Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Studies of the Be star X Persei during a bright infrared phase   We present multi-epoch photometric and spectroscopic near-infrared
observations of the Be star X Persei in the JHK bands covering the wavelength
range 1.08 to 2.35 micron. Combining results from our earlier studies with the
present observations, it is shown that the equivalent widths and line fluxes of
the prominent HI and HeI lines anti-correlate with the strength of the adjacent
continuum. That is, during the span of the observations, the JHK broad band
fluxes increase while the emission equivalent width values of the HI and HeI
lines decrease (the lines under consideration being the Paschen and Brackett
lines of hydrogen and the 1.7002 micron and 2.058 micron lines of helium). Such
an anti-correlation effect is not commonly observed in Be stars in the optical;
in the infrared this may possibly be the first reported case of such behavior.
We examine different mechanisms that could possibly cause it and suggest that
it could originate due to a radiatively warped, precessing circumstellar disk.
It is also shown that during the course of our studies X Per evolved to an
unprecedented state of high near-IR brightness with J, H, K magnitudes of 5.20,
5.05 and 4.84 respectively.

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The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg