Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pulsation Period Changes as a Tool to Identify Pre-Zero Age Horizontal
  Branch Stars   One of the most dramatic events in the life of a low-mass star is the He
flash, which takes place at the tip of the red giant branch (RGB) and is
followed by a series of secondary flashes before the star settles into the
zero-age horizontal branch (ZAHB). Yet, no stars have been positively
identified in this key evolutionary phase, mainly for two reasons: first, this
pre-ZAHB phase is very short compared to other major evolutionary phases in the
life of a star; and second, these pre-ZAHB stars are expected to overlap the
loci occupied by asymptotic giant branch (AGB), HB and RGB stars observed in
the color-magnitude diagram (CMD). We investigate the possibility of detecting
these stars through stellar pulsations, since some of them are expected to
rapidly cross the Cepheid/RR Lyrae instability strip in their route from the
RGB tip to the ZAHB, thus becoming pulsating stars along the way. As a
consequence of their very high evolutionary speed, some of these stars may
present anomalously large period change rates. We constructed an extensive grid
of stellar models and produced pre-ZAHB Monte Carlo simulations appropriate for
the case of the Galactic globular cluster M3 (NGC 5272), where a number of RR
Lyrae stars with high period change rates are found. Our results suggest that
some -- but certainly not all -- of the RR Lyrae stars in M3 with large period
change rates are in fact pre-ZAHB pulsators.

36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
24
The categories of this paper are: dg-ga
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex