Interstellar oxide grains from the Tieschitz ordinary chondrite

Nittler, L. R.; Alexander, Conel M. O'd.; Gao, Xia; Walker, R. M.; Zinner, E.

doi:10.1038/370443a0

Cited by 210 publications

(185 citation statements)

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“…Isotopically anomalous Ne and Xe noble gases (Reynolds & Turner 1964;Black & Pepin 1969) were traced through successive acid dissolution steps of the meteorite host rock, resulting in the discovery of three refractory, carbonaceous presolar minerals: nanodiamond (Lewis et al 1987), SiC (Bernatowicz et al 1987;Tang & Anders 1988), and graphite (Amari et al 1990). Other presolar grain phases were subsequently discovered through alternative chemical separations, in situ analyses of meteorite thin sections, and transmission electron microscopy (TEM); these include silicate , hibonite (CaAl 12 O 19 ; Choi et al 1999), corundum (Al 2 O 3 ; Hutcheon et al 1994;Nittler et al 1994), spinel (MgAl 2 O 4 ; Nittler et al 1994), silicon nitride (Si 3 N 4 ; Nittler et al 1995), and carbide subgrains within presolar SiC and graphite grains (Bernatowicz et al 1991).…”

Section: Introductionmentioning

confidence: 99%

“…Since then evidence for 26 Al was found in presolar graphite Jadhav et al 2013;Amari et al 2014), corundum (Hutcheon et al 1994;Nittler et al 1994Nittler et al , 1997, hibonite (Choi et al 1999;Nittler et al 2008), spinel (Zinner et al 2005), and silicate (Nguyen & Zinner 2004) grains. In SiC, graphite, corundum, and hibonite, Al/Mg ratios can be very high, so Mg sometimes consists mostly of radiogenic 26 Mg ( 26 Mg*).…”

Section: Introductionmentioning

confidence: 99%

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INFERRED INITIAL²⁶Al/²⁷Al RATIOS IN PRESOLAR STARDUST GRAINS FROM SUPERNOVAE ARE HIGHER THAN PREVIOUSLY ESTIMATED

Groopman

Zinner

Amari

et al. 2015

ApJ

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We performed an in-depth exploration of the Al-Mg system for presolar graphite, SiC, and Si 3 N 4 grains found to contain large excesses of 26 ratios that, on average, are ∼1.5-2 times larger than the ratios previously reported for the grains. The majority of presolar graphite and SiC grains are heavily affected by Al contamination, resulting in large negative Mg Mg 26 24 d intercepts of the isochron lines. Al contamination is potentially due to etching of the grains' surfaces and subsequent capture of dissolved Al during the acid dissolution of their meteorite host rocks. From the isochron fits, the magnitude of Al contamination was quantified for each grain. The amount of Al contamination on each grain was found to be random and independent of grain size, following a uniform distribution with an upper bound at 59% contamination. The Al contamination causes conventional whole-grain estimates to underpredict the initial Al Al ratios greatly exceed those predicted in the He/C and He/N zones of SN models.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

INFERRED INITIAL²⁶Al/²⁷Al RATIOS IN PRESOLAR STARDUST GRAINS FROM SUPERNOVAE ARE HIGHER THAN PREVIOUSLY ESTIMATED

Groopman

Zinner

Amari

et al. 2015

ApJ

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“…The discovery of circumstellar oxide grains in meteorites [67] [68] [69] [70] and the important and extensive results by Nittler et al [70][71] [72] revealed that most of these grains also appear to come from AGB sources. Fig.…”

Section: Circumstellar Dust Grainsmentioning

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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“…Later silicon carbide (SiC; Bernatowicz et al 1987), graphite (Amari et al 1990), corundum (Al 2 O 3 ; Hutcheon et al 1994;Nittler et al 1994), silicon nitride (Si 3 N 4 ; Russell et al 1995;Nittler et al 1995), and spinel (MgAl 2 O 4 ; Nittler et al 1994) were identified. Some of the SiC and graphite grains have been found to carry small inclusions of Ti-, Mo-, and Zr-carbides (Bernatowicz et al 1991).…”

Section: Introductionmentioning

confidence: 99%

Stellar abundances and presolar grains trace the nucleosynthetic origin of molybdenum and ruthenium

