Constraints on interstellar dust models from extinction and spectro-polarimetry
arXiv:1705.07828 · doi:10.1016/j.pss.2017.05.007
Abstract
We present polarisation spectra of seven stars in the lines-of-sight towards the Sco OB1 association. Our spectra were obtained within the framework of the Large Interstellar Polarization Survey carried out with the FORS instrument of the ESO VLT. We have modelled the wavelength-dependence of extinction and linear polarisation with a dust model for the diffuse interstellar medium which consists of a mixture of particles with size ranging from the molecular domain of 0.5 nm up to 350 nm. We have included stochastically heated small dust grains with radii between 0.5 and 6 nm made of graphite and silicate, as well as polycyclic aromatic hydrocarbon molecules (PAHs), and we have assumed that larger particles are prolate spheroids made of amorphous carbon and silicate. Overall, a dust model with eight free parameters best reproduces the observations. Reducing the number of free parameters leads to results that are inconsistent with cosmic abundance constraints. We found that aligned silicates are the dominant contributor to the observed polarisation, and that the polarisation spectra are best-fit by a lower limit of the equivolume sphere radius of aligned grains of 70 - 200nm.
Planetary and Space Science, Planetary and Space Science, DOI:10.1016/j.pss.2017.05.007
References in corpus (7)
- Infrared Emission from Interstellar Dust. IV. The Silicate-Graphite-PAH Model in the Post-Spitzer Era
- A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
- An Analysis of the Shapes of Interstellar Extinction Curves. V. The IR-Through-UV Curve Morphology
- The evolution of amorphous hydrocarbons in the ISM: dust modelling from a new vantage point
- Destruction of Interstellar Dust in Evolving Supernova Remnant Shock Waves
- A hidden reservoir of Fe/FeS in interstellar silicates?
- Effects of grain growth on the interstellar polarization curve