PAHs in protoplanetary disks: emission and X-ray destruction
arXiv:1204.3651 · doi:10.1051/0004-6361/201219039
Abstract
We study the PAH emission from protoplanetary disks. First, we discuss the dependence of the PAH band ratios on the hardness of the absorbed photons and the temperature of the stars. We show that the photon energy together with a varying degree of the PAH hydrogenation accounts for most of the observed PAH band ratios without the need to change the ionization degree of the molecules. We present an accurate treatment of stochastic heated grains in a vectorized three dimensional Monte Carlo dust radiative transfer code. The program is verified against results using ray tracing techniques. Disk models are presented for T Tauri and Herbig Ae stars. Particular attention is given to the photo-dissociation of the molecules. We consider beside PAH destruction also the survival of the molecules by vertical mixing within the disk. By applying typical X-ray luminosities the model accounts for the low PAH detection probability observed in T Tauri and the high PAH detection statistics found in Herbig Ae disks. Spherical halos above the disks are considered. We show that halos reduce the observed PAH band-to-continuum ratios when observed at high inclination. Finally, mid-IR images of disks around Herbig Ae disks are presented. We show that they are easier to resolve when PAH emission dominate.
Accepted for publication in A&A. 10 pages, 7 figures, 2 table
References in corpus (13)
- Infrared Emission from Interstellar Dust. IV. The Silicate-Graphite-PAH Model in the Post-Spitzer Era
- Particle Stirring in Turbulent Gas Disks: Including Orbital Oscillations
- Efficient 3D NLTE dust radiative transfer with SKIRT
- Variations of the Mid-IR Aromatic Features Inside and Among Galaxies
- Radiative transfer in very optically thick circumstellar disks
- HYPERION: An open-source parallelized three-dimensional dust continuum radiative transfer code
- Dust Extinction and Emission in a Clumpy Galactic Disk. An Application of the Radiative Transfer Code TRADING
- Spatially extended PAHs in circumstellar disks around T Tauri and Herbig Ae stars
- On the origin of the X-ray emission from Herbig Ae/Be stars
- Emission from Very Small Grains and PAH Molecules in Monte Carlo Radiation Transfer Codes: Application to the Edge-On Disk of Gomez's Hamburger
- GPU-based Monte Carlo dust radiative transfer scheme applied to AGN
- Stirring up the dust: A dynamical model for halo-like dust clouds in transitional disks
- Shadows, gaps, and ring-like structures in protoplanetary disks
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- Carbon Depletion in the Early Solar System
- Stability of Polycyclic Aromatic Hydrocarbon Clusters in Protoplanetary Disks
- Spinning dust emission from circumstellar disks and its role in excess microwave emission
- Turbulent processing of PAHs in protoplanetary discs -- Coagulation and freeze-out leading to depletion of gas-phase PAH
- Protoplanetary Disk Chemistry