Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Solar and Solar-type Stars Atmosphere's Activity at 11-year and
  Quasi-biennial Time Scales   We studied new simultaneous observations of the flux variations of the
photospheric and chromospheric emissions of 33 solar-type stars and Sun during
the HK-project that were conducted over the past 20 years. In addition to the
known cyclic chromospheric emission variations of stars at the 11-year time
scale, which were discovered at the Mount Wilson Observatory, we found a
recurrences that are similar to the quasi-biennial variations of solar
radiation. The results of calculations of the radiation fluxes variations
periods of stars at the quasi-biennial scale are given.

37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
0
The categories of this paper are: hep-ph
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
13
The categories of this paper are: quant-ph