Stellar populations of the globular cluster NGC 5053 investigated using AstroSat-Ultra Violet Imaging Telescope

Abstract

Globular clusters being old and densely packed serve as ideal laboratories to test stellar evolution theories. Although there is enormous literature on globular clusters in optical bands, studies in the ultraviolet (UV) regime are sparse. In this work, we study the stellar populations of a metal poor and a rather dispersed globular cluster, NGC 5053, using the UV instrument of AstroSat, namely the Ultra Violet Imaging Telescope in three far-UV (F154W, F169M, F172M) and three near-UV (N219M, N245M, N263M) filters. Photometry was carried out on these images to construct a catalogue of UV stars, of which the cluster members were identified using Gaia EDR3 catalogue. UV and optical CMDs help us locate known stellar populations such as BHB stars, RR-Lyrae stars, RHB stars, BSSs, SX-Phe, RGB and AGB stars. Based on their locations in the CMDs, we have identified 8 new BSS candidates, 6 probable eBSSs, and an EHB candidate. Their nature has been confirmed by fitting their spectral energy distributions with stellar atmospheric models. We believe the BSS population of this cluster is likely to have a collisional origin based on our analyses of their radial distribution and SEDs. BaSTI-IAC isochrones were generated to characterize the cluster properties, and we find that the observed brightness and colours of cluster members are best-fit with a model that is alpha-enhanced with a helium fraction of 0.247, metallicity of -1.9 dex and age within a range of 10.5-14.5 Gyr.

arXiv commentAccepted for publication in MNRAS, 14 pages, 12 figures, 3 Tables

References in corpus (67)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• The Gaia mission
• Multiple populations in globular clusters. Lessons learned from the Milky Way globular clusters
• The origin of sdB stars (II)
• Multiple Stellar Populations in Globular Clusters
• VOSA: Virtual Observatory SED Analyzer. An application to the Collinder 69 open cluster
• Gaia EDR3 view on Galactic globular clusters
• Accurate distances to Galactic globular clusters through a combination of Gaia EDR3, HST and literature data
• The binary fraction of extreme horizontal branch stars
• The Updated BaSTI Stellar Evolution Models and Isochrones: I. Solar Scaled Calculations
• Galactic Globular Cluster Metallicity Scale from the Calcium Triplet. II. Rankings, Comparisons and Puzzles
• Helium variation due to self-pollution among Globular Cluster stars: consequences on the horizontal branch morphology
• The Origin of Extreme Horizontal Branch Stars
• What is a globular cluster? An observational perspective
• Homogeneous age dating of 55 Galactic globular clusters. Clues to the Galaxy formation mechanisms
• Assessing the Milky Way Satellites Associated with the Sagittarius Dwarf Spheroidal Galaxy
• Galactic Globular Cluster Relative Ages
• In-orbit Calibrations of the Ultra-Violet Imaging Telescope
• Flash Mixing on the White Dwarf Cooling Curve: Understanding Hot Horizontal Branch Anomalies in NGC 2808
• The updated BaSTI stellar evolution models and isochrones: II. alpha-enhanced calculations
• Can Planets Influence the Horizontal Branch Morphology?
• Chemical Abundances and Rotation Velocities of Blue Horizontal-Branch Stars in Six Globular Clusters
• Blue Straggler Stars: The Spectacular Population in M80
• Multimodal Distributions along the Horizontal Branch
• Rotation Velocities of Red and Blue Field Horizontal-Branch Stars
• The peculiar Horizontal Branch of NGC 2808
• Blue Stragglers, Young White Dwarfs and UV-excess stars in the core of 47 Tuc
• Hot Stars in Globular Cluster - A Spectroscopist's View
• Globular cluster number density profiles using Gaia DR2
• Implications for the Formation of Blue Straggler Stars from HST Ultraviolet Observations of NGC 188
• Detection of white dwarf companions to blue stragglers in the open cluster NGC 188: direct evidence for recent mass transfer
• Blue Stragglers After the Main Sequence
• Lithium-Rich Giants in Globular Clusters
• A Far-Ultraviolet Survey of 47 Tucanae. I. Imaging
• Stellar Exotica in 47 Tucanae
• The Chemical Compositions of Non-Variable Red and Blue Field Horizontal Branch Stars
• A Spectroscopic Analysis of Blue Stragglers, Horizontal Branch and Turn-Off Stars in Four Globular Clusters
• UV Properties of Galactic Globular Clusters with GALEX I. The Color-Magnitude Diagrams
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. VII. Implications from the Nearly Universal Nature of Horizontal Branch Discontinuities
• The Blue Hook Populations of Massive Globular Clusters
• Chemical abundances of giant stars in NGC 5053 and NGC 5634, two globular clusters associated with the Sagittarius dwarf Spheroidal galaxy?
• CCD time-series photometry of the globular cluster NGC 5053: RR Lyrae, Blue Stragglers and SX Phoenicis stars revisited
• The Metal-poor non-Sagittarius (?) Globular Cluster NGC 5053: Orbit and Mg, Al and Si Abundances
• Far-Ultraviolet Observations of the Globular Cluster NGC 2808 Revisited: Blue Stragglers, White Dwarfs and Cataclysmic Variables
• A Far-UV Survey of M 80: X-ray Source Counterparts, Strange Blue Stragglers and the Recovery of Nova T Sco
• Asteroseismology and evolution of EHB stars
• The Frequency of Field Blue-Straggler Stars in the Thick Disk and Halo System of the Galaxy
• Detection of a White Dwarf companion to a Blue Straggler Star in the outskirts of globular cluster NGC 5466 with the Ultraviolet Imaging Telescope (UVIT)
• A population of binaries in the Asymptotic Giant Branch of 47 Tucanae?
• Catalog of Chromium, Cobalt, and Nickel Abundances in Globular Clusters and Dwarf Galaxies
• Flash Mixing on the White Dwarf Cooling Curve: Spectroscopic Confirmation in NGC 2808
• Spectral Energy Distribution of Blue Stragglers in the core of 47 Tucanae
• Isochrone fitting of Galactic globular clusters - I. NGC 5904
• Weighing stars: the identification of an Evolved Blue Straggler Star in the globular cluster 47 Tucanae
• The Horizontal Branch population of NGC 1851 as revealed by the Ultra-violet Imaging Telescope (UVIT)
• Chemical Abundances in NGC 5053: A Very Metal-Poor and Dynamically Complex Globular Cluster
• Formation and Evolution of Blue Stragglers in 47 Tucanae
• Abundances of alpha-Process Elements in Thin-Disk, Thick-Disk, and Halo Stars of the Galaxy: Non-LTE Analysis
• Blue Hook Stars in Globular Clusters
• Far-Ultraviolet Observation of the Globular Cluster NGC 6397
• UIT Detection of Hot Stars in the Globular Cluster NGC362
• Investigation of the Globular Cluster NGC 2808 with the Ultra-Violet Imaging Telescope
• Performance of the UVIT Level-2 Pipeline
• The temperature distribution of horizontal branch stars: methods and first results
• Formation Channels for Blue Straggler Stars
• The Hot End of Evolutionary Horizontal Branches
• Helium-rich EHB Stars in Globular Clusters