SIMBAD references

2016ApJ...825....2T - Astrophys. J., 825, 2-2 (2016/July-1)

Orion's Veil: magnetic field strengths and other properties of a PDR in front of the Trapezium cluster.

TROLAND T.H., GOSS W.M., BROGAN C.L., CRUTCHER R.M. and ROBERTS D.A.

Abstract (from CDS):

We present an analysis of physical conditions in the Orion Veil, an atomic photon-dominated region (PDR) that lies just in front (≃2 pc) of the Trapezium stars of Orion. This region offers an unusual opportunity to study the properties of PDRs, including the magnetic field. We have obtained 21 cm H i and 18 cm (1665 and 1667 MHz) OH Zeeman effect data that yield images of the line-of-sight magnetic field strength Blos in atomic and molecular regions of the Veil. We find Blos ≃ -50 to -75 µG in the atomic gas across much of the Veil (25'' resolution) and Blos ≃ -350 µG at one position in the molecular gas (40'' resolution). The Veil has two principal H i velocity components. Magnetic and kinematical data suggest a close connection between these components. They may represent gas on either side of a shock wave preceding a weak-D ionization front. Magnetic fields in the Veil H i components are 3-5 times stronger than they are elsewhere in the interstellar medium where N(H) and n(H) are comparable. The H i components are magnetically subcritical (magnetically dominated), like the cold neutral medium, although they are about 1 dex denser. Comparatively strong fields in the Veil H i components may have resulted from low-turbulence conditions in the diffuse gas that gave rise to OMC-1. Strong fields may also be related to magnetostatic equilibrium that has developed in the Veil since star formation. We also consider the location of the Orion-S molecular core, proposing a location behind the main Orion H+ region.

Abstract Copyright: © 2016. The American Astronomical Society. All rights reserved.

Journal keyword(s): H ii regions - ISM: individual objects Orion Nebula - ISM: magnetic fields - photon-dominated region , PDR

CDS comments: Table 6: Source B17S (=[BT2001] B-17S) is not in SIMBAD.

Simbad objects: 24

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2020.09.30-21:17:10

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