V772 Cas: an ellipsoidal HgMn star in an eclipsing binary

Abstract

The late B-type star V772 Cas (HD 10260) was previously suspected to be a rare example of a magnetic chemically peculiar star in an eclipsing binary system. Photometric observations of this star obtained by the TESS satellite show clear eclipses with a period of 5.0137 d accompanied by a significant out-of-eclipse variation with the same period. High-resolution spectroscopy reveals V772 Cas to be an SB1 system, with the primary component rotating about a factor two slower than the orbital period and showing chemical peculiarities typical of non-magnetic HgMn chemically peculiar stars. This is only the third eclipsing HgMn star known and, owing to its brightness, is one of the very few eclipsing binaries with chemically peculiar components accessible to detailed follow-up studies. Taking advantage of the photometric and spectroscopic observations available for V772 Cas, we performed modelling of this system with the PHOEBE code. This analysis provided fundamental parameters of the components and demonstrated that the out-of-eclipse brightness variation is explained by the ellipsoidal shape of the evolved, asynchronously rotating primary. This is the first HgMn star for which such variability has been definitively identified.

14 pages, 13 figures; accepted for publication in MNRAS

References in corpus (66)

• Astropy: A Community Python Package for Astronomy
• emcee: The MCMC Hammer
• The chemical composition of the Sun
• Gaia Data Release 2. Summary of the contents and survey properties
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• The Transiting Exoplanet Survey Satellite
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the construction of stellar isochrones
• Accurate masses and radii of normal stars: modern results and applications
• Astrophysics Source Code Library
• A Computational Guide to Physics of Eclipsing Binaries. Paper I. Demonstrations and Perspectives
• HERMES: a high-resolution fibre-fed spectrograph for the Mercator telescope
• A fossil origin for the magnetic fields of A-stars and white dwarfs
• Stellar magnetism: empirical trends with age and rotation
• Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
• The incidence of stellar mergers and mass gainers among massive stars
• Least squares deconvolution of the stellar intensity and polarization spectra
• Physics Of Eclipsing Binaries. II. Towards the Increased Model Fidelity
• Limb and gravity-darkening coefficients for the TESS satellite at several metallicities, surface gravities, and microturbulent velocities
• Weak magnetic fields in Ap/Bp stars: Evidence for a dipole field lower limit and a tentative interpretation of the magnetic dichotomy
• emcee v3: A Python ensemble sampling toolkit for affine-invariant MCMC
• How mergers magnetise massive stars
• A Stellar Rotation Census of B Stars: from ZAMS to TAMS
• Searching for links between magnetic fields and stellar evolution. II. The evolution of magnetic fields as revealed by observations of Ap stars in open clusters and associations
• Magnetic field measurements and their uncertainties: the FORS1 legacy
• Searching for links between magnetic fields and stellar evolution. I. A survey of magnetic fields in open cluster A- and B-type stars with FORS1
• Rejuvenation of stellar mergers and the origin of magnetic fields in massive stars
• Ap stars with resolved magnetically split lines: Magnetic field determinations from Stokes $I$ and $V$ spectra
• A Volume Limited Survey of mCP Stars Within 100pc II: Rotational and Magnetic Properties
• The dependence of convective core overshooting on stellar mass: reality check, and additional evidence
• The chemical abundance analysis of normal early A- and late B-type stars
• Beyond the Kepler/K2 bright limit: variability in the seven brightest members of the Pleiades
• Hyperfine Splitting in the VALD Database of Spectral-line Parameters
• New catalogue of Chemically Peculiar stars, and Statistical Analysis
• Weather in stellar atmosphere: the dynamics of mercury clouds in alpha Andromedae
• The search for magnetic fields in mercury-manganese stars
• No detection of large-scale magnetic fields at the surfaces of Am and HgMn stars
• Binary Asteroseismic Modelling: isochrone-cloud methodology and application to Kepler gravity-mode pulsators
• The TESS light curve of AI Phoenicis
• Magnetic field topologies of the bright, weak-field Ap stars theta Aurigae and epsilon Ursae Majoris
• Magnetic field, chemical composition and line profile variability of the peculiar eclipsing binary star AR Aur
• Magnetic fields of HgMn stars
• Dynamical evolution of titanium, strontium, and yttrium spots on the surface of the HgMn star HD 11753
• Are there tangled magnetic fields on HgMn stars?
• Non-LTE line formation for Si I-II-III in A-B stars and the origin of Si II emission lines in iota Her
• Magnetism, chemical spots, and stratification in the HgMn star phi Phoenicis
• Chemical spots in the absence of magnetic field in the binary HgMn star 66 Eridani
• Chemical surface inhomogeneities in late B-type stars with Hg and Mn peculiarity I Spot evolution in HD 11753 on short and long time scales
• HD66051: the first eclipsing binary hosting an early-type magnetic star
• The BinaMIcS project: understanding the origin of magnetic fields in massive stars through close binary systems
• A NLTE line formation for neutral and singly-ionised calcium in model atmospheres of B-F stars
• An empirical temperature calibration for the Delta a photometric system. II. The A-type and mid F-type star
• Magnetic Doppler imaging of the chemically peculiar star HD 125248
• HD 99458: First time ever Ap-type star as a $\delta$ Scuti pulsator in a short period eclipsing binary?
• A search for pulsations in the HgMn star HD 45975 with CoRoT photometry and ground-based spectroscopy
• Magnetic field topology of the cool, active, short-period binary system ${\sigma }^2$ Coronae Borealis
• BD-19 5044L: discovery of a short-period SB2 system with a magnetic Bp primary in the open cluster IC 4725
• An empirical temperature calibration for the Delta a photometric system. I. The B-type stars
• MOBSTER -- III. HD 62658: a magnetic Bp star in an eclipsing binary with a non-magnetic 'identical twin'
• No magnetic field in the spotted HgMn star mu Leporis
• A Spectroscopic and Photometric Investigation of the Mercury-Manganese Star KIC 6128830
• Variation of the line profile moments for stars pulsating in distorted oblique non-radial modes
• Neon Abundances of B-stars in the Solar Neighborhood
• The nature of the photometric variability of HgMn stars: A test of simulated light curves of ϕ Phe against the TESS data
• Compositional differences between the component stars of eclipsing close binary systems showing chemical peculiarities
• AO Vel: The role of multiplicity in the development of chemical peculiarities in late B-type stars

Cited by in corpus (6)

• TESS survey of rotational and pulsational variability of mercury-manganese stars
• V680 Mon -- a young mercury-manganese star in an eclipsing heartbeat system
• New eclipsing binaries with mercury-manganese stars
• FINKER: Frequency Identification through Nonparametric KErnel Regression in astronomical time series
• EPIC 206197016: A very hot white dwarf orbited by a strongly irradiated red dwarf
• A rare phosphorus-rich star in an eclipsing binary from TESS