgSiO 3 ) and 0.40 (close to Mg 1.5 SiO 3.5 or MgSiO 3 :Mg 2 SiO 4 = 50:50) were synthesized. The mass absorption coefficient (MAC) of the samples was measured in the spectral domain 30–1000 μ m for grain temperature in the range 300–10 K and at room temperature in the 5–40 μ m domain. Results. We find that the MAC of all samples varies with the grains temperature and that its spectral shape cannot be approximated by a single power law in λ − β . In the FIR/submm, and above 30 K, the MAC value at a given wavelength increases with the temperature as thermally activated absorption processes appear. The studied materials exhibit different and complex behaviors at long wavelengths ( λ ≥ 200 to 700 μ m depending on the samples). These behaviors are attributed to the amorphous nature of Dust and to the amount and nature of the defects within this amorphous structure. We do not observe MAC variations in the 10–30 K range. Above 20 μ m, the measured MAC are much higher than the MAC calculated from interstellar silicate Dust models indicating that the analogues measured in this study are more emissive than the silicates in Cosmic Dust models. Conclusions. The underestimated value of the MAC deduced from Cosmic Dust models in the FIR/submm has important astrophysical implications because masses are overestimated by the models. Moreover, constraints on elemental abundance of heavy elements in Cosmic Dust models are relaxed.
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low temperature mir to submillimeter mass absorption coefficient of interstellar Dust analogues i mg rich glassy silicates
arXiv: Astrophysics of Galaxies, 2017Co-Authors: K Demyk, Hugues Leroux, C Meny, G N Papatheodorou, M J Toplis, Christophe Depecker, Jeanblaise Brubach, Pascale Roy, Celine Nayral, Wilfriedsolo OjoAbstract:A wealth of data from the Herschel and Planck satellites and now from ALMA, revealing cold Dust thermal emission, is available for astronomical environments ranging from interstellar clouds, cold clumps, circumstellar envelops, and protoplanetary disks. The interpretation of these observations relies on the understanding and modeling of cold Dust emission and on the knowledge of the Dust optical properties. The aim of this work is to provide astronomers with a set of spectroscopic data of realistic interstellar Dust analogues that can be used to interpret the observations. Glassy silicates of mean composition (1-x)MgO - xSiO2 with x = 0.35, 0.40 and 0.50 were synthesized. The mass absorption coefficient (MAC) of the samples was measured in the spectral domain 30 - 1000 $\mu$m for grain temperature in the range 300 K - 10 K and at room temperature in the 5 - 40 $\mu$m domain. We find that the MAC of all samples varies with the grains temperature. In the FIR/submm, and above 30K, the MAC value at a given wavelength increases with the temperature as thermally activated absorption processes appear. The studied materials exhibit different and complex behaviors at long wavelengths (lambda $\geq$ 200 to 700 $\mu$m depending on the samples) and the MAC cannot be approximated by a single power law in ${\lambda}^{-\beta}$. These behaviors are attributed to the amorphous nature of Dust and to the amount and nature of the defects within this amorphous structure. Above 20 $\mu$m, the measured MAC are much higher than the MAC calculated from interstellar silicate Dust models indicating that the analogues measured in this study are more emissive than the silicates in Cosmic Dust models. This has important astrophysical implications because masses are overestimated by the models. Moreover, constraints on elemental abundance of heavy elements in Cosmic Dust models are relaxed
Yitian Gao - One of the best experts on this subject based on the ideXlab platform.
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3 1 dimensional generalized johnson model for Cosmic Dust ion acoustic nebulons with symbolic computation
Physics of Plasmas, 2006Co-Authors: Yitian GaoAbstract:In a Cosmic Dusty plasma, both azimuthal and height perturbations of a nonplanar cylindrical geometry are considered. For Dust-ion-acoustic waves and with symbolic computation, (3+1)-dimensional generalized Johnson [(3+1)DGJ] model is derived and analytic solutions are constructed. Supernova-shell-typed expanding bright (3+1)DGJ nebulons and Saturn-F-ring-type expanding dark (3+1)DGJ nebulons are both pictured and discussed. Essential difference of this letter from the existing literature is pointed out, with the relevant, possibly observable (3+1)DGJ-nebulonic structures for the future Cosmic experiments proposed.
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cylindrical nebulons symbolic computation and backlund transformation for the Cosmic Dust acoustic waves
Physics of Plasmas, 2005Co-Authors: Yitian GaoAbstract:In a Cosmic Dusty plasma, the Dust-acoustic-wave propagation may be described by a cylindrical Kadomtsev-Petviashvili equation. In this Letter, for such modeling of environments like supernova shells, Saturn’s F-ring, etc., cylindrical nebulons and an auto-Backlund transformation are presented via symbolic computation. Nebulon structures are discussed, and possibly observable effects are proposed for Cosmic plasmas.
Ralf Srama - One of the best experts on this subject based on the ideXlab platform.
