New Half-Life Measurement of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">H</mml:mi><mml:mi mathvariant="normal">f</mml:mi></mml:mrow><mml:mprescripts /><mml:none /><mml:mn>182</mml:mn></mml:mmultiscripts></mml:math>: Improved Chronometer for the Early Solar System

Vockenhuber, Christof; Oberli, Felix; Bichler, Max; Ahmad, I.; Quitté, G.; Meier, M. M. M.; Halliday, Alex N.; Lee, D.-C.; Kutschera, W.; Steier, Peter; Gehrke, R.J.; Helmer, R.G.

doi:10.1103/physrevlett.93.172501

Cited by 164 publications

(62 citation statements)

References 27 publications

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“…We review the situation concerning 182 Hf, which β − decays to 182 W. A greatly improved measurement ofτ182 Hf by Vockenhuber et al [266] has now establishedτ182 Hf = 12.8 ± 0. [269] and [270] was two orders of magnitude higher than reported by Harper [29].…”

Section: Hfmentioning

confidence: 99%

Short-lived nuclei in the early Solar System: Possible AGB sources

et al. 2006

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The abundances of short-lived radionuclides in the early solar system (ESS) are reviewed, as well as the methodology used in determining them. These results are compared with the inventory estimated for a uniform galactic production model. It is shown that, to within a factor of two, the observed abundances of 238 U, 235 U, 232 Th, 244 Pu, 182 Hf, 146 Sm, and 53 Mn are roughly compatible with long-term galactic nucleosynthesis. 129 I is an exception, with an ESS inventory much lower than expected from uniform production. The isotopes 107 Pd, 60 Fe, 41 Ca, 36 Cl, 26 Al, and 10 Be require late addition to the protosolar nebula. 10 Be is the product of energetic particle irradiation of the solar system as most probably is 36 Cl. Both of these nuclei appear to be present when 26 Al is absent. A late injection by a supernova (SN) cannot be responsible for most of the short-lived nuclei without excessively producing 53 Mn; it can however be the source of 53 Mn itself and possibly of 60 Fe. If a late SN injection is responsible for these two nuclei, then there remains the problem of the origin of 107 Pd and several other isotopes. Emphasis is given to an AGB star as a source of many of the nuclei, including 60 Fe; this possibility is explored with a new generation of stellar models. It is shown that if the dilution factor (i.e. the ratio of the contaminating mass to the solar parental cloud mass) is f 0 ∼ 4×10 −3 , a reasonable representation for many nuclei is obtained; this requires that ( 60 Fe/ 56 Fe) ESS ∼ 10 −7 to 2×10 −6 . The nuclei produced by an AGB source do not include 53 Mn, 10 Be or 36 Cl if it is very abundant. The role of irradiation is discussed with regard to 26 Al, 36 Cl and 41 Ca, and the estimates of bulk solar abundances of these isotopes are commented on. The conflict between various scenarios is emphasized as well as the current absence of an astrophysically plausible global interpretation for all the existing data. Examination of abundances for the actinides indicates that a quiescent interval of ∼ 10 8 years is required for actinide group production. This is needed in order to explain the data on 244 Pu and the new bounds on 247 Cm. Because this quiescent interval is not compatible with the 182 Hf data, a separate type of r-process event is needed for at least the actinides, distinct from the two types that have previously been identified. The apparent coincidence of the 129 I and trans-actinide time scales suggests that the last heavy r contribution was from an r-process that produced very heavy nuclei but without fission recycling so that the yields at Ba and below (including I) were governed by fission.

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Section: Hfmentioning

confidence: 99%

Short-lived nuclei in the early Solar System: Possible AGB sources

et al. 2006

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“…The isochron regression was done using the Isoplot 3.0 of Kenneth R. Ludwig, and the 95% confidence limit was selected as the uncertainties of the isochron. The ∆t was calculated using the relationship of ∆t = 1/λ × ln [( 182 Hf/ 180 Hf) CHUR / ( 182 Hf/ 180 Hf) GRA 95209 ], where λ = 0.0779 ± 0.0008 Myr −1 (Vockenhuber et al 2004). The upper limit of the ∆t uncertainty was assessed using the upper limit of the 182 Hf/ 180 Hf CHUR and the lower limit of the 182 Hf/ 180 Hf GRA 95209 and λ, and vice versa for the lower limit.…”

