Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evolution and period change in RR Lyr variables of the globular cluster
  M 3   The grid of evolutionary tracks of population II stars with initial masses
from $0.81M_\odot$ to $0.85M_\odot$ and chemical composition of the globular
cluster M 3 is computed. Selected models of horizontal branch stars were used
as initial conditions for solution of the equations of radiation hydrodynamics
and time--dependent convection describing radial stellar oscillations. The
boundaries of the instability strip on the Herztsprung--Russel diagram were
determined using nearly 100 hydrodynamic models of RR Lyr pulsating variables.
For each evolutionary track crossing the instability strip the pulsation period
was determined as a function of evolutionary time. The rate of period change of
most variables is shown to range within $-0.02\le\dot\Pi\le
0.05~\mathrm{day}/10^6\mathrm{yr}$. Theoretical estimate of the mean period
change rate obtained by the population synthesis method is
$\langle\dot\Pi\rangle=6.0\times 10^{-3}~\mathrm{day}/10^6\mathrm{yr}$ and
agrees well with observations of RR Lyr variables of the globular cluster M 3.

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The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
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The categories of this paper are: eess
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The categories of this paper are: nucl-ex
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The categories of this paper are: supr-con
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The categories of this paper are: funct-an
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The categories of this paper are: hep-th
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The categories of this paper are: quant-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: math-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: chem-ph