On the distribution of the modulation frequencies of RR lyrae stars

J. Jurcsik, B. Szeidl, A. Nagy, Á Sódor

Research output: Contribution to journalArticle

24 Citations (Scopus)


For the first time connection between the pulsation and modulation properties of RR Lyr stars has been detected. Based on the available data it is found that the possible range of the modulation frequencies, i.e., the possible maximum value of the modulation frequency depends on the pulsation frequency. Short period variables (P < 0.4 d) can have modulation period as short as some days, while longer period variables (P > 0.6 d) always exhibit modulation with Pmod > 20 d. We interpret this tendency with the equality of the modulation period with the surface rotation period, because similar distribution of the rotational periods is expected if an upper limit of the total angular momentum of stars leaving the RGB exists. The distribution of the projected rotational velocities of red and blue horizontal branch stars at different temperatures shows a similar behavior as νrot derived for RR Lyr stars from their modulation periods. This common behavior gives reason to identify the modulation period with the rotational period of the modulated RR Lyr stars.

Original languageEnglish
Pages (from-to)303-314
Number of pages12
JournalActa Astronomica
Issue number3
Publication statusPublished - Nov 18 2005


  • Stars: horizontal-branch
  • Stars: oscillations
  • Stars: variables: RR Lyr

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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