The Rise and Emergence of Untwisted Toroidal Flux Ropes on the Sun

Magnetic flux ropes (MFRs) rising buoyantly through the Sun's convection zone are thought to be subject viscous forces preventing them from coherently. Numerous studies have suggested that MFRs require a minimum twist in order remain coherent during their rise. Furthermore, even get photosphere may unable successfully emerge into corona unless they at least moderately twisted, since magnetic pressure gradient needs overcome weight of photospheric plasma. To date, however, no lower limit has been placed on critical required for an MFR rise coherently or photosphere. In this paper, we simulate untwisted toroidal which is able and as active region resembles those observed Sun. We show can then pile-up near photosphere, triggering undular instability, allowing propose geometry our its Upon emerging, pair lobes rises interact reconnect, resulting localized high speed jet. The magnetogram displays characteristic salt-and-pepper structure often seen observations. Our major result need not twisted