Nano-grain depletion in photon-dominated regions
arXiv:2209.04282 · doi:10.1051/0004-6361/202243635
Abstract
Context. Carbonaceous nano-grains play a fundamental role in the physico-chemistry of the interstellar medium (ISM) and especially of photon-dominated regions (PDRs). Their properties vary with the local physical conditions and affect the local chemistry and dynamics. Aims. We aim to highlight the evolution of carbonaceous nano-grains in three different PDRs and propose a scenario of dust evolution as a response to the physical conditions. Methods. We used Spitzer/IRAC (3.6, 4.5, 5.8, and 8 m) and Spitzer/MIPS (24 m) together with Herschel/PACS (70 m) to map dust emission in IC63 and the Orion Bar. To assess the dust properties, we modelled the dust emission in these regions using the radiative transfer code SOC together with the THEMIS dust model. Results. Regardless of the PDR, we find that nano-grains are depleted and that their minimum size is larger than in the diffuse ISM (DISM), which suggests that the mechanisms that lead nano-grains to be photo-destroyed are very efficient below a given critical size limit. The evolution of the nano-grain dust-to-gas mass ratio with both G0 and the effective temperature of the illuminating star indicates a competition between the nano-grain formation through the fragmentation of larger grains and nano-grain photo-destruction. We modelled dust collisions driven by radiative pressure with a classical 1D approach to show that this is a viable scenario for explaining nano-grain formation through fragmentation and, thus, the variations observed in nano-grain dust-to-gas mass ratios from one PDR to another. Conclusions. We find a broad variation in the nano-grain dust properties from one PDR to another, along with a general trend of nano-grain depletion in these regions. We propose a viable scenario of nano-grain formation through fragmentation of large grains due to radiative pressure-induced collisions.
References in corpus (19)
- The distance to the Orion Nebula
- The evolution of amorphous hydrocarbons in the ISM: dust modelling from a new vantage point
- Too little radiation pressure on dust in the winds of oxygen-rich AGB stars
- Formation and destruction of polycyclic aromatic hydrocarbon clusters in the interstellar medium
- Million-Degree Plasma Pervading the Extended Orion Nebula
- The effect of dust composition and shape on radiation-pressure forces and blowout sizes of particles in debris disks
- The Orion HII Region and the Orion Bar in the Mid-Infrared
- Spitzer Mapping of PAHs and H2 in Photodissociation Regions
- Bottlenecks to interstellar sulfur chemistry: Sulfur-bearing hydrides in UV-illuminated gas and grains
- SOC program for dust continuum radiative transfer
- Shiva: the dust destruction model
- An Infrared Census of Star Formation in the Horsehead Nebula
- Nano carbon dust emission in proto-planetary disks: the aliphatic-aromatic components
- Are the Carriers of Diffuse Interstellar Bands and Extended Red Emission the same?
- Direct estimation of electron density in the Orion Bar PDR from mm-wave carbon recombination lines
- Evidence of dust grain evolution from extinction mapping in the IC 63 photodissociation region
- Interstellar extinction, polarization, and grain alignment in the Sh 2-185 (IC 59 and IC 63) region
- Nano-grain depletion in photon-dominated regions
- On the collisional disalignment of dust grains in illuminated and shaded regions of IC 63