COSMIC RAY ORIGIN IN OB ASSOCIATIONS AND PREFERENTIAL ACCELERATION OF REFRACTORY ELEMENTS: EVIDENCE FROM ABUNDANCES OF ELEMENTS₂₆Fe THROUGH₃₄Se

Abstract

We report abundances of elements from 26 Fe to 34 Se in the cosmic radiation measured during fifty days of exposure of the Trans-Iron Galactic Element Recorder (TIGER) balloon-borne instrument. These observations add support to the concept that the bulk of cosmic ray acceleration takes place in OB associations, and they further support cosmic ray acceleration models in which elements present in interstellar grains are accelerated preferentially compared with those found in interstellar gas.