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 The Interstellar Dust Emission Seen by ISO

1998 ◽  
Vol 11 (2) ◽  
pp. 1142-1144 ◽  
Author(s):  
J.L. Puget
Keyword(s):  
Interstellar Medium ◽  
Small Molecules ◽  
Interstellar Dust ◽  
Solid Phase ◽  
Dust Emission ◽  
Atom Clusters ◽  
Interstellar Grains ◽  
Small Atom

Among the important contributions of ISO to the physics of the interstellar medium, this paper concentrates only on the emission from the solid phase (the interstellar grains) and the small atom clusters which are the bridge between the grains and the small molecules with less than about 10 atoms.

Near-Infrared Photometry of Southern Galactic Wolf-Rayet Stars

1982 ◽  
Vol 99 ◽  
pp. 67-72
Author(s):  
C. Sterken ◽  
C. de Loore
Keyword(s):  
Infrared Radiation ◽  
Interstellar Dust ◽  
Near Infrared ◽  
Thermal Emission ◽  
Dust Emission ◽  
Circumstellar Dust ◽  
Infrared Photometry ◽  
Energy Distributions ◽  
Circumstellar Shell

Allen et al. (1972) observed 40 WR stars in the |1.6µ| and |2.2µ| bands, and found evidence of interstellar dust emission in the WC9 stars Ve 2–45, AS320 and HD 313643. Hackwell et al. (1974) reported 2.3 to 23 µ photometry of 19 WR stars and concluded that the excess infrared radiation from the Wolf-Rayet stars (except for the WC9 stars) could be explained by free-free emission from a hot circumstellar shell. Gehrz and Hackwell (1974) found from 2.3 to 23 µ photometry that three out of four WC stars appear to be embedded in thick circumstellar dust (graphite) shells, and concluded that WC9 stars may form a distinct Wolf-Rayet class. Cohen et al. (1975) derived energy distributions of 23 Wolf-Rayet stars from 3µ-11µ scanner spectrophotometry and infrared photometry, and concluded that WN stars show only free-free emission whereas only WC stars show dust. The excesses in WC9 stars are interpreted as thermal emission by graphite grains.

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>

Luminescence Properties of Er3+/Tm3+-Doped Ga2O3-Bi2O3-PbO-GeO2 System Glasses

2011 ◽  
Vol 399-401 ◽  
pp. 982-986
Author(s):  
Jin Liu ◽  
Dong Mei Shi ◽  
Ying Gang Zhao ◽  
Xiao Feng Wang
Keyword(s):  
Emission Intensity ◽  
Near Infrared ◽  
Emission Spectra ◽  
Upconversion Emission ◽  
Infrared Emission ◽  
Optical Devices ◽  
Luminescence Properties ◽  
Red Emission ◽  
Fiber Optical ◽  
Near Infrared Emission

The visible and near infrared emission spectra of Er3+/Tm3+-doped Ga2O3-Bi2O3-PbO-GeO2(GBPG) glasses excited at 808 nm are experimentally investigated. The results reveal that 1.53 µm emission were enhanced with an increase of Er3+concentration. Furthermore, the incorporation of Er3+into Tm3+-doped systems has also resulted in intense 522, 545 and 693nm upconversion emission intensity and an weak 660 nm red emission. The possible mechanism and related discussions on this phenomenon have been presented. The results show that Er3+/Tm3+-codoped GBPG glass may be a promising materials for developing laser and fiber optical devices.

Tunable near-infrared emission of binary nano- and mesoscale GUMBOS

RSC Advances ◽  
2014 ◽  
Vol 4 (54) ◽  
pp. 28471-28480 ◽  
Author(s):  
Atiya N. Jordan ◽  
Noureen Siraj ◽  
Susmita Das ◽  
Isiah M. Warner
Keyword(s):  
Energy Transfer ◽  
Near Infrared ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Emission Spectra ◽  
Infrared Emission ◽  
Förster Resonance Energy Transfer ◽  
Near Infrared Emission ◽  
Tunable Emission ◽  
Förster Resonance

Mixtures of GUMBOS were used to form binary nanomaterials with tunable emission spectra due to Förster resonance energy transfer (FRET).

scholarly journals The dust content of the Crab Nebula

2019 ◽  
Vol 488 (1) ◽  
pp. 164-182 ◽  
Author(s):  
I De Looze ◽  
M J Barlow ◽  
R Bandiera ◽  
A Bevan ◽  
M F Bietenholz ◽  
...  
Keyword(s):  
Spectral Index ◽  
Near Infrared ◽  
Crab Nebula ◽  
Dust Emission ◽  
Infrared Emission ◽  
Small Contribution ◽  
Dust Extinction ◽  
Dust Mass ◽  
The Crab Nebula ◽  
Dust Condensation

