Magnetic characterization and variability study of the magnetic SPB star o Lup

Abstract

Thanks to large dedicated surveys, large-scale magnetic fields have been detected for about 10% of early-type stars. We aim to precisely characterize the large-scale magnetic field of the magnetic component of the wide binary $o$ Lup, by using high-resolution ESPaDOnS and HARPSpol spectropolarimetry to analyse the variability of the measured longitudinal magnetic field. In addition, we investigate the periodic variability using space-based photometry collected with the BRITE-Constellation by means of iterative prewhitening. The rotational variability of the longitudinal magnetic field indicates a rotation period $P_{\mathrm{rot}}=2.95333(2)$d and that the large-scale magnetic field is dipolar, but with a significant quadrupolar contribution. Strong differences in the strength of the measured magnetic field occur for various chemical elements as well as rotational modulation for Fe and Si absorption lines, suggesting a inhomogeneous surface distribution of chemical elements. Estimates of the geometry of the large-scale magnetic field indicate $i=27\pm 10^{\circ }$, $\beta =74_{-9}^{+7}{}^{\circ }$, and a polar field strength of at least 5.25 kG. The BRITE photometry reveals the rotation frequency and several of its harmonics, as well as two gravity mode pulsation frequencies. The high-amplitude g-mode pulsation at $f=1.1057{\mathrm{d}}^{-1}$ dominates the line-profile variability of the majority of the spectroscopic absorption lines. We do not find direct observational evidence of the secondary in the spectroscopy. Therefore, we attribute the pulsations and the large-scale magnetic field to the B5IV primary of the $o$ Lup system, but we discuss the implications should the secondary contribute to or cause the observed variability.

arXiv comment19 pages, 6 Tables, 9 Figures, Accepted for publication in A&A

References in corpus (44)

• emcee: The MCMC Hammer
• Mass-loss predictions for O and B stars as a function of metallicity
• Astrophysics Source Code Library
• A Grid of NLTE Line-Blanketed Model Atmospheres of Early B-type Stars
• Dynamical Simulations of Magnetically Channeled Line-Driven Stellar Winds: I. Isothermal, Nonrotating, Radially Driven Flow
• Internal Gravity Waves in Massive Stars: Angular Momentum Transport
• A Magnetic Confinement vs. Rotation Classification of Massive-Star Magnetospheres
• Long-Baseline Interferometric Multiplicity Survey of the Sco-Cen OB Association
• The MiMeS Survey of Magnetism in Massive Stars: Introduction and overview
• The MiMeS survey of magnetism in massive stars: Magnetic analysis of the O-type stars
• BRITE-Constellation: nanosatellites for precision photometry of bright stars
• Simulations of core convection in rotating A-type stars: Differential rotation and overshooting
• Signatures of internal rotation discovered in the Kepler data of five slowly pulsating B stars
• A New Stellar Atmosphere Grid and Comparisons with HST/STIS Calspec Flux Distributions
• Transport and mixing in the radiation zones of rotating stars II. Axisymmetric magnetic field
• Evidence for nonlinear resonant mode coupling in the Beta Cep star HD 180642 (V1449 Aql) from CoRoT space-based photometry
• Multi-Dimensional Bayesian Membership Analysis of the Sco OB2 moving Group
• Characterisation of the magnetic field of the Herbig Be star HD 200775
• Forward seismic modelling of the pulsating magnetic B-type star HD 43317
• CoRoT's view of newly discovered B-star pulsators: results for 358 candidate B pulsators from the initial run's exoplanet field data
• Multisite spectroscopic seismic study of the beta Cep star V2052 Oph: inhibition of mixing by its magnetic field
• KIC 10526294: a slowly rotating B star with rotationally split, quasi-equally spaced gravity modes
• A new method for the spectroscopic identification of stellar non-radial pulsation modes. I. The method and numerical tests
• The eccentric massive binary V380 Cyg: revised orbital elements and interpretation of the intrinsic variability of the primary component
• The BRITE Constellation nanosatellite mission: Testing, commissioning and operations
• The search for magnetic fields in mercury-manganese stars
• Triple system HD 201433 with a SPB star component seen by BRITE-Constellation: Pulsation, differential rotation, and angular momentum transfer
• Conversion of Internal Gravity Waves into Magnetic Waves
• Impact of rotation on stochastic excitation of gravity and gravito-inertial waves in stars
• K2 photometry and HERMES spectroscopy of the blue supergiant rho Leo: rotational wind modulation and low-frequency waves
• Kepler sheds new and unprecedented light on the variability of a blue supergiant: gravity waves in the O9.5Iab star HD 188209
• BRITE-Constellation: Data processing and photometry
• Probing the internal magnetic field of slowly pulsating B-stars through g modes
• The surface magnetic field and chemical abundance distributions of the B2V helium-strong star HD184927
• Low-frequency photospheric and wind variability in the early-B supergiant HD 2905
• First results from the LIFE project: discovery of two magnetic hot evolved stars
• First HARPSpol discoveries of magnetic fields in massive stars
• A multisite photometric study of two unusual Beta Cep stars: the magnetic V2052 Oph and the massive rapid rotator V986 Oph
• Combining BRITE and ground-based photometry for the Beta Cephei star Nu Eridani: impact on photometric pulsation mode identification and detection of several g modes
• A novel and sensitive method for measuring very weak magnetic fields of DA white dwarfs: A search for a magnetic field at the 250 G level in 40 Eri B
• Mixed poloidal-toroidal magnetic configuration and surface abundance distributions of the Bp star 36 Lyn
• Studying the photometric and spectroscopic variability of the magnetic hot supergiant $\zeta$ Orionis Aa
• Magnetic characterization of the SPB/$\beta$ Cep hybrid pulsator HD 43317
• A spectroscopic study of the open cluster NGC 6250

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