WorldWideScience

Sample records for volatile element abundances

  1. Photospheric Abundances of Volatile and Refractory Elements in Planet-Harboring Stars

    CERN Document Server

    Takeda, Y; Kambe, E; Aoki, W; Honda, S; Kawanomoto, S; Masuda, S; Izumiura, H; Watanabe, E; Koyano, H; Maehara, H; Norimoto, Y; Okada, T; Shimizu, Y; Uraguchi, F; Yanagisawa, K; Yoshida, M; Miyama, S; Ando, H

    2001-01-01

    By using the high-dispersion spectra of 14 bright planet-harboring stars (along with 4 reference stars) observed with the new coude echelle spectrograph at Okayama Astrophysical Observatory, we investigated the abundances of volatile elements (C, N, O, S, Zn; low condensation temperature Tc) in order to examine whether these show any significant difference compared to the abundances of other refractory elements (Si, Ti, V, Fe, Co, Ni; high Tc) which are known to be generally overabundant in those stars with planets, since a Tc-dependence is expected if the cause of such a metal-richness is due to the accretion of solid planetesimals onto the host star. We found, however, that all elements we studied behave themselves quite similarly to Fe (i.e., [X/Fe]~0) even for the case of volatile elements, which may suggest that the enhanced metallicity in those planet-bearing stars is not so much an acquired character (by accretion of rocky material) as rather primordial.

  2. Determination of Trace and Volatile Element Abundance Systematics of Lunar Pyroclastic Glasses 74220 and 15426 Using LA-ICP-MS

    Science.gov (United States)

    McIntosh, E. Carrie; Porrachia, Magali; McCubbin, Francis M.; Day, James M. D.

    2017-01-01

    Since their recognition as pyroclastic glasses generated by volcanic fire fountaining on the Moon, 74220 and 15426 have garnered significant scientific interest. Early studies recognized that the glasses were particularly enriched in volatile elements on their surfaces. More recently, detailed analyses of the interiors of the glasses, as well as of melt inclusions within olivine grains associated with the 74220 glass beads, have determined high H2O, F, Cl and S contents. Such elevated volatile contents seem at odds with evidence from moderately volatile elements (MVE), such as Zn and K, for a volatile- depleted Moon. In this study, we present initial results from an analytical campaign to study trace element abundances within the pyroclastic glass beads. We report trace element data determined by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for 15426 and 74220.

  3. Mars Accreted a Volatile Element-Depleted Late Veneer Indicating Early Delivery of Martian Volatiles

    Science.gov (United States)

    Becker, H.; Wang, Z.

    2016-08-01

    Chalcophile elements in SNC meteorites are used to constrain abundances in the Martian mantle. Strong depletion of Te relative to highly siderophile elements suggests a volatile element-depleted late veneer, requiring that volatiles arrived earlier.

  4. Sunspots, Starspots, and Elemental Abundances

    Science.gov (United States)

    Doschek, George A.; Warren, Harry P.

    2017-08-01

    The composition of plasma in solar and stellar atmospheres is not fixed, but varies from feature to feature. These variations are organized by the First Ionization Potential (FIP) of the element. Solar measurements often indicate that low FIP elements (10 eV, such as C, N, O, Ar, He) compared to abundances in the photosphere. Stellar observations have also shown similar enrichments. An inverse FIP effect, where the low FIP elements are depleted, has been observed in stellar coronae of stars believed to have large starspots in their photospheres. The abundances are important for determining radiative loss rates in models, tracing the origin of the slow solar wind, and for understanding wave propagation in the chromosphere and corona. Recently, inverse FIP effects have been discovered in the Sun (Doschek, Warren, & Feldman 2015, ApJ, 808, L7) from spectra obtained by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft. The inverse FIP regions seem always to be near sunspots and cover only a very small area (characteristic length = a few arcseconds). However, in pursuing the search for inverse FIP regions, we have found that in some sunspot groups the coronal abundance at a temperature of 3-4 MK can be near photospheric over much larger areas of the sun near the sunspots (e.g., 6,000 arcsec2). Also, sometimes the abundances at 3-4 MK are in between coronal and photospheric values. This can occur in small areas of an active region. It is predicted (Laming 2015, Sol. Phys., 12, 2) that the FIP effect should be highly variable in the corona. Several examples of coronal abundance variations are presented. Our work indicates that a comprehensive re-investigation of solar abundances is highly desirable. This work is supported by a NASA Hinode grant.

  5. Core-Mantle Partitioning of Volatile Siderophile Elements and the Origin of Volatile Elements in the Earth

    Science.gov (United States)

    Nickodem, K.; Righter, K.; Danielson, L.; Pando, K.; Lee, C.

    2012-01-01

    There are currently several hypotheses on the origin of volatile siderophile elements in the Earth. One hypothesis is that they were added during Earth s accretion and core formation and mobilized into the metallic core [1], others claim multiple stage origin [2], while some hypothesize that volatiles were added after the core already formed [3]. Several volatile siderophile elements are depleted in Earth s mantle relative to the chondrites, something which continues to puzzle many scientists. This depletion is likely due to a combination of volatility and core formation. The Earth s core is composed of Fe and some lighter constituents, although the abundances of these lighter elements are unknown [4]. Si is one of these potential light elements [5] although few studies have analyzed the effect of Si on metal-silicate partitioning, in particular the volatile elements. As, In, Ge, and Sb are trace volatile siderophile elements which are depleted in the mantle but have yet to be extensively studied. The metal-silicate partition coefficients of these elements will be measured to determine the effect of Si. Partition coefficients depend on temperature, pressure, oxygen fugacity, and metal and silicate composition and can constrain the concentrations of volatile, siderophile elements found in the mantle. Reported here are the results from 13 experiments examining the partitioning of As, In, Ge, and Sb between metallic and silicate liquid. These experiments will examine the effect of temperature, and metal-composition (i.e., Si content) on these elements in or-der to gain a greater understanding of the core-mantle separation which occurred during the Earth s early stages. The data can then be applied to the origin of volatile elements in the Earth.

  6. New functionalities in abundant element oxides: ubiquitous element strategy.

    Science.gov (United States)

    Hosono, Hideo; Hayashi, Katsuro; Kamiya, Toshio; Atou, Toshiyuki; Susaki, Tomofumi

    2011-06-01

    While most ceramics are composed of ubiquitous elements (the ten most abundant elements within the Earth's crust), many advanced materials are based on rare elements. A 'rare-element crisis' is approaching owing to the imbalance between the limited supply of rare elements and the increasing demand. Therefore, we propose a 'ubiquitous element strategy' for materials research, which aims to apply abundant elements in a variety of innovative applications. Creation of innovative oxide materials and devices based on conventional ceramics is one specific challenge. This review describes the concept of ubiquitous element strategy and gives some highlights of our recent research on the synthesis of electronic, thermionic and structural materials using ubiquitous elements.

  7. Element abundances at high redshift

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, D.M.; Welty, D.E.; York, D.G. (Northwestern Univ., Evanston, IL (USA); Chicago Univ., IL (USA))

    1989-08-01

    Abundances of Si(+), S(+), Cr(+), Mn(+), Fe( ), and Zn(+) are considered for two absorption-line systems in the spectrum of the QSO PKS 0528 - 250. Zinc and sulfur are underabundant, relative to H, by a factor of 10 compared to their solar and Galactic interstellar abundances. The silicon-, chromium-, iron-, and nickel-to-hydrogen ratios are less than the solar values and comparable to the local interstellar ratios. A straightforward interpretation is that nucleosynthesis in these high-redshift systems has led to only about one-tenth as much heavy production as in the gas clouds around the sun, and that the amount of the observed underabundances attributable to grain depletion is small. The dust-to-gas ratio in these clouds is less than 8 percent of the Galactic value. 25 refs.

  8. Element abundances at high redshift

    Science.gov (United States)

    Meyer, David M.; Welty, D. E.; York, D. G.

    1989-01-01

    Abundances of Si(+), S(+), Cr(+), Mn(+), Fe(_), and Zn(+) are considered for two absorption-line systems in the spectrum of the QSO PKS 0528 - 250. Zinc and sulfur are underabundant, relative to H, by a factor of 10 compared to their solar and Galactic interstellar abundances. The silicon-, chromium-, iron-, and nickel-to-hydrogen ratios are less than the solar values and comparable to the local interstellar ratios. A straightforward interpretation is that nucleosynthesis in these high-redshift systems has led to only about one-tenth as much heavy production as in the gas clouds around the sun, and that the amount of the observed underabundances attributable to grain depletion is small. The dust-to-gas ratio in these clouds is less than 8 percent of the Galactic value.

  9. Mars and earth - Origin and abundance of volatiles

    Science.gov (United States)

    Anders, E.; Owen, T.

    1977-01-01

    An investigation is conducted concerning the factors which are responsible for the tenuous nature of the Martian atmosphere in comparison to the terrestrial atmosphere, taking into account new data obtained in connection with the Viking missions. It is found that Mars was poor in volatiles from the start and fell further behind earth by less complete outgassing, by extensive retrapping, and by the partial loss of lighter gases. Attention is given to noble gases on earth and Mars, the condensation of noble gases and other volatiles, the sources of earth's volatiles, the bulk composition of earth, the release of volatiles from earth, clues to the volatile endowment of Mars, an abundance table for Mars, a comparison of terrestrial and Martian conditions, isotopic data on noble gases, xenon-129 on Mars and earth, possibilities concerning the loss of an early Martian atmosphere, the evolution of the atmosphere of Mars, conditions in the case of planet Venus, and the reasons for the poorness of small planets in volatiles.

  10. Coronae of Stars with Supersolar Elemental Abundances

    Science.gov (United States)

    Peretz, Uria; Behar, Ehud; Drake, Stephen A.

    2015-01-01

    Coronal elemental abundances are known to deviate from the photospheric values of their parent star, with the degree of deviation depending on the first ionization potential (FIP). This study focuses on the coronal composition of stars with supersolar photospheric abundances. We present the coronal abundances of six such stars: 11 LMi, iota Hor, HR 7291, tau Boo, and alpha Cen A and B. These stars all have high-statistics X-ray spectra, three of which are presented for the first time. The abundances we measured were obtained using the line-resolved spectra of the Reflection Grating Spectrometer (RGS) in conjunction with the higher throughput EPIC-pn camera spectra onboard the XMM-Newton observatory. A collisionally ionized plasma model with two or three temperature components is found to represent the spectra well. All elements are found to be consistently depleted in the coronae compared to their respective photospheres. For 11 LMi and tau Boo no FIP effect is present, while iota Hor, HR 7291, and alpha Cen A and B show a clear FIP trend. These conclusions hold whether the comparison is made with solar abundances or the individual stellar abundances. Unlike the solar corona, where low-FIP elements are enriched, in these stars the FIP effect is consistently due to a depletion of high-FIP elements with respect to actual photospheric abundances. A comparison with solar (instead of stellar) abundances yields the same fractionation trend as on the Sun. In both cases, a similar FIP bias is inferred, but different fractionation mechanisms need to be invoked.

  11. Stability and `volatility ` of element 104 oxychloride

    Energy Technology Data Exchange (ETDEWEB)

    Eichler, B.; Gaeggeler, H.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    The formation enthalpies {Delta}H{sup *} of solid and gaseous oxychlorides of element 104 from free atoms were estimated by extrapolation. Stability and volatility of these compounds are compared to those of the homologous and neighbouring elements in the periodic system. It can be supposed that in a gas adsorption chromatographic process with oxygen containing chlorinating carrier gas the transport with the carrier gas flow occurs in the chemical state 104Cl{sub 4}. Only in the absorbed state the compound 104OCl{sub 2} is formed. (author) 1 fig., 3 refs.

  12. Earth Abundant Element Type I Clathrate Phases

    Directory of Open Access Journals (Sweden)

    Susan M. Kauzlarich

    2016-08-01

    Full Text Available Earth abundant element clathrate phases are of interest for a number of applications ranging from photovoltaics to thermoelectrics. Silicon-containing type I clathrate is a framework structure with the stoichiometry A8-xSi46 (A = guest atom such as alkali metal that can be tuned by alloying and doping with other elements. The type I clathrate framework can be described as being composed of two types of polyhedral cages made up of tetrahedrally coordinated Si: pentagonal dodecahedra with 20 atoms and tetrakaidecahedra with 24 atoms in the ratio of 2:6. The cation sites, A, are found in the center of each polyhedral cage. This review focuses on the newest discoveries in the group 13-silicon type I clathrate family: A8E8Si38 (A = alkali metal; E = Al, Ga and their properties. Possible approaches to new phases based on earth abundant elements and their potential applications will be discussed.

  13. Earth's moderately volatile element composition may not be chondritic: Evidence from In, Cd and Zn

    Science.gov (United States)

    Wang, Zaicong; Laurenz, Vera; Petitgirard, Sylvain; Becker, Harry

    2016-02-01

    Current models assume that siderophile volatile elements (SVE) are depleted in bulk Earth to the same extent as lithophile elements of similar volatility. The observed additional depletion of many SVE relative to lithophile elements in the bulk silicate Earth (BSE) is ascribed to partitioning of SVE into Earth's core. However, the assumption of similar volatility of moderately volatile elements during Earth formation processes as in solar gas is quite uncertain. Here, these assumptions will be tested by assessing abundances and ratios of indium and cadmium in the BSE using new data on mantle rocks, and the application of high- and low-pressure-temperature metal-silicate partitioning data. New bulk rock abundance data of In and Cd obtained on bulk rocks of peridotite tectonites and xenoliths by isotope dilution refine previous results inferred from basalts and in-situ analyses of silicate minerals in peridotite xenoliths. The CI chondrite-normalized abundance of In in the BSE is similar to zinc and is 3-4 times higher than Cd. New and published low- and high-P-T metal-silicate partitioning data indicate that, during core formation at a range of conditions, In is always more siderophile than Zn and Cd. Adding the fraction of these elements in Earth's core to the BSE results in bulk Earth compositions that yield higher CI chondrite normalized abundances of In in the bulk Earth compared to Zn and Cd. Because In is more volatile than Zn and Cd in gas of solar composition, suprachondritic In/Zn and In/Cd in the bulk Earth suggest that during formation of Earth or its building materials, the volatilities of these elements and perhaps other volatile elements likely have changed significantly (i.e. In became less volatile). The results also suggest that known carbonaceous chondrites likely did not deliver the main volatile element-rich fraction of the Earth. Various arguments suggest that the loss of moderately volatile elements during planetary accretion should be limited

  14. Elemental Abundances of Solar Sibling Candidates

    Science.gov (United States)

    Ramírez, I.; Bajkova, A. T.; Bobylev, V. V.; Roederer, I. U.; Lambert, D. L.; Endl, M.; Cochran, W. D.; MacQueen, P. J.; Wittenmyer, R. A.

    2014-06-01

    Dynamical information along with survey data on metallicity and in some cases age have been used recently by some authors to search for candidates of stars that were born in the cluster where the Sun formed. We have acquired high-resolution, high signal-to-noise ratio spectra for 30 of these objects to determine, using detailed elemental abundance analysis, if they could be true solar siblings. Only two of the candidates are found to have solar chemical composition. Updated modeling of the stars' past orbits in a realistic Galactic potential reveals that one of them, HD 162826, satisfies both chemical and dynamical conditions for being a sibling of the Sun. Measurements of rare-element abundances for this star further confirm its solar composition, with the only possible exception of Sm. Analysis of long-term high-precision radial velocity data rules out the presence of hot Jupiters and confirms that this star is not in a binary system. We find that chemical tagging does not necessarily benefit from studying as many elements as possible but instead from identifying and carefully measuring the abundances of those elements that show large star-to-star scatter at a given metallicity. Future searches employing data products from ongoing massive astrometric and spectroscopic surveys can be optimized by acknowledging this fact.

  15. Elemental abundances of solar sibling candidates

    Energy Technology Data Exchange (ETDEWEB)

    Ramírez, I.; Lambert, D. L.; Endl, M.; Cochran, W. D.; MacQueen, P. J. [McDonald Observatory and Department of Astronomy, University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, Texas 78712-1205 (United States); Bajkova, A. T.; Bobylev, V. V. [Central (Pulkovo) Astronomical Observatory of RAS, 65/1, Pulkovskoye Chaussee, St. Petersburg 196140 (Russian Federation); Roederer, I. U. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Wittenmyer, R. A. [School of Physics, UNSW Australia, Sydney 2052 (Australia)

    2014-06-01

    Dynamical information along with survey data on metallicity and in some cases age have been used recently by some authors to search for candidates of stars that were born in the cluster where the Sun formed. We have acquired high-resolution, high signal-to-noise ratio spectra for 30 of these objects to determine, using detailed elemental abundance analysis, if they could be true solar siblings. Only two of the candidates are found to have solar chemical composition. Updated modeling of the stars' past orbits in a realistic Galactic potential reveals that one of them, HD 162826, satisfies both chemical and dynamical conditions for being a sibling of the Sun. Measurements of rare-element abundances for this star further confirm its solar composition, with the only possible exception of Sm. Analysis of long-term high-precision radial velocity data rules out the presence of hot Jupiters and confirms that this star is not in a binary system. We find that chemical tagging does not necessarily benefit from studying as many elements as possible but instead from identifying and carefully measuring the abundances of those elements that show large star-to-star scatter at a given metallicity. Future searches employing data products from ongoing massive astrometric and spectroscopic surveys can be optimized by acknowledging this fact.

  16. Elemental abundances and minimum mass of heavy elements in the envelope of HD 189733b

    CERN Document Server

    Mousis, Olivier; Tinetti, Giovanna; Griffith, Caitlin A; Showman, Adam P; Alibert, Yann; Beaulieu, Jean-Philippe

    2009-01-01

    Oxygen (O) and carbon (C) have been inferred recently to be subsolar in abundance from spectra of the atmosphere of the transiting hot Jupiter HD 189733b. Yet, the mass and radius of the planet coupled with structure models indicate a strongly supersolar abundance of heavy elements in the interior of this object. Here we explore the discrepancy between the large amount of heavy elements suspected in the planet's interior and the paucity of volatiles measured in its atmosphere. We describe the formation sequence of the icy planetesimals formed beyond the snow line of the protoplanetary disk and calculate the composition of ices ultimately accreted in the envelope of HD 189733b on its migration pathway. This allows us to reproduce the observed volatile abundances by adjusting the mass of ices vaporized in the envelope. The predicted elemental mixing ratios should be 0.15--0.3 times solar in the envelope of HD 189733b if they are fitted to the recent O and C determinations. However, our fit to the minimum mass o...

  17. Elemental Abundances of Solar Sibling Candidates

    CERN Document Server

    Ramirez, I; Bobylev, V V; Roederer, I U; Lambert, D L; Endl, M; Cochran, W D; MacQueen, P J; Wittenmyer, R A

    2014-01-01

    Dynamical information along with survey data on metallicity and in some cases age have been used recently by some authors to search for candidates of stars that were born in the cluster where the Sun formed. We have acquired high resolution, high signal-to-noise ratio spectra for 30 of these objects to determine, using detailed elemental abundance analysis, if they could be true solar siblings. Only two of the candidates are found to have solar chemical composition. Updated modeling of the stars' past orbits in a realistic Galactic potential reveals that one of them, HD162826, satisfies both chemical and dynamical conditions for being a sibling of the Sun. Measurements of rare-element abundances for this star further confirm its solar composition, with the only possible exception of Sm. Analysis of long-term high-precision radial velocity data rules out the presence of hot Jupiters and confirms that this star is not in a binary system. We find that chemical tagging does not necessarily benefit from studying a...

  18. New Elemental Abundances for V1974 Cygni

    CERN Document Server

    Vanlandingham, K M; Shore, S N; Starrfield, S; Wagner, R M

    2005-01-01

    We present a new analysis of existing optical and ultraviolet spectra of the ONeMg nova V1974 Cygni 1992. Using these data and the photoionization code Cloudy, we have determined the physical parameters and elemental abundances for this nova. Many of the previous studies of this nova have made use of incorrect analyses and hence a new study was required. Our results show that the ejecta are enhanced, relative to solar, in helium, nitrogen, oxygen, neon, magnesium and iron. Carbon was found to be subsolar. We find an ejected mass of ~2x10e-4 solar masses. Our model results fit well with observations taken at IR, radio, sub-millimeter and X-ray wavelengths.

  19. Core-Mantle Partitioning of Volatile Elements and the Origin of Volatile Elements in Earth and Moon

    Science.gov (United States)

    Righter, K.; Pando, K.; Danielson, L.; Nickodem, K.

    2014-01-01

    Depletions of siderophile elements in mantles have placed constraints on the conditions on core segregation and differentiation in bodies such as Earth, Earth's Moon, Mars, and asteroid 4 Vesta. Among the siderophile elements there are a sub-set that are also volatile (volatile siderophile elements or VSE; Ga, Ge, In, As, Sb, Sn, Bi, Zn, Cu, Cd), and thus can help to constrain the origin of volatile elements in these bodies, and in particular the Earth and Moon. One of the fundamental observations of the geochemistry of the Moon is the overall depletion of volatile elements relative to the Earth, but a satisfactory explanation has remained elusive. Hypotheses for Earth include addition during accretion and core formation and mobilized into the metallic core, multiple stage origin, or addition after the core formed. Any explanation for volatile elements in the Earth's mantle must also be linked to an explanation of these elements in the lunar mantle. New metal-silicate partitioning data will be applied to the origin of volatile elements in both the Earth and Moon, and will evaluate theories for exogenous versus endogenous origin of volatile elements.

  20. Origin of Volatiles in Earth: Indigenous Versus Exogenous Sources Based on Highly Siderophile, Volatile Siderophile, and Light Volatile Elements

    Science.gov (United States)

    Righter, K.; Danielson, L.; Pando, K. M.; Marin, N.; Nickodem, K.

    2015-01-01

    Origin of Earth's volatiles has traditionally been ascribed to late accretion of material after major differentiation events - chondrites, comets, ice or other exogenous sources. A competing theory is that the Earth accreted its volatiles as it was built, thus water and other building blocks were present early and during differentiation and core formation (indigenous). Here we discuss geochemical evidence from three groups of elements that suggests Earth's volatiles were acquired during accretion and did not require additional sources after differentiation.

  1. Abundance of He-3 and other solar-wind-derived volatiles in lunar soil

    Science.gov (United States)

    Swindle, Timothy D.

    Volatiles implanted into the lunar regolith by the solar wind are potentially important lunar resources. Wittenberg et al. (1986) have proposed that lunar He-3 could be used as a fuel for terrestrial nuclear fusion reactors. They argue that a fusion scheme involving D and He-3 would be cleaner and more efficient than currently-proposed schemes involving D and T. However, since the terrestrial inventory of He-3 is so small, they suggest that the lunar regolith, with concentrations of the order of parts per billion (by mass) would be an economical source of He-3. Solar-wind implantation is also the primary source of H, C, and N in lunar soil. These elements could also be important, particularly for life support and for propellant production. In a SERC study of the feasibility of obtaining the necessary amount of He-3, Swindle et al. (1990) concluded that the available amount is sufficient for early reactors, at least, but that the mining problems, while not necessarily insurmountable, are prodigious. The volatiles H, C, and N, on the other hand, come in parts per million level abundances. The differences in abundances mean that (1) a comparable amount of H, C, and/or N could be extracted with orders of magnitude smaller operations than required for He-3, and (2) if He-3 extraction ever becomes important, huge quantities of H, C, and N will be produced as by-products.

  2. Rubidium isotopes in primitive chondrites: Constraints on Earth's volatile element depletion and lead isotope evolution

    Science.gov (United States)

    Nebel, O.; Mezger, K.; van Westrenen, W.

    2011-05-01

    The bulk silicate Earth (BSE) shows substantial deficits in volatile elements compared to CI-chondrites and solar abundances. These deficits could be caused by pre-accretionary depletion in the solar nebula during condensation of solids, or by later heat-driven evaporation during collision of small bodies that later accreted to form the Earth. The latter is considered to result in isotope fractionation for elements with low condensation temperatures that correlates with the degree of depletion. Here, we report first high-precision isotope ratio measurements of the moderately volatile and lithophile trace element Rb. Data from seventeen chondrite meteorites show that their Rb isotope abundances are nearly indistinguishable from Earth, not deviating more than 1 per mil in their 87Rb/85Rb. The almost uniform solar system Rb isotope pool suggests incomplete condensation or evaporation in a single stage is unlikely to be the cause of the volatile element deficit of the Earth. As Rb and Pb have similar condensation temperatures, we use their different degrees of depletion in the BSE to address the mechanisms and timing of terrestrial volatile depletion. The Rb isotope data are consistent with a scenario in which the volatile budget of the Earth was generated by a mixture of a highly volatile-element depleted early Proto-Earth with undepleted material in the course of terrestrial accretion. Observed Pb and Rb abundances and U-Pb and Rb-Sr isotope systematics suggest that volatile addition occurred at approximately the same time at which last core-mantle equilibration was achieved. In line with previous suggestions, this last equilibration involved a second stage of Pb (but not Rb) depletion from the BSE. The timing of this second Pb loss event can be constrained to ~ 110 Ma after the start of the solar system. This model supports a scenario with core storage of Pb in the aftermath of a putative Moon forming giant impact that also delivered the bulk of the volatile

  3. Trace-element abundances in several new ureilites

    Science.gov (United States)

    Boynton, William V.; Hill, Dolores H.

    1993-01-01

    Four new ureilites are analyzed for trace-element abundances. Frontier Mountain (FRO) 90054 is an augite-rich ureilite and has high rare earth element (REE) abundances with a pattern expected of augite. FRO 90036 and Acfer 277 have REE patterns similar to the V-shape pattern of other ureilites. Nuevo Mercurio (b) has very high REE abundances, but they look like they are due to terrestrial alteration. The siderophile-element pattern of these ureilites are similar to those of known ureilites.

  4. Quasar Elemental Abundances at High Redshifts

    DEFF Research Database (Denmark)

    Dietrich, M.; Hamann, F.; Shields, J. C.