ABSTRACT We have modelled the near-infrared to radio images of the Crab Nebula with a Bayesian SED model to simultaneously fit its synchrotron, interstellar (IS), and supernova dust emission. We infer an IS dust extinction map with an average AV = 1.08 ± 0.38 mag, consistent with a small contribution (${\lesssim }22{{\ \rm per\ cent}}$) to the Crab’s overall infrared emission. The Crab’s supernova dust mass is estimated to be between 0.032 and 0.049 M⊙ (for amorphous carbon grains) with an average dust temperature Tdust = 41 ± 3 K, corresponding to a dust condensation efficiency of 8–12 ${{\ \rm per\ cent}}$. This revised dust mass is up to an order of magnitude lower than some previous estimates, which can be attributed to our different IS dust corrections, lower SPIRE flux densities, and higher dust temperatures than were used in previous studies. The dust within the Crab is predominantly found in dense filaments south of the pulsar, with an average V-band dust extinction of AV = 0.20–0.39 mag, consistent with recent optical dust extinction studies. The modelled synchrotron power-law spectrum is consistent with a radio spectral index αradio = 0.297 ± 0.009 and an infrared spectral index αIR = 0.429 ± 0.021. We have identified a millimetre excess emission in the Crab’s central regions, and argue that it most likely results from two distinct populations of synchrotron emitting particles. We conclude that the Crab’s efficient dust condensation (8–12 ${{\ \rm per\ cent}}$) provides further evidence for a scenario where supernovae can provide substantial contributions to the IS dust budgets in galaxies.

scholarly journals Near-infrared variability in dusty white dwarfs: tracing the accretion of planetary material

2020 ◽  
Vol 494 (2) ◽  
pp. 2861-2874 ◽  
Author(s):  
Laura K Rogers ◽  
Siyi Xu (许偲艺) ◽  
Amy Bonsor ◽  
Simon Hodgkin ◽  
Kate Y L Su ◽  
...  
Keyword(s):  
Time Scales ◽  
White Dwarf ◽  
White Dwarfs ◽  
Near Infrared ◽  
Dust Emission ◽  
Infrared Emission ◽  
Wide Field ◽  
Infrared Telescope ◽  
Infrared Monitoring ◽  
K Band

ABSTRACT The inwards scattering of planetesimals towards white dwarfs is expected to be a stochastic process with variability on human time-scales. The planetesimals tidally disrupt at the Roche radius, producing dusty debris detectable as excess infrared emission. When sufficiently close to the white dwarf, this debris sublimates and accretes on to the white dwarf and pollutes its atmosphere. Studying this infrared emission around polluted white dwarfs can reveal how this planetary material arrives in their atmospheres. We report a near-infrared monitoring campaign of 34 white dwarfs with infrared excesses with the aim to search for variability in the dust emission. Time series photometry of these white dwarfs from the United Kingdom Infrared Telescope (Wide Field Camera) in the J-, H-, and K-bands was obtained over baselines of up to 3 yr. We find no statistically significant variation in the dust emission in all three near-infrared bands. Specifically, we can rule out variability at ∼1.3 per cent for the 13 white dwarfs brighter than 16th mag in K-band, and at ∼10 per cent for the 32 white dwarfs brighter than 18th mag over time-scales of 3 yr. Although to date two white dwarfs, SDSS J095904.69−020047.6 and WD 1226+110, have shown K-band variability, in our sample we see no evidence of new K-band variability at these levels. One interpretation is that the tidal disruption events that lead to large variabilities are rare occur on short time-scales, and after a few years the white dwarfs return to being stable in the near-infrared.

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.

Near-infrared observations of dusty white dwarfs

2019 ◽  
Vol 15 (S357) ◽  
pp. 33-36
Author(s):  
Laura K. Rogers ◽  
Siyi Xu ◽  
Amy Bonsor ◽  
Simon Hodgkin ◽  
Kate Y. L. Su ◽  
...  
Keyword(s):  
Stochastic Process ◽  
White Dwarfs ◽  
Near Infrared ◽  
Dust Emission ◽  
Colour Change ◽  
Infrared Emission ◽  
Tidal Disruption ◽  
Process Variability ◽  
Infrared Observations ◽  
Excess Emission

AbstarctPlanetary material in the atmospheres of white dwarfs is thought to be scattered inwards from outer planetary systems. Dusty emission in the infrared traces the accretion. As the scattering of many small asteroids is a stochastic process, variability in the infrared emission is predicted. We report a 3 year near-infrared (J, H and K) monitoring campaign of 34 dusty, polluted white dwarfs which aims to search for dust emission variability. We find all white dwarfs have consistent near-infrared fluxes, implying the excess emission is stable. This suggests tidal disruption events which lead to large variabilities are rare and quick (<1 year) and become stable within a few years. For WD 0408–041, the system that shows both increases and decreases in dust emission over 11 years, our K band data suggest a potential colour change associated with the dust emission that needs further confirmation.

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