The globular cluster NGC 6981: Variable stars population, physical parameters and astrometry

R. Figuera Jaimes, D. M. Bramich, A. Arellano Ferro, S. Giridhar

Research output: Contribution to journalConference article

Abstract

We present the results of time-series CCD photometry of the globular cluster NGC 6981 for which no previous CCD photometry exist. Accurate photometry was achieved by the technique of difference image analysis. This allows to correctly classify the known variable stars, corroborate their variability and to discover new variables. In this paper we report 11 new RR Lyrae stars, 3 SX Phe. We show that 20 stars previously classified as variables are in fact non-variable and confirm the variability of 29 stars. News ephemerides are provided for all the variables in the cluster. By using the Fourier decomposition of light curves and semi-empirical calibrations available in the literature for RR Lyrae stars, we determined the physical parameters of these stars and hence the mean metallicity and distance of the cluster as [Fe/H]= -1.48 ± 0.03 in the Zinn & West (1984) scale; and ≈ 16.73 ± 0.36 kpc.

Original languageEnglish
Pages (from-to)235-236
Number of pages2
JournalRevista Mexicana de Astronomia y Astrofisica: Serie de Conferencias
Volume40
Publication statusPublished - 1 Dec 2011
Event13th Latin American Regional Meeting of the International Astronomical Union, LARIM 2010 - Morelia, Michoacan, Mexico
Duration: 8 Nov 201012 Nov 2010

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Keywords

  • Blue stragglers
  • Globular clusters: Individual (NGC 6981)
  • Stars: Evolution
  • Stars: Variables: RR Lyrae

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

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