  Sympathetic eruptions on the Sun have been observed for several decades, but
the mechanisms by which one eruption can trigger another one remain poorly
understood. We present a 3D MHD simulation that suggests two possible magnetic
trigger mechanisms for sympathetic eruptions. We consider a configuration that
contains two coronal flux ropes located within a pseudo-streamer and one rope
located next to it. A sequence of eruptions is initiated by triggering the
eruption of the flux rope next to the streamer. The expansion of the rope leads
to two consecutive reconnection events, each of which triggers the eruption of
a flux rope by removing a sufficient amount of overlying flux. The simulation
qualitatively reproduces important aspects of the global sympathetic event on
2010 August 1 and provides a scenario for so-called twin filament eruptions.
The suggested mechanisms are applicable also for sympathetic eruptions
occurring in other magnetic configurations.
