About 4.6 billion years ago, some event disturbed a cloud of gas and dust, triggering the gravitational collapse that led to the formation of the solar system. A core-collapse supernova, whose shock wave is capable of compressing such a cloud, is an obvious candidate for the initiating event. This hypothesis can be tested because supernovae also produce telltale patterns of short-lived radionuclides, which would be preserved today as isotopic anomalies. Previous studies of the forensic evidence have been inconclusive, finding a pattern of isotopes differing from that produced in conventional supernova models. Here we argue that these difficulties either do not arise or are mitigated if the initiating supernova was a special type, low in mass and explosion energy. Key to our conclusion is the demonstration that short-lived 10Be can be readily synthesized in such supernovae by neutrino interactions, while anomalies in stable isotopes are suppressed.
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We acknowledge helpful discussions with Bernhard M?ller and the late Jerry Wasserburg. We thank Takashi Yoshida for communications regarding ref. 12. This work was supported in part by the US DOE [DE-FG02-87ER40328 (UM), DE-SC00046548 (Berkeley), and DE-AC02-98CH10886 (LBL)], the US NSF [PHY-1430152 (JINA-CEE)], and ARC Future Fellowship FT120100363 (AH).