Section: Hf-w Isochron Ages Of Acapulcoites Versus Lodranitesmentioning

confidence: 99%

“…The short-lived chronometer 182 Hf-182 W, t 1/2 = 8.90 ± 0.09 million years (Vockenhuber et al 2004), has been shown to be one of the best tools for studying the metal-silicate differentiation and thermal history of early planetary bodies (Harper et al 1991;Harper and Jacobsen 1996;Halliday 1996, 1997;Horan et al 1998;Schoenberg et al 2002;Yin et al 2002;Kleine et al 2002Kleine et al , 2004Kleine et al , 2005aKleine et al , 2005bQuitté et al 2000Quitté et al , 2005Quitté and Birck 2004;Lee 2005;Markowski et al 2006aMarkowski et al , 2006b). This is due largely to the different chemical behavior between Hf and W, with Hf tending to concentrate in the silicate mantle, while W goes into the metal core during metal-silicate segregation (Lee and Halliday 1996;Kleine et al 2005aKleine et al , 2005bLee 2005;Quitté et al 2005;Markowski et al 2006aMarkowski et al , 2006b).…”

Section: Introductionmentioning

confidence: 99%

¹⁸²Hf‐¹⁸²W chronometry and the early evolution history in the acapulcoite‐lodranite parent body

Lee

2008

Meteorit & Planetary Scien

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Abstract-An acapulcoite, Northwest Africa (NWA) 725, a transitional acapulcoite, Graves Nunataks (GRA) 95209, and a lodranite, NWA 2235, have been studied with the short-lived chronometer 182 Hf-182 W system in order to better constrain the early evolution history in the acapulcoite-lodranite parent body. Unlike the more evolved achondrites originating from differentiated asteroids-e.g., eucrites and angrites-bulk rock acapulcoites and lodranite are characterized by distinct 182 W deficits relative to the terrestrial W, as well as to the undifferentiated chondrites, ε w varies from −2.7 to −2.4. This suggests that live-182 Hf was present during the formation of acapulcoites and lodranites, and their parent body probably had never experienced a global melting event. Due to the large uncertainties associated with the isochron for each sample, the bulk isochron that regressed through the mineral separates from all 3 samples has provided the best estimate to date for the timing of metamorphism in the acapulcoite-lodranite parent body, 5 (+6/−5) Myr after the onset of the solar system. It is thus inconclusive whether acapulcoites and lodranites have shared the same petrogenetic origin, based on the Hf-W data of this study. Nevertheless, the formation of acapulcoite-lodranite clan appears to have post-dated the metal-silicate segregation in differentiated asteroids. This can be explained by a slower accretion rate for the acapulcoite-lodranite parent body, or that it had never accreted to a critical mass that could allow the metal-silicate segregation to occur naturally.

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“…The most promising of these tracers currently appears to be the 182 Hf-182 W isotope system, introduced in Section 3.2. This short-lived system (t ½ for 182 Hf = 8.9 Ma; Vockenhuber et al, 2004) can be used to trace the early fractionation of an incompatible lithophile trace element (Hf) from a highly incompatible MSE (W), as a result of processes that occurred within the first ~60 Ma of solar system history. For example, the observation that the 182 W/ 184 W of terrestrial rocks are ~200 ppm more radiogenic than chondrites (Kleine et al, 2002;Schoenberg et al, 2002;Yin et al, 2002b;Burkhardt et al, 2008) has led to the interpretation that the majority of terrestrial core formation occurred within the first 30 Ma of solar system history (Kleine et al, 2002;Yin et al, 2002b;Halliday, 2004;Kleine et al, 2009).…”

Section: Tungsten Isotopes In the Mantlementioning

confidence: 99%

Siderophile Elements in Tracing Planetary Formation and Evolution

Walker

2016

Geochem. Persp.

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New Half-Life Measurement ofHf182: Improved Chronometer for the Early Solar System

Cited by 164 publications

References 27 publications

Short-lived nuclei in the early Solar System: Possible AGB sources

Short-lived nuclei in the early Solar System: Possible AGB sources

¹⁸²Hf‐¹⁸²W chronometry and the early evolution history in the acapulcoite‐lodranite parent body

Siderophile Elements in Tracing Planetary Formation and Evolution

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New Half-Life Measurement ofHf182: Improved Chronometer for the Early Solar System

Cited by 164 publications

References 27 publications

Short-lived nuclei in the early Solar System: Possible AGB sources

Short-lived nuclei in the early Solar System: Possible AGB sources

182Hf‐182W chronometry and the early evolution history in the acapulcoite‐lodranite parent body

Siderophile Elements in Tracing Planetary Formation and Evolution

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¹⁸²Hf‐¹⁸²W chronometry and the early evolution history in the acapulcoite‐lodranite parent body