    2003-01-01

    We examine rest-frame ultraviolet spectra of 70 high redshift quasars (z>3.5) to study the chemical enrichment history of the gas closely related to the quasars, and thereby estimate the epoch of first star formation. The fluxes of several ultraviolet emission lines were investigated within...... the framework of the most recent photoionization models to estimate the metallicity of the gas associated with the high-z quasars. Standard photoionization parameters and the assumption of secondary nitrogen enrichment indicate an average abundance of Z/Z_sol = 4 to 5 in the line emitting gas. Assuming a time...... scale of t_evol = 0.5 - 0.8 Gyrs for the chemical enrichment of the gas, the first major star formation for quasars with z>=4 should have started at a redshift of z_f = 6 - 8, corresponding to an age of the universe of several 10^8 yrs (H_o = 65 km/s/Mpc, Omega_M = 0.3, Omega_Lambda = 0.7). We note...

  5. Quasar Elemental Abundances at High Redshifts

    CERN Document Server

    Dietrich, M; Shields, J C; Constantin, A; Heidt, J; Jäger, K; Vestergaard, M; Wagner, S J

    2003-01-01

    We examine rest-frame ultraviolet spectra of 70 high redshift quasars (z>3.5) to study the chemical enrichment history of the gas closely related to the quasars, and thereby estimate the epoch of first star formation. The fluxes of several ultraviolet emission lines were investigated within the framework of the most recent photoionization models to estimate the metallicity of the gas associated with the high-z quasars. Standard photoionization parameters and the assumption of secondary nitrogen enrichment indicate an average abundance of Z/Z_sol = 4 to 5 in the line emitting gas. Assuming a time scale of t_evol = 0.5 - 0.8 Gyrs for the chemical enrichment of the gas, the first major star formation for quasars with z>=4 should have started at a redshift of z_f = 6 - 8, corresponding to an age of the universe of several 10^8 yrs (H_o = 65 km/s/Mpc, Omega_M = 0.3, Omega_Lambda = 0.7). We note that this also appears to be the era of re-ionization of the universe. Finally, there is some evidence for a positive lum...

  6. The RAVE Catalog of Stellar Elemental Abundances: First Data Release

    NARCIS (Netherlands)

    Boeche, C.; Siebert, A.; Williams, M.; de Jong, R. S.; Steinmetz, M.; Fulbright, J. P.; Ruchti, G. R.; Bienaymé, O.; Bland-Hawthorn, J.; Campbell, R.; Freeman, K. C.; Gibson, B. K.; Gilmore, G.; Grebel, E. K.; Helmi, A.; Munari, U.; Navarro, J. F.; Parker, Q. A.; Reid, W.; Seabroke, G. M.; Siviero, A.; Watson, F. G.; Wyse, R. F. G.; Zwitter, T.

    2011-01-01

    We present chemical elemental abundances for 36,561 stars observed by the RAdial Velocity Experiment (RAVE), an ambitious spectroscopic survey of our Galaxy at Galactic latitudes |b| > 25° and with magnitudes in the range 9

  7. The Solar Heavy Element Abundances: I. Constraints from Stellar Interiors

    CERN Document Server

    Delahaye, F; Delahaye, Franck; Pinsonneault, Marc

    2005-01-01

    The latest solar atmosphere models include non-LTE corrections and 3D hydrodynamic convection simulations. These models predict a significant reduction in the solar metal abundance, which leads to a serious conflict between helioseismic data and the predictions of solar interiors models. We demonstrate that the helioseismic constraints on the surface convection zone depth and helium abundance combined with stellar interiors models can be used to define the goodness of fit for a given chemical composition. After a detailed examination of the errors in the theoretical models we conclude that models constructed with the older solar abundances are consistent (<2 \\sigma) with the seismic data. Models constructed with the proposed new low abundance scale are strongly disfavored, disagreeing at the 15 \\sigma level. We then use the sensitivity of the seismic properties to abundance changes to invert the problem and infer a seismic solar heavy element abundance mix with two components: meteoritic abundances, and th...

  8. A Comparison of Stellar Elemental Abundance Techniques and Measurements

    CERN Document Server

    Hinkel, Natalie R; Pagano, Michael D; Desch, Steven J; Anbar, Ariel D; Adibekyan, Vardan; Blanco-Cuaresma, Sergi; Carlberg, Joleen K; Mena, Elisa Delgado; Liu, Fan; Nordlander, Thomas; Sousa, Sergio G; Korn, Andreas; Gruyters, Pieter; Heiter, Ulrike; Jofre, Paula; Santos, Nuno C; Soubiran, Caroline

    2016-01-01

    Stellar elemental abundances are important for understanding the fundamental properties of a star or stellar group, such as age and evolutionary history, as well as the composition of an orbiting planet. However, as abundance measurement techniques have progressed, there has been little standardization between individual methods and their comparisons. As a result, different stellar abundance procedures determine measurements that vary beyond quoted error for the same elements within the same stars (Hinkel et al. 2014). The purpose of this paper is to better understand the systematic variations between methods and offer recommendations for producing more accurate results in the future. We have invited a number of participants from around the world (Australia, Portugal, Sweden, Switzerland, and USA) to calculate ten element abundances (C, O, Na, Mg, Al, Si, Fe, Ni, Ba, and Eu) using the same stellar spectra for four stars (HD361, HD10700, HD121504, HD202206). Each group produced measurements for each of the sta...

  9. A Synthesis of Experimental Data Describing the Partitioning of Moderately Volatile Elements in Major Rock Forming Minerals: Implications for the Moon

    Science.gov (United States)

    Vander Kaaden, Kathleen E.; Draper, David S.; McCubbin, Francis M.; Neal, Clive R.; Taylor, G. Jeffrey

    2017-01-01

    Highly volatile elements [condensation temperatures below about 700 K] and water are highly informative about lunar bulk composition (hence origin), differentiation and magmatic evolution, and the role of impacts in delivering volatiles to the Moon. Fractionation of volatile elements compared to moderately volatile and refractory elements are informative about high-temperature conditions that operated in the proto-lunar disk. Existing data show clearly that the Moon is depleted in volatile elements compared to the bulk silicate Earth. For example, K/Th is 400-700 in the Moon compared to 2800-3000 in Earth. A complicating factor is that the abundances of the highly volatile elements in major lunar lithologies vary by approximately two orders of magnitude. Perhaps most interesting, H2O is not correlated with the concentration of volatile elements, indicating a decoupling of highly volatile elements from the even more volatile H2O. We contend that this decoupling could be a significant tracer of processes operating during lunar formation, differentiation, and bombardment, and the combination of analyzing both volatile elements and water is likely to provide significant insight into lunar geochemical history. This variation and lack of correlation raises the question: what were the relative contributions of crystallization in the magma ocean, subsequent mantle overturn, production of secondary magmas, and addition of volatiles by large impacts in producing this apparently large range in volatile abundances? This current study will produce new partitioning data relevant to the role and distribution of the volatile and non-volatile, yet geochemically significant elements (Co, Ni, Zn, Se, Rb, Sr, Mo, Ag, Cd, In, Sb, Ce, Yb, Tl, Pb, Bi) during the thermal and magmatic evolution of the Moon.

  10. Fe-peak element abundances in disk and halo stars

    CERN Document Server

    Bergemann, Maria

    2009-01-01

    At present none of Galactic chemical evolution (GCE) models provides a self-consistent description of observed trends for all iron-peak elements with metallicity simultaneously. The question is whether the discrepancy is due to deficiencies of GCE models, such as stellar yields, or due to erroneous spectroscopically-determined abundances of these elements in metal-poor stars. The present work aims at a critical reevaluation of the abundance trends for several odd and even-Z Fe-peak elements, which are important for understanding explosive nucleosynthesis in supernovae.

  11. Elemental abundances of intermediate age open cluster NGC 3680

    CERN Document Server

    Mitschang, A W; Zucker, D B

    2012-01-01

    We present a new abundance analysis of the intermediate age Galactic open cluster NGC 3680, based on high resolution, high signal-to-noise VLT/UVES spectroscopic data. Several element abundances are presented for this cluster for the first time, but most notably we derive abundances for the light and heavy s-process elements Y, Ba, La, and Nd. The serendipitous measurement of the rare-earth r-process element Gd is also reported. This cluster exhibits a significant enhancement of Na in giants as compared to dwarfs, which may be a proxy for an O to Na anti-correlation as observed in Galactic globular clusters but not open clusters. We also observe a step-like enhancement of heavy s-process elements towards higher atomic number, contrary to expectations from AGB nucleosynthesis models, suggesting that the r-process played a significant role in the generation of both La and Nd in this cluster

  12. The Origin of Element Abundance Variations in Solar Energetic Particles

    Science.gov (United States)

    Reames, Donald V.

    2016-08-01

    Abundance enhancements, during acceleration and transport in both gradual and impulsive solar energetic particle (SEP) events, vary approximately as power laws in the mass-to-charge ratio [A/Q] of the ions. Since the Q-values depend upon the electron temperature of the source plasma, this has allowed a determination of this temperature from the pattern of element-abundance enhancements and a verification of the expected inverse-time dependence of the power of A/Q for diffusive transport of ions from the SEP events, with scattering mean free paths found to be between 0.2 and 1 AU. SEP events derived from plasma of different temperatures map into different regions in typical cross-plots of abundances, spreading the distributions. In comparisons of SEP events with temperatures above 2 MK, impulsive events show much broader non-thermal variation of abundances than do gradual events. The extensive shock waves accelerating ions in gradual events may average over much of an active region where numerous but smaller magnetic reconnections, "nanojets", produce suprathermal seed ions, thus averaging over varying abundances, while an impulsive SEP event only samples one local region of abundance variations. Evidence for a reference He/O-abundance ratio of 91, rather than 57, is also found for the hotter plasma. However, while this is similar to the solar-wind abundance of He/O, the solar-wind abundances otherwise provide an unacceptably poor reference for the SEP-abundance enhancements, generating extremely large errors.

  13. The role of chondrules in nebular fractionations of volatiles and other elements

    Science.gov (United States)

    Grossman, J. N.

    1994-01-01

    For at least 30 years, cosmochemists have been grappling with the question of how and why groups of geochemically and volatility related elements became fractionated in the major chondrite groups. At least five relatively independent fractionations are known. Virtually everyone who has thought about these facts has been attempted to attribute at least some of the fractionations to the physical separation or mixing of the visible components. By far the most abundant of these components in meteorites is chondrules, and indeed chondrules have long been suspected of playing a direct role in fractionation of volatile elements. The question addressed here is whether chondrules formed before or after chemical components became separated is of fundamental importance to our understanding of the early solar system, as the answer constrains how, when, where, and from what chondrules formed, and tells us about how materials were processed in the nebula.

  14. Peculiarities of {\\alpha}-element abundances in Galactic open clusters

    CERN Document Server

    Marsakov, V A; Koval', V V; Shpigel', L V

    2016-01-01

    A catalog compiling the parameters of 346 open clusters, including their metallicities, positions, ages, and velocities has been composed. The elements of the Galactic orbits for 272 of the clusters have been calculated. Spectroscopic determinations of the relative abundances, [el/Fe], for 14 elements synthesized in various nuclear processes averaged over data from 109 publications are presented for 90 clusters. Since no systematic effects distorting the relative abundances of the studied elements in these clusters have been found, these difference suggest real differences between clusters with high, elongated orbits and field stars. In particular, this supports the earlier conclusion, based on an analysis of the elements of the Galactic orbits, that some clusters formed as a result of interactions between high-velocity, metal-poor clouds and the interstellar medium of the Galactic thin disk. On average, clusterswith high, elongated orbits and metallicities ${\\rm [Fe/H]} - 0.1$ formed as a result of interact...

  15. Effect of volatile elements on porosity formation in solidifying alloys

    Science.gov (United States)

    Couturier, G.; Rappaz, M.

    2006-03-01

    Besides dissolved gases such as hydrogen, the partial vapour pressure of volatile solute elements, such as zinc, has been accounted for in equations governing the nucleation and growth of pores in solidifying alloys. In particular, a simple analytical solution giving the porosity fraction as a function of the fraction of solid is proposed. This solution is then used to study the influence of zinc on porosity formation in aluminium- and copper-base alloys. It is shown that the zinc vapour pressure is too low to increase the porosity of aluminium-base alloys, whereas it has a significant effect in brasses. Implementing this contribution into an existing software which calculates the pressure drop in the mushy zone and the segregation of dissolved gases, simulations have been performed in order to assess in more realistic situations the influence of volatile solute elements on porosity.

  16. Element Abundances in Solar Energetic Particles and the Solar Corona

    CERN Document Server

    Reames, Donald V

    2013-01-01

    This is a study of abundances of the elements He, C, N, O, Ne, Mg, Si, S, Ar, Ca, and Fe in solar energetic particles (SEPs) in the 2 - 15 MeV amu-1 region measured on the Wind spacecraft during 54 large SEP events occurring between November 1994 and June 2012. The origin of most of the temporal and spatial variations in abundances of the heavier elements lies in rigidity-dependent scattering during transport of the particles away from the site of acceleration at shock waves driven out from the Sun by coronal mass ejections (CMEs). Variation in the abundance of Fe is correlated with the Fe spectral index, as expected from scattering theory but not previously noted. Clustering of Fe abundances during the "reservoir" period, late in SEP events, is also newly reported. Transport-induced enhancements in one region are balanced by depletions in another, thus, averaging over these variations produces SEP abundances that are energy independent, confirms previous SEP abundances in this energy region, and provides a c...

  17. Elemental Abundances of Ultra-Heavy Galactic Cosmic Rays from the SuperTIGER Instrument

    Science.gov (United States)

    Murphy, Ryan

    2016-07-01

    The SuperTIGER (Trans-Iron Galactic Element Recorder) experiment was launched on a long-duration balloon flight from Williams Field, Antarctica, on December 8, 2012. The instrument measured the relative elemental abundances of Galactic Cosmic Rays (GCR) for charge (Z) Z>10 with excellent charge resolution, displaying well resolved individual element peaks for 10 ≤ Z ≤ 40. During its record-breaking 55-day flight, SuperTIGER collected ˜4.73 x10^{6} Iron nuclei, ˜8 times as many as detected by its predecessor, TIGER, with charge resolution at iron of 0.17 cu. SuperTIGER measures charge (Z) and energy (E) using a combination of three scintillator and two Cherenkov detectors, and employs a scintillating fiber hodoscope for event trajectory determination. The SuperTIGER data have been analyzed to correct for instrument effects and remove events that underwent nuclear interactions within the instrument. The data include more than 600 events in the charge range 30 every element in this charge range with high statistics and single-element resolution. The relative abundances of the galactic cosmic ray source have been derived from the measured relative elemental abundances using atmospheric and interstellar propagations. The SuperTIGER measured abundances are generally consistent with previous experimental results from TIGER and ACE-CRIS, with improved statistical precision. The SuperTIGER results confirm the earlier results from TIGER, supporting a model of cosmic-ray origin in OB associations, with preferential acceleration of refractory elements over volatile elements ordered by atomic mass (A). A second SuperTIGER Antarctic flight is planned for December 2017. Details of the instrument, flight, data analysis, and ongoing preparations will be presented.

  18. Abundances and diffusion of elements in M67 stars

    CERN Document Server

    Önehag, Anna; Korn, Andreas

    2013-01-01

    We present a spectroscopic study at high resolution, R~50,000, of 14 stars located on the main sequence, at the turn-off point and on the early subgiant branch in the cluster M67 in order to investigate its detailed chemical composition, for comparison with the Sun and solar twins in the solar neighbourhood, and to explore selective atomic diffusion of chemical elements as predicted by stellar-structure theory. We have obtained VLT/FLAMES-UVES spectra and analysed these strictly differentially in order to explore chemical-abundance similarities and differences between the M67 stars and the Sun, and among the M67 stars themselves. Individual abundances of 19 different chemical elements are obtained for the stars. They are found to agree very well with solar abundances, with abundance ratios closer to solar than those of most solar twins in the solar neighbourhood. An exception is Li which shows a considerable scatter among the cluster stars. There is a tendency for the cluster-star abundances to be depleted re...

  19. Neutron-Capture Element Abundances in Magellanic Cloud Planetary Nebulae

    CERN Document Server

    Mashburn, A L; Madonna, S; Dinerstein, H L; Roederer, I U; Geballe, T

    2016-01-01

    We present near-infrared spectra of ten planetary nebulae (PNe) in the Large and Small Magellanic Clouds (LMC and SMC), acquired with the FIRE and GNIRS spectrometers on the 6.5-m Baade and 8.1-m Gemini South Telescopes, respectively. We detect Se and/or Kr emission lines in eight of these objects, the first detections of n-capture elements in Magellanic Cloud PNe. Our abundance analysis shows large s-process enrichments of Kr (0.6-1.3 dex) in the six PNe in which it was detected, and Se is enriched by 0.5-0.9 dex in five objects. We also estimate upper limits to Rb and Cd abundances in these objects. Our abundance results for the LMC are consistent with the hypothesis that PNe with 2--3 M$_{\\odot}$ progenitors dominate the bright end of the PN luminosity function in young gas-rich galaxies. We find no significant correlations between s-process enrichments and other elemental abundances, central star temperature, or progenitor mass, though this is likely due to our small sample size. We determine S abundances...

  20. A Comparison of Stellar Elemental Abundance Techniques and Measurements

    Science.gov (United States)

    Hinkel, Natalie R.; Young, Patrick A.; Pagano, Michael D.; Desch, Steven J.; Anbar, Ariel D.; Adibekyan, Vardan; Blanco-Cuaresma, Sergi; Carlberg, Joleen K.; Delgado Mena, Elisa; Liu, Fan; Nordlander, Thomas; Sousa, Sergio G.; Korn, Andreas; Gruyters, Pieter; Heiter, Ulrike; Jofré, Paula; Santos, Nuno C.; Soubiran, Caroline

    2016-09-01

    Stellar elemental abundances are important for understanding the fundamental properties of a star or stellar group, such as age and evolutionary history, as well as the composition of an orbiting planet. However, as abundance measurement techniques have progressed, there has been little standardization between individual methods and their comparisons. As a result, different stellar abundance procedures determine measurements that vary beyond the quoted error for the same elements within the same stars. The purpose of this paper is to better understand the systematic variations between methods and offer recommendations for producing more accurate results in the future. We invited a number of participants from around the world (Australia, Portugal, Sweden, Switzerland, and the United States) to calculate 10 element abundances (C, O, Na, Mg, Al, Si, Fe, Ni, Ba, and Eu) using the same stellar spectra for four stars (HD 361, HD 10700, HD 121504, and HD 202206). Each group produced measurements for each star using (1) their own autonomous techniques, (2) standardized stellar parameters, (3) a standardized line list, and (4) both standardized parameters and a line list. We present the resulting stellar parameters, absolute abundances, and a metric of data similarity that quantifies the homogeneity of the data. We conclude that standardization of some kind, particularly stellar parameters, improves the consistency between methods. However, because results did not converge as more free parameters were standardized, it is clear there are inherent issues within the techniques that need to be reconciled. Therefore, we encourage more conversation and transparency within the community such that stellar abundance determinations can be reproducible as well as accurate and precise.

  1. Chemical fractionations in meteorites. V - Volatile and siderophile elements in achondrites and ocean ridge basalts.

    Science.gov (United States)

    Laul, J. C.; Keays, R. R.; Ganapathy, R.; Anders, E.; Morgan, J. W.

    1972-01-01

    Eighteen achondrites and 4 terrestrial basalts (3 ocean ridge, 1 continental) were analyzed by radiochemical neutron activation analysis for Ag, Au, Bi, Br, Cd, Co, Cs, Cu, Ga, In, Ir, Rb, Se, Tl and Zn. Samples included 7 eucrites, 5 howardites, 2 nakhlites, 2 shergottites, an angrite, and an aubrite. Light and dark portions of the gas-rich meteorites Kapoeta and Pesyanoe were analyzed separately. Nakhlites and shergottites have volatile element abundances similar to those in ocean ridge basalts; eucrites, howardites, and angrites show greater depletions by an order of magnitude and less similar abundance patterns. In terms of a two-component model of planetary accretion, the parent planets contained the following percentages of low-temperature material: eucrites 0.8, nakhlites 38, shergottites 28. Shergottites may be genetically related to L-chondrites. The siderophile element pattern of achondrites resembles that of the moon, but with less extreme depletions.

  2. Solar Abundances of Rock Forming Elements, Extreme Oxygen and Hydrogen in a Young Polluted White Dwarf

    CERN Document Server

    Farihi, J; Zuckerman, B; Vican, L; Gänsicke, B T; Smith, N; Walth, G; Breedt, E

    2016-01-01

    The Teff = 20,800 K white dwarf WD 1536+520 is shown to have broadly solar abundances of the major rock forming elements O, Mg, Al, Si, Ca, and Fe, together with a strong relative depletion in the volatile elements C and S. In addition to the highest metal abundances observed to date, including log(O/He) = -3.4, the helium-dominated atmosphere has an exceptional hydrogen abundance at log(H/He) = -1.7. Within the uncertainties, the metal-to-metal ratios are consistent with the accretion of an H2O-rich and rocky parent body, an interpretation supported by the anomalously high trace hydrogen. The mixed atmosphere yields unusually short diffusion timescales for a helium atmosphere white dwarf, of no more than a few hundred yr, and equivalent to those in a much cooler, hydrogen-rich star. The overall heavy element abundances of the disrupted parent body deviate modestly from a bulk Earth pattern, and suggest the deposition of some core-like material. The total inferred accretion rate is 4.2e9 g/s, and at least 4 t...

  3. Trace Element Abundance Measurements on Cosmic Dust Particles

    Science.gov (United States)

    Flynn, George

    1996-01-01

    The X-Ray Microprobe on beamline X-26A at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory was used to determine the abundances of elements from Cr through Sr in individual interplanetary dust particles (IDPs) collected from the Earth's stratosphere and the Scanning Transmission X-ray Microscope (STXM) on beamline X-1A at the NSLS was used to determine the carbon abundances and spatial distributions in IDPs. In addition, modeling was performed in an attempt to associate particular types of IDPs with specific types of parent bodies, and thus to infer the chemistry, mineralogy, and structural properties of those parent bodies.

  4. Zinc and volatile element loss during planetary magma ocean phases

    Science.gov (United States)

    Dhaliwal, Jasmeet K.; Day, James M. D.; Moynier, Frédéric

    2016-10-01

    Zinc is a moderately volatile element and a key tracer of volatile depletion on planetary bodies due to lack of significant isotopic fractionation under high-temperature processes. Terrestrial basalts have δ66Zn values similar to some chondrites (+ 0.15 to 0.3‰ where [{66Zn/64Znsample/66Zn/64ZnJMC-Lyon-1} × 1000]) and elevated Zn concentrations (100 ppm). Lunar mare basalts yield a mean δ66Zn value of +1.4 ± 0.5‰ and have low Zn concentrations (~2 ppm). Late-stage lunar magmatic products, such as ferroan anorthosite, Mg-suite and Alkali suite rocks exhibit heavier δ66Zn values (+3 to +6‰). The heavy δ66Zn lunar signature is thought to reflect evaporative loss and fractionation of zinc, either during a giant impact or in a magma ocean phase.We explore conditions of volatile element loss within a lunar magma ocean (LMO) using models of Zn isotopic fractionation that are widely applicable to planetary magma oceans. For the Moon, our objective was to identify conditions that would yield a δ66Zn signature of ~ +1.4‰ within the mantle, assuming a terrestrial mantle zinc starting composition.We examine two cases of zinc evaporative fractionation: (1) lunar surface zinc fractionation that was completed prior to LMO crystallization and (2) lunar surface zinc fractionation that was concurrent with LMO crystallization. The first case resulted in a homogeneous lunar mantle and the second case yielded a stratified lunar mantle, with the greatest zinc isotopic enrichment in late-stage crystallization products. This latter case reproduces the distribution of zinc isotope compositions in lunar materials quite well.We find that hydrodynamic escape was not a dominant process in losing Zn, but that erosion of a nascent lunar atmosphere, or separation of condensates into a proto-lunar crust are possible. While lunar volatile depletion is still possible as a consequence of the giant impact, this process cannot reproduce the variable δ66Zn found in the Moon. Outgassing

  5. Origin of the earth's moon - Constraints from alkali volatile trace elements

    Science.gov (United States)

    Kreutzberger, M. E.; Drake, M. J.; Jones, J. H.

    1986-01-01

    Although the moon is depleted in volatile elements compared to the earth, these depletions are not in accord with simple volatility. For example, the Cs/Rb ratios of the earth and moon inferred from basalt are approximately one seventh and one half of the CI ratio, respectively. Volatility considerations alone predict that the lunar Cs/Rb ratio should be equal to or lower than the terrestrial ratio if the moon was derived entirely from earth mantle material. Thus hypotheses such as rotational fission which invoke derivation of lunar material entirely from the earth's mantle may be excluded. The collisional ejection hypothesis of lunar origin requires at least 18 percent of lunar material to be derived from a projectile with dehydrated CI composition to match the lunar Cs/Rb ratio, and 25-50 percent to match both the lunar Cs/Rb ratio and absolute concentrations of Cs and Rb. It remains to be demonstrated that this relatively large contribution of projectile material is consistent with other elemental abundances and element ratios in the moon.

  6. Element abundances in X-ray emitting plasmas in stars

    CERN Document Server

    Testa, Paola

    2010-01-01

    Studies of element abundances in stars are of fundamental interest for their impact in a wide astrophysical context, from our understanding of galactic chemistry and its evolution, to their effect on models of stellar interiors, to the influence of the composition of material in young stellar environments on the planet formation process. We review recent results of studies of abundance properties of X-ray emitting plasmas in stars, ranging from the corona of the Sun and other solar-like stars, to pre-main sequence low-mass stars, and to early-type stars. We discuss the status of our understanding of abundance patterns in stellar X-ray plasmas, and recent advances made possible by accurate diagnostics now accessible thanks to the high resolution X-ray spectroscopy with Chandra and XMM-Newton.

  7. Neutron-capture Element Abundances in Magellanic Cloud Planetary Nebulae

    Science.gov (United States)

    Mashburn, A. L.; Sterling, N. C.; Madonna, S.; Dinerstein, Harriet L.; Roederer, I. U.; Geballe, T. R.

