scholarly journals Graphene oxide nanoparticles in the interstellar medium

2019 ◽  
Vol 490 (1) ◽  
pp. L17-L20 ◽  
Author(s):  
P J Sarre
Keyword(s):  
Graphene Oxide ◽  
Interstellar Dust ◽  
Emission Spectra ◽  
Optical Emission ◽  
Infrared Emission ◽  
Dust Particles ◽  
Infrared Space Observatory ◽  
Interstellar Clouds ◽  
General Acceptance ◽  
Extended Red Emission

ABSTRACT 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 ‘extended red emission’ (ERE) feature which is attributed to luminescence of dust grains. Numerous potential carriers for ERE have been proposed but none has gained general acceptance. In this Letter it is shown that 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 these are a significant component of interstellar dust. The proposal is supported by infrared emission features detected by the Infrared Space Observatory (ISO) and the Spitzer Space Telescope.

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

<p>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 ‘extended red emission’ (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.  </p> <p>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 <em>Infrared Space Observatory (ISO)</em> and the <em>Spitzer Space Telescope</em>.  </p> <p>Insoluble Organic Material (IOM) has a chemical structure with some similarities to graphene oxide.  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.</p>

scholarly journals Carbonaceous nano-dust emission in proto-planetary discs: the aliphatic-aromatic components

2019 ◽  
Vol 623 ◽  
pp. A135 ◽  
Author(s):  
T. Boutéraon ◽  
E. Habart ◽  
N. Ysard ◽  
A. P. Jones ◽  
E. Dartois ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Interstellar Dust ◽  
Near Infrared ◽  
Solid Phase ◽  
Dust Emission ◽  
Emission Spectra ◽  
Infrared Emission ◽  
Constant Intensity ◽  
Aromatic Components ◽  
Nano Grains

Context. In the interstellar medium, carbon (nano-)grains are a major component of interstellar dust. This solid phase is more vulnerable to processing and destruction than its silicate counterpart. It exhibits a complex, size-dependent evolution that is due to interactions within different radiative and dynamical environments. Infrared signatures of these carbon nano-grains are seen in a large number of discs around Herbig HAeBe stars. Aims. We probe the composition and evolution of carbon nano-grains at the surface of (pre-)transitional proto-planetary discs around Herbig stars. Methods. We present spatially resolved infrared emission spectra obtained with the Nasmyth Adaptive Optics System (NAOS) Near-Infrared Imager and Spectrograph (CONICA) at the Very Large Telescope (VLT) in the 3–4 μm range with a spatial resolution of 0.1′′, which allowed us to trace aromatic, olefinic, and aliphatic bands that are attributed to sub-nanometer hydrocarbon grains. We applied a Gaussian fitting to analyse the observed spectral signatures. Finally, we propose an interpretation in the framework of the The Heterogeneous dust Evolution Model of Interstellar Solids (THEMIS). Results. We show the presence of several spatially extended spectral features that are related to aromatic and aliphatic hydrocarbon material in discs around Herbig stars, from ~10 to 50–100 au, and even in inner gaps that are devoid of large grains. The correlation and constant intensity ratios between aliphatic and aromatic CH stretching bands suggests a common nature of the carriers. Given their expected high destruction rates through UV photons, our observations suggest that they are continuously replenished at the disc surfaces.

scholarly journals Infrared Emission at High Galactic Latitude

1990 ◽  
Vol 139 ◽  
pp. 139-148
Author(s):  
F. Boulanger
Keyword(s):  
Interstellar Dust ◽  
Optical Emission ◽  
Infrared Emission ◽  
Infrared Astronomy ◽  
Molecular Gas ◽  
Galactic Latitude ◽  
High Galactic Latitude ◽  
Present Evidence ◽  
Galactic Emission ◽  
Ir Emission

Results obtained with the Infrared Astronomy Satellite (IRAS) on the IR emission at high galactic latitude are reviewed. We present evidence for the detection of galactic emission at 12, 25, 60, and 100 μm. We describe the morphology of this emission and summarize work on the correlation of IR cirrus with H I, CO, and optical emission. We discuss the contribution of the neutral atomic, ionized, and molecular gas to the total IR emission and the contribution of different components of interstellar dust to the emission seen at different wavelengths.

scholarly journals Infrared Emission from Dust in Supernovae and Supernova Remnants

1989 ◽  
Vol 135 ◽  
pp. 479-486
Author(s):  
Eli Dwek
Keyword(s):  
Supernova Remnants ◽  
Interstellar Dust ◽  
Infrared Emission ◽  
Dust Particles ◽  
Actual Process ◽  
Supernovae And Supernova Remnants ◽  
Infrared Observations ◽  
Interstellar Dust Grains ◽  
The Galaxy ◽  
Astronomical Satellite

