Mid-infrared Polarization of the Diffuse Interstellar Medium toward CygOB2-12

We present the first mid-IR detection of the linear polarization toward the star CygOB2-12, a luminous blue hypergiant that, with A V ≈ 10 mag of foreground extinction, is a benchmark in the study of the properties of dust in the diffuse interstellar medium. The 8–13 μ m spectropolarimetry, obtained...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2022-11, Vol.940 (1), p.L26
Main Authors: Telesco, Charles M., Varosi, Frank, Wright, Christopher, Draine, Bruce T., Fernández Acosta, Sergio José, Packham, Christopher
Format: Article
Language:English
Subjects:
Diffuse interstellar clouds
Dust
Dust composition
Interstellar magnetic fields
Interstellar matter
Interstellar medium
Linear polarization
Magnetic fields
Polarization
Position measurement
Silicate grains
Spectropolarimetry
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Summary:We present the first mid-IR detection of the linear polarization toward the star CygOB2-12, a luminous blue hypergiant that, with A V ≈ 10 mag of foreground extinction, is a benchmark in the study of the properties of dust in the diffuse interstellar medium. The 8–13 μ m spectropolarimetry, obtained with the CanariCam multimode camera at the Gran Telescopio CANARIAS shows clear trends with wavelength characteristic of silicate grains aligned in the interstellar magnetic field. The maximum polarization, detected with 7.8 σ statistical significance near 10.2 μ m, is (1.24 ± 0.28)% with position angle 126° ± 8°. We comment on these measurements in the context of recent models for the dust composition in the diffuse interstellar medium.
ISSN:2041-8205
2041-8213
DOI:10.3847/2041-8213/ac9b56