A framework for resolving the origin, nature and evolution of the diffuse interstellar band carriers?

Koehler

Ysard

et al. 2017

A&A

259

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: Future Developmentsmentioning

confidence: 99%

The global dust modelling framework THEMIS

Koehler

Ysard

et al. 2017

A&A

259

345

“…mantles can probably only form in the transition from the diffuse ISM to the dense molecular clouds where there is moderate extinction (A V ∼ 0.5−1.5, Jones et al 2014). A self-consistent approach to the formation and (photo-)evolution of interstellar a-C(:H) materials appears to be able to explain many dust observables (Jones 2012a(Jones ,b,c, 2013(Jones , 2014Jones et al 2013Jones et al , 2014Köhler et al 2014Köhler et al , 2015Fanciullo et al 2015;Ysard et al 2015;Paper II).…”

Section: A-c:h Formationmentioning

confidence: 99%

“…This model was then extended to allow us to follow the evolution of the dust properties in the transition between diffuse and dense interstellar media Köhler et al 2015; and also the companion paper, Ysard et al 2016, hereafter called Paper II). This modelling approach provides a general framework within which the solutions to several interesting interstellar conundrums such as volatile silicon Article published by EDP Sciences A43, page 1 of 10 A&A 588, A43 (2016) in photo-dissociation regions (PDRs), sulphur and nitrogen depletions, the origin of the blue and red photoluminescence and the diffuse interstellar bands (DIBs) may yet be found (Jones 2013(Jones , 2014. This approach has also led to suggestions for viable routes to interstellar/circumstellar fullerene formation and to the formation of molecular hydrogen in moderately excited photo-dissociation regions (Jones & Habart 2015).…”

Section: Introductionmentioning

confidence: 99%

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

Koehler

Ysard

et al. 2016

A&A

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.

“…with small variations in the physical and optical properties of carbonaceous grains, it is possible to describe the evolution of dust in a wide range of ISM environments (Jones 2013;Jones et al 2014;Köhler, in prep. ).…”

Section: The Jones Et Al (2013) Dust Modelmentioning

confidence: 99%

A re-evaluation of dust processing in supernova shock waves

Bocchio

Slavin

2014

A&A

Self Cite

109

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.