Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: VLBA Observations of G5.89-0.39: OH masers and magnetic field structure   We present VLBA observations of 1667 MHz OH maser emission from the massive
star formation region G5.89-0.39. The observations were phase referenced
allowing the absolute positions of the masers to be obtained. The 1667 MHz
masers have radial velocities that span ~50 km/s but show little evidence of
tracing the bipolar molecular outflow, as has been claimed in previous studies.
We identify 23 Zeeman pairs through comparison of masers in left and right
circular polarization. Magnetic field strengths range from -2 mG to +2 mG, and
an ordered reversal in magnetic field direction is observed toward the southern
region of the UC HII region. We suggest that the velocity and magnetic field
structure of the 1667 MHz masers can be explained in the context of a model in
which the masers arise in a neutral shell just outside a rapidly exanding
ionized shell.

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The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
3
The categories of this paper are: physics
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The categories of this paper are: acc-phys
4
The categories of this paper are: cond-mat
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The categories of this paper are: eess
29
The categories of this paper are: funct-an
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph