Fred C. Adams, Michael J. Cai, Daniele Galli, Susana Lizano, Frank H. Shu
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 $E_{\rm int}$ 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.
View original:
http://arxiv.org/abs/1110.4562
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