Short-lived radioactive nuclides in meteorites and early solar system processes

Now extinct, short-lived radioactive nuclides, such as Be-7 (T-1/2 = 53 days), Be-10 (T-1/2 = 1.5 Ma), Al-26 (T-1/2 = 0.74 Ma), Cl-36 (T-1/2 = 0.3 Ma), Ca-41 (T-1/2 = 0.1 Ma), Mn-53 (T-1/2 = 3.7 Ma) and Fe-60 (T-1/2 = 1.5 Ma), were present in the protosolar nebula when the various components of meteorites formed. The presence of these radioactive isotopes requires a 'last-minute' origin, either nucleosynthesis in a massive star dying close in space and time to the nascent solar system or production-by local irradiation of part of the protosolar disk by high-energy solar cosmic rays. In this review, we list: (i) the different observations indicating the existence of multiple origins for short-lived radioactive nuclides, namely Be-7, Be-10 and Cl-36 for irradiation scenario and Fe-60 for injection scenario; (ii) the constraints that exist on their distribution (homogeneous or heterogeneous) in the accretion disk; (iii) the constraints they brought on the timescales of nebular processes (from Ca-Al-rich inclusions to chondrules) and of the accretion and differentiation of planetesimals.