CCD photometry of RR Lyrae stars in the globular cluster M68

Abstract

view Abstract Citations (18) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS CCD Photometry of RR Lyrae Stars in the Globular Cluster M68 Brocato, E. ; Castellani, V. ; Ripepi, V. Abstract We present a charge coupled device (CCD) investigation of the light curves of a sample of RR Lyrae in the metal-poor galactic globular cluster NGC 4590 (= M68). Observations were carried out at European Southern Observatory (ESO) in both B and V bands, using the 1.5 m Danish Telescope. Light curves for 21 variables have been derived, giving pulsational amplitude together with mean magnitudes and colors for a subsample of 17 variables. Comparison of the period-amplitude relation with the similar relation for variables in M15 shows a close similarity between the two clusters. The color-period relation supports previous suggestions for a M15 reddening larger than that of M68 by about delta-E(B - V) = 0.04. Effective temperatures for M68 pulsators have been derived under selected assumptions about the cluster reddening. Adopting currrent evaluation for this reddening (E(B - V) approximately = 0.03) one finds that the RR Lyrae in this metal-poor globular do not show any period shift to M3, as required by the current evolutionary scenario. The mass-luminosity ratio of the cluster variables is finally discussed, also in connection with recent estimates of such a paramenter in M15. Publication: The Astronomical Journal Pub Date: February 1994 DOI: 10.1086/116881 Bibcode: 1994AJ....107..622B Keywords: Globular Clusters; Interstellar Extinction; Light Curve; Stellar Color; Stellar Luminosity; Stellar Magnitude; Stellar Mass; Stellar Spectrophotometry; Variable Stars; Charge Coupled Devices; Stellar Temperature; Astronomy; GLOBULAR CLUSTERS: INDIVIDUAL: M68; STARS: RR LYRAE full text sources ADS | data products SIMBAD (28) CDS (1)