Magnetic Interactions in Pre-Main-Sequence Binaries

Abstract

Young stars typically have strong magnetic fields, so that the magnetospheres of newly formed close binaries can interact, dissipate energy, and produce synchrotron radiation. The V773 Tau A binary system, a pair of T Tauri stars with a 51 day orbit, displays such a signature, with peak emission taking place near periastron. This paper proposes that the observed emission arises from the change in energy stored in the composite magnetic field of the system. We model the fields using the leading order (dipole) components and show that this picture is consistent with current observations. In this model, the observed radiation accounts for a fraction of the available energy of interaction between the magnetic fields from the two stars. Assuming antisymmetry, we compute the interaction energy $E_{\mathrm{int}}$ as a function of the stellar radii, the stellar magnetic field strengths, the binary semi-major axis, and orbital eccentricity, all of which can be measured independently of the synchrotron radiation. The variability in time and energetics of the synchrotron radiation depend on the details of the annihilation of magnetic fields through reconnection events, which generate electric fields that accelerate charged particles, and how those charged particles, especially fast electrons, are removed from the interaction region. However, the major qualitative features are well described by the background changes in the global magnetic configuration driven by the orbital motion. The theory can be tested by observing a collection of pre-main-sequence binary systems.

32 pages, 5 figures, accepted to ApJ

References in corpus (6)

• Synchrotron emission from the T Tauri binary system V773 Tau A
• Interacting coronae of two T Tauri stars: first observational evidence for solar-like helmet streamers
• Dynamical Masses for Pre-Main Sequence Stars: A Preliminary Physical Orbit for V773 Tau A
• The Young Binary DQ Tau: A Hunt For X-ray Emission From Colliding Magnetospheres
• The magnetic fields of forming solar-like stars
• Captured at Millimeter Wavelengths: a Flare from the Classical T Tauri Star DQ Tau

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• A Search For X-ray Emission From Colliding Magnetospheres In Young Eccentric Stellar Binaries
• The JCMT Transient Survey: Single Epoch Transients and Variability of Faint Sources
• Discovery of Magnetospheric Interactions in the Doubly-Magnetic Hot Binary $\epsilon$ Lupi
• Discovery of extraordinary X-ray emission from magnetospheric interaction in the unique binary stellar system $\epsilon$ Lupi