VR CCD photometry of variable stars in globular cluster NGC 4147

Abstract

We present results of a search for variable stars in a region of the globular cluster NGC 4147 based on photometric observations with 4k x 4k CCD imager mounted at the axial port of the recently installed 3.6 m Devasthal optical telescope at Aryabhatta Research Institute of Observational Sciences, Nainital, India. We performed time series photometry of NGC 4147 in V and R bands, and identified 42 periodic variables in the region of NGC 4147, 28 of which have been detected for the first time. Seventeen variable stars are located within the half light radius $\lesssim$ 0.48 arcmin, of which 10 stars are newly identified variables. Two of 10 variables are located within the core radius $\lesssim$ 0.09 arcmin. Based on the location in the $V/(V-R)$ colour magnitude diagram and variability characteristics, 7, 8, 5 and 1 newly identified probable member variables are classified as RRc, EA/E, EW and SX Phe, respectively. The metallicity of NGC 4147 estimated from light curves of RRab and RRc stars with the help of Fourier decomposition is found to be characteristics of Oosterhoff II. The distance derived using light curves of RRab stars is consistent with that obtained from the observed $V/(V-R)$ colour-magnitude diagram.

20 pages, 13 Figures, accepted for publication in Astronomical Journal

References in corpus (3)

• The Period-Luminosity Relation of RR Lyrae Stars in the SDSS Photometric System
• Image-Subtraction Photometry of Variable Stars in the Globular Clusters NGC 6388 and NGC 6441
• New SX Phe variables in the globular cluster NGC 288

Cited by in corpus (4)

• Accurate distances to Galactic globular clusters through a combination of Gaia EDR3, HST and literature data
• Zwicky Transient Facility and Globular Clusters: the Period-Luminosity and Period-Luminosity-Color Relations for Late-Type Contact Binaries
• Zwicky Transient Facility and Globular Clusters: The Period-Luminosity and Period-Wesenheit Relations for SX Phoenicis Variables in the gri-Band
• Optical Observations of star clusters NGC 1513 and NGC 4147; white dwarf WD1145+017 and $K$ band imaging of star forming region Sh2-61 with the 3.6 meter Devasthal Optical Telescope