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modelling destiny interplanetary and interstellar Dust measurements en route to the active asteroid 3200 phaethon
Planetary and Space Science, 2019Co-Authors: Harald Kruger, Ralf Srama, Nicolas Altobelli, Hiroshi Kimura, Georg Moragasklostermeyer, P Strub, Masanori Kobayashi, Tomoko Arai, Takayuki Hirai, Veerle J SterkenAbstract:Abstract The JAXA/ISAS spacecraft DESTINY+ will be launched to the active asteroid (3200) Phaethon in 2022. Among the proposed core payload is the DESTINY+ Dust Analyzer (DDA) which is an upgrade of the Cosmic Dust Analyzer flown on the Cassini spacecraft to Saturn (Srama et al., 2011). We use two up-to-date computer models, the ESA Interplanetary Meteoroid Engineering Model (IMEM, Dikarev et al., 2005a, c), and the interstellar Dust module of the Interplanetary Meteoroid environment for EXploration model (IMEX;Sterken et al. 2013; Strub et al., 2019) to study the detection conditions and fluences of interplanetary and interstellar Dust with DDA. Our results show that a statistically significant number of interplanetary and interstellar Dust particles will be detectable with DDA during the 4-years interplanetary cruise of DESTINY+. The particle impact direction and speed can be used to descriminate between interstellar and interplanetary particles and likely also to distinguish between cometary and asteroidal particles.
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impact ionization mass spectra of anorthite Cosmic Dust analogue particles
Journal of Geophysical Research, 2012Co-Authors: Jon K Hillier, Frank Postberg, S Sestak, Ralf Srama, S KempfAbstract:[1] Anorthite, the Ca-rich end-member of plagioclase feldspar, is a dominant mineral component of the Lunar highlands. Plagioclase feldspar is also found in comets, meteorites and stony asteroids. It is therefore expected to contribute to the population of interplanetary (and circumplanetary) Dust grains within the solar system. After coating micron- and submicron-sized grains of Anorthite with a conductive layer of Platinum, the mineral was successfully accelerated to hypervelocity speeds in the Max Planck Institut fur Kernphysik's Van de Graaff accelerator. We present impact ionization mass spectra generated following the impacts of anorthite grains with a prototype mass spectrometer (the Large Area Mass Analyser, LAMA) designed for use in space, and discuss the behavior of the spectra with increasing impact energy. Correlation analysis is used to identify the compositions and sources of cations present in the spectra, enabling the identification of several molecular cations (e.g., CaAlO2, CaSiO2, Ca2AlO3/CaAlSi2O2) which identify anorthite as the progenitor bulk grain material.
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the composition of saturn s e ring
Monthly Notices of the Royal Astronomical Society, 2007Co-Authors: Jon K Hillier, Frank Postberg, Ralf Srama, S Kempf, S F Green, Neil Mcbride, James Schwanethal, Georg Moragasklostermeyer, J A M Mcdonnell, E GrunAbstract:We present the first in situ direct measurement of the composition of particles in Saturn's rings. The Cassini Cosmic Dust analyser (CDA) measured the mass spectra of nearly 300 impacting Dust particles during the 2004 October E ring crossing. An initial interpretation of the data shows that the particles are predominantly water ice, with minor contributions from possible combinations of silicates, carbon dioxide, ammonia, molecular nitrogen, hydrocarbons and perhaps carbon monoxide. This places constraints on both the composition of Enceladus, the main source of the E ring, as well as the grain formation mechanisms.
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cassini Dust measurements at enceladus and implications for the origin of the e ring
Science, 2006Co-Authors: Frank Spahn, Ralf Srama, S Kempf, Jurgen Schmidt, Nicole Albers, Marcel Horning, Martin Makuch, Martin Seis, Valeri DikarevAbstract:During Cassini's close flyby of Enceladus on 14 July 2005, the High Rate Detector of the Cosmic Dust Analyzer registered micron-sized Dust particles enveloping this satellite. The Dust impact rate peaked about 1 minute before the closest approach of the spacecraft to the moon. This asymmetric signature is consistent with a locally enhanced Dust production in the south polar region of Enceladus. Other Cassini experiments revealed evidence for geophysical activities near Enceladus' south pole: a high surface temperature and a release of water gas. Production or release of Dust particles related to these processes may provide the dominant source of Saturn's E ring.
K Demyk - One of the best experts on this subject based on the ideXlab platform.
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low temperature mir to submillimeter mass absorption coefficient of interstellar Dust analogues ii mg and fe rich amorphous silicates
arXiv: Astrophysics of Galaxies, 2017Co-Authors: K Demyk, Hugues Leroux, C Meny, Christophe Depecker, Jeanblaise Brubach, Pascale Roy, Celine Nayral, Wilfriedsolo OjoAbstract: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. 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. Ferromagnesium amorphous silicate Dust analogues were produced with a mean composition close to $\mathrm{Mg_{1-x}Fe_{x}SiO_3}$ with x = 0.1, 0.2, 0.3, 0.4. Part of each sample was annealed at 500$^{\circ}$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 ferromagnesium amorphous silicate Dust analogues in the spectral domain 30 - 1000 $\mu$m for grain temperature in the range 10 - 300 K and at room temperature in the 5 - 40 $\mu$m range. 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 ${\lambda}^{-\beta}$. The MAC of all the samples is much higher than the MAC calculated by Dust models. 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.
