Characterization of hot populations of Melotte 66 open cluster using Swift/UVOT

Abstract

Ultraviolet (UV) wavelength observations have made a significant contribution to our understanding of hot stellar populations of star clusters. Multi-wavelength spectral energy distributions (SEDs) of stars, including ultraviolet observations, have proven to be an excellent tool for discovering unresolved hot companions in exotic stars such as blue straggler stars (BSS), thereby providing helpful clues to constrain their formation mechanisms. Melotte 66 is a 3.4 Gyr old open cluster located at a distance of 4810 pc. We identify the cluster members by applying the ML-MOC algorithm on Gaia EDR3 data. Based on our membership identification, we find 1162 members, including 14 BSS candidates, 2 yellow straggler candidates (YSS), and one subdwarf B candidate (sdB). We generated SEDs for 11 BSS candidates and the sdB candidate using Swift/UVOT data combined with other archival data in the optical and IR wavelengths. We discover a hot companion of one BSS candidate, BSS3, with temperature of 38000${}_{-6000}^{+7000}$ K, luminosity of 2.99${}_{-1.86}^{+5.47}$ L${}_{\odot }$, and radius of 0.04${}_{-0.005}^{+0.008}$ R${}_{\odot }$. This hot companion is a likely low-mass WD with an estimated mass of 0.24 $\text{-}$ 0.44 M${}_{\odot }$. We report one BSS candidate, BSS6, as an Algol-type eclipsing binary with a period of 0.8006 days, based on the Gaia DR3 variability classification. We suggest that BSS3 is formed via either the Case A or Case B mass-transfer channel, whereas BSS6 is formed via the Case A mass transfer.

References in corpus (51)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Astropy: A Community Python Package for Astronomy
• Gaia Data Release 2. Summary of the contents and survey properties
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The Gaia mission
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• The Transiting Exoplanet Survey Satellite
• The Infrared Array Camera (IRAC) for the Spitzer Space Telescope
• Correcting for the Effects of Interstellar Extinction
• The Swift Ultra-Violet/Optical Telescope
• Young massive star clusters
• The Wavelength Dependence of Interstellar Extinction from 1.25 to 8.0 microns Using GLIMPSE Data
• The Origin of Subdwarf B Star (I): the Formation Channels
• Spectral Irradiance Calibration in the Infrared. XIV: the Absolute Calibration of 2MASS
• The TESS Input Catalog and Candidate Target List
• A Gaia DR2 view of the Open Cluster population in the Milky Way
• The origin of sdB stars (II)
• VOSA: Virtual Observatory SED Analyzer. An application to the Collinder 69 open cluster
• Hot subluminous stars
• The binary fraction of extreme horizontal branch stars
• Close binary EHB stars from SPY
• Mass transfer from a giant star to a main sequence companion and its contribution to long-orbital-period blue stragglers
• Open clusters as key tracers of Galactic chemical evolution. III. Element abundances in Berkeley 20, Berkeley 29, Collinder 261, and Melotte 66
• Radial velocity measurements of Subdwarf B stars
• Hot Stars in Globular Cluster - A Spectroscopist's View
• Population of hot subdwarf stars studied with Gaia III. Catalogue of known hot subdwarf stars: Data Release 2
• Implications for the Formation of Blue Straggler Stars from HST Ultraviolet Observations of NGC 188
• A new, Gaia based, catalogue of blue straggler stars in open clusters
• Detection of white dwarf companions to blue stragglers in the open cluster NGC 188: direct evidence for recent mass transfer
• A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- I. Search for exoplanets and variable stars in the field of 47 Tuc
• ML-MOC: Machine Learning (kNN and GMM) based Membership Determination for Open Clusters
• A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- II. Search for exoplanets in open clusters of the southern ecliptic hemisphere and their frequency
• White dwarf-main sequence binaries from Gaia EDR3: the unresolved 100pc volume-limited sample
• A catalog of wide binary and multiple systems of bright stars from Gaia-DR2 and the Virtual Observatory
• Blue Straggler Stars in Open Clusters using Gaia: Dependence on Cluster Parameters and Possible Formation Pathways
• UVIT Open Cluster Study. II. Detection of extremely low mass white dwarfs and post-mass transfer binaries in M67
• Ecology of Blue Straggler Stars
• UVIT Open Cluster Study. I. Detection of a White Dwarf Companion to a Blue Straggler in M67: Evidence of Formation through Mass Transfer
• A Census of Blue Stragglers in Gaia DR2 Open Clusters as a Test of Population Synthesis and Mass Transfer Physics
• Hot subdwarf stars identified in Gaia DR2 with spectra of LAMOST DR6 and DR7 I. Single-lined spectra
• Blue Straggler Populations of Seven Open Clusters with Gaia DR2
• UOCS VII. Blue Straggler Populations of Open Cluster NGC 7789 with UVIT/AstroSat
• 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)
• The Swift/UVOT Stars Survey. III. Photometry and Color-Magnitude Diagrams of 103 Galactic Open Clusters
• UOCS. IV. Discovery of diverse hot companions to blue stragglers in the old open cluster King 2
• Determination of dynamical ages of open clusters through the A${}^{+}$ parameter -- I
• Peculiarities in the horizontal branch stars of globular cluster NGC 1851: Discovery of a Blue straggler companion to an EHB star
• Updated properties of the old open cluster Melotte 66: Searching for multiple stellar populations
• Variable stars in the field of the old open cluster Melotte 66
• UOCS. V. UV study of the old open cluster NGC 188 using AstroSat

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• Discovery of double BSS sequences in the old Galactic open cluster Berkeley 17
• UVIT Open Cluster Study. X. Rich Collection of Post Mass Transfer Systems in NGC 6791
• UOCS. XIV. Uncovering extremely low mass white dwarfs and blue lurkers in NGC 752
• Unveiling Bifurcated Blue Straggler Sequences in NGC 2173: Insights from Binary Evolution
• On the detectability and parameterisation of binary stars through spectral energy distributions