The need to replenish the reservoir of interstellar dust grains that are continuously being destroyed in the interstellar medium, and the presence of isotopic anomalies in meteorites, suggest that supernovae may be important sources of interstellar dust. Infrared observations of supernovae or their unmixed ejecta may provide the first direct evidence for newly-formed grains in this environment. The recently discovered supernova, SN 1987A, currently offers the best prospects for observing the actual process of dust formation in a supernova.In contrast, supernova remnants constitute the most important grain destruction mechanism in the galaxy. Interstellar dust swept up by the expanding blast wave is predominantly heated and destroyed by collisions with a shocked x-ray emitting plasma. Infrared observations of remnants can therefore provide valuable information on the interaction between dust particles and a hot gas. This interaction can best be studied in supernova remnants detected with the Infrared Astronomical Satellite (IRAS). This paper reviews what we have learned so far on the subjects of grain formation and destruction by studying the infrared emission from supernovae and supernova remnants.

scholarly journals Dust distribution and temperature in the Magellanic Clouds interstellar medium

1991 ◽  
Vol 148 ◽  
pp. 407-414 ◽  
Author(s):  
M. Sauvage ◽  
L. Vigroux
Keyword(s):  
Interstellar Dust ◽  
Hubble Space Telescope ◽  
Infrared Emission ◽  
Magellanic Clouds ◽  
Infrared Space Observatory ◽  
Chemical Abundances ◽  
The Galaxy ◽  
Recent Developments ◽  
Dust Composition ◽  
Dust Distribution

This review deals with the various aspects of interstellar dust in the Magellanic Clouds (MCs). Dust properties can be traced from interstellar absorption, with an emphasis on UV properties, and from infrared emission. Thanks to IRAS, most of the recent developments in this field have been found in the infrared. The low resolution of IRAS was, in fact, well suited for MC mapping and these observations offer a unique opportunity to study the dust properties in various conditions of the Interstellar Radiation Field (ISRF) and of chemical abundances. The proximity of the MCs allows a direct study of the link between the stellar population and the dust properties via the ISRF. On the other hand, the comparison of IRAS data in the MCs and in the Galaxy allows us to study the dust composition for metallicity varying by a factor of 10. From these data and the previous results on UV absorption, it emerges that if the gas-to-dust ratio changes with metallicity, there is also a variation in the relative abundances of the dust components. In this review, we will also discuss how our knowledge of the MCs will be used to prepare for observations of more distant galaxies, with the next generation of space observatories such as the Hubble Space Telescope and the Infrared Space Observatory.

scholarly journals Dust evolution in the star forming turbulent interstellar medium

2006 ◽  
Vol 2 (S237) ◽  
pp. 47-52
Author(s):  
François Boulanger
Keyword(s):  
Interstellar Medium ◽  
Interstellar Dust ◽  
Dust Particles ◽  
Interstellar Clouds ◽  
Star Forming ◽  
Interstellar Turbulence ◽  
Star Forming Regions ◽  
Potential Impact ◽  
Dust Evolution ◽  
Small Dust

AbstractUnderstanding interstellar dust evolution is a major challenge underlying the interpretation of Spitzer observations of interstellar clouds, star forming regions and galaxies. I illustrate on-going work along two directions. I outline the potential impact of interstellar turbulence on the abundance of small dust particles in the diffuse interstellar medium and translucent sections of molecular clouds. I present results from an analysis of ISO and Spitzer observations of the central part of 30 Doradus, looking for dust evolution related to the radiative and dynamical impact of the R136 super star cluster on its parent molecular cloud.

scholarly journals Interstellar Dust in Collected Interplanetary Dust Particles

1989 ◽  
Vol 135 ◽  
pp. 403-414
Author(s):  
Scott A. Sandford
Keyword(s):  
Interstellar Dust ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Interplanetary Dust Particles ◽  
Interstellar Clouds ◽  
Interstellar Dust Grains ◽  
Isotopic Studies ◽  
Interstellar Material ◽  
Deuterium Enrichment ◽  
Simple Molecules

During the past decade interplanetary dust particles (IDPs) have been collected in the earth's stratosphere. Isotopic studies of these particles have demonstrated that many of them are greatly enriched in deuterium and at least some of them carry this enrichment in smaller subcomponents. Deuterium enrichments of a similar magnitude are seen in simple molecules in interstellar clouds. Deuterium enrichment in IDPs can be taken as evidence for the presence of interstellar material. It is not clear at this time whether the carriers of the isotopic anomalies represent true, unaltered interstellar dust grains, or whether they represent an altered component with a molecular ‘memory’ of original interstellar grains. The spectra of different components in the collected dust provide suggestive matches to similar components evident in the astronomical spectra of dust in comets, dense molecular clouds, and emission nebulae. The known extraterrestrial nature of the particles, the possible presence of interstellar material in them, and their spectral similarity to many astronomical objects all argue that the collected IDPs provide useful analogs for the modelling of interstellar dust.

