Interstellar Dust Chemistry and Catalysis

Astronomy Unit Seminars
Anthony Jones
Melanie Koehler
November 18th, 2016 at 14:30
GO Jones Room 610
In this talk I will focus on three aspects of interstellar dust that have a direct bearing on its chemistry and its effects on interstellar chemistry.  These are: 
  1. the nano-particle-driven catalytic formation of the key interstellar species H2 and OH, 
  2. the relationship between dust and the diffuse interstellar bands (DIBs) and 
  3. the nature and evolution of core/mantle grains in the interstellar medium. 
I will introduce these three topics and discuss what I would consider to be the fundamental links between them within the framework the recent interstellar dust model THEMIS (The Heterogeneous dust Evolution Model for Interstellar Solids; Jones et al. 2013, Köhler et al. 2014, 2015). In essence, it is my view that we can no longer think of dust as only providing a passive surface for the hit-stick-react-unstick formation of radicals and simple molecules such as molecular hydrogen. Instead we should consider the dust itself as a chemically-active source. As proposed within the THEMIS framework, dust is likely undergoing continuous evolution as it responds to its local environment, with the nature of the outer mantle layers playing a key role in that evolution (e.g., Jones et al. 2016, Ysard et al. 2016). This talk takes these ideas further and explores the consequences of an active evolution of dust within the ISM and its effects on the chemistry of the ISM. 
All of the ideas presented within this talk are currently in the process of publication in Royal Society Open Science (Jones 2016a,b,c).
Jones, A.P.,  Fanciullo, L., Köhler, M., Verstraete, L., Guillet, V., Bocchio, M., Ysard, N. The evolution of amorphous hydrocarbons in the ISM: dust modelling from a new vantage point. 2013, A&A, 558, A62.
Jones, A.P., Dust evolution, a global view: I. Nano-particles, nascence, nitrogen and natural selection . . . joining the dots. 2016a, Royal Society Open Science (RSOS), under review. 
Jones, A.P., Dust evolution, a global view: II. Top-down branching, nano-particle fragmentation and the mystery of the diffuse interstellar band carriers. 2016b, Royal Society Open Science (RSOS), accepted for publication. 
Jones, A.P., Dust evolution, a global view: III. Core/mantle grains, organic nano-globules, comets and surface chemistry. 2016c, Royal Society Open Science (RSOS), under review.
Jones, A.P., Köhler, M., Ysard, N., Dartois, E., Godard, M. and Gavilan, L. Mantle formation, coagulation and the origin of cloud/core shine: I. Dust scattering and absorption in the infra-red. 2016, A\&A, 588, A43.
Köhler, M., Jones, A., Ysard, N. A hidden reservoir of Fe/FeS in interstellar silicates? 2014, A&A, 565, L9.
Köhler, M., Ysard, N. and Jones, A.P. et al. Dust evolution in the transition towards the denser ISM: impact on dust temperature, opacity, and spectral index. 2015, A&A, 579, A15.
Ysard, N., Köhler, M., Jones, A.P., Dartois, E., Godard, M. and Gavilan, L. Mantle formation, coagulation and the origin of cloud/core shine: II. Comparison with observations. 2016, A\&A, 588, A44.