Recurring millimeter flares as evidence for star-star magnetic reconnection events in the DQ Tauri PMS binary system - Astrophysics > Solar and Stellar AstrophysicsReportar como inadecuado




Recurring millimeter flares as evidence for star-star magnetic reconnection events in the DQ Tauri PMS binary system - Astrophysics > Solar and Stellar Astrophysics - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: Observations of the T Tauri spectroscopic binary DQ Tau in April 2008captured an unusual flare at 3 mm, which peaked at an observed max flux of 0.5Jy about 27x the quiescent value. Here we present follow-up mm observationsthat demonstrate a periodicity to the phenomenon. While monitoring 3 newperiastron encounters, we detect flares within 17.5 hrs or 4.6% of theorbital phase of the first reported flare, and we constrain the main emittingregion to a stellar height of 3.7-6.8 Rstar. The recorded activity isconsistent with the proposed picture for synchrotron emission initiated by amagnetic reconnection event when the two stellar magnetospheres of the highlyeccentric e=0.556 binary are believed to collide near periastron as the starsapproach a minimum separation of 8 Rstar ~13 Rsolar. The similar light curvedecay profiles allow us to estimate an average flare duration of 30 hrs.Assuming one mm flare per orbit, DQ Tau could spend approximately 8% of its15.8-d orbital period in an elevated flux state. Our analysis of the mmemission provides an upper limit of 5% on the linear polarization. We discussthe extent to which a severely entangled magnetic field structure and Faradayrotation effects are likely to reduce the observed polarization fraction. Wealso predict that, for the current picture, the stellar magnetospheres must bemisaligned at a significant angle or, alternatively, that the topologies of theouter magnetospheres are poorly described by a well-ordered dipole inside aradius of 7 Rstar. Finally, to investigate whether reorganization of themagnetic field during the interaction affects mass accretion, we also presentsimultaneous optical VRI monitoring, as an established tracer of accretionactivity in this system. We find that an accretion event can occur coincidentin both time and duration with the synchrotron fallout of a magneticreconnection event.



Autor: D.M. Salter Leiden, Á. Kóspál Leiden, K.V. Getman Penn State, M.R. Hogerheijde Leiden, T.A. van Kempen Harvard-CfA, J.M. Carpe

Fuente: https://arxiv.org/



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