Magnetic Fields in Massive Star-forming Regions (MagMaR). I. Linear Polarized Imaging of the Ultracompact H II Region G5.89-0.39
Abstract
We report 1.2 mm polarized continuum emission observations carried out with the Atacama Large Millimeter/submillimeter Array toward the high-mass star formation region G5.89-0.39. The observations show a prominent 0.2 pc north-south filamentary structure. The ultracompact H II region in G5.89-0.39 breaks the filament into two pieces. Its millimeter emission shows a dusty belt with a mass of 55-115 M⊙ and 4500 au in radius, surrounding an inner part comprising mostly ionized gas, with dust emission only accounting for about 30% of the total millimeter emission. We also found a lattice of convex arches that may be produced by dragged dust and gas from the explosive dispersal event involving the O5 Feldt's star. The north-south filament has a mass between 300 and 600 M⊙ and harbors a cluster of about 20 mm envelopes with a median size and mass of 1700 au and 1.5 M⊙, respectively, some of which are already forming protostars. We interpret the polarized emission in the filament as mainly coming from magnetically aligned dust grains. The polarization fraction is ∼4.4% in the filaments and 2.1% at the shell. The magnetic fields are along the North Filament and perpendicular to the South Filament. In the Central Shell, the magnetic fields are roughly radial in a ring surrounding the dusty belt between 4500 and 7500 au, similar to the pattern recently found in the surroundings of Orion BN/KL. This may be an independent observational signpost of explosive dispersal outflows and should be further investigated in other regions.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 2021
- DOI:
- 10.3847/1538-4357/abf2b6
- arXiv:
- arXiv:2104.03331
- Bibcode:
- 2021ApJ...913...29F
- Keywords:
-
- Protostars;
- Polarimetry;
- Dust continuum emission;
- Star formation;
- Interstellar magnetic fields;
- 1302;
- 1278;
- 412;
- 1569;
- 845;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Accepted in ApJ. 26 pages, 17 figures