    2016-11-01

    We present near-infrared spectra of 10 planetary nebulae (PNe) in the Large and Small Magellanic Clouds (LMC and SMC), acquired with the FIRE and GNIRS spectrometers on the 6.5 m Baade and 8.1 m Gemini South Telescopes, respectively. We detect Se and/or Kr emission lines in eight of these objects, the first detections of n-capture elements in Magellanic Cloud PNe. Our abundance analysis shows large s-process enrichments of Kr (0.6–1.3 dex) in the six PNe in which it was detected, and Se is enriched by 0.5–0.9 dex in five objects. We also estimate upper limits to Rb and Cd abundances in these objects. Our abundance results for the LMC are consistent with the hypothesis that PNe with 2–3 M ⊙ progenitors dominate the bright end of the PN luminosity function in young gas-rich galaxies. We find no significant correlations between s-process enrichments and other elemental abundances, central star temperature, or progenitor mass, though this is likely due to our small sample size. We determine S abundances from our spectra and find that [S/H] agrees with [Ar/H] to within 0.2 dex for most objects, but is lower than [O/H] by 0.2–0.4 dex in some PNe, possibly due to O enrichment via third dredge-up. Our results demonstrate that n-capture elements can be detected in PNe belonging to nearby galaxies with ground-based telescopes, allowing s-process enrichments to be studied in PN populations with well-determined distances. This paper includes data obtained with the 6.5-m Magellan Telescopes located at Las Campanas Observatory, Chile, and with the Gemini-South Telescope at Cerro Pachon, Chile.

  8. Element Abundances and Source Plasma Temperatures of Solar Energetic Particles

    Science.gov (United States)

    Reames, Donald V.

    2016-11-01

    Thirty years ago Breneman and Stone [1] observed that the enhancement or suppression of element abundances in large solar energetic-particle (SEP) events varies as a power of the mass-to-charge ratio, A/Q, of the elements. Since Q during acceleration or transport may depend upon the source plasma temperature T, the pattern of element enhancements can provide a best-fit measure of T. The small SEP events we call 3He-rich or “impulsive” show average enhancements, relative to coronal abundances, rising as the 3.6 power of A/Q to a factor of ∼1000 for (76magnetic reconnection on open field lines in solar flares and jets. It has been recently found that the large shock-accelerated “gradual” SEP events have a broad range of source plasma temperatures; 69% have coronal temperatures of T seed population containing residual impulsive suprathermal ions. Most of the large event-to-event abundance variations and their time variation are largely explained by variations in T magnified by A/Q-dependent fractionation during transport. However, the non-thermal variance of impulsive SEP events (∼30%) exceeds that of the ∼3 MK gradual events (∼10%) so that several small impulsive events must be averaged together with the ambient plasma to form the seed population for shock acceleration in these events.

  9. Chemical Cartography in the Milky Way with SDSS/APOGEE: Multi-element abundances and abundance ratio variations

    Science.gov (United States)

    Holtzman, Jon A.; Hasselquist, Sten; Johnson, Jennifer; Bird, Jonathan C.; Majewski, Steven R.; SDSS/APOGEE Team

    2017-01-01

    The SDSS/APOGEE project is measuring abundances of multiple elements for several hundred thousand stars across the Milky Way. These allow the mapping of abundances and abundance ratio variations. Results will be presented for multiple abundance ratios across of the Galactic disk. The interpretation of mean abundance maps is complicated by variations in star formation history across the disk and by changing abundance ratios that result from an overall metallicity gradient. Variations in chemical abundance sequences, however, show the potential for using abundance ratios to track the movement of stars through the disk, and provide key information for constraining Galaxy formation and chemical evolution models.

  10. The double-lined spectroscopic binary $\\alpha$ Andromedae orbital elements and elemental abundances

    CERN Document Server

    Ryabchikova, T A; Adelman, S J

    1998-01-01

    We performed a spectroscopic study of the SB2 Mercury-Manganese star alpha And. Our measurements of the secondary's radial velocities result in improved orbital elements. The secondary shows abundances typical of the metallic-line stars: a Ca deficiency, small overabundances of the iron-peak elements, and 1.0 dex overabundances of Sr and Ba.

  11. Elemental abundances of flaring solar plasma - Enhanced neon and sulfur

    Science.gov (United States)

    Schmelz, J. T.

    1993-01-01

    Elemental abundances of two flares observed with the SMM Flat Crystal Spectrometer are compared and contrasted. The first had a gradual rise and a slow decay, while the second was much more impulsive. Simultaneous spectra of seven bright soft X-ray resonance lines provide information over a broad temperature range and are available throughout both flares, making these events unique in the SMM data base. For the first flare, the plasma seemed to be characterized by coronal abundances but, for the second, the plasma composition could not be coronal, photospheric, or a linear combination of both. A good differential emission measure fit required enhanced neon such that Ne/O = 0.32 +/- 0.02, a value which is inconsistent with the current models of coronal abundances based on the elemental first-ionization potential. Similar values of enhanced neon are found for flaring plasma observed by the SMM gamma-ray spectrometer, in (He-3)-rich solar energetic particle events, and in the decay phase of several long duration soft X-ray events. Sulfur is also enhanced in the impulsive flare, but not as dramatically as neon. These events are compared with two models which attempt to explain the enhanced values of neon and sulfur.

  12. A complete dataset of copper for investigation of element abundance

    Science.gov (United States)

    Zeng, Jiaolong; Liu, Yanpeng; Yuan, Jianmin

    2014-05-01

    The abundance of copper plays an important role in the chemical evolution of various stars, such as giant stars and solar-type stars. Accurate determination of its abundance helps to clarify a number of problems including the quite different behavior from other Fe-peak elements both in our Galaxy and extragalactic systems and the [Cu/Fe] ratios in Galactic stars. To accurately determine the copper abundance, it is necessary to include the non-local thermodynamic equilibrium (NLTE) effects, which depend on a complete dataset of atomic data. However, the complexity of electronic structure of copper makes the accurate prediction of a complete set of atomic data difficult. For both atomic Cu and the first ionized Cu II, the energies of 3d and 4s orbitals are very close and their competition results in complex energy levels. The excitation energy of 3d orbital is very low resulting in an opening 3d atomic system which is difficult to deal with theoretically due to the strong electron correlations. We present a complete set of atomic data including the energy levels, oscillator strengths, and photoionization cross sections of Cu I for the NLTE modeling in copper abundance investigation of astrophysical objects. The calculations are performed with the R-matrix method.

  13. The Origin of Element Abundance Variations in Solar Energetic Particles

    CERN Document Server

    Reames, Donald V

    2016-01-01

    Abundance enhancements, during acceleration and transport in both gradual and impulsive solar energetic particle (SEP) events, vary approximately as power laws in the mass-to-charge ratio A/Q of the ions. Since the Q values depend upon the electron temperature of the source plasma, this has allowed a determination of this temperature from the pattern of element abundance enhancements and a verification of the expected inverse-time dependence of the power of A/Q for diffusive transport of ions from the SEP events, with scattering mean free paths found to be between 0.2 and 1 AU. SEP events derived from plasma of different temperatures map into different regions in typical cross-plots of abundances, spreading the distributions. In comparisons of SEP events with temperatures above 2 MK, impulsive events show much broader non-thermal variation of abundances than do gradual events. The extensive shock waves accelerating ions in gradual events may average over much of an active region where numerous but smaller mag...

  14. Element Abundances and Source Plasma Temperatures of Solar Energetic Particles

    CERN Document Server

    Reames, Donald V

    2016-01-01

    Thirty years ago Breneman and Stone observed that the enhancement or suppression of element abundances in large solar energetic-particle (SEP) events varies as a power of the mass-to-charge ratio, A/Q, of the elements. Since Q during acceleration or transport may depend upon the source plasma temperature T, the pattern of element enhancements can provide a best-fit measure of T. The small SEP events we call 3He-rich or "impulsive" show average enhancements, relative to coronal abundances, rising as the 3.6 power of A/Q to a factor of ~1000 for (76<=Z<=82)/O and temperature in the range 2-4 MK. This acceleration is believed to occur in islands of magnetic reconnection on open field lines in solar flares and jets. It has been recently found that the large shock-accelerated "gradual" SEP events have a broad range of source plasma temperatures; 69% have coronal temperatures of T < 1.6 MK, while 24% have T ~ 3 MK, the latter suggesting a seed population containing residual impulsive suprathermal ions. Mos...

  15. Heavy element abundances in planetary nebulae: A theorist's perspective

    CERN Document Server

    Karakas, Amanda I

    2009-01-01

    The determination of heavy element abundances from planetary nebula (PN) spectra provides an exciting opportunity to study the nucleosynthesis occurring in the progenitor asymptotic giant branch (AGB) star. We perform post-processing calculations on AGB models of a large range of mass and metallicity to obtain predictions for the production of neutron-capture elements up to the first s-process peak at strontium. We find that solar metallicity intermediate-mass AGB models provide a reasonable match to the heavy element composition of Type I PNe. Likewise, many of the Se and Kr enriched PNe are well fitted by lower mass models with solar or close-to-solar metallicities. However the most Kr-enriched objects, and the PN with sub-solar Se/O ratios are difficult to explain with AGB nucleosynthesis models. Furthermore, we compute s-process abundance predictions for low-mass AGB models of very low metallicity ([Fe/H] =-2.3) using both scaled solar and an alpha-enhanced initial composition. For these models, O is dred...

  16. The isotope composition of selenium in chondrites constrains the depletion mechanism of volatile elements in solar system materials

    Science.gov (United States)

    Vollstaedt, Hauke; Mezger, Klaus; Leya, Ingo

    2016-09-01

    Solar nebula processes led to a depletion of volatile elements in different chondrite groups when compared to the bulk chemical composition of the solar system deduced from the Sun's photosphere. For moderately-volatile elements, this depletion primarily correlates with the element condensation temperature and is possibly caused by incomplete condensation from a hot solar nebula, evaporative loss from the precursor dust, and/or inherited from the interstellar medium. Element concentrations and interelement ratios of volatile elements do not provide a clear picture about responsible mechanisms. Here, the abundance and stable isotope composition of the moderately- to highly-volatile element Se are investigated in carbonaceous, ordinary, and enstatite chondrites to constrain the mechanism responsible for the depletion of volatile elements in planetary bodies of the inner solar system and to define a δ 82 / 78 Se value for the bulk solar system. The δ 82 / 78 Se of the studied chondrite falls are identical within their measurement uncertainties with a mean of - 0.20 ± 0.26 ‰ (2 s.d., n = 14, relative to NIST SRM 3149) despite Se abundance depletions of up to a factor of 2.5 with respect to the CI group. The absence of resolvable Se isotope fractionation rules out a kinetic Rayleigh-type incomplete condensation of Se from the hot solar nebula or partial kinetic evaporative loss on the precursor material and/or the parent bodies. The Se depletion, if acquired during partial condensation or evaporative loss, therefore must have occurred under near equilibrium conditions to prevent measurable isotope fractionation. Alternatively, the depletion and cooling of the nebula could have occurred simultaneously due to the continuous removal of gas and fine particles by the solar wind accompanied by the quantitative condensation of elements from the pre-depleted gas. In this scenario the condensation of elements does not require equilibrium conditions to avoid isotope

  17. The interstellar abundances of tin and four other heavy elements

    Science.gov (United States)

    Hobbs, L. M.; Welty, D. E.; Morton, D. C.; Spitzer, L.; York, D. G.

    1993-01-01

    Spectra recorded at 1150-1600 A with an instrumental resolution near 16 km/s were obtained with the Goddard High-Resolution Spectrograph on board the HST. The gaseous interstellar abundances of five heavy elements along the light paths to 23 Ori, 15 Mon, 1 Sco, Pi Sco, and Pi Aqr were determined from the observations. The 1400.450 A line of Sn II was detected and identified toward three stars; at Z = 50, tin is the first element from the fifth row of the periodic table to be identified in the interstellar medium. One spectral line of each of Cu II (Z = 29) and Ga II (Z = 31), three lines of Ge II (Z = 32), and two lines of Kr I (Z = 36) were also detected toward some or all of the five stars. The depletions of these five heavy elements generally decrease monotonically with increasing atomic number toward each of the six stars, and tin is generally undepleted within the observational errors. The depletions of 26 elements from the interstellar gas in an average dense interstellar cloud appear to correlate with the elemental 'nebular' condensation temperatures more closely than with the first ionization potentials.

  18. Quest for the Sun's siblings based on elemental abundances

    Science.gov (United States)

    Liu, C.; Ruchti, G.; Feltzing, S.; Martínez-Barbosa, C. A.

    2014-07-01

    We present stellar parameters, stellar ages, and detailed elemental abundances for Na, Mg, Al, Si, Ca, Ti, Cr, Fe, and Ni for 32 solar sibling candidates. Technique of chemical tagging gives us a high probability that four stars might be from the same open cluster. Only one candidate HIP 40317 which has solar metallicity and age could be a solar sibling. We performed simulations of the Sun's birth cluster in analytical Galactic model and found that there is quite low probability to find solar siblings with radial velocity up to Vr = 34.2 km s-1.

  19. Highly siderophile element abundances in Eoarchean komatiite and basalt protoliths

    Science.gov (United States)

    Frank, Elizabeth A.; Maier, Wolfgang D.; Mojzsis, Stephen J.

    2016-03-01

    Plume-derived, Mg-rich, volcanic rocks (komatiites, high-Mg basalts, and their metamorphic equivalents) can record secular changes in the highly siderophile element (HSE) abundances of mantle sources. An apparent secular time-dependent enrichment trend in HSE abundances from Paleoarchean to Paleoproterozoic mantle-derived rocks could represent the protracted homogenization of a Late Veneer chondritic contaminant into the pre-Late Veneer komatiite source. To search for a possible time dependence of a late accretion signature in the Eoarchean mantle, we report new data from rare >3700 Myr-old mafic and ultramafic schists locked in supracrustal belts from the Inukjuak domain (Québec, Canada) and the Akilia association (West Greenland). Our analysis shows that some of these experienced HSE mobility and/or include a cumulate component (Touboul et al. in Chem Geol 383:63-75, 2014), whereas several of the oldest samples show some of the most depleted HSE abundances measured for rocks of this composition. We consider these new data for the oldest documented rocks of komatiite protolith in light of the Late Veneer hypothesis.

  20. Two Extrasolar Asteroids with Low Volatile-Element Mass Fractions

    CERN Document Server

    Jura, M; Klein, B; Koester, D; Zuckerman, B

    2012-01-01

    Using ultraviolet spectra obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope, we extend our previous ground-based optical determinations of the composition of the extrasolar asteroids accreted onto two white dwarfs, GD 40 and G241-6. Combining optical and ultraviolet spectra of these stars with He-dominated atmospheres, 13 and 12 polluting elements are confidently detected in GD 40 and G241-6, respectively. For the material accreted onto GD 40, the volatile elements C and S are deficient by more than a factor of 10 and N by at least a factor of 5 compared to their mass fractions in primitive CI chondrites and approach what is inferred for bulk Earth. A similar pattern is found for G241-6 except that S is undepleted. We have also newly detected or placed meaningful upper limits for the amount of Cl, Al, P, Ni and Cu in the accreted matter. Extending results from optical studies, the mass fractions of refractory elements in the accreted parent bodies are similar to what is measured for ...

  1. Distribution of moderately volatile trace elements in fine-grained chondrule rims in the unequilibrated CO3 chondrite, ALH A77307.

    Science.gov (United States)

    Brearley, A J; Bajt, S; Sutton, S R

    1995-10-01

    The concentrations of Ni, Cu, Zn, Ga, Ge, and Se in five, fine-grained chondrule rims in the highly unequilibrated CO3 chondrite ALH A77307 (3.0) have been determined for the first time by synchrotron X-ray fluorescence (SXRF) microprobe at Brookhaven National Laboratory. These elements are especially useful for tracing the role of condensation and evaporation processes which occurred at moderate temperatures in the solar nebula. Understanding the distribution of moderately volatile elements between matrix and chondrules is extremely important for evaluating the different models for the volatile depletions in chondritic meteorites. The data show that the trace element chemistry of rims on different chondrules is remarkably similar, consistent with data obtained for the major and minor elements by electron microprobe. These results support the idea that rims are not genetically related to individual chondrules, but all sampled the same reservoir of homogeneously mixed dust. Of the trace elements analyzed, Zn and Ga show depletions relative to CI chondrite values, but in comparison with bulk CO chondrites all the elements are enriched by approximately 1.5 to 3.5 x CO. The abundance patterns for moderately volatile elements in ALH A77307 chondrule rims closely mimic those observed in the bulk chondrite, indicating that matrix is the major reservoir for these elements. The close matching of the patterns for the volatile depleted bulk chondrite and enriched matrix is especially striking for Na, which is anomalously depleted in ALH A77307 in comparison with average CO chondrite abundances. The depletion in Na is probably attributable to the effects of leaching in Antarctica. With the exception of Na, the volatile elements show a relatively smooth decrease in abundance as a function of condensation temperature, indicating that their behavior is largely controlled by their volatility.

  2. Abundances of heavy elements in ultra-metal-poor star CS 22892-052

    Institute of Scientific and Technical Information of China (English)

    张波; 张彩霞; 李冀; 梁艳春; 彭秋和

    1999-01-01

    Based on the heavy element nucleosynthesis theory, with the solar heavy-nuclide abundances and the observed abundances of three elements which are the representatives of the individul neutron-capture processes, a method to determine the relative contributions from the individul neutron-capture processes to the abundances of heavy elements in metal-poor stars is applied. With this method, the abundances of heavy elements in ultra-metal-poor star CS 22892-052 are calculated. It is found that the observed abundances of heavy elements in this star are well matched by our calculations in error limits, except for thorium.

  3. Trace Element Abundances in Refractory Inclusions from Antarctic Micrometeorites

    Science.gov (United States)

    Greshake, A.; Hoppe, P.; Bischoff, A.

    1995-09-01

    Refractory inclusions are charcteristic components in carbonaceous chondrites. Therefore, refractory inclusions found in micrometeorites can give important hints about the relationship between micrometeorites and carbonaceous chondrites. So far, only a few inclusions were found in micrometeorites [1-4]. In this study we report the first trace element analysis of perovskite and fassaite found in micrometeorites. We studied two Antarctic micrometeorites by ASEM, EMP, and SIMS. The first particle is 120 micrometers in size mainly consisting of a fine-grained matrix of dehydrated former phyllosilikates that enclose a 5 micrometers sized perovskite [5]. The perovskite is surrounded by a 1 micrometers thick rim of ilmenite and contains up to 1.3 wt% FeO as determined by EMP. The trace element abundances were determined by SIMS following the procedure described by [6]. The REE pattern of the perovskite is shown in Fig. 1. The pattern is closely related to the Group II pattern with its typical depletion of the more refractory REEs [7]. It is also very similar to the REE abundances of perovskite from Murchison (CM) [8] and CH-chondrites [9]. This may indicate a relationship between this micrometeorite and components in carbonaceous chondrites. The second micrometeorite is 100 micrometers in size consisting of a fine-grained (20 micrometers across) and a coarse-grained (80 micrometers across) area. Both areas contain fassaite with different chemical compositions. The particle was previously analyzed by Lindstrom and Kloeck [1] without knowing the mineralogy. We carried out SIMS analysis of each area of the micrometeorite separately. The TEE patterns of these two areas are similar and show in general a Group III pattern (20-30x CI) in which the more refractory REEs are not fractionated. The negative Eu anomaly is much more apparent in the coarse-grained area and no Yb anomaly is apparent in one of the areas. This is the first CAI of a micrometeorite showing a Group III REE

  4. On the volatile enrichments and heavy element content in HD 189733b

    CERN Document Server

    Mousis, O; Petit, J -M; Zahnle, K; Biennier, L; Picaud, S; Johnson, T V; Mitchell, J B A; Boudon, V; Cordier, D; Devel, M; Georges, R; Griffith, C; Iro, N; Marley, M S; Marboeuf, U

    2010-01-01

    Favored theories of giant planet formation center around two main paradigms, namely the core accretion model and the gravitational instability model. These two formation scenarios support the hypothesis that the giant planet metallicities should be higher or equal to that of the parent star. Meanwhile, spectra of the transiting hot Jupiter HD189733b suggest that carbon and oxygen abundances range from depleted to enriched with respect to the star. Here, using a model describing the formation sequence and composition of planetesimals in the protoplanetary disk, we determine the range of volatile abundances in the envelope of HD189733b that is consistent with the 20--80 Earth-masses of heavy elements estimated to be present in the planet's envelope. We then compare the inferred carbon and oxygen abundances to those retrieved from spectroscopy and we find a range of supersolar values that directly fit both spectra and internal structure models. In some cases, we find that the apparent contradiction between the s...

  5. Some refractory and volatile element chemistry of CaS in enstatite chondrites

    Institute of Scientific and Technical Information of China (English)

    陈永亨; Paul H.Benoit

    1996-01-01

    INAA data for REE, Sc, Se, Br and Zn in CaS extracted from 5 enstatite chondrites (Qingzhen EH3, St. Marks EH5, Atlanta EL6, Hvittis EL6 and Pillistfer EL6) are reported. The results indicate that the REE abundances in CaS from unequilibrated enstatite chondrite, Qingzhen, are much higher than that from equilibrated ones. Similarly, the abundances of Sc, Se, Br and Zn in CaS from Qingzhen are higher than that in CaS grains from equilibrated chondrites, revealing that CaS is a previous condensate and is not simple residues of an evaporative process. Secondly, metamorphism has caused the redistribution of the trace elements among the minerals in enstatite chondrites, and this metamorphic fractionation reflects the differences from element volatilities and chemical properties. The REE patterns of CaS of enstatite chondrites and aubrites could not explain that aubrites were derived from known enstatite chondrites by igneous processing. And depleted europium in metamorphism and igneous process may be carried

  6. Solar-system abundances of the elements - A new table

    Science.gov (United States)

    Grevesse, Nicolas; Anders, Edward

    1989-01-01

    This paper presents an abridged version of a new abundance compilation (Anders and Grevesse, 1988), representing an update of Anders and Ebihara (1982) and Grevesse (1984). It includes revised meteoritic abundances as well as photospheric and coronal abundances, based on literature through mid-1988.

  7. The Law of Element Abundance Relationships in Igneous Rocks Petrogenetically Associated with Fractional Crystallization

    Institute of Scientific and Technical Information of China (English)

    汪云亮; 王旺章

    1991-01-01

    Reported in this paper are:1)the law of element abundance relationships:element abun-dances are of power function with each other in an igneous rock petrogenetically associated with fractional crystallization,2)deduction of the law and relevant parameters:abundance relationship constant(a°) and phase constant? from Henry's law and the law of mass conservation,3)the data basis and evidence of the law of element abundance relationships,4)establishment of the equa-bions for element abundance relationships in igneous rocks formed from the same parental magma during the same fractional crystallization stage ,and all measurable parameters involved in the equations.

  8. Abundances of neutron-capture elements in G 24-25

    DEFF Research Database (Denmark)

    Liu, S.; Nissen, Poul Erik; Schuster, W. J.

    2012-01-01

    Aims. The differences between the neutron-capture element abundances of halo stars are important to our understanding of the nucleosynthesis of elements heavier than the iron group. We present a detailed abundance analysis of carbon and twelve neutron-capture elements from Sr up to Pb...... overabundances of carbon and heavy s-process elements and mild overabundances of Eu and light s-process elements. This abundance distribution is consistent with that of a typical CH giant. The abundance pattern can be explained by mass transfer from a former asymptotic giant branch component, which is now...

  9. Abundances of neutron-capture elements in G 24-25

    DEFF Research Database (Denmark)

    Liu, S.; Nissen, Poul Erik; Schuster, W. J.

    2012-01-01

    Aims. The differences between the neutron-capture element abundances of halo stars are important to our understanding of the nucleosynthesis of elements heavier than the iron group. We present a detailed abundance analysis of carbon and twelve neutron-capture elements from Sr up to Pb...... overabundances of carbon and heavy s-process elements and mild overabundances of Eu and light s-process elements. This abundance distribution is consistent with that of a typical CH giant. The abundance pattern can be explained by mass transfer from a former asymptotic giant branch component, which is now...

  10. THE CURIOUS CASE OF ELEMENTAL ABUNDANCE DIFFERENCES IN THE DUAL HOT JUPITER HOSTS WASP-94A AND B

    Energy Technology Data Exchange (ETDEWEB)

    Teske, Johanna K. [Carnegie Department of Terrestrial Magnetism, 5241 Broad Branch Road, NW, Washington, DC 20015 (United States); Khanal, Sandhya; Ramírez, Ivan, E-mail: jteske@carnegiescience.edu [McDonald Observatory and Department of Astronomy, University of Texas at Austin, 2515 Speedway, Stop C1402, Austin, TX 78712-1205 (United States)

    2016-03-01

    Binary stars provide an ideal laboratory for investigating the potential effects of planet formation on stellar composition. Assuming that the stars formed in the same environment/from the same material, any compositional anomalies between binary components might indicate differences in how material was sequestered in planets, or accreted by the star in the process of planet formation. We present here a study of the elemental abundance differences between WASP-94A and B, a pair of stars that each host a hot Jupiter exoplanet. The two stars are very similar in spectral type (F8 and F9), and their ∼2700 au separation suggests that their protoplanetary disks were likely not influenced by stellar interactions, but WASP-94Ab’s orbit—misaligned with the host star spin axis and likely retrograde—points toward a dynamically active formation mechanism, perhaps different from that of WASP-94Bb, which is not misaligned and has a nearly circular orbit. Based on our high-quality spectra and strictly relative abundance analysis, we detect a depletion of volatiles (∼−0.02 dex, on average) and enhancement of refractories (∼0.01 dex) in WASP-94A relative to B (standard errors are ∼0.005 dex). This is different from every other published case of binary host star abundances, in which either no significant abundance differences are reported or there is some degree of enhancement in all elements, including volatiles. Several scenarios that may explain the abundance trend are discussed, but none can be definitively accepted or rejected. Additional high-contrast imaging observations to search for companions that may be dynamically affecting the system, as well as a larger sample of binary host star studies, are needed to better understand the curious abundance trends we observe in WASP-94A and B.

