2022A&A...666A..49S


Query : 2022A&A...666A..49S

2022A&A...666A..49S - Astronomy and Astrophysics, volume 666A, 49 (2022/10-1)

Nano-grain depletion in photon-dominated regions.

SCHIRMER T., YSARD N., HABART E., JONES A.P., ABERGEL A. and VERSTRAETE L.

Abstract (from CDS):


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 µm) and Spitzer/MIPS (24 µm) together with Herschel/PACS (70 µm) 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.

Abstract Copyright: © T. Schirmer et al. 2022

Journal keyword(s): photon-dominated region (PDR) - dust - extinction - evolution

Simbad objects: 8

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Number of rows : 8
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 IC 63 HII 00 59 01.37 +60 53 17.8   13.33       ~ 100 1
2 * tet01 Ori C SB* 05 35 16.4662967280 -05 23 22.921811880 4.20 5.15 5.13 4.91 4.73 O7Vp 1406 1
3 NAME Ori Trapezium OpC 05 35 16.5 -05 23 14           ~ 1621 1
4 M 42 HII 05 35 17 -05 23.4           ~ 4083 0
5 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 878 0
6 NAME Horsehead Nebula DNe 05 40 59.0 -02 27 30           ~ 512 0
7 NAME Orion Molecular Cloud MoC 05 56 -01.8           ~ 1101 1
8 * zet Oph Be* 16 37 09.5400587698 -10 34 01.509742704 1.73 2.58 2.56 2.46 2.50 O9.2IVnn 1840 0

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