Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Investigating the origin of cyclical wind variability in hot, massive
  stars - I. On the dipolar magnetic field hypothesis   OB stars exhibit various types of spectral variability associated with wind
structures, including the apparently ubiquitous discrete absorption components
(DACs). These are proposed to be caused by either magnetic fields or non-radial
pulsations (NRPs). In this paper, we evaluate the possible relation between
large-scale, dipolar magnetic fields and the DAC phenomenon by investigating
the magnetic properties of a sample of 13 OB stars exhibiting well-documented
DAC behaviour.
  Using high-precision spectropolarimetric data acquired in part in the context
of the Magnetism in Massive Stars (MiMeS) project, we find no evidence for
surface dipolar magnetic fields in any of these stars. Using Bayesian
inference, we compute upper limits on the strengths of the fields and use these
limits to assess two potential mechanisms by which the field may influence wind
outflow: magnetic wind confinement and local photospheric brightness
enhancements. Within the limits we derive, both mechanisms fail to provide a
systematic process capable of producing DACs in all of the stars of our sample.
Therefore, this implies that dipolar fields are highly unlikely to be
responsible for these structures in all massive stars, meaning that some other
mechanism must come into play.

11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs