Discovery of extraordinary X-ray emission from magnetospheric interaction in the unique binary stellar system $\epsilon$ Lupi

Abstract

We report detailed X-ray observations of the unique binary system $\epsilon$ Lupi, the only known short-period binary consisting of two magnetic early-type stars. The components have comparably strong, but anti-aligned magnetic fields. The orbital and magnetic properties of the system imply that the magnetospheres overlap at all orbital phases, suggesting the possibility of variable inter-star magnetospheric interaction due to the non-negligible eccentricity of the orbit. To investigate this effect, we observed the X-ray emission from $\epsilon$ Lupi both near and away from periastron passage, using the Neutron Star Interior Composition Explorer mission (NICER) X-ray Telescope. We find that the system produces excess X-ray emission at the periastron phase, suggesting the presence of variable inter-star magnetospheric interaction. We also discover that the enhancement at periastron is confined to a very narrow orbital phase range ($\approx 5\%$ of the orbital period), but the X-ray properties close to periastron phase are similar to those observed away from periastron. From these observations, we infer that the underlying cause is magnetic reconnection heating the stellar wind plasma, rather than shocks produced by wind-wind collision. Finally, by comparing the behavior of $\epsilon$ Lupi with that observed for cooler magnetic binary systems, we propose that elevated X-ray flux at periastron phase is likely a general characteristic of interacting magnetospheres irrespective of the spectral types of the constituent stars.

arXiv commentAccepted for publication in MNRAS (20 pages, 17 figures)

References in corpus (59)

• The Transiting Exoplanet Survey Satellite
• Binary interaction dominates the evolution of massive stars
• Collisional Plasma Models with APEC/APED: Emission Line Diagnostics of Hydrogen-like and Helium-like Ions
• Magnetic fields of non-degenerate stars
• A fossil origin for the magnetic fields of A-stars and white dwarfs
• How mergers magnetise massive stars
• A Magnetic Confinement vs. Rotation Classification of Massive-Star Magnetospheres
• The MiMeS survey of magnetism in massive stars: Magnetic analysis of the O-type stars
• BRITE-Constellation: nanosatellites for precision photometry of bright stars
• An Empirical Background Model for the NICER X-ray Timing Instrument
• Chandra HETGS Multi-Phase Spectroscopy of the Young Magnetic O Star theta^1 Orionis C
• Global X-ray properties of the O and B stars in Carina
• Magnetic massive stars as progenitors of "heavy" stellar-mass black holes
• The Magnetic Early B-type Stars III: A main sequence magnetic, rotational, and magnetospheric biography
• X-ray emission from magnetic massive stars
• X-rays from Magnetically Confined Wind Shocks: Effect of Cooling-Regulated Shock Retreat
• Revisiting the Rigidly Rotating Magnetosphere model for sigma Ori E. I. Observations and Data Analysis
• X-ray emission from interacting massive binaries: a review of 15 years of progress
• The effects of surface fossil magnetic fields on massive star evolution: I. Magnetic field evolution, mass-loss quenching and magnetic braking
• A Volume-Limited Survey of mCP Stars Within 100pc I: Fundamental Parameters and Chemical Abundances
• MOBSTER -- VI. The crucial influence of rotation on the radio magnetospheres of hot stars
• Synchrotron emission from the T Tauri binary system V773 Tau A
• New magnetic field measurements of beta Cephei stars and Slowly Pulsating B stars
• A Disk-based Dynamical Constraint on the Mass of the Young Binary DQ Tau
• Hard X-ray emission from Eta Carinae
• The Magnetic Early B-type Stars IV: Breakout or Leakage? H$\alpha$ emission as a diagnostic of plasma transport in centrifugal magnetospheres
• The effects of surface fossil magnetic fields on massive star evolution: II. Implementation of magnetic braking in MESA and implications for the evolution of surface rotation in OB stars
• Recurring millimeter flares as evidence for star-star magnetic reconnection events in the DQ Tauri PMS binary system
• A scaling relationship for non-thermal radio emission from ordered magnetospheres: from the top of the Main Sequence to planets
• The detection of variable radio emission from the fast rotating magnetic hot B-star HR7355 and evidence for its X-ray aurorae
• Detection of magnetic fields in both B-type components of the $\epsilon$ Lupi system: a new constraint on the origin of fossil fields?
• The Young Binary DQ Tau: A Hunt For X-ray Emission From Colliding Magnetospheres
• Captured at Millimeter Wavelengths: a Flare from the Classical T Tauri Star DQ Tau
• How the breakout-limited mass in B-star centrifugal magnetospheres controls their circumstellar H-alpha emission
• Critical evaluation of magnetic field detections reported for pulsating B-type stars in the light of ESPaDOnS, Narval and reanalyzed FORS1/2 observations
• Centrifugal breakout reconnection as the electron acceleration mechanism powering the radio magnetospheres of early-type stars
• Magnetic fields driven by tidal mixing in radiative stars
• HD 156324: a tidally locked magnetic triple spectroscopic binary with a disrupted magnetosphere
• Evidence for radio and X-ray auroral emissions from the magnetic B-type star rho Oph A
• The BinaMIcS project: understanding the origin of magnetic fields in massive stars through close binary systems
• Fossil field decay due to nonlinear tides in massive binaries
• The X-ray light curve of the massive colliding wind Wolf-Rayet + O binary WR21a
• The effects of surface fossil magnetic fields on massive star evolution: IV. Grids of models at Solar, LMC, and SMC metallicities
• The orbit of the close spectroscopic binary epsilon Lupi and the intrinsic variability of its early B-type components
• The effects of surface fossil magnetic fields on massive star evolution: III. The case of $\tau$ Sco
• $\epsilon$ Lupi: measuring the heartbeat of a doubly-magnetic massive binary with BRITE-Constellation
• X-ray emission from the giant magnetosphere of the magnetic O-type star NGC 1624-2
• Magnetic topology in coupled binaries, spin-orbital resonances, and flares
• Magnetic Interactions in Pre-Main-Sequence Binaries
• MOBSTER -- V: Discovery of a magnetic companion star to the magnetic $\beta$ Cep pulsator HD 156424
• Chandra grating spectroscopy of embedded wind shock X-ray emission from O stars shows low plasma temperatures and significant wind absorption
• A changing wind collision
• A Search For X-ray Emission From Colliding Magnetospheres In Young Eccentric Stellar Binaries
• An X-ray view of HD166734, a massive supergiant system
• X-ray emission of massive stars and their winds
• Magnetic properties of three cool CP stars with strong fields
• How unique is Plaskett's star? A search for organized magnetic fields in short period, interacting or post-interaction massive binary systems
• The Young Binary DQ Tau Produces Another X-ray Flare Near Periastron
• Magnetically confined wind shock

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