2018/02/21 by Archana Soam, G. Maheswar, Chang Won Lee +4
Physics and Astronomy · #Astro and Planetary Science #Astrophysics #Astrophysics and Star Formation Studies #Ion #Ionization #Magnetic field #Molecular cloud #Optics #Physics #Polarization (electrochemistry) #Radiation #Sky #Star formation #Stars #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.1093/mnras/sty517
13 pages, 8 figures, accepted for publication in MNRAS
arxiv created 2018/02/21 · openalex publication_date 2018/02/27 · openalex created_date 2018/03/06 · arxiv updated 2018/04/25 · openalex updated_date 2026/08/05
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.