Origin of excess 176Hf in meteorites
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Origin of excess 176Hf in meteorites. / Thrane, Kristine; Connelly, James; Bizzarro, Martin; Meyer, Bradley S.; The, Lin-Sin.
I: The Astrophysical Journal, Bind 717, Nr. 2, 2010, s. 861-867.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Origin of excess 176Hf in meteorites
AU - Thrane, Kristine
AU - Connelly, James
AU - Bizzarro, Martin
AU - Meyer, Bradley S.
AU - The, Lin-Sin
PY - 2010
Y1 - 2010
N2 - After considerable controversy regarding the (176)Lu decay constant (lambda(176)Lu), there is now widespread agreement that (1.867 +/- 0.008) x 10(-11) yr(-1) as confirmed by various terrestrial objects and a 4557 Myr meteorite is correct. This leaves the (176)Hf excesses that are correlated with Lu/Hf elemental ratios in meteorites older than similar to 4.56 Ga meteorites unresolved. We attribute (176)Hf excess in older meteorites to an accelerated decay of (176)Lu caused by excitation of the long-lived (176)Lu ground state to a short-lived (176m)Lu isomer. The energy needed to cause this transition is ascribed to a post-crystallization spray of cosmic rays accelerated by nearby supernova(e) that occurred after 4564.5 Ma. The majority of these cosmic rays are estimated to penetrate accreted material down to 10-20 m, whereas a small fraction penetrate as deep as 100-200 m, predicting decreased excesses of (176)Hf with depth of burial at the time of the irradiation event.
AB - After considerable controversy regarding the (176)Lu decay constant (lambda(176)Lu), there is now widespread agreement that (1.867 +/- 0.008) x 10(-11) yr(-1) as confirmed by various terrestrial objects and a 4557 Myr meteorite is correct. This leaves the (176)Hf excesses that are correlated with Lu/Hf elemental ratios in meteorites older than similar to 4.56 Ga meteorites unresolved. We attribute (176)Hf excess in older meteorites to an accelerated decay of (176)Lu caused by excitation of the long-lived (176)Lu ground state to a short-lived (176m)Lu isomer. The energy needed to cause this transition is ascribed to a post-crystallization spray of cosmic rays accelerated by nearby supernova(e) that occurred after 4564.5 Ma. The majority of these cosmic rays are estimated to penetrate accreted material down to 10-20 m, whereas a small fraction penetrate as deep as 100-200 m, predicting decreased excesses of (176)Hf with depth of burial at the time of the irradiation event.
U2 - 10.1088/0004-637X/717/2/861
DO - 10.1088/0004-637X/717/2/861
M3 - Journal article
VL - 717
SP - 861
EP - 867
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
ER -
ID: 34202435