Mid-infrared polarization of Herbig Ae/Be discs. Issue 2 (28th October 2017)

• Record Type: Journal Article
• Authors: Li, Dan; Telesco, Charles M.; Zhang, Han; Wright, Christopher M.; Pantin, Eric; Barnes, Peter J.; Packham, Chris
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 473:Issue 2(2018)
• Page Start: 1427
• Page End: 1437
• Publication Date: 2017-10-28
• Subjects: magnetic fields -- polarization -- circumstellar matter -- infrared: ISM; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stx2228
• Languages: English
• ISSNs: 0035-8711

Abstract

Abstract: We measured mid-infrared polarization of protoplanetary discs to gain new insight into their magnetic fields. Using CanariCam at the 10.4-m Gran Telescopio Canarias, we detected linear polarization at 8.7, 10.3 and 12.5 μm from discs around eight Herbig Ae/Be stars and one T-Tauri star. We analysed polarimetric properties of each object to find out the most likely interpretation of the data. While the observed mid-infrared polarization from most objects is consistent with polarized emission and/or absorption arising from aligned dust particles, we cannot rule out polarization due to dust scattering for a few objects in our sample. For those objects for which polarization can be explained by polarized emission and/or absorption, we examined how the derived magnetic field structure correlates with the disc position angle and inclination. We found no preference for a certain type of magnetic field. Instead, various configurations (toroidal, poloidal or complex) are inferred from the observations. The detection rate (64 per cent) of polarized mid-infrared emission and/or absorption supports the expectation that magnetic fields and suitable conditions for grain alignment are common in protoplanetary discs around Herbig Ae/Be stars.