  11. Composite Stellar Populations and Element by Element Abundances in the Milky Way Bulge and Elliptical Galaxies

    CERN Document Server

    Tang, Baitian; Davis, A Bianca

    2014-01-01

    This paper explores the integrated-light characteristics of the Milky Way (MW) bulge and to what extent they match those of elliptical galaxies in the local universe. We model composite stellar populations with realistic abundance distribution functions (ADFs), tracking the trends of individual elements as a function of overall heavy element abundance as actually observed in MW bulge stars. The resultant predictions for absorption feature strengths from the MW bulge mimic elliptical galaxies better than solar neighborhood stars do, but the MW bulge does not match elliptical galaxies, either. Comparing bulge versus elliptical galaxies, Fe, Ti, and Mg trend about the same for both but C, Na, and Ca seem irreconcilably different. Exploring the behavior of abundance compositeness leads to the concepts of "red lean" where a narrower ADF appears more metal rich than a wide one, and "red spread" where the spectral difference between wide and narrow ADFs increases as the ADF peak is moved to more metal-rich values. T...

  12. Early accretion of water and volatile elements to the inner Solar System: evidence from angrites

    Science.gov (United States)

    Sarafian, Adam R.; Hauri, Erik H.; McCubbin, Francis M.; Lapen, Thomas J.; Berger, Eve L.; Nielsen, Sune G.; Marschall, Horst R.; Gaetani, Glenn A.; Righter, Kevin; Sarafian, Emily

    2017-04-01

    Inner Solar System bodies are depleted in volatile elements relative to chondrite meteorites, yet the source(s) and mechanism(s) of volatile-element depletion and/or enrichment are poorly constrained. The timing, mechanisms and quantities of volatile elements present in the early inner Solar System have vast implications for diverse processes, from planetary differentiation to the emergence of life. We report major, trace and volatile-element contents of a glass bead derived from the D'Orbigny angrite, the hydrogen isotopic composition of this glass bead and that of coexisting olivine and silicophosphates, and the 207Pb-206Pb age of the silicophosphates, 4568 ± 20 Ma. We use volatile saturation models to demonstrate that the angrite parent body must have been a major body in the early inner Solar System. We further show via mixing calculations that all inner Solar System bodies accreted volatile elements with carbonaceous chondrite H and N isotope signatures extremely early in Solar System history. Only a small portion (if any) of comets and gaseous nebular H species contributed to the volatile content of the inner Solar System bodies. This article is part of the themed issue 'The origin, history and role of water in the evolution of the inner Solar System'.

  13. Early accretion of water and volatile elements to the inner Solar System: evidence from angrites.

    Science.gov (United States)

    Sarafian, Adam R; Hauri, Erik H; McCubbin, Francis M; Lapen, Thomas J; Berger, Eve L; Nielsen, Sune G; Marschall, Horst R; Gaetani, Glenn A; Righter, Kevin; Sarafian, Emily

    2017-05-28

    Inner Solar System bodies are depleted in volatile elements relative to chondrite meteorites, yet the source(s) and mechanism(s) of volatile-element depletion and/or enrichment are poorly constrained. The timing, mechanisms and quantities of volatile elements present in the early inner Solar System have vast implications for diverse processes, from planetary differentiation to the emergence of life. We report major, trace and volatile-element contents of a glass bead derived from the D'Orbigny angrite, the hydrogen isotopic composition of this glass bead and that of coexisting olivine and silicophosphates, and the (207)Pb-(206)Pb age of the silicophosphates, 4568 ± 20 Ma. We use volatile saturation models to demonstrate that the angrite parent body must have been a major body in the early inner Solar System. We further show via mixing calculations that all inner Solar System bodies accreted volatile elements with carbonaceous chondrite H and N isotope signatures extremely early in Solar System history. Only a small portion (if any) of comets and gaseous nebular H species contributed to the volatile content of the inner Solar System bodies.This article is part of the themed issue 'The origin, history and role of water in the evolution of the inner Solar System'. © 2017 The Author(s).

  14. Solar abundances of rock-forming elements, extreme oxygen and hydrogen in a young polluted white dwarf

    Science.gov (United States)

    Farihi, J.; Koester, D.; Zuckerman, B.; Vican, L.; Gänsicke, B. T.; Smith, N.; Walth, G.; Breedt, E.

    2016-12-01

    The Teff = 20 800 K white dwarf WD 1536+520 is shown to have broadly solar abundances of the major rock-forming elements O, Mg, Al, Si, Ca, and Fe, together with a strong relative depletion in the volatile elements C and S. In addition to the highest metal abundances observed to date, including log (O/He) = -3.4, the helium-dominated atmosphere has an exceptional hydrogen abundance at log (H/He) = -1.7. Within the uncertainties, the metal-to-metal ratios are consistent with the accretion of an H2O-rich and rocky parent body, an interpretation supported by the anomalously high trace hydrogen. The mixed atmosphere yields unusually short diffusion time-scales for a helium atmosphere white dwarf, of no more than a few hundred years, and equivalent to those in a much cooler, hydrogen-rich star. The overall heavy element abundances of the disrupted parent body deviate modestly from a bulk Earth pattern, and suggest the deposition of some core-like material. The total inferred accretion rate is 4.2 × 109 g s-1, and at least four times higher than for any white dwarf with a comparable diffusion time-scale. Notably, when accretion is exhausted in this system, both metals and hydrogen will become undetectable within roughly 300 Myr, thus supporting a scenario where the trace hydrogen is related to the ongoing accretion of planetary debris.

  15. Organic and volatile elements in the solar system

    Directory of Open Access Journals (Sweden)

    Remusat L.

    2012-01-01

    Full Text Available Chondrites and comets have accreted primitive materials from the early solar system. Those materials include organics, water and other volatile components. The most primitive chondrites and comets have undergone few modifications on their respective parent bodies and can deliver to laboratories components that were present at the origin of the protosolar nebula. Here I present a review of the organic material and volatile components that have been studied in the most primitive chondrites, and the last data from the stardust mission about the cometary record. This paper focuses on materials that can be studied in laboratories, by mass spectrometry, ion probes or organic chemistry techniques.

  16. Occurrence and volatility of several trace elements in pulverized coal boiler

    Institute of Scientific and Technical Information of China (English)

    HUANG Ya-ji; JIN Bao-sheng; ZHONG Zhao-ping; XIAO Rui; TANG Zhi-yong; REN Hui-feng

    2004-01-01

    The contents of eight trace elements(Mn, Cr, Pb, As, Se, Zn, Cd, Hg) in raw coal, bottom ash and flyash were measured in a 220 t/h pulverized coal boiler. Factors affecting distribution of trace elements wereinvestigated, including fly ash diameter, furnace temperature, oxygen content and trace elements' characters. Onecoefficient of Meij was also improved to more directly show element enrichment in combustion products. Theseelements may be classified into three groups according to their distribution: Group 1: Hg, which is very volatile.Group 2: Pb, Zn, Cd, which are partially volatile. Group 3: Mn, which is hardly volatile. Se may be locatedbetween groups 1 and 2. Cr has properties of both group 1 and 3. In addition, the smaller diameter of fly ash, themore relative enrichment of trace elements( except Mn). The fly ash showed different adsorption mechanisms oftrace elements and the volatilization of trace elements rises with furnace temperature. Relative enrichments of traceelements(except Mn and Cr) in fly ash are larger than that in bottom ash. Low oxygen content can not alwaysimprove the volatilization of trace elements. Pb is easier to form chloride than Cd during coal combustion. Traceelements should be classified in accordance with factors.

  17. Petrogenesis of high-CaO lavas from Mauna Kea, Hawaii: Constraints from trace element abundances

    Science.gov (United States)

    Huang, Shichun; Humayun, Munir

    2016-07-01

    The role of a mafic component in the petrogenesis of Oceanic Island Basalts (OIBs) is highly debated. As the best studied OIB, Hawaiian lavas provide critical insights into OIB genesis. At a given MgO content, the CaO content in the melt has been used to distinguish between partial melts of peridotite and garnet pyroxenite/eclogite. However, calculations using the BATCH program show that CaO contents in volatile-free melts saturated with all four phases, garnet, clinopyroxene, orthopyroxene and olivine, are controlled by both degrees of partial melting and source compositions, and low melt CaO content is not diagnostic of partial melts from garnet pyroxenite/eclogite. This is an important consideration in understanding the origin of high-CaO lavas recovered from the Hawaii Scientific Drilling Project (HSDP). Detailed geochemical and isotopic studies have been focused on the HSDP high- and low-SiO2 group lavas, and high-CaO lavas were not well studied because they were not included in the original reference suite samples. Here, we report trace element abundances obtained on a suite of high-CaO glasses and compared the trace element abundances of high-CaO lavas to those in high- and low-SiO2 lavas. When normalized to the average composition of low-SiO2 lavas, high-CaO lavas form a U-shaped trace element pattern, enriched in both the most incompatible (Nb, Th) and the least incompatible (Sc, V) elements. This compositional distinction is best explained if high-CaO parental magma represents a mixture of a low degree partial melt of the low-SiO2 mantle source with a high degree (>80%) partial melt derived from a mafic cumulate component. This mafic cumulate must be clinopyroxene-rich, and it could be delaminated mafic cumulate formed under arcs during continent formation, lower continental crust, recycled lower oceanic crust, or high pressure cumulates from a magma chamber.

  18. Diversity of Abundance Patterns of Light Neutron-capture Elements in Very-metal-poor Stars

    Science.gov (United States)

    Aoki, Misa; Ishimaru, Yuhri; Aoki, Wako; Wanajo, Shinya

    2017-03-01

    We determine the abundances of neutron-capture elements from Sr to Eu for five very-metal-poor stars (-3 universal pattern in the main r-process, similar to the abundance pattern of the r-process component of solar-system material. Still, it is uncertain whether the abundance pattern of the weak r-process shows universality or diversity, due to the sparseness of measured light neutron-capture elements. We have detected the key elements, Mo, Ru, and Pd, in five target stars to give an answer to this question. The abundance patterns of light neutron-capture elements from Sr to Pd suggest a diversity in the weak r-process. In particular, scatter in the abundance ratio between Ru and Pd is significant when the abundance patterns are normalized at Zr. Our results are compared with the elemental abundances predicted by nucleosynthesis models of supernovae with parameters such as electron fraction or proto-neutron-star mass, to investigate sources of such diversity in the abundance patterns of light neutron-capture elements. This paper presents that the variation in the abundances of observed stars can be explained with a small range of parameters, which can serve as constraints on future modeling of supernova models. Study based on data collected with the Subaru Telescope, operated by the National Astronomical Observatory of Japan.

  19. 187Re-187Os systematics, highly siderophile element, S-Se-Te abundances in the components of unequilibrated L chondrites

    Science.gov (United States)

    Kadlag, Yogita; Becker, Harry

    2016-01-01

    The 187Re-187Os systematics, abundances of highly siderophile elements (HSE: Re, platinum group elements and Au), Te, Se and S as well as major and minor elements were determined in separated components of two unequilibrated L chondrites QUE 97008 (L3.05) and Ceniceros (L3.7). The 187Re-187Os systematics are disturbed in the components of both meteorites, most likely due to open system behavior of Re during terrestrial weathering of QUE 97008 and alteration on the L chondrite parent body as indicated by an internal errorchron generated for components of Ceniceros. The HSE abundance patterns suggest that the bulk rock abundances were mainly controlled by two different end members. Non-magnetic fractions display lower Re/Os and HSE/Ir than CI chondrites. Chondrules, metal-troilite spherules and fine magnetic fractions, are depleted in refractory HSE and show higher Rh/Ir, Pd/Ir and Au/Ir than in CI chondrites. The different HSE compositions indicate the presence of unequilibrated alloys and loss of refractory HSE-rich carrier phases from the precursors of some L chondrite components. Gold is decoupled from other HSE in magnetic fractions and shows chalcophile affinities with a grain size dependent variation similar to S and Se, presumably inherited from preaccretionary processes. Tellurium is depleted in all components compared to other analysed siderophile elements, and its abundance was most likely controlled by fractional condensation and different geochemical affinities. The volatility dependent depletion of Te requires different physical and chemical conditions than typical for the canonical condensation sequence as represented by carbonaceous chondrites. Tellurium also shows variable geochemical behavior, siderophile in Ceniceros, predominantly chalcophile in QUE 97008. These differences may have been inherited from element partitioning during chondrule formation. Selenium and S on the other hand are almost unfractionated from each other and only show

  20. The Elemental Abundance Distributions of Milky Way Satellite Galaxies

    CERN Document Server

    Kirby, Evan N

    2010-01-01

    The chemical compositions of the stars in Milky Way (MW) satellite galaxies reveals the history of gas flows and star formation (SF) intensity. This talk presented a Keck/DEIMOS spectroscopic survey of the Fe, Mg, Si, Ca, and Ti abundances of nearly 3000 red giants in eight MW dwarf satellites. The metallicity and alpha-to-iron ratio distributions obey the following trends: (1) The more luminous galaxies are more metal-rich, indicating that they retained gas more efficiently than the less luminous galaxies. (2) The shapes of the metallicity distributions of the more luminous galaxies require gas infall during their SF lifetimes. (3) At [Fe/H] < -1.5, [alpha/Fe] falls monotonically with increasing [Fe/H] in all MW satellites. One interpretation of these trends is that the SF timescale in any MW satellite is long enough that Type Ia supernovae exploded for nearly the entire SF lifetime.

  1. Anatomy of a cluster IDP. Part 2: Noble gas abundances, trace element geochemistry, isotopic abundances, and trace organic chemistry of several fragments from L2008#5

    Science.gov (United States)

    Thomas, K. L.; Clemett, S. J.; Flynn, G. J.; Keller, L. P.; Mckay, David S.; Messenger, S.; Nier, A. O.; Schlutter, D. J.; Sutton, S. R.; Walker, R. M.

    1994-01-01

    The topics discussed include the following: noble gas content and release temperatures; trace element abundances; heating summary of cluster fragments; isotopic measurements; and trace organic chemistry.

  2. Peculiarities of the abundances of neutron-capture elements in Galactic open clusters

    CERN Document Server

    Marsakov, V A; Koval', V V; Shpigel', L V

    2016-01-01

    The properties of the relative abundances of rapid and slow neutron-capture elements are studied using a catalog containing spectroscopic abundance determinations for 14~elements produced in various nuclear-synthesis processes for 90~open clusters. The catalog also contains the positions, ages, velocities, and elements of the Galactic orbits of the clusters. The relative abundances of both $r$-elements (Eu) and $s$-elements (Y, Ba, La, and Ce) in clusters with high, elongated orbits and in field stars of the Galactic thin disk display different dependences on metallicity, age, Galactocentric distance, and the elements of the Galactic orbits, supporting the view that these objects have different natures. In young clusters, not only barium, but also the three other studied $s$-elements display significantly higher relative abundances than field stars of the same metallicity. The relative abundances of Eu are lower in high-metallicity clusters (${\\rm [Fe/H]} > -0.1$) with high, elongated orbits than in field gia...

  3. Parent Stars of Extrasolar Planets. VIII. Chemical Abundances for 18 Elements in 31 Stars

    CERN Document Server

    Gonzalez, Guillermo

    2007-01-01

    We present the results of detailed spectroscopic abundance analyses for 18 elements in 31 nearby stars with planets. The resulting abundances are combined with other similar studies of nearby stars with planets and compared to a sample of nearby stars without detected planets. We find some evidence for abundance differences between these two samples for Al, Si and Ti. Some of our results are in conflict with a recent study of stars with planets in the SPOCS database. We encourage continued study of the abundance patterns of stars with planets to resolve these discrepancies.

  4. Study of Neutron-Capture Element Abundances in Metal-Poor Stars

    CERN Document Server

    Li, Hongjie; Liang, Shuai; Cui, Wenyuan; Zhang, Bo

    2013-01-01

    This work describes a study of elemental abundances for 30 metal-poor stars whose chemical abundances provide excellent information for setting constraints on models of neutron-capture processes. Based on the abundances of main r- and weak r-process stars, the abundance patterns of main r-process and weak r-process are obtained. The two r-process component coefficients are defined to determine the relative contributions from individual neutron-capture process to abundances of metal-poor stars. Based on the component coefficients, we find that metal-poor stars BD+4 2621 and HD 4306 are also weak r-process stars, which means that the abundance pattern produced by weak r-process is stable. All metal-poor star abundances contain the contributions of both main r-process and weak r-process. The elements produced by weak r-process have increased along with Fe over the polluted history. Most of the metal-poor star abundances do not follow the pattern observed in solar system, but there is a small fraction that do. Fo...

  5. Developing ISM Dust Grain Models with Precision Elemental Abundances from IXO

    Science.gov (United States)

    Valencic, L. A.; Smith, R. K.; Juet, A.

    2009-01-01

    The exact nature of interstellar dust grains in the Galaxy remains mysterious, despite their ubiquity. Many viable models exist, based on available IR-UV data and assumed elemental abundances. However, the abundances, which are perhaps the most stringent constraint, are not well known: modelers must use proxies in the absence of direct measurements for the diffuse interstellar medium (ISM). Recent revisions of these proxy values have only added to confusion over which is the best representative for the diffuse ISM, and highlighted the need for direct, high signal-to-noise measurements from the ISM itself. The International X-ray Observatory's superior facilities will enable high-precision elemental abundance measurements. We ill show how these results will measure both the overall ISM abundances and challenge dust models, allowing us to construct a more realistic picture of the ISM.

  6. Determination of refractive and volatile elements in sediment using laser ablation inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Duodu, Godfred Odame; Goonetilleke, Ashantha; Allen, Charlotte; Ayoko, Godwin A

    2015-10-22

    Wet-milling protocol was employed to produce pressed powder tablets with excellent cohesion and homogeneity suitable for laser ablation (LA) analysis of volatile and refractive elements in sediment. The influence of sample preparation on analytical performance was also investigated, including sample homogeneity, accuracy and limit of detection. Milling in volatile solvent for 40 min ensured sample is well mixed and could reasonably recover both volatile (Hg) and refractive (Zr) elements. With the exception of Cr (-52%) and Nb (+26%) major, minor and trace elements in STSD-1 and MESS-3 could be analysed within ±20% of the certified values. Comparison of the method with total digestion method using HF was tested by analysing 10 different sediment samples. The laser method recovers significantly higher amounts of analytes such as Ag, Cd, Sn and Sn than the total digestion method making it a more robust method for elements across the periodic table. LA-ICP-MS also eliminates the interferences from chemical reagents as well as the health and safety risks associated with digestion processes. Therefore, it can be considered as an enhanced method for the analysis of heterogeneous matrices such as river sediments.

  7. The Abundance of Iron-Peak Elements and the Dust Composition in eta Carinae: Manganese

    Science.gov (United States)

    Bautista, M. A.; Melendez, M.; Hartman, H.; Gull, T. R.; Lodders, K.

    2010-01-01

    We study the chemical abundances of the Strontium Filament found in the ejecta of (eta) Carinae. In particular, we derive the abundances of iron-peak elements front spectra of their singly ionized ions present in the optical/IR spectra. In this paper we analyze the spectrum of Mn II using a new non-LTE model for this system. In constructing this models we carried out theoretical calculations of radiative transition rates and electron impact excitation rate coefficients. We find that relative to Ni the gas phase abundance ratio of Mn is roughly solar, similar to the Cr abundance but in contrast to the large enhancements in the abundances of Sc and Ti. NVe interpret this result as an indication of non-equilibrium condensation in the ejecta of (eta) Carinae.

  8. Open Cluster Neutron Capture Element Abundances and Milky Way Disk Evolution

    Science.gov (United States)

    Jacobson, Heather R.; Friel, E. D.

    2012-01-01

    Open clusters, whose ages and distances can be precisely determined, are useful probes of the chemical evolution of the Milky Way disk. The sample sizes of clusters subject to homogeneous analysis of high resolution spectra have grown in recent years, and increased attention has turned to measuring the abundances of neutron capture elements. The relative abundances of r-process elements (e.g., europium) to s-process elements (e.g., barium, lanthanum and zirconium) in cluster stars reveal the relative contributions of Type II supernovae and low-mass AGB stars to the chemical evolution of the galactic disk. A recent study of cluster s-process element abundances has revealed a surprising trend of increasing s-process element abundance ([s/Fe]) with decreasing cluster age, at odds with current s-process yield predictions (D'Orazi et al. 2009, Maiorca et al. 2011). We have undertaken an analysis of Zr, Ba, La, and Eu abundances in 17 open clusters based on high resolution optical spectra. The sample spans 700 Myr to 10 Gyr in age and Rgc 7-22 kpc in galactocentric distance, allowing for the exploration of neutron capture [x/Fe] ratios as a function of age and location in the disk. Preliminary results confirm the trend of enhanced [s/Fe] with decreasing cluster age found by other studies, though with a weaker correlation. Here we present the latest results of this analysis, including newly-determined abundances for the r-process element Eu for an expanded cluster sample that includes outer disk objects. This research is supported by a National Science Foundation Astronomy and Astrophysics Postdoctoral Fellowship to HRJ under award AST-0901919.

  9. Elemental abundance studies of the Ultraviolet Gallium CP star HD 168733

    Science.gov (United States)

    Collado, A. E.; López-García, Z.; Levato, H.; Malaroda, S.

    2009-05-01

    We report elemental abundance studies of the ultraviolet gallium CP star HD 168733. It is neither a silicon, nor a mercury-manganese star and a longitudinal magnetic field of the order of -594 gauss has been detected in it. The high resolution spectra were obtained with the EBASIM spectrograph attached to the 2.10 m telescope at CASLEO Observatory. The abundances results obtained show that Si es normal, Ti Cr and Fe are rich, PII, SII, GaII, SrII, YII, ZrII are present and its abundances are being determined. The presence of RE will be also investigated.

  10. Complete element abundances of nine stars in the r-process galaxy Reticulum II

    CERN Document Server

    Ji, Alexander P; Simon, Joshua D; Chiti, Anirudh

    2016-01-01

    We present chemical abundances derived from high-resolution Magellan/MIKE spectra of the nine brightest known red giant members of the ultra-faint dwarf galaxy Reticulum II. These stars span the full metallicity range of Ret II (-3.5 < [Fe/H] < -2). Seven of the nine stars have extremely high levels of r-process material ([Eu/Fe]~1.7), in contrast to the extremely low neutron-capture element abundances found in every other ultra-faint dwarf galaxy studied to date. The other two stars are the most metal-poor stars in the system ([Fe/H] < -3), and they have neutron-capture element abundance limits similar to those in other ultra-faint dwarf galaxies. We confirm that the relative abundances of Sr, Y, and Zr in these stars are similar to those found in r-process halo stars but ~0.5 dex lower than the solar r-process pattern. If the universal r-process pattern extends to those elements, the stars in Ret II display the least contaminated known r-process pattern. The abundances of lighter elements up to the...

  11. Determination of refractive and volatile elements in sediment using laser ablation inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Duodu, Godfred Odame [School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology (QUT), 2 George St, 4001, QLD (Australia); Goonetilleke, Ashantha [School of Civil Engineering and Built Environment, Science and Engineering Faculty, Queensland University of Technology (QUT), 2 George St, 4001, QLD (Australia); Allen, Charlotte [Institute for Future Environments, Queensland University of Technology (QUT), 2 George St, 4001, QLD (Australia); Ayoko, Godwin A., E-mail: g.ayoko@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology (QUT), 2 George St, 4001, QLD (Australia)

    2015-10-22

    Wet-milling protocol was employed to produce pressed powder tablets with excellent cohesion and homogeneity suitable for laser ablation (LA) analysis of volatile and refractive elements in sediment. The influence of sample preparation on analytical performance was also investigated, including sample homogeneity, accuracy and limit of detection. Milling in volatile solvent for 40 min ensured sample is well mixed and could reasonably recover both volatile (Hg) and refractive (Zr) elements. With the exception of Cr (−52%) and Nb (+26%) major, minor and trace elements in STSD-1 and MESS-3 could be analysed within ±20% of the certified values. Comparison of the method with total digestion method using HF was tested by analysing 10 different sediment samples. The laser method recovers significantly higher amounts of analytes such as Ag, Cd, Sn and Sn than the total digestion method making it a more robust method for elements across the periodic table. LA-ICP-MS also eliminates the interferences from chemical reagents as well as the health and safety risks associated with digestion processes. Therefore, it can be considered as an enhanced method for the analysis of heterogeneous matrices such as river sediments. - Highlights: • Wet milling was used to produce pressed tablet sediment for LA-ICP-MS analysis. • Milling was effective for refractive elements with narrow range of particle size. • This is the first use of LA-ICP-MS for Hg analysis in sediment samples. • Acceptable accuracy and precision were obtained for most of the elements studied. • Detection limits down to parts per trillion were observed for some elements.

  12. New Rare Earth Element Abundance Distributions for the Sun and Five r-Process-Rich Very Metal-Poor Stars

    CERN Document Server

    Sneden, Christopher; Cowan, John J; Ivans, Inese I; Hartog, Elizabeth A Den

    2009-01-01

    We have derived new abundances of the rare-earth elements Pr, Dy, Tm, Yb, and Lu for the solar photosphere and for five very metal-poor, neutron-capture r-process-rich giant stars. The photospheric values for all five elements are in good agreement with meteoritic abundances. For the low metallicity sample, these abundances have been combined with new Ce abundances from a companion paper, and reconsideration of a few other elements in individual stars, to produce internally-consistent Ba, rare-earth, and Hf (56<= Z <= 72) element distributions. These have been used in a critical comparison between stellar and solar r-process abundance mixes.

