Solar-type stars exhibit their highest levels of magnetic activity during their early convective pre-main-sequence (PMS) phase of evolution. The most powerful PMS flares, superflares and megaflares, have peak X-ray luminosities of log(L_X_)=30.5-34.0erg/s and total energies log(E_X_)=34-38erg. Among >24000 X-ray-selected young (t36.2erg) from solar-mass stars have an occurrence rate of 1.7_-0.6_^+1.0^ flares/star/year and contribute at least 10%-20% to the total PMS X-ray energetics. These explosive events may have important astrophysical effects on protoplanetary disk photoevaporation, ionization of disk gas, production of spallogenic radionuclides in disk solids, and hydrodynamic escape of young planetary atmospheres. Our following paper details plasma and magnetic loop modeling of the >50 brightest X-ray megaflares.

Cone search capability for table J/ApJ/916/32/table1 (MYStIX and SFiNCs regions)

Cone search capability for table J/ApJ/916/32/table2 (MYStIX and SFiNCs F+R+D flare host star properties)

Cone search capability for table J/ApJ/916/32/table4 (Super-flares from protostellar candidates)