Papers by Charles Hohenberg
Abstracts of the 5th …, 1974
... C. Phinney, Consortium Leader, E. Anders, 0. Bogard, P. Butler, E. Gibson, W. Gose, G. Heiken... more ... C. Phinney, Consortium Leader, E. Anders, 0. Bogard, P. Butler, E. Gibson, W. Gose, G. Heiken, C. Hohenberg,L. Nyquist, W. Pearce, M. Rhodes, L. Silver, C. Simonds, D. Strangway, G. Turner, R. Walker, J. Warner, D. Yuhas P~DGRESS RE~RT HIIN1~JEY et al. ...
Workshop on The …, 2007
291 was the first decay product of a short-lived radionuclide to be identified in the early solar... more 291 was the first decay product of a short-lived radionuclide to be identified in the early solar system [ 1] The methodology set the precedent for future identification of other extinct radioisotopes; excesses of the decay product, 129 Xe, were identified and the magnitude ...
I-Xe isochrons are mixing lines between a single trapped and a single iodine derived component. T... more I-Xe isochrons are mixing lines between a single trapped and a single iodine derived component. The slope of this line establishes initial iodine and hence the I-Xe age. One end of the isochron is fixed by the composition of the trapped Xe component, which should be representative of the Xe that was present in the early solar system (Q-Xe or OC-Xe). Because the I/Xe ratio in the solar nebular was ~1, and the I-129/I-127 was about 10-4, the Xe-129 in trapped Xe cannot evolve appreciably with decay of I-129. While it may be possible for Xe in a closed system with elevated I/Xe ratios to evolve producing trapped components with higher Xe-129/Xe-132 ratios, trapped Xe compositions with lower (sub-planetary) Xe-129/Xe-132 ratios seem implausible.
Meteorites and the Early Solar System II
Most groups of chondritic meteorites experienced diverse styles of secondary alteration to variou... more Most groups of chondritic meteorites experienced diverse styles of secondary alteration to various degrees that resulted in formation of hydrous and anhydrous minerals (e.g., phyllosilicates, magnetite, carbonates, ferrous olivine, hedenbergite, wollastonite, grossular, andradite, nepheline, sodalite, Fe,Ni-carbides, pentlandite, pyrrhotite, and Ni-rich metal). Mineralogical, petrographic, and isotopic observations suggest that the alteration occurred in the presence of aqueous solutions under variable conditions (temperature, water/rock ratio, redox conditions, and fluid compositions) in an asteroidal setting, and, in many cases, was multistage. Although some alteration predated agglomeration of the final chondrite asteroidal bodies (i.e., was preaccretionary), it seems highly unlikely that the alteration occurred in the solar nebula, nor in planetesimals of earlier generations. Short-lived isotope chronologies (26 Al-26 Mg, 53 Mn-53 Cr, 129 I-129 Xe) of the secondary minerals indicate that the alteration started within 1-2 m.y. after formation of the Ca,Al-rich inclusions and lasted up to 15 m.y. These observations suggest that chondrite parent bodies must have accreted within the first 1-2 m.y. after collapse of the protosolar molecular cloud and provide strong evidence for an early onset of aqueous activity on these bodies.
Meteoritics
We have measured Ne, Ar, Kr, and Xe in Si2O3 'smokes' that were condensed on Al substrate... more We have measured Ne, Ar, Kr, and Xe in Si2O3 'smokes' that were condensed on Al substrates, vapor-deposited with various mixtures of CH4, NH3, H2O3 and noble gases at 10 K and subsequently irradiated with 1 MeV protons to simulate conditions during grain mantle formation in interstellar clouds. Neither Ne nor Ar is retained by the samples upon warming to
Proceedings of the 14th International Symposium on Nuclei in the Cosmos (NIC2016), 2017
The preserved record of decay of now-extinct 129 I into 129 Xe forms the basis of the I-Xe chrono... more The preserved record of decay of now-extinct 129 I into 129 Xe forms the basis of the I-Xe chronometer. Comparison of the high precision I-Xe and Pb-Pb ages of chondrules and pure mineral phases separated from eight meteorites suggests the 17.5 ÷ 14.6 Ma range for the 129 I half-life, assuming that the 235 U and 238 U half-lives are correct. The mean value of 16 Ma indicates that the 15.7 Ma half-life of 129 I used here for the I-Xe age calculations is most probably correct. Since the 129 I half-life value only affects the relative I-Xe ages, the few Ma relative to the Shallowater standard, the absolute I-Xe ages are almost immune to this uncertainty in the 129 I half-life.
Models of planetary evolution require knowledge of the base reservoir of the solar system, which ... more Models of planetary evolution require knowledge of the base reservoir of the solar system, which is dominated by the sun. Currently, the only way to accurately determine the composition of trace elements in the sun is by examining the solar wind (SW). Previous solar wind ...
Lunar and Planetary Science Conference, Mar 1, 2002
... References: [ 1] Nichols et a!. (1991) Meteoritics, in press; [2] Lewis et a!. (1990) Nature ... more ... References: [ 1] Nichols et a!. (1991) Meteoritics, in press; [2] Lewis et a!. (1990) Nature 348, 293298; [3] Gallino et a!. (1990) Nature 348, 298-302; [4] Amari et al. ... 14 ~ 12 ~ 10* ~: ~- 1 gas-r!èh~~ ~ gas-poor I ~ RII~II ``II~n JflJ ~r-~ 10 1O4~ 8 7 . `2C/'3C Fig. ...
Lunar and Planetary Science Conference, Feb 1, 2001
New, suggestive results of selective laser extraction of Xe-H were obtained for Indarch and Allen... more New, suggestive results of selective laser extraction of Xe-H were obtained for Indarch and Allende nanodiamonds. However, due to large experimental uncertainties we cannot make any certain conclusions on the separability of Xe-HL.
Lunar and Planetary Science Conference, Mar 1, 2009
Lunar and Planetary Science Conference, Mar 1, 2010
Small but statistically significant excess of 21Ne is found in outer layer of Stardust aerogel ex... more Small but statistically significant excess of 21Ne is found in outer layer of Stardust aerogel exposed to the comet.
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Papers by Charles Hohenberg