  13. Elemental abundance differences in the 16 Cygni binary system: a signature of gas giant planet formation?

    CERN Document Server

    Ramirez, I; Cornejo, D; Roederer, I U; Fish, J R

    2011-01-01

    The atmospheric parameters of the components of the 16Cygni binary system, in which the secondary has a gas giant planet detected, are measured accurately using high quality observational data. Abundances relative to solar are obtained for 25 elements with a mean error of 0.023 dex. The fact that 16CygA has about four times more lithium than 16CygB is normal considering the slightly different masses of the stars. The abundance patterns of 16CygA and B, relative to iron, are typical of that observed in most of the so-called solar twin stars, with the exception of the heavy elements (Z>30), which can, however, be explained by Galactic chemical evolution. Differential (A-B) abundances are measured with even higher precision (0.018 dex, on average). We find that 16CygA is more metal-rich than 16CygB by 0.041+/-0.007 dex. On an element-to-element basis, no correlation between the A-B abundance differences and dust condensation temperature (Tc) is detected. Based on these results, we conclude that if the process of...

  14. Heavy elements abundances in turn-off stars and early subgiants in NGC 6752

    CERN Document Server

    James, G; Bonifacio, P; Bragaglia, A; Carretta, E; Centurion, M; Clementini, G; Desidera, S; Gratton, R G; Grundahl, F; Lucatello, S; Molaro, P; Pasquini, L; Sneden, C; Spite, F

    2004-01-01

    High resolution spectra (R > 40 000) for 9 main sequence turn-off stars and 9 subgiants in the globular cluster NGC 6752 were acquired with UVES on the VLT-Kueyen (UT2). These data have been used to determine the abundances of some heavy elements (strontium, yttrium, barium and europium). This paper presents for the first time accurate results for heavy elements in this globular cluster. We did not find any systematic effect between the abundances found in turn-off stars, subgiants, and giants. We obtain the following mean abundances for these elements in our sample (turn-off stars and subgiants): [Sr/Fe] = 0.06 +/- 0.16, [Y/Fe] = -0.01 +/- 0.12, [Ba/Fe] = 0.18 +/- 0.11, and [Eu/Fe] = 0.41 +/- 0.09. The dispersion in the abundance ratios of the different elements is low and can be totally explained by uncertainties in their derivation. These ratios are in agreement with the values found in field halo stars with the same metallicity. We did not observe any correlation between the [n-capture/Fe] ratios and the ...

  15. Elemental abundances of Galactic bulge planetary nebulae from optical recombination lines

    CERN Document Server

    Wang, W

    2007-01-01

    (abridged) Deep long-slit optical spectrophotometric observations are presented for 25 Galactic bulge planetary nebulae (GBPNe) and 6 Galactic disk planetary nebulae (GDPNe). The spectra, combined with archival ultraviolet spectra obtained with the International Ultraviolet Explorer (IUE) and infrared spectra obtained with the Infrared Space Observatory (ISO), have been used to carry out a detailed plasma diagnostic and element abundance analysis utilizing both collisional excited lines (CELs) and optical recombination lines (ORLs). Comparisons of plasma diagnostic and abundance analysis results obtained from CELs and from ORLs reproduce many of the patterns previously found for GDPNe. In particular we show that the large discrepancies between electron temperatures (Te's) derived from CELs and from ORLs appear to be mainly caused by abnormally low values yielded by recombination lines and/or continua. Similarly, the large discrepancies between heavy element abundances deduced from ORLs and from CELs are large...

  16. The Open Cluster Chemical Abundances and Mapping (OCCAM) Survey: Optical Extension for Neutron Capture Elements

    Science.gov (United States)

    Melendez, Matthew; O'Connell, Julia; Frinchaboy, Peter M.; Donor, John; Cunha, Katia M. L.; Shetrone, Matthew D.; Majewski, Steven R.; Zasowski, Gail; Pinsonneault, Marc H.; Roman-Lopes, Alexandre; Stassun, Keivan G.; APOGEE Team

    2017-01-01

    The Open Cluster Chemical Abundance & Mapping (OCCAM) survey is a systematic survey of Galactic open clusters using data primarily from the SDSS-III/APOGEE-1 survey. However, neutron capture elements are very limited in the IR region covered by APOGEE. In an effort to fully study detailed Galactic chemical evolution, we are conducting a high resolution (R~60,000) spectroscopic abundance analysis of neutron capture elements for OCCAM clusters in the optical regime to complement the APOGEE results. As part of this effort, we present Ba II, La II, Ce II and Eu II results for a few open clusters without previous abundance measurements using data obtained at McDonald Observatory with the 2.1m Otto Struve telescope and Sandiford Echelle Spectrograph.This work is supported by an NSF AAG grant AST-1311835.

  17. A Low Abundance of 135Cs in the Early Solar System from Barium Isotopic Signatures of Volatile-depleted Meteorites

    Science.gov (United States)

    Brennecka, Gregory A.; Kleine, Thorsten

    2017-03-01

    Precise knowledge of the abundances of short-lived radionuclides at the start of the solar system leads to fundamental information about the stellar environment of solar system formation. Previous investigations of the short-lived {}135{Cs} \\to {}135{Ba} system (t 1/2 = 2.3 Ma) have resulted in a range of calculated initial amounts of 135Cs, with most estimates elevated to a level that requires extraneous input of material to the protoplanetary disk. Such an array of proposed 135Cs/133Cs initial solar system values has severely restricted the system’s use as both a possible chronometer and as an informant about supernovae input. However, if 135Cs was as abundant in the early solar system as previously proposed, the resulting deficits in its daughter product 135Ba would be easily detectable in volatile-depleted parent bodies (i.e., having sub-chondritic Cs/Ba) from the very early solar system. In this work, we show that angrites and eucrites, which were volatile-depleted within ∼1 million years of the start of the solar system, do not possess deficits in 135Ba compared to other planetary bodies. From this, we calculate an upper limit for the initial 135Cs/133Cs of 2.8 × 10‑6, well below previous estimates. This significantly lower initial 135Cs/133Cs ratio now suggests that all of the 135Cs present in the early solar system was inherited simply from galactic chemical evolution and no longer requires an addition from an external stellar source such as an asymptotic giant branch star or SN II, corroborating evidence from several other short-lived radionuclides.

  18. Volatiles in protoplanetary disks

    CERN Document Server

    Pontoppidan, Klaus M; Bergin, Edwin A; Brittain, Sean; Marty, Bernard; Mousis, Olvier; Oberg, Karin L

    2014-01-01

    Volatiles are compounds with low sublimation temperatures, and they make up most of the condensible mass in typical planet-forming environments. They consist of relatively small, often hydrogenated, molecules based on the abundant elements carbon, nitrogen and oxygen. Volatiles are central to the process of planet formation, forming the backbone of a rich chemistry that sets the initial conditions for the formation of planetary atmospheres, and act as a solid mass reservoir catalyzing the formation of planets and planetesimals. This growth has been driven by rapid advances in observations and models of protoplanetary disks, and by a deepening understanding of the cosmochemistry of the solar system. Indeed, it is only in the past few years that representative samples of molecules have been discovered in great abundance throughout protoplanetary disks - enough to begin building a complete budget for the most abundant elements after hydrogen and helium. The spatial distributions of key volatiles are being mapped...

  19. Gaia FGK benchmark stars: abundances of alpha and iron-peak elements

    CERN Document Server

    Jofré, P; Soubiran, C; Blanco-Cuaresma, S; Masseron, T; Nordlander, T; Chemin, L; Worley, C C; Van Eck, S; Hourihane, A; Gilmore, G; Adibekyan, V; Bergemann, M; Cantat-Gaudin, T; Delgado-Mena, E; Hernández, J I González; Guiglion, G; Lardo, C; de Laverny, P; Lind, K; Magrini, L; Mikolaitis, S; Montes, D; Pancino, E; Recio-Blanco, A; Sordo, R; Sousa, S; Tabernero, H M; Vallenari, A

    2015-01-01

    In the current era of large spectroscopic surveys of the Milky Way, reference stars for calibrating astrophysical parameters and chemical abundances are of paramount importance. We determine elemental abundances of Mg, Si, Ca, Sc, Ti, V, Cr, Mn, Co and Ni for our predefined set of Gaia FGK benchmark stars. By analysing high-resolution and high-signal to noise spectra taken from several archive datasets, we combined results of eight different methods to determine abundances on a line-by-line basis. We perform a detailed homogeneous analysis of the systematic uncertainties, such as differential versus absolute abundance analysis, as well as we assess errors due to NLTE and the stellar parameters in our final abundances. Our results are provided by listing final abundances and the different sources of uncertainties, as well as line-by-line and method-by-method abundances. The Gaia FGK benchmark stars atmospheric parameters are already being widely used for calibration of several pipelines applied to different su...

  20. Diversity of abundance patterns of neutron-capture elements in very metal-poor stars

    Science.gov (United States)

    Aoki, Misa; Aoki, Wako; Ishimaru, Yuhri; Wanajo, Shinya

    2014-05-01

    Observations of Very Metal-Poor stars indicate that there are at least two sites to r-process; "weak r-process" and "main r-process". A question is whether these two are well separated or there exists a variation in the r-process. We present the results of abundance analysis of neutron-capture elements in the two Very Metal-Poor stars HD107752 and HD110184 in the Milky Way halo observed with the Subaru Telescope HDS. The abundance patterns show overabundace at light n-capture elements (e.g. Sr, Y), inferring the element yielding of weak r-process, while heavy neutron-capture elements (e.g. Ba, Eu) are deficient; however, the overabundance of light ones is not as significant as that previously found in stars representing the weak r-process (e.g. HD122563; Honda et al. 2006). Our study show diversity in the abundance patterns from light to heavy neutron-capture elements in VMP stars, suggesting a variation in r-process, which may depend on electron fraction of environment.

  1. Diversity of abundance patterns of neutron-capture elements in very metal-poor stars

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, Misa; Ishimaru, Yuhri [International Christian University 10-2, Osawa, Mitaka, Tokyo 181-0015 (Japan); Aoki, Wako; Wanajo, Shinya [National Astronomical Observatory of Japan (NAOJ) 2-21-1, Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2014-05-02

    Observations of Very Metal-Poor stars indicate that there are at least two sites to r-process; “weak r-process” and “main r-process”. A question is whether these two are well separated or there exists a variation in the r-process. We present the results of abundance analysis of neutron-capture elements in the two Very Metal-Poor stars HD107752 and HD110184 in the Milky Way halo observed with the Subaru Telescope HDS. The abundance patterns show overabundace at light n-capture elements (e.g. Sr, Y), inferring the element yielding of weak r-process, while heavy neutron-capture elements (e.g. Ba, Eu) are deficient; however, the overabundance of light ones is not as significant as that previously found in stars representing the weak r-process (e.g. HD122563; Honda et al. 2006). Our study show diversity in the abundance patterns from light to heavy neutron-capture elements in VMP stars, suggesting a variation in r-process, which may depend on electron fraction of environment.

  2. Subaru/HDS study of CH stars: elemental abundances for stellar neutron-capture process studies

    Science.gov (United States)

    Goswami, Aruna; Aoki, Wako; Karinkuzhi, Drisya

    2016-01-01

    A comprehensive abundance analysis providing rare insight into the chemical history of lead stars is still lacking. We present results from high-resolution (R ˜ 50 000) spectral analyses of three CH stars, HD 26, HD 198269 and HD 224959, and, a carbon star with a dusty envelope, HD 100764. Previous studies on these objects are limited by both resolution and wavelength regions and the results differ significantly from each other. We have undertaken to reanalyse the chemical composition of these objects based on high-resolution Subaru spectra covering the wavelength regions 4020-6775 Å. Considering local thermodynamic equilibrium and using model atmospheres, we have derived the stellar parameters, the effective temperatures Teff, surface gravities log g, and metallicities [Fe/H] for these objects. The derived parameters for HD 26, HD 100764, HD 198269 and HD 224959 are (5000, 1.6, -1.13), (4750, 2.0 -0.86), (4500, 1.5, -2.06) and (5050, 2.1, -2.44), respectively. The stars are found to exhibit large enhancements of heavy elements relative to iron in conformity to previous studies. Large enhancement of Pb with respect to iron is also confirmed. Updates on the elemental abundances for several s-process elements (Y, Zr, La, Ce, Nd, Sm and Pb) along with the first-time estimates of abundances for a number of other heavy elements (Sr, Ba, Pr, Eu, Er and W) are reported. Our analysis suggests that neutron-capture elements in HD 26 primarily originate in the s-process while the major contributions to the abundances of neutron-capture elements in the more metal-poor objects HD 224959 and HD 198269 are from the r-process, possibly from materials that are pre-enriched with products of the r-process.

  3. The Volatility and condensation behaviour of elements in dependence of T and fO2: a novel experimental approach

    Science.gov (United States)

    Ertel-Ingrisch, Werner; Dingwell, Don B.

    2010-05-01

    The volatility of elements is one of the most important variables during geological processes on Earth: its impact ranges from daily out gassing of volcanic vents to catastrophic emissions during volcanic eruptions which might scale up to global impacts on our climate. Volatility played, however, already a major role during the formation of our solar system: the nebular gases and their element budget passed through an elemental fractionation process based on differences in the evaporation and condensation behaviour of matter within the solar nebula - the origin of all the planets within our solar system. Precise knowledge of the parameters controlling volatility as well as condensation of elements is still lacking. Whether an element behaves volatile or refractory depends highly on the temperature and oxygen fugacity (fO2) conditions prevailing. To address this issue, we initiated a systematic study of the volatility of 18 volatile elements in respect to fO2 and temperature applying a modified mechanically assisted equilibration technique (MAE): Approx. 60 g of a haplobasaltic starting composition (An-Di) doped with up to 5000 ppm of volatile elements (Li, K, Na, Ti, Cr, Mn, Co, Cu, Cu, Zn, Ga, Rb, Cd, In, Sn, Sb, Cs, Tl) was heated to run temperatures. To investigate the fO2 dependence 2 experiments at logfO2 = -11.3 (~ IW -0.5) and - 0,7 (pure air) at a constant temperature of 1300 °C were performed, while T dependence was investigated at 1300 and 1500 °C at constant fO2 in pure air. The original MAE technique was modified by two Al2O3 plates extending from the hot spot region up to the upper, cooler regions of the muffle tube. These plates function as condensation traps. The temperature profile of the entire setup including the Al2O3 plates under run conditions was calibrated prior to any run. Experiments lasted for up two weeks while experimental conditions were kept strictly constant and were monitored. Up to 46 samples were taken from the melt by time

  4. Volatile abundances and oxygen isotopes in basaltic to dacitic lavas on mid-ocean ridges: The role of assimilation at spreading centers

    Science.gov (United States)

    Wanless, V.D.; Perfit, M.R.; Ridley, W.I.; Wallace, P.J.; Grimes, Craig B.; Klein, E.M.

    2011-01-01

    Most geochemical variability in MOR basalts is consistent with low- to moderate-pressure fractional crystallization of various mantle-derived parental melts. However, our geochemical data from MOR high-silica glasses, including new volatile and oxygen isotope data, suggest that assimilation of altered crustal material plays a significant role in the petrogenesis of dacites and may be important in the formation of basaltic lavas at MOR in general. MOR high-silica andesites and dacites from diverse areas show remarkably similar major element trends, incompatible trace element enrichments, and isotopic signatures suggesting similar processes control their chemistry. In particular, very high Cl and elevated H2O concentrations and relatively light oxygen isotope ratios (~ 5.8‰ vs. expected values of ~ 6.8‰) in fresh dacite glasses can be explained by contamination of magmas from a component of ocean crust altered by hydrothermal fluids. Crystallization of silicate phases and Fe-oxides causes an increase in δ18O in residual magma, but assimilation of material initially altered at high temperatures results in lower δ18O values. The observed geochemical signatures can be explained by extreme fractional crystallization of a MOR basalt parent combined with partial melting and assimilation (AFC) of amphibole-bearing altered oceanic crust. The MOR dacitic lavas do not appear to be simply the extrusive equivalent of oceanic plagiogranites. The combination of partial melting and assimilation produces a distinct geochemical signature that includes higher incompatible trace element abundances and distinct trace element ratios relative to those observed in plagiogranites.

  5. CD -24_17504 revisited: a new comprehensive element abundance analysis

    CERN Document Server

    Jacobson, Heather R

    2015-01-01

    With [Fe/H] ~ -3.3, CD -24_17504 is a canonical metal-poor main sequence turn-off star. Though it has appeared in numerous literature studies, the most comprehensive abundance analysis for the star based on high resolution, high signal-to-noise spectra is nearly 15 years old. We present a new detailed abundance analysis for 21 elements based on combined archival Keck-HIRES and VLT-UVES spectra of the star that is higher in both spectral resolution and signal-to-noise than previous data. Our results for many elements are very similar to those of an earlier comprehensive study of the star, but we present for the first time a carbon abundance from the CH G-band feature as well as improved upper limits for neutron-capture species such as Y, Ba and Eu. In particular, we find that CD -24_17504 has [Fe/H] = -3.41, [C/Fe] = +1.10, [Sr/H] = -4.68 and [Ba/H] <= -4.46, making it a carbon enhanced metal-poor star with neutron-capture element abundances among the lowest measured in Milky Way halo stars.

  6. A Large-Scale Survey of Neutron-Capture Element Abundances in Planetary Nebulae

    CERN Document Server

    Sterling, N C; Kallman, T R

    2007-01-01

    We present results from the first large-scale survey of neutron(n)-capture element abundances in planetary nebulae (PNe). This survey was motivated by the fact that a PN may be enriched in n-capture elements if its progenitor star experienced s-process nucleosynthesis during the asymptotic giant branch (AGB) phase. [Kr III] 2.199 and/or [Se IV] 2.287 $\\mu$m were detected in 81 PNe out of 120 PNe, for a detection rate of nearly 70%. We derive Se and Kr abundances or upper limits using ionization correction factors derived from photoionization models. A significant range is found in the Se and Kr abundances, from near solar (no enrichment), to enriched by a factor of ten. Our survey has increased the number of PNe with known n-capture element abundances by an order of magnitude, enabling us to explore correlations between s-process enrichments and other nebular and central star properties. In particular, the Se and Kr enrichments display a positive correlation with nebular C/O ratios, as theoretically expected....

  7. Chemical Elements Abundance in the Universe and the Origin of Life

    CERN Document Server

    Valkovic, Vlado

    2016-01-01

    Element synthesis which started with p-p chain has resulted in several specific characteristics including lack of any stable isotope having atomic masses 5 or 8. The carbon to oxygen ratio is fixed early by the chain of coincidences. These, remarkably fine-tuned, conditions are responsible for our own existence and indeed the existence of any carbon based life in the Universe. Chemical evolution of galaxies reflects in the changes of chemical composition of stars, interstellar gas and dust. The evolution of chemical element abundances in a galaxy provides a clock for galactic aging. On the other hand, the living matter on the planet Earth needs only some elements for its existence. Compared with element requirements of living matter a hypothesis is put forward, by accepting the Anthropic Principle, which says: life as we know, (H-C-N-O) based, relying on the number of bulk and trace elements originated when two element abundance curves, living matter and galactic, coincided. This coincidence occurring at part...

  8. X-shooter spectroscopy of young stellar objects in Lupus. Lithium, iron, and barium elemental abundances

    Science.gov (United States)

    Biazzo, K.; Frasca, A.; Alcalá, J. M.; Zusi, M.; Covino, E.; Randich, S.; Esposito, M.; Manara, C. F.; Antoniucci, S.; Nisini, B.; Rigliaco, E.; Getman, F.

    2017-09-01

    Aims: With the purpose of performing a homogeneous determination of elemental abundances for members of the Lupus T association, we analyzed three chemical elements: lithium, iron, and barium. The aims were: 1) to derive the lithium abundance for the almost complete sample ( 90%) of known class II stars in the Lupus I, II, III, and IV clouds; 2) to perform chemical tagging of a region where few iron abundance measurements have been obtained in the past, and no determination of the barium content has been done up to now. We also investigated possible barium enhancement at the very young age of the region, as this element has become increasingly interesting in the last few years following the evidence of barium over-abundance in young clusters, the origin of which is still unknown. Methods: Using the X-shooter spectrograph mounted on the Unit 2 (UT2) at the Very Large Telescope (VLT), we analyzed the spectra of 89 cluster members, both class II (82) and class III (7) stars. We measured the strength of the lithium line at λ6707.8 Å and derived the abundance of this element through equivalent width measurements and curves of growth. For six class II stars we also derived the iron and barium abundances using the spectral synthesis method and the code MOOG. The veiling contribution was taken into account in the abundance analysis for all three elements. Results: We find a dispersion in the strength of the lithium line at low effective temperatures and identify three targets with severe Li depletion. The nuclear age inferred for these highly lithium-depleted stars is around 15 Myr, which exceeds by an order of magnitude the isochronal one. We derive a nearly solar metallicity for the members whose spectra could be analyzed. We find that Ba is over-abundant by 0.7 dex with respect to the Sun. Since current theoretical models cannot reproduce this abundance pattern, we investigated whether this unusually large Ba content might be related to effects due to stellar

  9. The elemental abundances in the intracluster medium as observed with XMM-Newton

    CERN Document Server

    Tamura, T; Herder, J W A; Bleeker, J A M; Peterson, J R

    2004-01-01

    XMM-Newton observations of 19 galaxy clusters are used to measure the elemental abundances and their spatial distributions in the intracluster medium. The sample mainly consists of X-ray bright and relaxed clusters with a cD galaxy. Along with detailed Si, S and Fe radial abundance distributions within 300-700 kpc in radius, the O abundances are accurately derived in the central region of the clusters. The Fe abundance maxima towards the cluster center, possibly due to the metals from the cD galaxy,are spatially resolved. The Si and S abundances also exhibit central increases in general, resulting in uniform Fe-Si-S ratios within the cluster. In contrast, the O abundances are in general uniform over the cluster. The mean O to Fe ratio within the cluster core is sub-solar, while that of the cluster scale is larger than the solar ratio. These measurements indicate that most of the Fe-Si-S and O in the intracluster medium have different origins, presumably in supernovae Ia and II, respectively. The obtained Fe a...

  10. Dynamic measurement of coal thermal properties and elemental composition of volatile matter during coal pyrolysis

    Directory of Open Access Journals (Sweden)

    Rohan Stanger

    2014-01-01

    Full Text Available A new technique that allows dynamic measurement of thermal properties, expansion and the elemental chemistry of the volatile matter being evolved as coal is pyrolysed is described. The thermal and other properties are measured dynamically as a function of temperature of the coal without the need for equilibration at temperature. In particular, the technique allows for continuous elemental characterisation of tars as they are evolved during pyrolysis and afterwards as a function of boiling point. The technique is demonstrated by measuring the properties of maceral concentrates from a coal. The variation in heats of reaction, thermal conductivity and expansion as a function of maceral composition is described. Combined with the elemental analysis, the results aid in the interpretation of the chemical processes contributing to the physical and thermal behaviour of the coal during pyrolysis. Potential applications in cokemaking studies are discussed.

  11. Siderophile and chalcophile element abundances in oceanic basalts, Pb isotope evolution and growth of the earth's core

    Science.gov (United States)

    Newsom, H. E.; White, W. M.; Jochum, K. P.; Hofmann, A. W.

    1986-01-01

    The hypothesis that the mantle Pb isotope ratios reflect continued extraction of Pb into the earth's core over geologic time is evaluated by studying the depeletion of chalcophile and siderophile elements in the mantle. Oceanic basalt samples are analyzed in order to determine the Pb, Sr, and Nd isotropic compositions and the abundances of siderophile and chalcophile elements and incompatible lithophile elements. The data reveal that there is no systematic variation of siderophile or chalcophile element abundances relative to abundances of lithophile elements and the Pb/Ce ratio of the mantle is constant. It is suggested that the crust formation involves nonmagmatic and magmatic processes.

  12. Detailed Chemical Abundances in NGC 5824: Another Metal-Poor Globular Cluster with Internal Heavy Element Abundance Variations

    CERN Document Server

    Roederer, Ian U; Bailey, John I; Spencer, Meghin; Crane, Jeffrey D; Shectman, Stephen A

    2015-01-01

    We present radial velocities, stellar parameters, and detailed abundances of 39 elements derived from high-resolution spectroscopic observations of red giant stars in the luminous, metal-poor globular cluster NGC 5824. We observe 26 stars in NGC 5824 using the Michigan/Magellan Fiber System (M2FS) and two stars using the Magellan Inamori Kyocera Echelle (MIKE) spectrograph. We derive a mean metallicity of [Fe/H]=-1.94+/-0.02 (statistical) +/-0.10 (systematic). The metallicity dispersion of this sample of stars, 0.08 dex, is in agreement with previous work and does not exceed the expected observational errors. Previous work suggested an internal metallicity spread only when fainter samples of stars were considered, so we cannot exclude the possibility of an intrinsic metallicity dispersion in NGC 5824. The M2FS spectra reveal a large internal dispersion in [Mg/Fe], 0.28 dex, which is found in a few other luminous, metal-poor clusters. [Mg/Fe] is correlated with [O/Fe] and anti-correlated with [Na/Fe] and [Al/F...

  13. The Origin of Solar Filament Plasma Inferred from In Situ Observations of Elemental Abundances

    Science.gov (United States)

    Song, H. Q.; Chen, Y.; Li, B.; Li, L. P.; Zhao, L.; He, J. S.; Duan, D.; Cheng, X.; Zhang, J.

    2017-02-01

    Solar filaments/prominences are one of the most common features in the corona, which may lead to energetic coronal mass ejections (CMEs) and flares when they erupt. Filaments are about 100 times cooler and denser than the coronal material, and physical understanding of their material origin remains controversial. Two types of scenarios have been proposed: one argues that the filament plasma is brought into the corona from photosphere or chromosphere through a siphon or evaporation/injection process, while the other suggests that the material condenses from the surrounding coronal plasma due to thermal instability. The elemental abundance analysis is a reasonable clue to constrain the models, as the siphon or evaporation/injection model would predict that the filament material abundances are close to the photospheric or chromospheric ones, while the condensation model should have coronal abundances. In this Letter, we analyze the elemental abundances of a magnetic cloud that contains the ejected filament material. The corresponding filament eruption occurred on 1998 April 29, accompanying an M6.8 class soft X-ray flare located at the heliographic coordinates S18E20 (NOAA 08210) and a fast halo CME with the linear velocity of 1374 km s‑1 near the Sun. We find that the abundance ratios of elements with low and high first ionization potential such as Fe/O, Mg/O, and Si/O are 0.150, 0.050, and 0.070, respectively, approaching their corresponding photospheric values 0.065, 0.081, and 0.066, which does not support the coronal origin of the filament plasma.

