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: Chapter in Book/Report/Conference proceedingConference contribution

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
Title of host publicationRevista Mexicana de Astronomia y Astrofisica: Serie de Conferencias
Pages235-236
Number of pages2
Volume40
Publication statusPublished - 2011
Externally publishedYes
Event13th Latin American Regional Meeting of the International Astronomical Union, LARIM 2010 - Morelia, Michoacan, Mexico
Duration: 8 Nov 201012 Nov 2010

Other

Other13th Latin American Regional Meeting of the International Astronomical Union, LARIM 2010
CountryMexico
CityMorelia, Michoacan
Period8/11/1012/11/10

Fingerprint

astrometry
variable stars
globular clusters
image analysis
time series
decomposition
calibration
stars
photometry
charge coupled devices
ephemerides
news
light curve
metallicity
parameter

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

Cite this

Figuera Jaimes, R., Bramich, D. M., Arellano Ferro, A., & Giridhar, S. (2011). The globular cluster NGC 6981: Variable stars population, physical parameters and astrometry. In Revista Mexicana de Astronomia y Astrofisica: Serie de Conferencias (Vol. 40, pp. 235-236)

The globular cluster NGC 6981 : Variable stars population, physical parameters and astrometry. / Figuera Jaimes, R.; Bramich, D. M.; Arellano Ferro, A.; Giridhar, S.

Revista Mexicana de Astronomia y Astrofisica: Serie de Conferencias. Vol. 40 2011. p. 235-236.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Figuera Jaimes, R, Bramich, DM, Arellano Ferro, A & Giridhar, S 2011, The globular cluster NGC 6981: Variable stars population, physical parameters and astrometry. in Revista Mexicana de Astronomia y Astrofisica: Serie de Conferencias. vol. 40, pp. 235-236, 13th Latin American Regional Meeting of the International Astronomical Union, LARIM 2010, Morelia, Michoacan, Mexico, 8/11/10.
Figuera Jaimes R, Bramich DM, Arellano Ferro A, Giridhar S. The globular cluster NGC 6981: Variable stars population, physical parameters and astrometry. In Revista Mexicana de Astronomia y Astrofisica: Serie de Conferencias. Vol. 40. 2011. p. 235-236
Figuera Jaimes, R. ; Bramich, D. M. ; Arellano Ferro, A. ; Giridhar, S. / The globular cluster NGC 6981 : Variable stars population, physical parameters and astrometry. Revista Mexicana de Astronomia y Astrofisica: Serie de Conferencias. Vol. 40 2011. pp. 235-236
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