Photometric variability of blue straggler stars in M67 with TESS and K2

Abstract

Blue straggler stars (BSSs) are formed through mass transfer or mergers in binaries. The recent detections of white dwarf (WD) companions to BSSs in M67 suggested a mass transfer pathway of formation. In search of a close companion to five BSSs in M67 that are known to be spectroscopic binaries, we study the light curves from K2 and TESS data. We use PHOEBE to analyse the light curves and estimate the properties of the companions. We detect variability in WOCS 1007, and the light curve is dominated by ellipsoidal variation. Using the light curve and radial velocity measurements, we estimate its orbital period to be 4.212$\pm$0.041 d and $e$ = 0.206$\pm$002. The mass of the companion is estimated to be 0.22$\pm$0.05 M${}_{\odot }$ with a radius of 0.078$\pm$0.027 R${}_{\odot }$, confirming it to be a low mass WD with T${}_{\mathrm{eff}}$ = 14300$\pm$1100 K. The estimated mass of the BSS, 1.95$\pm$0.26 M${}_{\odot }$, is similar to that estimated from isochrones. The BSS in WOCS 1007 shows $\delta$ Scuti pulsations, although it is slightly deformed and likely to be formed through an efficient mass transfer. Though we detect a light curve for WOCS 4003 showing grazing eclipse with ellipsoidal variation, the estimated parameters are inconclusive. Apart from the 0.44 d period, we found smaller eclipses with a period of 1.1 d, suggesting a compact triple system. In the case of WOCS 4003, WOCS 5005, and WOCS 1025, no eclipses or pulsations are detected, confirming the absence of any short-period inner binary with high inclination in these BSSs.

arXiv comment15 pages, 10 figures. Accepted for publication in MNRAS

References in corpus (55)

• Array Programming with NumPy
• Astropy: A Community Python Package for Astronomy
• emcee: The MCMC Hammer
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• Modules for Experiments in Stellar Astrophysics (MESA)
• Gaia Data Release 3: Summary of the content and survey properties
• The Transiting Exoplanet Survey Satellite
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• Modules for Experiments in Stellar Astrophysics (MESA): Binaries, Pulsations, and Explosions
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• The SIMBAD astronomical database
• Modules for Experiments in Stellar Astrophysics (MESA): Convective Boundaries, Element Diffusion, and Massive Star Explosions
• MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the construction of stellar isochrones
• The K2 Mission: Characterization and Early results
• Efficient, uninformative sampling of limb darkening coefficients for two-parameter laws
• A Computational Guide to Physics of Eclipsing Binaries. Paper I. Demonstrations and Perspectives
• Overview of the Kepler Science Processing Pipeline
• A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission
• STARRY: Analytic Occultation Light Curves
• On the triple origin of blue stragglers
• Mergers and Obliquities in Stellar Triples
• K2SC: Flexible systematics correction and detrending of K2 light curves using Gaussian Process regression
• Eclipsing binaries in ASAS catalog
• {\em Gaia}-derived luminosities of {\em Kepler} A/F stars and the pulsator fraction across the δ Scuti instability strip
• Analytic Planetary Transit Light Curves and Derivatives for Stars with Polynomial Limb Darkening
• Characterising the observational properties of δ Sct stars in the era of space photometry from the Kepler mission
• Stellar Radial Velocities in the Old Open Cluster M67 (NGC 2682) I. Memberships, Binaries, and Kinematics
• Catalogue and Properties of δ Scuti Stars in Binaries
• Finding binaries from phase modulation of pulsating stars with Kepler: V. Orbital parameters, with eccentricity and mass-ratio distributions of 341 new binaries
• Implications for the Formation of Blue Straggler Stars from HST Ultraviolet Observations of NGC 188
• Detection of a large sample of Gamma Dor stars from Kepler space photometry and high-resolution ground-based spectroscopy
• Tidally Trapped Pulsations in a close binary star system discovered by TESS
• Blue Lurkers: Hidden Blue Stragglers on the M67 Main Sequence Identified from their Kepler/K2 Rotation Periods
• Stellar Exotica in 47 Tucanae
• Time-Series Photometry of M67: W UMa Systems, Blue Stragglers, and Related Systems
• Discovery of tidally-perturbed pulsations in the eclipsing binary U Gru: a pioneering system for tidal asteroseismology
• 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
• A Chandra observation of the old open cluster M67
• UVIT Open Cluster Study. I. Detection of a White Dwarf Companion to a Blue Straggler in M67: Evidence of Formation through Mass Transfer
• Close binary stars in the solar-age Galactic open cluster M67
• Constraining Mass Transfer Histories of Blue Straggler Stars with COS Spectroscopy of White Dwarf Companions
• An all-sky catalog of solar-type dwarfs for exoplanetary transit surveys
• Multisite campaign on the open cluster M67. III. Delta Scuti pulsations in the blue stragglers
• Multi-band photometry and spectroscopy of an all-sky sample of bright white dwarfs
• 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)
• Ultraviolet stellar population of the old open cluster M67 (NGC 2682)
• UOCS.VI. UVIT/AstroSat detection of low-mass white dwarf companions to 4 more blue stragglers in M67
• UVIT/ASTROSAT studies of Blue Straggler stars and post-mass transfer systems in star clusters: Detection of one more blue lurker in M67
• A chemical study of M67 candidate blue stragglers and evolved blue stragglers observed with APOGEE DR14
• The Nature of V1464 Aql: A New Ellipsoidal Variable with a Delta Scuti Component
• Dynamically Forming Extremely Low-Mass White Dwarf Binaries in Wide Orbits
• Detection of White Dwarf Companions to Blue Straggler Stars from UVIT Observations of M67
• On the pulsations of the $\delta$ Scuti star of the binary system KIC 6629588

Cited by in corpus (1)

• UVIT Open Cluster Study. X. Rich Collection of Post Mass Transfer Systems in NGC 6791