  14. Revisiting the plant hyperaccumulation criteria to rare plants and earth abundant elements

    Energy Technology Data Exchange (ETDEWEB)

    Branquinho, Cristina [Universidade de Lisboa, Faculdade de Ciencias, Centro de Ecologia e Biologia Vegetal, Campo Grande C2, Piso 4, 1749-016 Lisbon (Portugal) and Universidade Atlantica, Antiga Fabrica da Polvora de Barcarena, 2745-615 Barcarena (Portugal)]. E-mail: cmbranquinho@fc.ul.pt; Serrano, Helena Cristina [Universidade de Lisboa, Museu Nacional de Historia Natural, Jardim Botanico (Portugal); Pinto, Manuel Joao [Universidade de Lisboa, Museu Nacional de Historia Natural, Jardim Botanico (Portugal); Martins-Loucao, Maria Amelia [Universidade de Lisboa, Faculdade de Ciencias, Centro de Ecologia e Biologia Vegetal, Campo Grande C2, Piso 4, 1749-016 Lisbon (Portugal); Universidade de Lisboa, Museu Nacional de Historia Natural, Jardim Botanico (Portugal)

    2007-03-15

    The several established criteria to define a hyperaccumulator plant were applied to a rare and endangered species, Plantago almogravensis, and to the 3rd most abundant element in the earth crust, Al. Using the most common criteria, P. almogravensis undoubtedly is an Al hyperaccumulator plant. If the recent proposed requirements were considered, most of them matching those for a plant to be used in phytoextraction, it can only be considered an unusual accumulator of Al. A discussion is made concerning the several criteria of a hyperaccumulator plant in order to include rare and endemic ones and abundant elements. In ecological terms, the enrichment in Al and Fe observed may account for the differences in the vegetation pattern. Due to the rarity and endangered nature of this plant, the contribution of this work is also relevant for the ecological understanding and the development of conservation options of this endemic species. - Revisiting plant hyperaccumulation criteria.

  15. Abundances of TC and related elements in stars of type M, MS, and S

    Science.gov (United States)

    Vanture, Andrew D.; Wallerstein, George; Brown, Jeffrey A.; Bazan, Grant

    1991-11-01

    Abundances of Co, Zr, Nb, and Tc relative to V have been derived for a sample of ten M and MS stars from 0.10 A/pixel and 0.04 A/pixel Reticon spectra. On a scale with log N(H) = 12.0 and log N(V) = 4.0, it is found that log N(Tc) is about 1.4 for M stars 1.0 MS stars with Tc. It has been suggested by Dominy and Wallerstein that the presence of Tc in M stars which show no enhancements of other s-process elements can be explained by a 'mini s-process'. Detailed calculations and the observed abundances and Tc and related elements presented in this study put this interpretation in doubt. The observations also fail to support the alternative hypothesis suggested by Malaney and Lattanzio that Tc is produced by the photofission of Th and U.

  16. Abundances of Refractory Elements for G-type Stars with Extrasolar Planets

    CERN Document Server

    Kang, Wonseok; Kim, Kang-Min

    2011-01-01

    We confirm the difference of chemical abundance between stars with and without exoplanet, as well as present the relation between chemical abundances and the physical properties of exoplanets such as planetary mass and semi-major axis of planetary orbit. We have obtained the spectra of 52 G-type stars with BOES (BOAO Echelle Spectrograph) and carried out the abundance analysis for 12 elements of Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Co, and Ni. We first have found that the [Mn/Fe] ratios of planet-host stars are higher than those of comparisons in the whole metallicity range, and in metal-poor stars of [Fe/H] $<$ -0.4, the abundance difference have been larger than in metal-rich samples, especially for the elements of Mg, Al, Sc, Ti, V, and Co. When examined the relation between planet properties and metallicities of planet-host stars, we have observed that planet-host stars with low-metallicity tend to bear several low-mass planets ($< M_J$) instead of a massive gas-giant planet.

  17. Volatile Elements Retention During Injection Casting of Metallic Fuel Slug for a Recycling Fast Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong-Hwan; Song, Hoon; Kim, Hyung-Tae; Oh, Seok-Jin; Kuk, Seoung-Woo; Keum, Chang-Woon; Lee, Jung-Won; Kim, Ki-Hwan; Lee, Chan-Bock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    The as-cast fuels prepared by injection casting were sound and the internal integrities were found to be satisfactory through gamma-ray radiography. U and Zr were uniform throughout the matrix of the slug, and the impurities, i.e., oxygen, carbon, and nitrogen, satisfied the specification of the total impurities of less than 2000 ppm. The losses of the volatile Mn were effectively controlled using argon over pressures, and dynamic pumping for a period of time before injection showed no detrimental effect on the Mn loss by vaporization. This result suggests that volatile minor actinide-bearing fuels for SFRs can be prepared by improved injection methods. A practical process of metallic fuel fabrication for an SFR needs to be cost efficient, suitable for remote operation, and capable of mass production while reducing the amount of radioactive waste. Injection casting was chosen as the most promising technique, and this technique has been applied to fuel slug fabrication for the Experimental Breeder Reactor-II (EBR-II) driver and the Fast Flux Test Facility (FFTF) fuel pins. Because of the simplistic nature of the process and equipment, compared to other processes examined, this process has been successfully used in a remote operation environment for fueling of the EBR-II reactor. In this study, several injection casting methods were applied in order to prepare metallic fuel for an fast reactor that control the transport of volatile elements during fuel melting and casting. Mn was selected as a surrogate alloy since it possesses a total vapor pressure equivalent to that of a volatile minor actinide-bearing fuel. U.10Zr and U.10Zr.5Mn (wt%) metallic fuels were injection cast under various casting conditions and their soundness was characterized.

  18. Elemental abundance anomalies in the late Cenomanian extinction interval: a search for the source(s)

    Science.gov (United States)

    Orth, C.J.; Attrep, M.; Quintana, L.R.; Elder, W.P.; Kauffman, E.G.; Diner, R.; Villamil, T.

    1993-01-01

    Elemental abundances have been measured by neutron activation methods across the Cenomanian-Turonian (late Cretaceous) extinction interval in samples collected from sixteen sites in the Western Interior Basin of North America and from twelve widely separated locations around the globe, including six ODP/DSDP sites. In most Western Interior Basin sites, in Colombia, and in western Europe (weaker), two closely spaced elemental abundance peaks occur in the upper Cenomanian (??? 92 m.y.), spanning the ammonite zones of Sciponoceras gracile through Neocardioceras juddii. Elements with anomalously high concentrations include Sc, Ti, V, Cr, Mn, Co, Ni, Ir, Pt and Au. The lower peak coincides with the disappearance (extinction) of the foraminifer Rotalipora cushmani. In North American sections R. greenhornensis also disappears at or just below this horizon, but in Europe it disappears considerably earlier than R. cushmani. A series of molluscan extinction and speciation or migration events also begins near the stratigraphic level of the lower elemental abundance peak. The well-documented positive ?? 13C excursion begins just before the extinctions and the elemental anomalies, and continues into the lower Turonian, well above the upper anomaly. This carbon isotope excursion has been observed in East European sections where we find little or no evidence of the elemental anomalies, suggesting that the two phenomena may not be tightly coupled. Elemental abundance ratios in the anomalies closely resemble those of Mid-Atlantic Ridge basalt or Hawaiian lava (tholeiitic), but not those of C1 chondrite, black shale, average crustal rocks, or lamproite and kimberlite of roughly similar age in southeastern Kansas. The excess Ir and other siderophiles hint at possible large-body impact(s) for the source. However, we have not located microspherules (other than biogenic calcispheres) or shocked mineral grains in any of our samples. Furthermore, Sc, Ti, V and Mn are not enriched in

  19. The Volatile Element Evolution of Intra-plate Alkaline Rocks as Recorded by Apatite: An Example from the Hegau Volcanic Field (Southwest Germany)

    Science.gov (United States)

    Von Der Handt, A.; Rahn, M. K. W.; Wang, L. X.; Marks, M. A. W.

    2014-12-01

    The role of volatiles in the petrogenesis of alkaline intra-plate magmas has been the subject of an increasing number of experimental studies. The study of naturally occurring rocks and their volatile contents is often complicated by syn- and post-eruptive degassing and alteration processes. Minerals that incorporate volatiles into their structure such as apatites are often more faithful recorders of the pre-eruptive volatile budget. The Hegau volcanic field in Southwest Germany is part of the Central European Volcanic Province, lies around 60-70 km to the east of the Upper Rhine graben and of Miocene age. Three main lithological units can be distinguished (1) olivine melilites (2) phonolites and (3) the "Deckentuff" series referring to a series of diatreme-filling pipe breccias and lapilli tuff layers. Carbonatites occur subordinately in the Hegau province. Earlier radiometric age dating suggested distinct phases of volcanic activity of Deckentuffs, melilites and phonolites with little overlap, but new apatite fission-track and (U-Th)/He age data suggest a synchronous activity. Apatite is an abundant accessory phase in the Deckentuff and phonolite series and we investigated its major, trace and volatile element composition by EPMA, SIMS and cathodoluminescence imaging. Pronounced core-rim zoning of apatite in places attests that diffusional equilibration was very limited and they likely retained their primary compositions. This allows us to trace the entire magmatic evolution of the Hegau province from its most primitive to most evolved products as well as resolve it in time by combining age dating with compositional analysis. Apatite compositions fall along the OH-F join with low Cl-contents (<0.5 wt%). Volatile contents (Cl, OH, S) are highest in most primitive compositions and decrease with further evolution while F increases. Multiple magmatic cycles can be discerned with a general trend to the more evolved phonolite compositions toward the end of volcanic

  20. Abundances of neutron-capture elements in the Hot Extreme-Helium Stars V1920 Cygni and HD 124448

    CERN Document Server

    Pandey, G; Rao, N K; Jeffery, C S; Pandey, Gajendra; Lambert, David L.

    2004-01-01

    Analysis of HST STIS ultraviolet spectra of two hot extreme helium stars (EHes): V1920 Cyg and HD 124448 provide the first measurements of abundances of neutron-capture elements for EHes. Although the two stars have similar abundances for elements up through the iron-group, they differ strikingly in their abundances of heavier elements: V1920 Cyg is enriched by a factor of 30 in light neutron-capture elements (Y/Fe, Zr/Fe) relative to HD 124448. These differences in abundances of neutron-capture elements among EHes mirrors that exhibited by the RCrB stars, and is evidence supporting the view that there is an evolutionary connection between these two groups of hydrogen-deficient stars. Also, the abundances of Y and Zr in V1920 Cyg provide evidence that at least one EHe star went through a s-process synthesis episode in its earlier evolution.

  1. Disk Evolution, Element Abundances and Cloud Properties of Young Gas Giant Planets

    Directory of Open Access Journals (Sweden)

    Christiane Helling

    2014-04-01

    Full Text Available We discuss the chemical pre-conditions for planet formation, in terms of gas and ice abundances in a protoplanetary disk, as function of time and position, and the resulting chemical composition and cloud properties in the atmosphere when young gas giant planets form, in particular discussing the effects of unusual, non-solar carbon and oxygen abundances. Large deviations between the abundances of the host star and its gas giants seem likely to occur if the planet formation follows the core-accretion scenario. These deviations stem from the separate evolution of gas and dust in the disk, where the dust forms the planet cores, followed by the final run-away accretion of the left-over gas. This gas will contain only traces of elements like C, N and O, because those elements have frozen out as ices. PRODIMO protoplanetary disk models are used to predict the chemical evolution of gas and ice in the midplane. We find that cosmic rays play a crucial role in slowly un-blocking the CO, where the liberated oxygen forms water, which then freezes out quickly. Therefore, the C/O ratio in the gas phase is found to gradually increase with time, in a region bracketed by the water and CO ice-lines. In this regions, C/O is found to approach unity after about 5 Myrs, scaling with the cosmic ray ionization rate assumed. We then explore how the atmospheric chemistry and cloud properties in young gas giants are affected when the non-solar C/O ratios predicted by the disk models are assumed. The DRIFT cloud formation model is applied to study the formation of atmospheric clouds under the influence of varying premordial element abundances and its feedback onto the local gas. We demonstrate that element depletion by cloud formation plays a crucial role in converting an oxygen-rich atmosphere gas into carbon-rich gas when non-solar, premordial element abundances are considered as suggested by disk models.

  2. Disk evolution, element abundances and cloud properties of young gas giant planets.

    Science.gov (United States)

    Helling, Christiane; Woitke, Peter; Rimmer, Paul B; Kamp, Inga; Thi, Wing-Fai; Meijerink, Rowin

    2014-04-14

    We discuss the chemical pre-conditions for planet formation, in terms of gas and ice abundances in a protoplanetary disk, as function of time and position, and the resulting chemical composition and cloud properties in the atmosphere when young gas giant planets form, in particular discussing the effects of unusual, non-solar carbon and oxygen abundances. Large deviations between the abundances of the host star and its gas giants seem likely to occur if the planet formation follows the core-accretion scenario. These deviations stem from the separate evolution of gas and dust in the disk, where the dust forms the planet cores, followed by the final run-away accretion of the left-over gas. This gas will contain only traces of elements like C, N and O, because those elements have frozen out as ices. PRODIMO protoplanetary disk models are used to predict the chemical evolution of gas and ice in the midplane. We find that cosmic rays play a crucial role in slowly un-blocking the CO, where the liberated oxygen forms water, which then freezes out quickly. Therefore, the C/O ratio in the gas phase is found to gradually increase with time, in a region bracketed by the water and CO ice-lines. In this regions, C/O is found to approach unity after about 5 Myrs, scaling with the cosmic ray ionization rate assumed. We then explore how the atmospheric chemistry and cloud properties in young gas giants are affected when the non-solar C/O ratios predicted by the disk models are assumed. The DRIFT cloud formation model is applied to study the formation of atmospheric clouds under the influence of varying premordial element abundances and its feedback onto the local gas. We demonstrate that element depletion by cloud formation plays a crucial role in converting an oxygen-rich atmosphere gas into carbon-rich gas when non-solar, premordial element abundances are considered as suggested by disk models.

  3. Semi-volatile organic compounds and trace elements in the Yangtze River source of drinking water.

    Science.gov (United States)

    Wu, Bing; Zhang, Xuxiang; Zhang, Xiaolin; Yasun, Aishangjiang; Zhang, Yan; Zhao, Dayong; Ford, Tim; Cheng, Shupei

    2009-08-01

    Determination of 24 semi-volatile organic compounds (SVOCs) and 24 trace elements in water samples was conducted in order to investigate the quality of the Nanjing source of drinking water taken from Yangtze River. The total concentrations of SVOCs and trace elements were in the range of 1,951-11,098 ng/l and 51,274-72,384 microg/l, respectively. No significant seasonal changes were found for the pollutants' concentrations. A primary health risk assessment was carried out to evaluate potential health effects. Risk quotients involving carcinogenic effects for benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, dibenz(a,h)anthracene, bis(2-ethylhexyl)phthalate and arsenic were >1 under the worst-case scenario. The results of this study demonstrate the importance of further studies on the environmental health effects of exposure to the source water.

  4. Abundances of Volatile - Bearing Species from Evolved Gas Analysis of Samples from the Rocknest Aeolian Bedform in Gale Crater

    Science.gov (United States)

    Archer, P. D., Jr.; Franc, H. B.; Sutter, B.; McAdam, A.; Ming, D. W.; Morris, R. V.; Mahaffy, P. R.

    2013-01-01

    The Sample Analysis at Mars (SAM) instrument suite on board the Mars Science Laboratory (MSL) recently ran four samples from an aeolian bedform named Rocknest. SAM detected the evolution of H2O, CO2, O2, and SO2, indicative of the presence of multiple volatile bearing species (Fig 1). The Rocknest bedform is a windblown deposit selected as representative of both the windblown material in Gale crater as well as the globally-distributed martian dust. Four samples of Rocknest material were analyzed by SAM, all from the fifth scoop taken at this location. The material delivered to SAM passed through a 150 m sieve and is assumed to have been well mixed during the sample acquisition/preparation/handoff process. SAM heated the Rocknest samples to approx.835 C at a ramp rate of 35 C/min with a He carrier gas flow rate of apprx.1.5 standard cubic centimeters per minute and at an oven pressure of 30 mbar [1]. Evolved gases were detected by a quadrupole mass spectrometer (QMS). This abstract presents the molar abundances of H2O, CO2, O2, and SO2 as well as their concentration in rocknest samples using an estimated sample mass.

  5. Trace element abundances in megacrysts and their host basalts - Constraints on partition coefficients and megacryst genesis

    Science.gov (United States)

    Irving, A. J.; Frey, F. A.

    1984-01-01

    Rare earth and other trace element abundances are determined in megacrysts of clinopyroxene, orthopyroxene, amphibole, mica, anorthoclase, apatite and zircon, as well as their host basalts, in an effort to gather data on mineral/melt trace element partitioning during the high pressure petrogenesis of basic rocks. Phase equilibria, major element partitioning and isotopic ratio considerations indicate that while most of the pyroxene and amphibole megacrysts may have been in equilibrium with their host magmas at high pressures, mica, anorthoclase, apatite, and zircon megacrysts are unlikely to have formed in equilibrium with their host basalts. It is instead concluded that they were precipitated from more evolved magmas, and have been mixed into their present hosts.

  6. Complete Element Abundances of Nine Stars in the r-process Galaxy Reticulum II

    Science.gov (United States)

    Ji, Alexander P.; Frebel, Anna; Simon, Joshua D.; Chiti, Anirudh

    2016-10-01

    We present chemical abundances derived from high-resolution Magellan/Magellan Inamori Kyocera Echelle spectra of the nine brightest known red giant members of the ultra-faint dwarf galaxy Reticulum II (Ret II). These stars span the full metallicity range of Ret II (‑3.5 date. The other two stars are the most metal-poor stars in the system ([Fe/H] up to the iron peak are otherwise similar to abundances of stars in the halo and in other ultra-faint dwarf galaxies. However, the scatter in abundance ratios is large enough to suggest that inhomogeneous metal mixing is required to explain the chemical evolution of this galaxy. The presence of low amounts of neutron-capture elements in other ultra-faint dwarf galaxies may imply the existence of additional r-process sites besides the source of r-process elements in Ret II. Galaxies like Ret II may be the original birth sites of r-process enhanced stars now found in the halo. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

  7. Elemental abundances of low-mass stars in the young clusters 25 Ori and lambda Ori

    CERN Document Server

    Biazzo, K; Palla, F; Briceno, C

    2011-01-01

    Aims. We aim to derive the chemical pattern of the young clusters 25 Orionis and lambda Orionis through homogeneous and accurate measurements of elemental abundances. Methods. We present FLAMES/UVES observations of a sample of 14 K-type targets in the 25 Ori and lambda Ori clusters; we measure their radial velocities, in order to confirm cluster membership. We derive stellar parameters and abundances of Fe, Na, Al, Si, Ca, Ti, and Ni using the code MOOG. Results. All the 25 Ori stars are confirmed cluster members without evidence of binarity; in lambda Ori we identify one non-member and one candidate single-lined binary star. We find an average metallicity [Fe/H]=-0.05+/-0.05 for 25 Ori, where the error is the 1sigma standard deviation from the average. lambda Ori members have a mean iron abundance value of 0.01+/-0.01. The other elements show close-to-solar ratios and no star-to-star dispersion. Conclusions. Our results, along with previous metallicity determinations in the Orion complex, evidence a small bu...

  8. Spatial Distribution of Element Abundances and Ionization States in Solar Energetic-Particle Events

    Science.gov (United States)

    Reames, Donald V.

    2017-08-01

    We have studied the spatial and temporal distribution of abundances of chemical elements in large "gradual" solar energetic-particle (SEP) events, and especially the source plasma temperatures, derived from those abundances, using measurements from the Wind and Solar TErrestrial RElations Observatory (STEREO) spacecraft, widely separated in solar longitude. A power-law relationship between abundance enhancements and mass-to-charge ratios [A/Q] of the ions can be used to determine Q-values and source plasma temperatures at remote spacecraft with instruments that were not designed for charge-state measurements. We search for possible source variations along the accelerating shock wave, finding one clear case where the accelerating shock wave appears to dispatch ions from 3.2± 0.8 MK plasma toward one spacecraft and those from 1.6± 0.2 MK plasma toward another, 116∘ away. The difference persists for three days and then fades away. Three other SEP events show less-extreme variation in source temperatures at different spacecraft, in one case observed over 222∘ in longitude. This initial study shows how the power-law relation between abundance enhancements and ion A/Q-values provides a new technique to determine Q and plasma temperatures in the seed population of SEP ions over a broad region of space using remote spacecraft with instruments that were not originally designed for measurements of ionization states.

  9. Gaia FGK benchmark stars: opening the black box of stellar element abundance determination

    Science.gov (United States)

    Jofré, P.; Heiter, U.; Worley, C. C.; Blanco-Cuaresma, S.; Soubiran, C.; Masseron, T.; Hawkins, K.; Adibekyan, V.; Buder, S.; Casamiquela, L.; Gilmore, G.; Hourihane, A.; Tabernero, H.

    2017-05-01

    Gaia and its complementary spectroscopic surveys combined will yield the most comprehensive database of kinematic and chemical information of stars in the Milky Way. The Gaia FGK benchmark stars play a central role in this matter as they are calibration pillars for the atmospheric parameters and chemical abundances for various surveys. The spectroscopic analyses of the benchmark stars are done by combining different methods, and the results will be affected by the systematic uncertainties inherent in each method. In this paper, we explore some of these systematic uncertainties. We determined line abundances of Ca, Cr, Mn and Co for four benchmark stars using six different methods. We changed the default input parameters of the different codes in a systematic way and found, in some cases, significant differences between the results. Since there is no consensus on the correct values for many of these default parameters, we urge the community to raise discussions towards standard input parameters that could alleviate the difference in abundances obtained by different methods. In this work, we provide quantitative estimates of uncertainties in elemental abundances due to the effect of differing technical assumptions in spectrum modelling.

  10. Modelling of Equilibrium Between Mantle and Core: Refractory, Volatile, and Highly Siderophile Elements

    Science.gov (United States)

    Righter, K.; Danielson, L.; Pando, K.; Shofner, G.; Lee, C. -T.

    2013-01-01

    Siderophile elements have been used to constrain conditions of core formation and differentiation for the Earth, Mars and other differentiated bodies [1]. Recent models for the Earth have concluded that the mantle and core did not fully equilibrate and the siderophile element contents of the mantle can only be explained under conditions where the oxygen fugacity changes from low to high during accretion and the mantle and core do not fully equilibrate [2,3]. However these conclusions go against several physical and chemical constraints. First, calculations suggest that even with the composition of accreting material changing from reduced to oxidized over time, the fO2 defined by metal-silicate equilibrium does not change substantially, only by approximately 1 logfO2 unit [4]. An increase of more than 2 logfO2 units in mantle oxidation are required in models of [2,3]. Secondly, calculations also show that metallic impacting material will become deformed and sheared during accretion to a large body, such that it becomes emulsified to a fine scale that allows equilibrium at nearly all conditions except for possibly the length scale for giant impacts [5] (contrary to conclusions of [6]). Using new data for D(Mo) metal/silicate at high pressures, together with updated partitioning expressions for many other elements, we will show that metal-silicate equilibrium across a long span of Earth s accretion history may explain the concentrations of many siderophile elements in Earth's mantle. The modeling includes refractory elements Ni, Co, Mo, and W, as well as highly siderophile elements Au, Pd and Pt, and volatile elements Cd, In, Bi, Sb, Ge and As.

  11. What are the Sources of Solar Energetic Particles? Element Abundances and Source Plasma Temperatures

    CERN Document Server

    Reames, Donald V

    2015-01-01

    We have spent 50 years in heated discussion over which populations of solar energetic particles (SEPs) are accelerated at flares and which by shock waves driven out from the Sun by coronal mass ejections (CMEs). The association of the large "gradual" SEP events with shock acceleration is supported by the extensive spatial distribution of SEPs and by the delayed acceleration of the particles. The relative abundances of the elements in these gradual events are a measure of those in the ambient solar corona, differing from those in the photosphere by a widely-observed function of the first ionization potential (FIP) of the elements. SEP events we call "impulsive", the traditional "3He-rich" events with enhanced heavy-element abundances, are associated with type III radio bursts, flares, and narrow CMEs; they selectively populate flux tubes that thread a localized source, and they are fit to new particle-in-cell models of magnetic reconnection on open field lines as found in solar jets. These models help explain ...

  12. New Atomic Data for Trans-Iron Elements and Their Application to Abundance Determinations in Planetary Nebulae

    CERN Document Server

    Sterling, N C; Esteves, D A; Bilodeau, R C; Kilcoyne, A L D; Red, E C; Phaneuf, R A; Alna'Washi, G; Aguilar, A

    2010-01-01

    [Abridged] Investigations of neutron(n)-capture element nucleosynthesis and chemical evolution have largely been based on stellar spectroscopy. However, the recent detection of these elements in several planetary nebulae (PNe) indicates that nebular spectroscopy is a promising new tool for such studies. In PNe, n-capture element abundance determinations reveal details of s-process nucleosynthesis and convective mixing in evolved low-mass stars, as well as the chemical evolution of elements that cannot be detected in stellar spectra. Only one or two ions of a given trans-iron element can typically be detected in individual nebulae. Elemental abundance determinations thus require corrections for the abundances of unobserved ions. Such corrections rely on the availability of atomic data for processes that control the ionization equilibrium of nebulae. Until recently, these data were unknown for virtually all n-capture element ions. For the first five ions of Se, Kr, and Xe -- the three most widely detected n-cap...

  13. Trace Element Abundances in an Unusual Hibonite-Perovskite Refractory Inclusion from Allende

    Science.gov (United States)

    Mane, Prajkta; Wadhwa, M.; Keller, L. P.

