Two papers on which I’m the third author recently got accepted for publication in Astronomy & Astrophysics, the major European journal for all astronomical and astrochemical research. Both of them make use of the infrared emission model for polycyclic aromatic hydrocarbons (PAHs) that I developed over the past three years. My own (first-authored) paper, describing this model in more detail, was published in A&A earlier this year.
The first of the two new papers, “Dust sedimentation in protoplanetary disks with PAHs”, looks into the effects of dust settling on PAH emission from protoplanetary disks. Dust tends to fall towards the midplane of a protoplanetary disk due to gravity, and larger dust grains do so more quickly than smaller ones. Since PAHs can be considered very small grains, they should stay up at higher altitudes for longer times than the rest of the dust. This is expected to enhance the PAH emission features with respect to the continuum emission. However, this enhancement is not found in observations. The paper discusses turbulence and coagulations as possible answers to this discrepancy. The research was led by Kees Dullemond, who did his PhD in Leiden and is now at the Max-Planck-Institut fü Astronomie in Heidelberg, Germany.
The other paper was written primarily by Vincent Geers, a fellow PhD student here in Leiden. He will graduate next Tuesday and this paper is the basis for one of the chapters of his thesis. Titled “Spatially extended PAHs in circumstellar disks around T Tauri and Herbig Ae stars”, it describes highly detailed observations of PAH emission from protoplanetary disks around solar-type stars. Vincent found that the PAH emission is extended on a scale similar to the size of these disks. This shows that PAHs are present throughout the disk and emit everywhere, as predicted by theoretical models.
The abstracts and full texts are available from my list of publications.