Accretion to Magnetized Stars through the Rayleigh-Taylor Instability: Global Three-Dimensional Simulations - AstrophysicsReport as inadecuate




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Abstract: We present results of 3D simulations of MHD instabilities at the accretiondisk-magnetosphere boundary. The instability is Rayleigh-Taylor, and developsfor a fairly broad range of accretion rates and stellar rotation rates andmagnetic fields. It manifests itself in the form of tall, thin tongues ofplasma that penetrate the magnetosphere in the equatorial plane. The shape andnumber of the tongues changes with time on the inner-disk dynamical timescale.In contrast with funnel flows, which deposit matter mainly in the polar region,the tongues deposit matter much closer to the stellar equator. The instabilityappears for relatively small misalignment angles, $\Theta\lesssim30^\circ$,between the star-s rotation and magnetic axes, and is associated with higheraccretion rates. The hot spots and light curves during accretion throughinstability are generally much more chaotic than during stable accretion. Theunstable state of accretion has possible implications for quasi-periodicoscillations and intermittent pulsations from accreting systems, as well asplanet migration.



Author: Akshay K. Kulkarni, Marina M. Romanova

Source: https://arxiv.org/







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