    2013-01-01

    Calcium-aluminum-rich refractory inclusions (CAIs) are thought to be the first-formed solids in the Solar protoplanetary disk and can provide information about the earliest Solar System processes (e.g., [1]). A hibonite-perovskitebearing CAI from the Allende CV3 chondrite (SHAL, [2]) contains a single of 500 micrometers hibonite grain and coarse-grained perovskite. The mineralogy and oxygen isotopic composition of this CAI shows similarities with FUN inclusions, especially HAL [2]. Here we present trace element abundances in SHAL.

  14. Aerosols in the tropical and subtropical UT/LS: in-situ measurements of submicron particle abundance and volatility

    Directory of Open Access Journals (Sweden)

    S. Borrmann

    2010-06-01

    Full Text Available Processes occurring in the tropical upper troposphere (UT, the Tropical Transition Layer (TTL, and the lower stratosphere (LS are of importance for the global climate, for stratospheric dynamics and air chemistry, and for their influence on the global distribution of water vapour, trace gases and aerosols. In this contribution we present aerosol and trace gas (in-situ measurements from the tropical UT/LS over Southern Brazil, Northern Australia, and West Africa. The instruments were operated on board of the Russian high altitude research aircraft M-55 "Geophysica" and the DLR Falcon-20 during the campaigns TROCCINOX (Araçatuba, Brazil, February 2005, SCOUT-O3 (Darwin, Australia, December 2005, and SCOUT-AMMA (Ouagadougou, Burkina Faso, August 2006. The data cover submicron particle number densities and volatility from the COndensation PArticle counting System (COPAS, as well as relevant trace gases like N2O, ozone, and CO. We use these trace gas measurements to place the aerosol data into a broader atmospheric context. Also a juxtaposition of the submicron particle data with previous measurements over Costa Rica and other tropical locations between 1999 and 2007 (NASA DC-8 and NASA WB-57F is provided. The submicron particle number densities, as a function of altitude, were found to be remarkably constant in the tropical UT/LS altitude band for the two decades after 1987. Thus, a parameterisation suitable for models can be extracted from these measurements. Compared to the average levels in the period between 1987 and 2007 a slight increase of particle abundances was found for 2005/2006 at altitudes with potential temperatures, Θ, above 430 K. The origins of this increase are unknown except for increases measured during SCOUT-AMMA. Here the eruption of the Soufrière Hills volcano in the Caribbean caused elevated particle mixing ratios. The vertical profiles from Northern hemispheric mid-latitudes between 1999 and 2006 also are

  15. Aerosols in the tropical and subtropical UT/LS: in-situ measurements of submicron particle abundance and volatility

    Science.gov (United States)

    Borrmann, S.; Kunkel, D.; Weigel, R.; Minikin, A.; Deshler, T.; Wilson, J. C.; Curtius, J.; Volk, C. M.; Homan, C. D.; Ulanovsky, A.; Ravegnani, F.; Viciani, S.; Shur, G. N.; Belyaev, G. V.; Law, K. S.; Cairo, F.

    2010-06-01

    Processes occurring in the tropical upper troposphere (UT), the Tropical Transition Layer (TTL), and the lower stratosphere (LS) are of importance for the global climate, for stratospheric dynamics and air chemistry, and for their influence on the global distribution of water vapour, trace gases and aerosols. In this contribution we present aerosol and trace gas (in-situ) measurements from the tropical UT/LS over Southern Brazil, Northern Australia, and West Africa. The instruments were operated on board of the Russian high altitude research aircraft M-55 "Geophysica" and the DLR Falcon-20 during the campaigns TROCCINOX (Araçatuba, Brazil, February 2005), SCOUT-O3 (Darwin, Australia, December 2005), and SCOUT-AMMA (Ouagadougou, Burkina Faso, August 2006). The data cover submicron particle number densities and volatility from the COndensation PArticle counting System (COPAS), as well as relevant trace gases like N2O, ozone, and CO. We use these trace gas measurements to place the aerosol data into a broader atmospheric context. Also a juxtaposition of the submicron particle data with previous measurements over Costa Rica and other tropical locations between 1999 and 2007 (NASA DC-8 and NASA WB-57F) is provided. The submicron particle number densities, as a function of altitude, were found to be remarkably constant in the tropical UT/LS altitude band for the two decades after 1987. Thus, a parameterisation suitable for models can be extracted from these measurements. Compared to the average levels in the period between 1987 and 2007 a slight increase of particle abundances was found for 2005/2006 at altitudes with potential temperatures, Θ, above 430 K. The origins of this increase are unknown except for increases measured during SCOUT-AMMA. Here the eruption of the Soufrière Hills volcano in the Caribbean caused elevated particle mixing ratios. The vertical profiles from Northern hemispheric mid-latitudes between 1999 and 2006 also are compact enough to derive a

  16. Volatile Constituents, Inorganic Elements and Primary Screening of Bioactivity of Black Coral Cigarette Holders

    Directory of Open Access Journals (Sweden)

    Ganggang Shi

    2011-05-01

    Full Text Available Black corals (BC have been used for a long time in Chinese medicine, and may have some pharmaceutical functions when used as material for cigarette holders in southeast China. This study is aimed to investigate the bioactivities of volatile constituents in BC and to explore the folklore behind the use of BC cigarette holders (BCCHs. We extracted the volatile constituents of BC by supercritical fluid extraction (SFE with carbon dioxide (CO2-SFE, then identified and analyzed the constituents by gas chromatography-mass spectrometry (GC-MS. In total, 15 components were reliably identified in BC and found to be biologically active. These included triethyl phosphate, butylated hydroxytoluene, cedrol, n-hexadecanoic acid, squalene, and cholesterol. Meanwhile 13 inorganic elements (P, Ca, Mg, S, B, Si, Fe, Cu, Zn, Ba, etc. were determined by inductively coupled plasma spectrometer (ICPS. In the bioactivity tests, the BC extract (BCE showed a scavenging activity of 2,2-diphenyl-1-picrylhydrazyl free radicals and hydroxyl radicals by phenanthroline-Fe (II oxidation and moderate inhibition of Gram-positive microorganisms. The antioxidant and antimicrobial activities of BC, which are related to the active chemical composition, may explain the perceived benefit for cigarette smokers who use BCCHs.

  17. Neutral Theory Predicts the Relative Abundance and Diversity of Genetic Elements in a Broad Array of Eukaryotic Genomes

    Science.gov (United States)

    Serra, François; Becher, Verónica; Dopazo, Hernán

    2013-01-01

    It is universally true in ecological communities, terrestrial or aquatic, temperate or tropical, that some species are very abundant, others are moderately common, and the majority are rare. Likewise, eukaryotic genomes also contain classes or “species” of genetic elements that vary greatly in abundance: DNA transposons, retrotransposons, satellite sequences, simple repeats and their less abundant functional sequences such as RNA or genes. Are the patterns of relative species abundance and diversity similar among ecological communities and genomes? Previous dynamical models of genomic diversity have focused on the selective forces shaping the abundance and diversity of transposable elements (TEs). However, ideally, models of genome dynamics should consider not only TEs, but also the diversity of all genetic classes or “species” populating eukaryotic genomes. Here, in an analysis of the diversity and abundance of genetic elements in >500 eukaryotic chromosomes, we show that the patterns are consistent with a neutral hypothesis of genome assembly in virtually all chromosomes tested. The distributions of relative abundance of genetic elements are quite precisely predicted by the dynamics of an ecological model for which the principle of functional equivalence is the main assumption. We hypothesize that at large temporal scales an overarching neutral or nearly neutral process governs the evolution of abundance and diversity of genetic elements in eukaryotic genomes. PMID:23798991

  18. Radial Transport in the Solar Nebula: Implications for Moderately Volatile Element Depletions in Chondritic Meteorites

    CERN Document Server

    Ciesla, F J

    2007-01-01

    In this paper, the possibility that the moderately volatile element depletions observed in chondritic meteorites are the results of planetesimals accreting in a solar nebula that cooled from an initially hot state (temperatures > 1350 K out to ~2-4 AU) is explored. A model is developed to track the chemical inventory of planetesimals that accrete in a viscously evolving protoplanetary disk, accounting for the redistribution of solids and vapor by advection, diffusion, and gas drag. It is found that depletion trends similar to those observed in the chondritic meteorites can be reproduced for a small range of model parameters. However, the necessary range of parameters is inconsistent with observations of disks around young stars and other constraints on meteorite parent body formation. Thus, counter to previous work, it is concluded that the global scale evolution of the solar nebula is not the cause for the observed depletion trends.

  19. Multi-Element Abundance Measurements from Medium-Resolution Spectra. IV. Alpha Element Distributions in Milky Way Satellite Galaxies

    CERN Document Server

    Kirby, Evan N; Smith, Graeme H; Majewski, Steven R; Sohn, Sangmo Tony; Guhathakurta, Puragra

    2010-01-01

    We derive the star formation histories of eight dwarf spheroidal (dSph) Milky Way satellite galaxies from their alpha element abundance patterns. Nearly 3000 stars from our previously published catalog (Paper II) comprise our data set. The average [alpha/Fe] ratios for all dSphs follow roughly the same path with increasing [Fe/H]. We do not observe the predicted knees in the [alpha/Fe] vs. [Fe/H] diagram, corresponding to the metallicity at which Type Ia supernovae begin to explode. Instead, we find that Type Ia supernova ejecta contribute to the abundances of all but the most metal-poor ([Fe/H] < -2.5) stars. We have also developed a chemical evolution model that tracks the star formation rate, Types II and Ia supernova explosions, and supernova feedback. Without metal enhancement in the supernova blowout, massive amounts of gas loss define the history of all dSphs except Fornax, the most luminous in our sample. All six of the best-fit model parameters correlate with dSph luminosity but not with velocity ...

  20. Origin of the heavy elements in HD 140283. Measurement of europium abundance

    CERN Document Server

    Mello, C Siqueira; Spite, M; Spite, F

    2012-01-01

    HD 140283 is a nearby (V=7.7) subgiant metal-poor star, extensively analysed in the literature. Although many spectra have been obtained for this star, none showed a signal-to-noise (S/N) ratio high enough to enable a very accurate derivation of abundances from weak lines. The detection of europium proves that the neutron-capture elements in this star originate in the r-process, and not in the s-process, as recently claimed in the literature. Based on the OSMARCS 1D LTE atmospheric model and with a consistent approach based on the spectrum synthesis code Turbospectrum, we measured the europium lines at 4129 {\\AA} and 4205 {\\AA}, taking into account the hyperfine structure of the transitions. The spectrum, obtained with a long exposure time of seven hours at the Canada-France-Hawaii Telescope (CFHT), has a resolving power of 81000 and a S/N ratio of 800 at 4100 {\\AA}. We were able to determine the abundance A(Eu)=-2.35 dex, compatible with the value predicted for the europium from the r-process. The abundance ...

  1. Solar Flare Element Abundances from the Solar Assembly for X-rays (SAX) on MESSENGER

    CERN Document Server

    Dennis, B R; Schwartz, R A; Tolbert, A K; Starr, R D; Nittler, L R

    2015-01-01

    X-ray spectra in the range $1.5-8.5$~keV have been analyzed for 526 large flares detected with the Solar Assembly for X-rays (SAX) on the Mercury {\\em MESSENGER} spacecraft between 2007 and 2013. For each flare, the temperature and emission measure of the emitting plasma were determined from the spectrum of the continuum. In addition, with the SAX energy resolution of 0.6 keV (FWHM) at 6~keV, the intensities of the clearly resolved Fe-line complex at 6.7~keV and the Ca-line complex at 3.9~keV were determined, along with those of unresolved line complexes from S, Si, and Ar at lower energies. Comparisons of these line intensities with theoretical spectra allow the abundances of these elements relative to hydrogen to be derived, with uncertainties due to instrument calibration and the unknown temperature distribution of the emitting plasma. While significant deviations are found for the abundances of Fe and Ca from flare to flare, the abundances averaged over all flares are found to be enhanced over photospheri...

  2. Beryllium and Alpha-Element Abundances in a Large Sample of Metal-Poor Stars

    CERN Document Server

    Boesgaard, Ann Merchant; Levesque, Emily M; Bowler, Brendan P

    2011-01-01

    The light elements, Li, Be, and B, provide tracers for many aspects of astronomy including stellar structure, Galactic evolution, and cosmology. We have taken spectra of Be in 117 metal-poor stars ranging in metallicity from [Fe/H] = -0.5 to -3.5 with Keck I + HIRES at a resolution of 42,000 and signal-to-noise ratios of near 100. We have determined the stellar parameters spectroscopically from lines of Fe I, Fe II, Ti I and Ti II. The abundances of Be and O were derived by spectrum synthesis techniques, while abundances of Fe, Ti, and Mg were found from many spectral line measurements. There is a linear relationship between [Fe/H] and A(Be) with a slope of +0.88 +-0.03 over three orders of magnitude in [Fe/H]. We fit the relationship between A(Be) and [O/H] with both a single slope and with two slopes. The relationship between [Fe/H] and [O/H] seems robustly linear and we conclude that the slope change in Be vs. O is due to the Be abundance. Although Be is a by-product of CNO, we have used Ti and Mg abundanc...

  3. Hitomi results on the Perseus cluster thermodynamics, elemental abundances, and emission processes

    Science.gov (United States)

    Markevitch, Maxim L.; Hitomi Collaboration

    2017-01-01

    Hitomi SXS spectrum of the Perseus cluster above E=2 keV is a treasure trove of emission lines, most of them seen for the first time from a diffuse source such as the plasma atmosphere of a galaxy cluster. Several trace elements are detected for the first time in the intracluster medium, lines from several key elements, such as S/Ar and Fe/Ni, are disentangled, and sensitivity to faint lines is dramatically higher compared to previous, lower-resolution cluster studies. This allows us to determine accurate relative abundances of heavy elements, a sensitive test for sources of enrichment of the intergalactic medium. For many elements, lines from multiple ions are observed, as well as multiple transitions from the same ion, providing plasma temperature diagnostics previously unavailable for clusters. The brightest line -- the resonant component of the Fe He-alpha triplet -- is found to be affected by resonant scattering. For the most prominent ions, very high-level transitions are observed, placing constraints on such emission mechanisms as charge exchange with cold gas. Finally, we do not observe a previously reported 3.5 keV emission line from the Perseus core and place an upper limit on it.

  4. Abundances of chemical elements of the granitoids in different geotectonic units of China and their characteristics

    Institute of Scientific and Technical Information of China (English)

    SHI Changyi; YAN Mingcai; CHI Qinghua

    2007-01-01

    On the basis of actual analytical data of 767 composited samples collected mainly from about 750 large to middle representative granitoid bodies all over China, the average chemical compositions and element abundances of about 70 chemical elements of SiO2, Al2O3, Fe2O3, FeO, MgO,CaO, Na2O, K2O, H2O+, CO2, TFe2O3, Ag, As, Au, B, Ba, Be,Bi, Cd, Cl, Co, Cr, Cs, Cu, F, Ga, Ge, Hf, Hg, Li, Mn, Mo, Nb,Ni, P, Pb, Rb, S, Sb, Sc, Se, Sn, Sr, Ta, Th, Ti, Tl, U, V, W, Zn,Zr, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y in alkalifeldspar granite, syenogranite and adamellite in 7 geotectonic units in China such as Tianshan-Xing'an orogenic series, Sino-Korean metaplatform, Kunlun-Qilian-Qinling orogenic series, Yunnan-Tibet orogenic series,Yangtze metaplatform, South China-Youjiang orogenic zone and Himalayan orogenic belt, are calculated and presented in this paper. In addition, the characteristics of petrochemical parameters, trace element contents and rare earth element dis-tributions of different rock types of the granitoids in different geotectonic units are also sufficiently discussed.

  5. The Gaia-ESO Survey: Stellar content and elemental abundances in the massive cluster NGC\\,6705

    CERN Document Server

    Cantat-Gaudin, T; Zaggia, S; Bragaglia, A; Sordo, R; Drew, J E; Eisloeffel, J; Farnhill, H J; Gonzalez-Solares, E; Greimel, R; Irwin, M J; Kupcu-Yoldas, A; Jordi, C; Blomme, R; Sampedro, L; Costado, M T; Alfaro, E; Smiljanic, R; Magrini, L; Donati, P; Friel, E D; Jacobson, H; Abbas, U; Hatzidimitriou, D; Spagna, A; Vecchiato, A; Balaguer-Nunez, L; Lardo, C; Tosi, M; Pancino, E; Klutsch, A; Tautvaisiene, G; Drazdauskas, A; Puzeras, E; Jimenez-Esteban, F; Maiorca, E; Geisler, D; San, I; Villanova, S; Gilmore, G; Randich, S; Bensby, T; Flaccomio, E; Lanzafame, A; Recio-Blanco, A; Damiani, F; Hourihane, A; Jofre, P; deLaverny, P; Masseron, T; Morbidelli, L; Prisinzano, L; Sacco, G G; Sbordone, L; Worley, C C

    2014-01-01

    Chemically inhomogeneous populations are observed in most globular clusters, but not in open clusters. Cluster mass seems to play a key role in the existence of multiple populations. Studying the chemical homogeneity of the most massive open clusters is necessary to better understand the mechanism of their formation and determine the mass limit under which clusters cannot host multiple populations. Here we studied NGC6705, that is a young and massive open cluster located towards the inner region of the Milky Way. This cluster is located inside the solar circle. This makes it an important tracer of the inner disk abundance gradient. This study makes use of BVI and ri photometry and comparisons with theoretical isochrones to derive the age of NGC6705. We study the density profile of the cluster and the mass function to infer the cluster mass. Based on abundances of the chemical elements distributed in the first internal data release of the Gaia-ESO Survey, we study elemental ratios and the chemical homogeneity ...

  6. Probabilistic geobiological classification using elemental abundance distributions and lossless image compression in fossils, meteorites, and microorganisms

    Science.gov (United States)

    Storrie-Lombardi, Michael C.; Hoover, Richard B.

    2005-09-01

    Last year at this symposium we introduced a strategy for the automated detection of fossils during robotic missions to Mars using both structural and chemical signatures. The strategy employs a measure derived from information theory, lossless compression of photographic images, to estimate the relative complexity of a putative fossil compared to the rock matrix. Following target selection unsupervised multifactor cluster analysis of elemental abundance distributions provides an initial classification of the data. This autonomous classification is then confirmed using a non-linear stochastic neural network to produce a Bayesian estimate of classification accuracy. We have now employed this strategy to explore extant and fossil cyanobacteria from a variety of extreme terrestrial environments and microfossils and abiotic microstructures found in-situ in freshly fractured internal surfaces of carbonaceous meteorite. Elemental abundances (C, N, O, Na, Mg, Al, Si, P, S, Cl, K, Ca, Fe) obtained for both extant and fossil cyanobacteria produce signatures distinguishing them from meteorite targets and from one another. Fossil cyanobacteria exhibit significant loss of C, N, O, P, and Ca and increases in Al, Si, S, and Fe relative to extant organisms. Orgueil structures exhibit decreased abundances for C, N, Na, P, Cl, K, and Ca; and increases in Mg, S, and Fe relative to extant cyanobacteria. Fossil cyanobacteria are distinguished from Orgueil samples by relative increases in Al, Si, and Fe; and by diminished O and Mg. Compression indices verify that variations in random and redundant textural patterns between perceived forms and the background matrix contribute significantly to morphological visual identification. The results provide a quantitative probabilistic methodology for discriminating putatitive fossils from the surrounding rock matrix and from extant organisms using both structural and chemical information. The techniques described appear applicable to the

  7. Rare Earth Element Abundances and Pb-Pb Ages of Merrillite in Jinju H5 Chondrite: Implications to Shock Metamorphism

    Science.gov (United States)

    Goh, S.; Choi, B.-G.

    2016-08-01

    Jinju merrillite shows homogeneous REE abundances and relatively young Pb-Pb ages. Jinju H5 chondrite was probably neither equilibrated nor compacted prior to the impact and the shock made trace elements including REEs and U-Pb equilibrated.

  8. Abundance, distribution and potential impact of transposable elements in the genome of Mycosphaerella fijiensis

    Directory of Open Access Journals (Sweden)

    Santana Mateus F

    2012-12-01

    Full Text Available Abstract Background Mycosphaerella fijiensis is a ascomycete that causes Black Sigatoka in bananas. Recently, the M. fijiensis genome was sequenced. Repetitive sequences are ubiquitous components of fungal genomes. In most genomic analyses, repetitive sequences are associated with transposable elements (TEs. TEs are dispersed repetitive DNA sequences found in a host genome. These elements have the ability to move from one location to another within the genome, and their insertion can cause a wide spectrum of mutations in their hosts. Some of the deleterious effects of TEs may be due to ectopic recombination among TEs of the same family. In addition, some transposons are physically linked to genes and can control their expression. To prevent possible damage caused by the presence of TEs in the genome, some fungi possess TE-silencing mechanisms, such as RIP (Repeat Induced Point mutation. In this study, the abundance, distribution and potential impact of TEs in the genome of M. fijiensis were investigated. Results A total of 613 LTR-Gypsy and 27 LTR-Copia complete elements of the class I were detected. Among the class II elements, a total of 28 Mariner, five Mutator and one Harbinger complete elements were identified. The results of this study indicate that transposons were and are important ectopic recombination sites. A distribution analysis of a transposable element from each class of the M. fijiensis isolates revealed variable hybridization profiles, indicating the activity of these elements. Several genes encoding proteins involved in important metabolic pathways and with potential correlation to pathogenicity systems were identified upstream and downstream of transposable elements. A comparison of the sequences from different transposon groups suggested the action of the RIP silencing mechanism in the genome of this microorganism. Conclusions The analysis of TEs in M. fijiensis suggests that TEs play an important role in the evolution of

  9. Abundance, distribution and potential impact of transposable elements in the genome of Mycosphaerella fijiensis.

    Science.gov (United States)

    Santana, Mateus F; Silva, José C F; Batista, Aline D; Ribeiro, Lílian E; da Silva, Gilvan F; de Araújo, Elza F; de Queiroz, Marisa V

    2012-12-22

    Mycosphaerella fijiensis is a ascomycete that causes Black Sigatoka in bananas. Recently, the M. fijiensis genome was sequenced. Repetitive sequences are ubiquitous components of fungal genomes. In most genomic analyses, repetitive sequences are associated with transposable elements (TEs). TEs are dispersed repetitive DNA sequences found in a host genome. These elements have the ability to move from one location to another within the genome, and their insertion can cause a wide spectrum of mutations in their hosts. Some of the deleterious effects of TEs may be due to ectopic recombination among TEs of the same family. In addition, some transposons are physically linked to genes and can control their expression. To prevent possible damage caused by the presence of TEs in the genome, some fungi possess TE-silencing mechanisms, such as RIP (Repeat Induced Point mutation). In this study, the abundance, distribution and potential impact of TEs in the genome of M. fijiensis were investigated. A total of 613 LTR-Gypsy and 27 LTR-Copia complete elements of the class I were detected. Among the class II elements, a total of 28 Mariner, five Mutator and one Harbinger complete elements were identified. The results of this study indicate that transposons were and are important ectopic recombination sites. A distribution analysis of a transposable element from each class of the M. fijiensis isolates revealed variable hybridization profiles, indicating the activity of these elements. Several genes encoding proteins involved in important metabolic pathways and with potential correlation to pathogenicity systems were identified upstream and downstream of transposable elements. A comparison of the sequences from different transposon groups suggested the action of the RIP silencing mechanism in the genome of this microorganism. The analysis of TEs in M. fijiensis suggests that TEs play an important role in the evolution of this organism because the activity of these elements, as well

  10. The light element abundance distribution in NGC 5128 from planetary nebulae

    Science.gov (United States)

    Walsh, J. R.; Jacoby, G. H.; Peletier, R. F.; Walton, N. A.

    2012-08-01

    Context. Planetary nebulae in the nearest large elliptical galaxy provide light element abundances difficult or impossible to measure by other means in a stellar system very different from the galaxies in the Local Group. Aims: The light element abundance pattern from many planetary nebulae (PNe) at a range of radial distances was measured from optical spectroscopy in the elliptical galaxy NGC 5128, which hosts the radio source Centaurus A. The PN abundances, in particular for oxygen, and the PN progenitor properties are related to the galaxy stellar properties. Methods: PNe in NGC 5128 covering the upper 4 mag of the luminosity function were selected from a catalogue. VLT FORS1 multi-slit spectra in blue and red ranges were obtained over three fields at 3, 9 and 15' projected radii (4, 8 and 17 kpc, for an adopted distance of 3.8 Mpc) and spectra were extracted for 51 PNe. Accurate electron temperature and density diagnostics are usually required for abundance determination, but were not available for most of the PNe. Cloudy photoionization models were run to match the spectra by a spherical, constant density nebula ionized by a black body central star. He, N, O and Ne abundances with respect to H were determined and, for brighter PN, S and Ar; central star luminosities and temperatures are also derived. Results: Emission line ratios for the 51 PNe are entirely typical of PN such as in the Milky Way. The temperature sensitive [O III]4363 Å line was weakly detected in 10 PNe, both [O II] and [O III] lines were detected in 30 PNe, and only the bright [O III]5007 Å line was detected in 7 PN. For 40 PNe with Cloudy models, from the upper 2 mag of the [O III] luminosity function, the most reliably estimated element, oxygen, has a mean 12 + log(O/H) of 8.52 with a narrow distribution. No obvious radial gradient is apparent in O/H over a range 2-20 kpc. Comparison of the PN abundances with the stellar population, from the spectra of the integrated stellar light on the

  11. The origin of aubrites: Evidence from lithophile trace element abundances and oxygen isotope compositions

    Science.gov (United States)

    Barrat, J. A.; Greenwood, R. C.; Keil, K.; Rouget, M. L.; Boesenberg, J. S.; Zanda, B.; Franchi, I. A.

