Magnetic fields in multiple bright-rimmed clouds in different directions of H ii region IC 1396. Issue 4 (6th April 2018)

• Record Type: Journal Article
• Authors: Soam, Archana; Maheswar, G; Lee, Chang Won; Neha, S; Kim, Kee-Tae
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 476:Issue 4(2018)
• Page Start: 4782
• Page End: 4793
• Publication Date: 2018-04-06
• Subjects: polarization -- ISM: clouds -- dust, extinction -- H ii regions -- ISM: magnetic fields; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/sty517
• Languages: English
• ISSNs: 0035-8711

Abstract

Abstract: Bright-rimmed clouds (BRCs) form on the edges of H ii regions affected by high-energy radiation from a central ionizing source. The UV radiation from the ionizing source results in compression and ionization, causing either cloud disruption or further star formation. In this work, we present R -band polarization measurements towards four BRCs, namely IC 1396A, BRC 37, BRC 38 and BRC 39, located in different directions in the H ii region, Sh2-131, in order to map the magnetic field (B-field) in the plane of the sky. These BRCs are illuminated by the O star HD 206267 and present a range of projected on-sky geometries. This provides an opportunity to gain an understanding of the magnetized evolution of BRCs. The B-field geometries of the clouds deduced from the polarization data, after correction for foreground contamination by the interstellar medium, are seen to be connected to the ambient B-fields on large scales. They seem to play an important role in shaping the clouds IC 1396A and BRC 37. BRCs 38 and 39 show a broader and snubber head morphology, possibly because the B-fields are aligned with incoming radiation, as revealed in the simulations. A good general agreement is noted on comparing our observational results with the simulations, supporting the importance of B-fields in BRC evolution. This work is the first step towards systematic mapping the B-fields morphology in multiple BRCs in an expanding H ii region, extending our previous work.