scholarly journals IGNITION AND PROPERTIES OF RF CAPACITIVE DISCHARGE IN ACETYLENE

2019 ◽  
pp. 135-140
Author(s):  
V.A. Lisovskiy ◽  
S.V. Dudin ◽  
P.P. Platonov ◽  
S.I. Bogatyrenko ◽  
A.A. Minenkov
Keyword(s):  
Molecular Hydrogen ◽  
Emission Spectra ◽  
Optical Emission ◽  
Gas Pressure ◽  
Dust Particles ◽  
Power Increase ◽  
Breakdown Curve ◽  
Optical Emission Spectra ◽  
Radio Frequency Discharge ◽  
Deposited Films

In the present work, we measured breakdown and extinction curves of radio-frequency discharge in acetylene as well as dependences of active current, power and gas pressure on the discharge burning time, and also optical emission spectra. It was found that in the region of low acetylene pressures (to the left of the minimum of the breakdown curve), the discharge can cover only a part of the electrode surface. Immediately after the ignition of the discharge, due to the intense deposition of the polymer film and the formation of dust particles in the plasma volume, the gas pressure decreases sharply (by the factor of 2-5), while the active current and power increase and then reach saturation. In the discharge with intense polymerization, the lines of atomic and molecular hydrogen dominate in the emission spectrum of the discharge. The film deposited on the surface of the electrodes and the tube walls, as well as the dust particles formed, are amorphous, the maximum peak of XRD spectrum is observed at 2θ = 18°, and the light absorption by the deposited films is highest at 440 nm wavelength.

The Use of Ratio-Recording Interferometry for the Measurement of Infrared Emission Spectra: Applications to Oxide Films on Copper Surfaces

1975 ◽  
Vol 29 (6) ◽  
pp. 496-500 ◽  
Author(s):  
D. Kember ◽  
N. Sheppard
Keyword(s):  
Emission Spectra ◽  
Black Body ◽  
Infrared Emission ◽  
Thin Layers ◽  
Oxide Surface ◽  
Surface Layers ◽  
Selective Reflection ◽  
Copper Surfaces ◽  
Emission And Absorption Spectra ◽  
Direct Correspondence

Infrared emission spectra from metal samples with oxide surface layers are shown to be very advantageously studied using the spectrum-ratioing facility of a recording infrared interferometer. The emission from a given sample is ratioed against that from a black-body emitter at the same temperature so as to give emittance as a function of wavenumber directly. This method has very useful application to irregularly shaped metal emitters. In the absence of selective reflection there is a direct correspondence between emission and absorption spectra for thin layers of an emitting substance. However, the presence of selective reflection leads to reduced emission and to considerable differences in the appearance of “absorption” and emission spectra in regions of strong absorption. Emission spectra obtained from copper plates heated, above 150°C, for different periods in air are shown clearly to indicate the presence of cuprous, Cu(I), and cupric, Cu(II), oxides in the surface layer.

Ionized AGN outflows are less powerful than assumed: A multi-wavelength census of outflows in type II AGN

2019 ◽  
Vol 15 (S356) ◽  
pp. 225-225
Author(s):  
Dalya Baron
Keyword(s):  
Optical Emission ◽  
Infrared Emission ◽  
Type Ii ◽  
Ionized Gas ◽  
Kinetic Coupling ◽  
Mass Outflow ◽  
Multi Wavelength ◽  
Novel Method ◽  
First Time ◽  
Ionization Parameter

AbstractIn this talk I will show that multi-wavelength observations can provide novel constraints on the properties of ionized gas outflows in AGN. I will present evidence that the infrared emission in active galaxies includes a contribution from dust which is mixed with the outflow and is heated by the AGN. We detect this infrared component in thousands of AGN for the first time, and use it to constrain the outflow location. By combining this with optical emission lines, we constrain the mass outflow rates and energetics in a sample of 234 type II AGN, the largest such sample to date. The key ingredient of our new outflow measurements is a novel method to estimate the electron density using the ionization parameter and location of the flow. The inferred electron densities, ∼104.5 cm−3, are two orders of magnitude larger than found in most other cases of ionized outflows. We argue that the discrepancy is due to the fact that the commonly-used [SII]-based method underestimates the true density by a large factor. As a result, the inferred mass outflow rates and kinetic coupling efficiencies are 1–2 orders of magnitude lower than previous estimates, and 3–4 orders of magnitude lower than the typical requirement in hydrodynamic cosmological simulations. These results have significant implications for the relative importance of ionized outflows feedback in this population.

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