Variations on a theme – the evolution of hydrocarbon solids ( Corrigendum )

Koehler

Ysard

et al. 2017

A&A

Self Cite

273

345

Here we introduce the interstellar dust modelling framework THEMIS (The Heterogeneous dust Evolution Model for Interstellar Solids), which takes a global view of dust and its evolution in response to the local conditions in interstellar media. This approach is built upon a core model that was developed to explain the dust extinction and emission in the diffuse interstellar medium. The model was then further developed to self-consistently include the effects of dust evolution in the transition to denser regions. The THEMIS approach is under continuous development and we are currently extending the framework to explore the implications of dust evolution in HII regions and the photon-dominated regions associated with star formation. We provide links to the THEMIS, DustEM and DustPedia websites where more information about the model, its input data and applications can be found.

Section: Dust Evolution In Pdrs and Hii Regionsmentioning

confidence: 99%

The global dust modelling framework THEMIS

Koehler

Ysard

et al. 2017

A&A

Self Cite

273

345

“…1 we show the Jones et al (2013) dust model spectrum in the 3.1−3.7 μm region as a function of the a-C(:H) mantle composition. As per Jones (2012b) we use the Tauc definition of the band gap, E g , to characterise the a-C(:H) materials considered here.…”

Section: The Spectroscopy Of A-c(:h) Materials In the 3 μM Regionmentioning

confidence: 99%

Mantle formation, coagulation, and the origin of cloud/core shine

Koehler

Ysard

et al. 2016

A&A

Self Cite

Context. The observed cloudshine and coreshine (C-shine) have been explained in terms of grain growth leading to enhanced scattering from clouds in the J, H, and K photometric bands and the Spitzer IRAC 3.6 and 4.5 μm bands. Aims. Using our global dust-modelling approach THEMIS (The Heterogeneous dust Evolution Model at the IaS), we explore the effects of dust evolution in dense clouds, through aliphatic-rich carbonaceous mantle formation and grain-grain coagulation. Methods. We model the effects of wide band gap a-C:H mantle formation and the low-level aggregation of diffuse interstellar medium dust in the moderately-extinguished outer regions of molecular clouds. Results. The formation of wide band gap a-C:H mantles on amorphous silicate and amorphous carbon (a-C) grains leads to a decrease in their absorption cross-sections but no change in their scattering cross-sections at near-infrared wavelengths, resulting in higher albedos. Conclusions. The evolution of dust, with increasing density and extinction in the diffuse-to-dense molecular cloud transition, through mantle formation and grain aggregation, appears to be a likely explanation for the observed C-shine.

“…However, energetic ion collisions and photon irradiation are able to re-aromatise the outer layer of the carbonaceous grains. Firstly, the available timescale is sufficiently long (∼10 5 yr) that the radiation field (G 0 > 1) would aromatise carbonaceous grain surfaces to a maximum depth of ∼20 nm (Jones 2012d;Jones et al 2014). Furthermore, sufficiently energetic ions can penetrate carbonaceous grains up to ∼5 nm 5 contributing to the aromatisation of the outer layer.…”

Section: Dust Emission and Extinctionmentioning

confidence: 99%

A re-evaluation of dust processing in supernova shock waves

Bocchio

Slavin

2014

A&A

110

154

Context. There is a long-standing and large discrepancy between the timescale for dust formation around evolved stars and the rapid dust destruction timescale in interstellar shocks. Aims. We use our latest estimates for dust processing to re-evaluate the dust destruction efficiency in supernova triggered shock waves, estimate the dust lifetime, and calculate the emission and extinction from shocked dust. Methods. We modelled the sputtering and fragmentation of grains in interstellar shocks for shock velocities between 50 km s −1 and 200 km s −1 . We constrained the dust destruction using our recent dust model. Finally, we coupled our code to the DustEM code in order to estimate the emission and extinction from the dust post-shock. Results. Carbonaceous grains are quickly destroyed, even in a 50 km s −1 shock, leading to a shorter lifetime than in previous studies. Silicate grains appear to be more resilient, but the new destruction lifetime that we find is similar to previous studies and short compared to the dust injection timescale. Conclusions. The calculated fraction of elements locked in grains is not compatible with the observed values and therefore implies the re-formation of dust in the dense regions of the interstellar medium. Better modelling of the silicate sputtering together with hydrodynamical simulations of interstellar shocks, appears to reduce the silicate destruction and may close the destruction-formation timescale gap.