Hansen¹,

Andersen

Christlieb³

2014

A&A

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This work presents a large consistent study of molybdenum (Mo) and ruthenium (Ru) abundances in the Milky Way. These two elements are important nucleosynthetic diagnostics. In our sample of 71 Galactic metal-poor field stars, we detect Ru and/or Mo in 52 of these (59 including upper limits). The sample consists of high-resolution, high signal-to-noise spectra covering both dwarfs and giants from [Fe/H] = −0.63 down to −3.16. Thus we provide information on the behaviour of Mo I and Ru I at higher and lower metallicity than is currently known. In this sample we find a wide spread in the Mo and Ru abundances, which is typical of heavy elements. We confirm earlier findings of Mo enhanced stars around [Fe/H] = −1.5 and add ∼15 stars both dwarfs and giants with normal (<0.3 dex) Mo and Ru abundances, as well as more than 15 Mo and Ru enhanced (>0.5 dex) stars to the currently known stellar sample. This indicates that several formation processes, in addition to high entropy winds, can be responsible for the formation of elements like Mo and Ru. We trace the formation processes by comparing Mo and Ru to elements (Sr, Zr, Pd, Ag, Ba, and Eu) with known formation processes. Based on how tight the two elements correlate with each other, we are able to distinguish if they share a common formation process and how important this contribution is to the element abundance. We find clear indications of contributions from several different formation processes, namely the p-process, and the slow (s-), and rapid (r-) neutron-capture processes. From these correlations we find that Mo is a highly convolved element that receives contributions from both the s-process and the p-process and less from the main and weak r-processes, whereas Ru is mainly formed by the weak r-process as is silver. We also compare our absolute elemental stellar abundances to relative isotopic abundances of presolar grains extracted from meteorites. Their isotopic abundances can be directly linked to the formation process (e.g. r-only isotopes) providing a unique comparison between observationally derived abundances and the nuclear formation process. The comparison to abundances in presolar grains shows that the r-/s-process ratios from the presolar grains match the total elemental chemical composition derived from metal-poor halo stars with [Fe/H] around −1.5 to −1.1 dex. This indicates that both grains and stars around and above [Fe/H] = −1.5 are equally (well) mixed and therefore do not support a heterogeneous presolar nebula. An inhomogeneous interstellar medium (ISM) should only be expected at lower metallicities. Our data, combined with the abundance ratios of presolar grains, could indicate that the AGB yields are less efficiently mixed into stars than into presolar grains. Finally, we detect traces of s-process material at [Fe/H] = −1.5, indicating that this process is at work at this and probably at even lower metallicity.

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Interstellar oxide grains from the Tieschitz ordinary chondrite

Cited by 210 publications

References 17 publications

INFERRED INITIAL²⁶Al/²⁷Al RATIOS IN PRESOLAR STARDUST GRAINS FROM SUPERNOVAE ARE HIGHER THAN PREVIOUSLY ESTIMATED

INFERRED INITIAL²⁶Al/²⁷Al RATIOS IN PRESOLAR STARDUST GRAINS FROM SUPERNOVAE ARE HIGHER THAN PREVIOUSLY ESTIMATED

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

Stellar abundances and presolar grains trace the nucleosynthetic origin of molybdenum and ruthenium

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Interstellar oxide grains from the Tieschitz ordinary chondrite

Cited by 210 publications

References 17 publications

INFERRED INITIAL26Al/27Al RATIOS IN PRESOLAR STARDUST GRAINS FROM SUPERNOVAE ARE HIGHER THAN PREVIOUSLY ESTIMATED

INFERRED INITIAL26Al/27Al RATIOS IN PRESOLAR STARDUST GRAINS FROM SUPERNOVAE ARE HIGHER THAN PREVIOUSLY ESTIMATED

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

Stellar abundances and presolar grains trace the nucleosynthetic origin of molybdenum and ruthenium

Contact Info

Product

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INFERRED INITIAL²⁶Al/²⁷Al RATIOS IN PRESOLAR STARDUST GRAINS FROM SUPERNOVAE ARE HIGHER THAN PREVIOUSLY ESTIMATED

INFERRED INITIAL²⁶Al/²⁷Al RATIOS IN PRESOLAR STARDUST GRAINS FROM SUPERNOVAE ARE HIGHER THAN PREVIOUSLY ESTIMATED