Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Towards an understanding of the Of?p star HD191612: Phase-resolved
  multiwavelength observations   We present the analysis of phase-resolved X-ray and optical observations of
the peculiar hot star HD191612 (Of?p). This star is known to display
line-profile variations that are recurrent with a period of 538d and its
spectrum was found to present the signature of a magnetic field. In the X-rays,
it is slightly overluminous compared to the canonical L_X/L_BOL relation and
appears brighter when the optical lines are strongest. Our XMM-Newton
observations further reveal that the X-ray spectrum of \hd exhibits rather
broad lines and is dominated by a `cool' (0.2-0.6 keV) thermal component, two
characteristics at odds with the proposed magnetic rotator model. We also
report for the first time the low-level variability of the metallic (abs/em)
lines and HeII absorptions that appear to be associated with radial-velocity
shifts. Finally, we compare our results with observations of the early-type
stars and discuss several possible scenarios.

21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc