The evolution of horizontal-branch stars: Theoretical sequences

Young Wook Lee, Pierre Demarque

Research output: Contribution to journalArticlepeer-review

75 Citations (Scopus)


A new grid of standard (i.e., solar CNO/Fe, no core rotation, and including semiconvection) horizontal-branch evolutionary sequences are presented which extend the grid of Sweigart both by including the final phase of core helium exhaustion and by using a finer grid of compositions. These sequences were constructed specifically for the studies of the Sandage period-shift effect and the second parameter phenomenon among the Galactic globular clusters. The numerical results for the observable characteristics of the sequences are tabulated which can be directly used to synthesize the observed horizontal-branch distributions. The present computations suggest that the observed difference in period change of RR Lyrae stars in the globular clusters M3 and M15 could be attributed, at least in the mean, to stellar evolution.

Original languageEnglish
Pages (from-to)709-746
Number of pages38
JournalAstrophysical Journal, Supplement Series
Issue number4
Publication statusPublished - 1990 Aug

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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