Origin of excess 176Hf in meteorites

Kristine Thrane; James Connelly; Martin Bizzarro; Bradley S. Meyer; Lin-Sin The

doi:10.1088/0004-637X/717/2/861

Origin of excess ¹⁷⁶Hf in meteorites

Kristine Thrane, James Connelly, Martin Bizzarro, Bradley S. Meyer, Lin-Sin The

25 Citations (Scopus)

Abstract

After considerable controversy regarding the ¹⁷⁶Lu decay constant (λ¹⁷⁶Lu), there is now widespread agreement that (1.867 ± 0.008) × 10^-11 yr^-1 as confirmed by various terrestrial objects and a 4557 Myr meteorite is correct. This leaves the ¹⁷⁶Hf excesses that are correlated with Lu/Hf elemental ratios in meteorites older than ∼ 4.56 Ga meteorites unresolved. We attribute ¹⁷⁶Hf excess in older meteorites to an accelerated decay of ¹⁷⁶Lu caused by excitation of the long-lived ¹⁷⁶Lu ground state to a short-lived ^176mLu 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 10-20m, whereas a small fraction penetrate as deep as 100-200 m, predicting decreased excesses of ¹⁷⁶Hf with depth of burial at the time of the irradiation event.

Original language	English
Journal	The Astrophysical Journal
Volume	717
Issue number	2
Pages (from-to)	861-867
Number of pages	7
ISSN	0004-637X
DOIs	https://doi.org/10.1088/0004-637X/717/2/861
Publication status	Published - 2010

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title = "Origin of excess 176Hf in meteorites",

abstract = "After considerable controversy regarding the 176Lu decay constant (λ176Lu), there is now widespread agreement that (1.867 ± 0.008) × 10-11 yr-1 as confirmed by various terrestrial objects and a 4557 Myr meteorite is correct. This leaves the 176Hf excesses that are correlated with Lu/Hf elemental ratios in meteorites older than ∼ 4.56 Ga meteorites unresolved. We attribute 176Hf excess in older meteorites to an accelerated decay of 176Lu caused by excitation of the long-lived 176Lu ground state to a short-lived 176mLu 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 10-20m, whereas a small fraction penetrate as deep as 100-200 m, predicting decreased excesses of 176Hf with depth of burial at the time of the irradiation event.",

author = "Kristine Thrane and James Connelly and Martin Bizzarro and Meyer, {Bradley S.} and Lin-Sin The",

year = "2010",

doi = "10.1088/0004-637X/717/2/861",

language = "English",

volume = "717",

pages = "861--867",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "Institute of Physics Publishing, Inc",

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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 176Lu decay constant (λ176Lu), there is now widespread agreement that (1.867 ± 0.008) × 10-11 yr-1 as confirmed by various terrestrial objects and a 4557 Myr meteorite is correct. This leaves the 176Hf excesses that are correlated with Lu/Hf elemental ratios in meteorites older than ∼ 4.56 Ga meteorites unresolved. We attribute 176Hf excess in older meteorites to an accelerated decay of 176Lu caused by excitation of the long-lived 176Lu ground state to a short-lived 176mLu 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 10-20m, whereas a small fraction penetrate as deep as 100-200 m, predicting decreased excesses of 176Hf with depth of burial at the time of the irradiation event.

AB - After considerable controversy regarding the 176Lu decay constant (λ176Lu), there is now widespread agreement that (1.867 ± 0.008) × 10-11 yr-1 as confirmed by various terrestrial objects and a 4557 Myr meteorite is correct. This leaves the 176Hf excesses that are correlated with Lu/Hf elemental ratios in meteorites older than ∼ 4.56 Ga meteorites unresolved. We attribute 176Hf excess in older meteorites to an accelerated decay of 176Lu caused by excitation of the long-lived 176Lu ground state to a short-lived 176mLu 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 10-20m, whereas a small fraction penetrate as deep as 100-200 m, predicting decreased excesses of 176Hf 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

SN - 0004-637X

VL - 717

SP - 861

EP - 867

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

ER -

Origin of excess 176Hf in meteorites

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Origin of excess ¹⁷⁶Hf in meteorites