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low temperature mir to submillimeter mass absorption coefficient of interstellar Dust analogues i mg rich glassy silicates
Astronomy and Astrophysics, 2017Co-Authors: K Demyk, Hugues Leroux, C Meny, G N Papatheodorou, M J Toplis, Christophe Depecker, Jeanblaise Brubach, Pascale Roy, Celine Nayral, Wilfriedsolo OjoAbstract:Context. The submillimeter spectral domain has been extensively explored by the Herschel and Planck satellites and is now reachable from the ground with ALMA. A wealth of data, revealing cold Dust thermal emission, is available for astronomical environments ranging from interstellar clouds, cold clumps, circumstellar envelops, and protoplanetary disks. The interpretation of these observations relies on the understanding and modeling of cold Dust emission and on the knowledge of the Dust optical properties. Aims. The aim of this work is to provide astronomers with a set of spectroscopic data of realistic interstellar Dust analogues that can be used to interpret the observations. It pursues the experimental effort aimed at characterizing the spectroscopic properties of interstellar Dust analogues at low temperature in the mid-infrared (MIR) to millimeter spectral domain. Compared to previous studies, it extends the range of studied Dust analogues in terms of composition and of structure of the material. Methods. Glassy silicates of mean composition (1− x )MgO – x SiO 2 with x = 0.35 (close to forsterite, Mg 2 SiO 4 ), 0.50 (close to enstatite, MgSiO 3 ) and 0.40 (close to Mg 1.5 SiO 3.5 or MgSiO 3 :Mg 2 SiO 4 = 50:50) were synthesized. The mass absorption coefficient (MAC) of the samples was measured in the spectral domain 30–1000 μ m for grain temperature in the range 300–10 K and at room temperature in the 5–40 μ m domain. Results. We find that the MAC of all samples varies with the grains temperature and that its spectral shape cannot be approximated by a single power law in λ − β . In the FIR/submm, and above 30 K, the MAC value at a given wavelength increases with the temperature as thermally activated absorption processes appear. The studied materials exhibit different and complex behaviors at long wavelengths ( λ ≥ 200 to 700 μ m depending on the samples). These behaviors are attributed to the amorphous nature of Dust and to the amount and nature of the defects within this amorphous structure. We do not observe MAC variations in the 10–30 K range. Above 20 μ m, the measured MAC are much higher than the MAC calculated from interstellar silicate Dust models indicating that the analogues measured in this study are more emissive than the silicates in Cosmic Dust models. Conclusions. The underestimated value of the MAC deduced from Cosmic Dust models in the FIR/submm has important astrophysical implications because masses are overestimated by the models. Moreover, constraints on elemental abundance of heavy elements in Cosmic Dust models are relaxed.
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low temperature mir to submillimeter mass absorption coefficient of interstellar Dust analogues i mg rich glassy silicates
arXiv: Astrophysics of Galaxies, 2017Co-Authors: K Demyk, Hugues Leroux, C Meny, G N Papatheodorou, M J Toplis, Christophe Depecker, Jeanblaise Brubach, Pascale Roy, Celine Nayral, Wilfriedsolo OjoAbstract:A wealth of data from the Herschel and Planck satellites and now from ALMA, revealing cold Dust thermal emission, is available for astronomical environments ranging from interstellar clouds, cold clumps, circumstellar envelops, and protoplanetary disks. The interpretation of these observations relies on the understanding and modeling of cold Dust emission and on the knowledge of the Dust optical properties. The aim of this work is to provide astronomers with a set of spectroscopic data of realistic interstellar Dust analogues that can be used to interpret the observations. Glassy silicates of mean composition (1-x)MgO - xSiO2 with x = 0.35, 0.40 and 0.50 were synthesized. The mass absorption coefficient (MAC) of the samples was measured in the spectral domain 30 - 1000 $\mu$m for grain temperature in the range 300 K - 10 K and at room temperature in the 5 - 40 $\mu$m domain. We find that the MAC of all samples varies with the grains temperature. In the FIR/submm, and above 30K, the MAC value at a given wavelength increases with the temperature as thermally activated absorption processes appear. The studied materials exhibit different and complex behaviors at long wavelengths (lambda $\geq$ 200 to 700 $\mu$m depending on the samples) and the MAC cannot be approximated by a single power law in ${\lambda}^{-\beta}$. These behaviors are attributed to the amorphous nature of Dust and to the amount and nature of the defects within this amorphous structure. Above 20 $\mu$m, the measured MAC are much higher than the MAC calculated from interstellar silicate Dust models indicating that the analogues measured in this study are more emissive than the silicates in Cosmic Dust models. This has important astrophysical implications because masses are overestimated by the models. Moreover, constraints on elemental abundance of heavy elements in Cosmic Dust models are relaxed
