المؤلفون: King, A. J., Phillips, K. J. H., Strekopytov, S., Vita-Finzi, C., Russell, S. S.

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics

الوصف: The rare CI carbonaceous chondrites are the most aqueously altered and chemically primitive meteorites but due to their porous nature and high abundance of volatile elements are susceptible to terrestrial weathering. The Ivuna meteorite, type specimen for the CI chondrites, is the largest twentieth-century CI fall and least affected by terrestrial alteration. The main mass of Ivuna (BM2008 M1) has been stored in a nitrogen atmosphere at least since 2008 and is the most pristine CI chondrite stone. We report the mineralogy, petrography and bulk elemental composition of BM2008 M1 and a second Ivuna stone (BM1996 M4) stored in air. Both Ivuna stones are breccias consisting of multiple rounded, phyllosilicate-rich clasts formed through aqueous alteration followed by impact processing. A polished thin section of BM2008 M1 analysed immediately after preparation was found to contain sulphate-bearing veins formed when primary sulphides reacted with oxygen and atmospheric water. A section of BM1996 M4 lacked veins but had sulphate grains on the surface recently formed (last 6 years). Differences in the extent of terrestrial alteration recorded by BM2008 M1 and BM1996 M4 probably reflect variations in the post-recovery curation history of the stones before entering the NHM collection, and indicate that where possible pristine samples of hydrated carbonaceous should be kept out of the terrestrial environment in a stable environment to avoid modification. The bulk elemental composition of the two Ivuna stones show some variability due to their heterogeneous nature but in general are similar to previous analyses of CI chondrites. We combine our elemental abundances with literature values to calculate a new average composition for the Ivuna meteorite, which is in good agreement with existing compilations of CI chondrites and the most recent solar photospheric abundances.
Comment: Geochimica et Cosmochimica Acta (to be published)

الوصول الحر: http://arxiv.org/abs/1909.13064Test

المؤلفون: Vita-Finzi, C

المصدر: UCL Earth Sciences: London, UK. (2022)

وصف الملف: text

العلاقة: https://discovery.ucl.ac.uk/id/eprint/10141373/1Test/Vita-Finzi_The%20butterfly%20and%20the%20Sun.pdf; https://discovery.ucl.ac.uk/id/eprint/10141373Test/

الإتاحة: https://discovery.ucl.ac.uk/id/eprint/10141373/1Test/Vita-Finzi_The%20butterfly%20and%20the%20Sun.pdf
https://discovery.ucl.ac.uk/id/eprint/10141373Test/

المؤلفون: King, A.J., Phillips, K.J.H., Strekopytov, S., Vita-Finzi, C., Russell, S.S.

المساهمون: Natural History Museum, Science and Technology Facilities Council

المصدر: Geochimica et Cosmochimica Acta ; volume 268, page 73-89 ; ISSN 0016-7037

مصطلحات موضوعية: Geochemistry and Petrology

الإتاحة: https://doi.org/10.1016/j.gca.2019.09.041Test
https://api.elsevier.com/content/article/PII:S0016703719306271?httpAccept=text/xmlTest
https://api.elsevier.com/content/article/PII:S0016703719306271?httpAccept=text/plainTest

المؤلفون: Vita-Finzi, C

المصدر: UCL Department of Earth Sciences: London, UK. (2021)

مصطلحات موضوعية: solar cycle, sunspot numbers, Babcock-Leighton model, solar wind, cosmogenic isotopes, planetary hypothesis

الوصف: Sunspot numbers and shifts in their distribution display a period of approximately 11 yr, a value sometimes uncritically applied to other measures of solar activity, direct and indirect, including the 10.7 cm radio flux, the inflow of galactic cosmic rays, solar flare frequency, terrestrial weather, and components of space climate, with a possible resulting loss of information. The ruling (Babcock) hypothesis and its derivatives link the sunspot cycle to dynamo processes mediated by differential solar rotation, but despite 60 years of observation and analysis the ~11 yr periodicity remains difficult to model; the possible contribution of planetary dynamics is also still controversial. The various solar sequences that genuinely display an ~11 yr cycle stand to benefit from an understanding of its periodicity that goes beyond statistical rigour. The outcome could ironically prompt the demotion of sunspots from their dominant historical role in favour of other possible indicators of solar cyclicity, such as the solar wind flux and its isotopic signatures, even if they are less accessible.

وصف الملف: text

العلاقة: https://discovery.ucl.ac.uk/id/eprint/10140133/1Test/Vita-Finzi_dec%208%2021.pdf; https://discovery.ucl.ac.uk/id/eprint/10140133Test/

الإتاحة: https://discovery.ucl.ac.uk/id/eprint/10140133/1Test/Vita-Finzi_dec%208%2021.pdf
https://discovery.ucl.ac.uk/id/eprint/10140133Test/

المؤلفون: Vita-Finzi, C

المصدر: ArXiv: Ithaca, NY, USA. (2021)

الوصف: Operating experience from fusion research shows how Spitzer resistivity may render ohmic heating in the chromosphere self limiting and thus serve to define the lower margin of the transition region. Its upper margin is at about 6000 K, where radiative cooling of He:H plasma decelerates sharply. The third and last stage in the proposed scheme is expansion into the tenuous plasma of space, which leads to the acceleration of ions to high energies, long recorded by spacecraft instruments. There is thus dynamic continuity all the way from the solar interior, the energy source for spinning columns in the Rayleigh Benard setting of the convection zone, to the coronal exhalation of the solar wind, a finding which should benefit the analysis of space weather, witness the association between helium in the solar wind and the incidence of coronal mass ejections.

وصف الملف: text

العلاقة: https://discovery.ucl.ac.uk/id/eprint/10139899/1Test/Vita-Finzi_2101.08251.pdf; https://discovery.ucl.ac.uk/id/eprint/10139899Test/

الإتاحة: https://discovery.ucl.ac.uk/id/eprint/10139899/1Test/Vita-Finzi_2101.08251.pdf
https://discovery.ucl.ac.uk/id/eprint/10139899Test/

المؤلفون: Vita-Finzi, C.

المصدر: Philosophical Transactions: Mathematical, Physical and Engineering Sciences, 2012 May . 370(1966), 2173-2192.

الوصول الحر: https://www.jstor.org/stable/23250625Test

المؤلفون: Vita-Finzi, C.

المصدر: Astronomy & Geophysics ; volume 55, issue 4, page 4.27-4.29 ; ISSN 1366-8781 1468-4004

مصطلحات موضوعية: Geochemistry and Petrology, Geophysics, Astronomy and Astrophysics

الإتاحة: https://doi.org/10.1093/astrogeo/atu163Test

المؤلفون: Hancock, P. L., Maddock, R., Zoback, M. L., Skipp, B., Vita-Finzi, C.

المصدر: Philosophical Transactions: Physical Sciences and Engineering, 1991 Oct . 337(1645), 29-40.

الوصول الحر: https://www.jstor.org/stable/53858Test

المؤلفون: Kusznir, N. J., Vita-Finzi, C., Whitmarsh, R. B., England, P., Bott, M. H. P., Govers, R., Cartwright, J., Murrell, S.

المصدر: Philosophical Transactions: Physical Sciences and Engineering, 1991 Oct . 337(1645), 95-110.

الوصول الحر: https://www.jstor.org/stable/53863Test

المؤلفون: Vita-Finzi, C.

المصدر: The Geographical Journal, 1975 Nov 01. 141(3), 415-420.

الوصول الحر: https://www.jstor.org/stable/1796475Test