    2016-11-01

    We report the abundances of a selected set of "lithophile" trace elements (including lanthanides, actinides and high field strength elements) and high-precision oxygen isotope analyses of a comprehensive suite of aubrites. Two distinct groups of aubrites can be distinguished: (a) the main-group aubrites display flat or light-REE depleted REE patterns with variable Eu and Y anomalies; their pyroxenes are light-REE depleted and show marked negative Eu anomalies; (b) the Mount Egerton enstatites and the silicate fraction from Larned display distinctive light-REE enrichments, and high Th/Sm ratios; Mount Egerton pyroxenes have much less pronounced negative Eu anomalies than pyroxenes from the main-group aubrites. Leaching experiments were undertaken to investigate the contribution of sulfides to the whole rock budget of the main-group aubrites. Sulfides contain in most cases at least 50% of the REEs and of the actinides. Among the elements we have analyzed, those displaying the strongest lithophile behaviors are Rb, Ba, Sr and Sc. The homogeneity of the Δ17O values obtained for main-group aubrite falls [Δ17O = +0.009 ± 0.010‰ (2σ)] suggests that they originated from a single parent body whose differentiation involved an early phase of large-scale melting that may have led to the development of a magma ocean. This interpretation is at first glance in agreement with the limited variability of the shapes of the REE patterns of these aubrites. However, the trace element concentrations of their phases cannot be used to discuss this hypothesis, because their igneous trace-element signatures have been modified by subsolidus exchange. Finally, despite similar O isotopic compositions, the marked light-REE enrichments displayed by Mount Egerton and Larned suggest that they are unrelated to the main-group aubrites and probably originated from a distinct parent body.

  12. Measurement of Gas and Volatile Elements Production Cross Section in a Molten Lead-Bismuth Target

    CERN Multimedia

    2002-01-01

    MEGAPIE is a project for a 1 MW liquid PbBi spallation source, to be built at the SINQ facility at the Paul Scherrer Institut, which will be an important step in the roadmap towards the demonstration of the ADS concept and high power molten metal targets in general. In the design and construction of such a challenging project it is extremely important to evaluate the amount and type of gas and volatile elements which will be produced, for a reliable and safe operation of the experiment. Both stable (H, $^{4}$He and other noble gases) and radioactive isotopes are of interest. Currently, different design options are under consideration to deal with the gas produced during operation. \\\\ For a correct estimation of the production cross sections, a measurement with a liquid PbBi target and a proton beam of energy close to the one of MEGAPIE (575 MeV) is necessary. We would like to use the ISOLDE facility, which offers the unique opportunity via its mass spectrometric analysis of the elements present in the gas pha...

  13. Oxygen, {\\alpha}-element and iron abundance distributions in the inner part of the Galactic thin disc

    CERN Document Server

    Martin, R P; Kovtyukh, V V; Korotin, S A; Yegorova, I A; Saviane, Ivo

    2015-01-01

    We derived elemental abundances in 27 Cepheids, the great majority situated within a zone of Galactocentric distances ranging from 5 to 7 kpc. One star of our sample, SU Sct, has a Galactocentric distance of about 3 kpc, and thus falls in a poorly investigated region of the inner thin disc. Our new results, combined with data on abundances in the very central part of our Galaxy taken from literature, show that iron, magnesium, silicon, sulfur, calcium and titanium LTE abundance radial distributions, as well as NLTE distribution of oxygen reveal a plateau-like structure or even positive abundance gradient in the region extending from the Galactic center to about 5 kpc.

  14. The case for high precision in elemental abundances of stars in the era of large spectroscopic surveys

    CERN Document Server

    Lindegren, Lennart

    2013-01-01

    A number of large spectroscopic surveys of stars in the Milky Way are under way or are being planned. In this context it is important to discuss the extent to which elemental abundances can be used as discriminators between different (known and unknown) stellar populations in the Milky Way. We aim to establish the requirements in terms of precision in elemental abundances, as derived from spectroscopic surveys of the Milky Way's stellar populations, in order to detect interesting substructures in elemental abundance space. We present a simple relation between the minimum number of stars needed to detect a given substructure and the precision of the measurements. The results are in agreement with recent small- and large-scale studies, with high and low precision, respectively. Large-number statistics cannot fully compensate for low precision in the abundance measurements and each survey should carefully evaluate what the main science drivers are for the survey and ensure that the chosen observational strategy ...

  15. CaII Absorbers in the Sloan Digital Sky Survey: Element Abundances and Dust

    CERN Document Server

    Sardane, Gendith M; Rao, Sandhya M

    2015-01-01

    We present measurements of element abundance ratios and dust in CaII~absorbers identified in SDSS DR7+DR9. In an earlier paper we formed a statistical sample of 435 CaII absorbers and postulated that their statistical properties might be representative of at least two populations of absorbers. Here we show that if the absorbers are roughly divided into two subsamples with CaII rest equivalent widths larger and smaller than $W_0^{\\lambda 3934} = 0.7$ \\AA, they are then representative of two physically different populations. Comparisons of abundance ratios between the two CaII absorber populations indicate that the weaker $W_0^{\\lambda 3934}$ absorbers have properties consistent with halo-type gas, while the stronger absorbers have properties intermediate between halo- and disk-type gas. We also show that, on average, the dust extinction properties of the overall sample is consistent with a LMC or SMC dust law, and the stronger absorbers are nearly 6 times more reddened than their weaker counterparts. The absor...

  16. SP_Ace: a new code to derive stellar parameters and elemental abundances

    CERN Document Server

    Boeche, C

    2015-01-01

    Aims: We developed a new method of estimating the stellar parameters Teff, log g, [M/H], and elemental abundances. This method was implemented in a new code, SP_Ace (Stellar Parameters And Chemical abundances Estimator). This is a highly automated code suitable for analyzing the spectra of large spectroscopic surveys with low or medium spectral resolution (R=2,000-20,000). Methods: After the astrophysical calibration of the oscillator strengths of 4643 absorption lines covering the wavelength ranges 5212-6860\\AA\\ and 8400-8924\\AA, we constructed a library that contains the equivalent widths (EW) of these lines for a grid of stellar parameters. The EWs of each line are fit by a polynomial function that describes the EW of the line as a function of the stellar parameters. The coefficients of these polynomial functions are stored in a library called the "$GCOG$ library". SP_Ace, a code written in FORTRAN95, uses the GCOG library to compute the EWs of the lines, constructs models of spectra as a function of the s...

  17. The Curious Case of Elemental Abundance Differences in the Dual Hot Jupiter Hosts WASP-94AB

    CERN Document Server

    Teske, Johanna K; Ramírez, Ivan

    2016-01-01

    Binary stars provide an ideal laboratory for investigating the potential effects of planet formation on stellar composition. Assuming the stars formed in the same environment/from the same material, any compositional anomalies between binary components might indicate differences in how material was sequestered in planets, or accreted by the star in the process of planet formation. We present here a study of the elemental abundance differences between WASP-94AB, a pair of stars that each host a hot Jupiter exoplanet. The two stars are very similar in spectral type (F8 and F9), and their ~2700 AU separation suggests their protoplanetary disks were likely not influenced by stellar interactions, but WASP-94Ab's orbit -- misaligned with the host star spin axis and likely retrograde -- points towards a dynamically active formation mechanism, perhaps different than that of WASP-94Bb, which is not misaligned and has nearly circular orbit. Based on our high-quality spectra and strictly relative abundance analysis, we ...

  18. Short interspersed element (SINE) depletion and long interspersed element (LINE) abundance are not features universally required for imprinting.

    Science.gov (United States)

    Cowley, Michael; de Burca, Anna; McCole, Ruth B; Chahal, Mandeep; Saadat, Ghazal; Oakey, Rebecca J; Schulz, Reiner

    2011-04-20

    Genomic imprinting is a form of gene dosage regulation in which a gene is expressed from only one of the alleles, in a manner dependent on the parent of origin. The mechanisms governing imprinted gene expression have been investigated in detail and have greatly contributed to our understanding of genome regulation in general. Both DNA sequence features, such as CpG islands, and epigenetic features, such as DNA methylation and non-coding RNAs, play important roles in achieving imprinted expression. However, the relative importance of these factors varies depending on the locus in question. Defining the minimal features that are absolutely required for imprinting would help us to understand how imprinting has evolved mechanistically. Imprinted retrogenes are a subset of imprinted loci that are relatively simple in their genomic organisation, being distinct from large imprinting clusters, and have the potential to be used as tools to address this question. Here, we compare the repeat element content of imprinted retrogene loci with non-imprinted controls that have a similar locus organisation. We observe no significant differences that are conserved between mouse and human, suggesting that the paucity of SINEs and relative abundance of LINEs at imprinted loci reported by others is not a sequence feature universally required for imprinting.

  19. Short interspersed element (SINE depletion and long interspersed element (LINE abundance are not features universally required for imprinting.

    Directory of Open Access Journals (Sweden)

    Michael Cowley

    Full Text Available Genomic imprinting is a form of gene dosage regulation in which a gene is expressed from only one of the alleles, in a manner dependent on the parent of origin. The mechanisms governing imprinted gene expression have been investigated in detail and have greatly contributed to our understanding of genome regulation in general. Both DNA sequence features, such as CpG islands, and epigenetic features, such as DNA methylation and non-coding RNAs, play important roles in achieving imprinted expression. However, the relative importance of these factors varies depending on the locus in question. Defining the minimal features that are absolutely required for imprinting would help us to understand how imprinting has evolved mechanistically. Imprinted retrogenes are a subset of imprinted loci that are relatively simple in their genomic organisation, being distinct from large imprinting clusters, and have the potential to be used as tools to address this question. Here, we compare the repeat element content of imprinted retrogene loci with non-imprinted controls that have a similar locus organisation. We observe no significant differences that are conserved between mouse and human, suggesting that the paucity of SINEs and relative abundance of LINEs at imprinted loci reported by others is not a sequence feature universally required for imprinting.

  20. Cosmic-ray origin in OB associations and preferential acceleration of refractory elements: Evidence from abundances of elements 26Fe through 34Se

    CERN Document Server

    Rauch, B F; Lodders, K; Israel, M H; Barbier, L M; Binns, W R; Christian, E R; Cummings, J R; De Nolfo, G A; Geier, S; Mewaldt, R A; Mitchell, J W; Schindler, S M; Scott, L M; Stone, E C; Streitmatter, R E; Waddington, C J; Wiedenbeck, M E

    2009-01-01

    We report abundances of elements from 26Fe to 34Se in the cosmic radiation measured during fifty days of exposure of the Trans-Iron Galactic Element Recorder (TIGER) balloon-borne instrument. These observations add support to the concept that the bulk of cosmic-ray acceleration takes place in OB associations, and they further support cosmic-ray acceleration models in which elements present in interstellar grains are accelerated preferentially compared with those found in interstellar gas.

  1. Identifying Type Ia Supernova Mechanisms in Dwarf Spheroidal Galaxies through Analysis of Iron-peak Elemental Abundances

    Science.gov (United States)

    Guo, Rachel; Xie, Justin Long; Kirby, Evan N.

    2017-01-01

    Through the fusion of nucleons to produce elements heavier than hydrogen and helium, stellar nucleosynthesis produces most of the elements in the universe. Such is the case in a supernova explosion, which creates most of the elements on the periodic table—including iron-peak elements, atomic numbers 21 through 30—through nucleosynthesis and ejects them into the interstellar medium. In this study, we determine the best theoretical supernova model appropriate for the stars in the dwarf spheroidal galaxies Sculptor, Fornax, Ursa Minor, and Leo II by calculating the abundances of iron-peak elements in these stars. To determine iron-peak elemental abundances, we compare synthesized spectra with observed spectra from medium-resolution spectroscopy and determine the best-fitting spectrum by way of a chi-squared minimization. Through inspecting the relationship between the iron-peak element abundances and the abundance of iron itself and by comparing them to previously hypothesized supernova model theories, we discover that the near-Chandrasekhar mass “n1” model, as predicted by Seitenzahl et al., most accurately represents the trends and patterns within our data, presenting new insight into Type Ia supernovae mechanisms within the Milky Way and beyond.

  2. Characterisation of inorganic elements and volatile organic compounds in the dried sea cucumber Stichopus japonicus.

    Science.gov (United States)

    Lee, Hae-Won; Lim, Na-Lae; Cho, Kichul; Yang, Hye Young; Yim, Kyung June; Kim, Mi-Ju; Lee, Myunglip; Kim, Dong Hyeun; Koh, Hyoung Bum; Jung, Won-Kyo; Roh, Seong Woon; Kim, Daekyung

    2014-03-15

    The sea cucumber Stichopus japonicus lives in a variety of marine habitats and is an important cultivated edible aquatic species in East Asia. In this study, S. japonicus, collected from the sea near Jeju Island of Korea, was lyophilised or vacuum-dried and then analysed by gas chromatography-mass spectrometry (GC-MS) or inductively coupled plasma mass spectrometry (ICP-MS). The GC-MS profiles of vacuum-dried and lyophilised samples differed. Based on direct injection and static headspace analysis, 37 volatile organic compounds (VOCs) were identified in vacuum-dried samples and 33 VOCs were identified in lyophilised samples. Therefore, the odour of vacuum-dried sea cucumber is thought to be due to the presence of various VOCs that are absent in lyophilised sea cucumber. According to ICP-MS analysis, the levels of 15 inorganic elements were slightly higher in lyophilised samples than in vacuum-dried samples. The results of the inorganic and organic chemical analyses provide information about the composition of dried sea cucumber. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Abundances of platinum group elements in native sulfur condensates from the Niuatahi-Motutahi submarine volcano, Tonga rear arc: Implications for PGE mineralization in porphyry deposits

    Science.gov (United States)

    Park, Jung-Woo; Campbell, Ian H.; Kim, Jonguk

    2016-02-01

    -forming fluid exsolved. Pd-rich porphyry Cu-Au deposits are associated with highly oxidized magmas. Prior to sulfide saturation Pd, Au and Cu behave as incompatible elements and concentrate in the melt with fractional crystallization, whereas Pt is depleted by early crystallization of a Pt-rich alloy and the other PGEs by the co-crystallization of the Pt-rich alloy and Cr spinel. As a consequence the Pd/Pt and Pd/Ir in the evolving melt and the magmatic volatile phases that exsolve from that melt, increase with increased fractionation. The high Pd content and high Pd/Pt (∼7-60) of Cu-Au porphyry ores therefore require the parent magma to have undergone extensive sulfide-undersaturated fractional crystallization prior to volatile exsolution. Our study also showed that the altered dacites contain PGE abundances that are similar to those of fresh dacites although Pt and Rh are slightly enriched in the altered dacites, which indicates low mobility of PGEs during secondary hydrothermal alteration.

  4. Al-26, Pu-244, Ti-50, REE, and trace element abundances in hibonite grains from CM and CV meteorites

    Science.gov (United States)

    Fahey, A. J.; Mckeegan, K. D.; Zinner, E.; Goswami, J. N.

    1987-01-01

    Hibonites from the CM meteorites Murchison, Murray, and Cold Bokkeveld, and hibonites and Ti-rich pyroxene from the CV chondrite Allende are studied. Electron microprobe measurements of major element concentrations and track and ion probe measurements of Mg and Ti isotopic ratios, rare earth elements (REEs), and trace element abundances are analyzed. Correlations between isotopic anomalies in Ti, Al-26, Pu-244, and Mg-26(asterisk) are examined. Ti isotopic anomalies are compared with REE and trace element abundance patterns. Reasons for the lack of Al-26 in the hibonites are investigated and discussed. It is observed that there is no correlation between the Ti isotopic compositions, and the presence of Mg-26(asterisk), Pu-244, and REE and trace element patterns in individual hibonite samples. The data reveal that hibonites are not interstellar dust grains but formed on a short time scale and in localized regions of the early solar system.

  5. Volatile (sulphur and chlorine), major, and trace element geochemistry of mafic to intermediate tephras from the Chilean Southern Volcanic Zone (33-43°S)

    Science.gov (United States)

    Wehrmann, Heidi; Hoernle, Kaj; Jacques, Guillaume; Garbe-Schönberg, Dieter; Schumann, Kai; Mahlke, Julia; Lara, Luis E.

    2014-10-01

    Here we present the first systematic investigation of volatile geochemistry along the Southern Volcanic Zone (SVZ) of Chile. Holocene olivine-hosted melt inclusions in the most mafic tephras sampled from 16 volcanoes along the volcanic front of the SVZ between 33°S and 43°S were analysed for pre-eruptive sulphur, chlorine, and major element contents. These results are combined with trace element compositions of the host whole rocks. The highest fractionation-corrected gas contents occur in the least-degassed melt inclusions from small monogenetic cones of Los Hornitos, Cabeza de Vaca, and Apagado from both the transitional and the southern-central SVZ, reaching ~3,000 μg/g S and 1,400 μg/g Cl, while the lowest abundances of ~1,100 μg/g S and ~600 μg/g Cl were found in the central SVZ at Volcán Lonquimay, Volcán Llaima, and Volcán Villarrica. Chlorine co-varies with trace element indicators for the degree of melting and/or source enrichment, such that the lowest Cl contents are found in high-degree melts from the most depleted mantle sources. The size of the volcanic edifices correlates inversely with Cl abundances in the melt. This could reflect more extensive degassing during ascent through the complex magma plumbing systems beneath the stratovolcanoes or greater dilution during larger degrees of melting of more depleted sources, or a combination of these factors. Compared to other subduction zones, the SVZ melt inclusions exhibit Cl and S abundances in the same range as most of those from the Central American and those from the Marianas arcs.

  6. The Abundances of Light Neutron-Capture Elements in Planetary Nebulae III. The Impact of New Atomic Data on Nebular Selenium and Krypton Abundance Determinations

    CERN Document Server

    Sterling, N C; Dinerstein, H L

    2015-01-01

    The detection of neutron(n)-capture elements in several planetary nebulae (PNe) has provided a new means of investigating s-process nucleosynthesis in low-mass stars. However, a lack of atomic data has inhibited accurate trans-iron element abundance determinations in astrophysical nebulae. Recently, photoionization and recombination data were determined for Se and Kr, the two most widely detected n-capture elements in nebular spectra. We have incorporated these new data into the photoionization code Cloudy. To test the atomic data, numerical models were computed for 15 PNe that exhibit emission lines from multiple Kr ions. We found systematic discrepancies between the predicted and observed emission lines that are most likely caused by inaccurate photoionization and recombination data. These discrepancies were removed by adjusting the Kr$^+$--Kr$^{3+}$ photoionization cross sections within their cited uncertainties and the dielectronic recombination rate coefficients by slightly larger amounts. From grids of ...

  7. HAT-P-26b: A Neptune-mass Exoplanet with Primordial Solar Heavy Element Abundance

    Science.gov (United States)

    Wakeford, Hannah R.; Sing, David K.; Kataria, Tiffany; Deming, Drake; Nikolov, Nikolay; Lopez, Eric; Tremblin, Pascal; Skalid Amundsen, David; Lewis, Nikole K.; Mandell, Avi; Fortney, Jonathan J.; Knutson, Heather; Benneke, Björn; Evans, Tom M.

    2017-01-01

    A trend in giant planet mass and atmospheric heavy elemental abundance was first noted last century from observations of planets in our own solar system. These four data points from Jupiter, Saturn, Uranus, and Neptune have served as a corner stone of planet formation theory. Here we add another point in the mass-metallicity trend from a detailed observational study of the extrasolar planet HAT-P-26b, which inhabits the critical mass regime near Neptune and Uranus. Neptune-sized worlds are among the most common planets in our galaxy and frequently exist in orbital periods very different from that of our own solar system ice giants. Atmospheric studies are the principal window into these worlds, and thereby into their formation and evolution, beyond those of our own solar system. Using the Hubble Space Telescope and Spitzer, from the optical to the infrared, we conducted a detailed atmospheric study of the Neptune-mass exoplanet HAT-P-26b over 0.5 to 4.5 μm. We detect prominent H2O absorption at 1.4 μm to 525 ppm in the atmospheric transmission spectrum. We determine that HAT-P-26b’s atmosphere is not rich in heavy elements (≈1.8×solar), which goes distinctly against the solar system mass-metallicity trend. This likely indicates that HAT-P-26b’s atmosphere is primordial and obtained its gaseous envelope late in its disk lifetime with little contamination from metal-rich planetesimals.

  8. HAT-P-26b: A Neptune-mass Exoplanet with Primordial Solar Heavy Element Abundance

    Science.gov (United States)

    Wakeford, Hannah; Sing, David; Deming, Drake; Kataria, Tiffany; Lopez, Eric

    2016-10-01

    A trend in giant planet mass and atmospheric heavy elemental abundance was first noted last century from observations of planets in our own solar system. These four data points from Jupiter, Saturn, Uranus, and Neptune have served as a corner stone of planet formation theory. Here we add another point in the mass-metallicity trend from a detailed observational study of the extrasolar planet HAT-P-26b, which inhabits the critical mass regime near Neptune and Uranus. Neptune-sized worlds are among the most common planets in our galaxy and frequently exist in orbital periods very different from that of our own solar system ice giants. Atmospheric studies are the principal window into these worlds, and thereby into their formation and evolution, beyond those of our own solar system. Using the Hubble Space Telescope and Spitzer, from the optical to the infrared, we conducted a detailed atmospheric study of the Neptune-mass exoplanet HAT-P-26b over 0.5 to 4.5 μm. We detect prominent H2O absorption at 1.4 μm to 525 ppm in the atmospheric transmission spectrum. We determine that HAT-P-26b's atmosphere is not rich in heavy elements (≈1.8×solar), which goes distinctly against the solar system mass-metallicity trend. This likely indicates that HAT-P-26b's atmosphere is primordial and obtained its gaseous envelope late in its disk lifetime with little contamination from metal-rich planetesimals.

  9. Trace element abundances of high-MgO glasses from Kilauea, Mauna Loa and Haleakala volcanoes, Hawaii

    Science.gov (United States)

    Wagner, T.P.; Clague, D.A.; Hauri, E.H.; Grove, T.L.

    1998-01-01

    We performed an ion-microprobe study of eleven high-MgO (6.7-14.8 wt%) tholeiite glasses from the Hawaiian volcanoes Kilauea, Mauna Loa and Haleakala. We determined the rare earth (RE), high field strength, and other selected trace element abundances of these glasses, and used the data to establish their relationship to typical Hawaiian shield tholeiite and to infer characteristics of their source. The glasses have trace element abundance characteristics generally similar to those of typical shield tholeiites, e.g. L(light)REE/H(heavy)REE(C1) > 1. The Kilauea and Mauna Loa glasses, however, display trace and major element characteristics that cross geochemical discriminants observed between Kilauea and Mauna Loa shield lavas. The glasses contain a blend of these discriminating chemical characteristics, and are not exactly like the typical shield lavas from either volcano. The production of these hybrid magmas likely requires a complexly zoned source, rather than two unique sources. When corrected for olivine fractionation, the glass data show correlations between CaO concentration and incompatible trace element abundances, indicating that CaO may behave incompatibly during melting of the tholeiite source. Furthermore, the tholeiite source must contain residual garnet and clinopyroxene to account for the variation in trace element abundances of the Kilauea glasses. Inversion modeling indicates that the Kilauea source is flat relative to C1 chondrites, and has a higher bulk distribution coefficient for the HREE than the LREE.

  10. Formation of Apollo 16 impactites and the composition of late accreted material: Constraints from Os isotopes, highly siderophile elements and sulfur abundances

    Science.gov (United States)

    Gleißner, Philipp; Becker, Harry

    2017-03-01

    Fe-Ni metal-schreibersite-troilite intergrowths in Apollo 16 impact melt rocks and new highly siderophile element (HSE) and S abundance data indicate that millimeter-scale closed-system fractional crystallization processes during cooling of impactor-derived metal melt droplets in impact-melts are the main reason for compositional variations and strong differences in abundances and ratios of HSE in multiple aliquots from Apollo 16 impact melt rocks. Element ratios obtained from linear regression of such data are therefore prone to error, but weighted averages take into account full element budgets in the samples and thus represent a more accurate estimate of their impactor contributions. Modeling of solid metal-liquid metal partitioning in the Fe-Ni-S-P system and HSE patterns in impactites from different landing sites suggest that bulk compositions of ancient lunar impactites should be representative of impact melt compositions and that large-scale fractionation of the HSE by in situ segregation of solid metal or sulfide liquid in impact melt sheets most likely did not occur. The compositional record of lunar impactites indicates accretion of variable amounts of chondritic and non-chondritic impactor material and the mixing of these components during remelting of earlier ejecta deposits. The non-chondritic composition appears most prominently in some Apollo 16 impactites and is characterized by suprachondritic HSE/Ir ratios which increase from refractory to moderately volatile HSE and exhibit a characteristic enrichment of Ru relative to Pt. Large-scale fractional crystallization of solid metal from sulfur and phosphorous rich metallic melt with high P/S in planetesimal or embryo cores is currently the most likely process that may have produced these compositions. Similar materials or processes may have contributed to the HSE signature of the bulk silicate Earth (BSE).

  11. Light and Heavy Element Abundance Variations in the Outer Halo Globular Cluster NGC 6229

    Science.gov (United States)

    Johnson, Christian I.; Caldwell, Nelson; Rich, R. Michael; Walker, Matthew G.

    2017-10-01

    NGC 6229 is a relatively massive outer halo globular cluster that is primarily known for exhibiting a peculiar bimodal horizontal branch morphology. Given the paucity of spectroscopic data on this cluster, we present a detailed chemical composition analysis of 11 red giant branch members based on high resolution (R ≈ 38,000), high S/N (>100) spectra obtained with the MMT-Hectochelle instrument. We find the cluster to have a mean heliocentric radial velocity of -{138.1}-1.0+1.0 {km} {{{s}}}-1, a small dispersion of {3.8}-0.7+1.0 {km} {{{s}}}-1, and a relatively low {(M/{L}{{V}})}ȯ ={0.82}-0.28+0.49. The cluster is moderately metal-poor with =-1.13 dex and a modest dispersion of 0.06 dex. However, 18% (2/11) of the stars in our sample have strongly enhanced [La, Nd/Fe] ratios that are correlated with a small (∼0.05 dex) increase in [Fe/H]. NGC 6229 shares several chemical signatures with M75, NGC 1851, and the intermediate metallicity populations of ω Cen, which lead us to conclude that NGC 6229 is a lower mass iron-complex cluster. The light elements exhibit the classical (anti-)correlations that extend up to Si, but the cluster possesses a large gap in the O–Na plane that separates first and second generation stars. NGC 6229 also has unusually low [Na, Al/Fe] abundances that are consistent with an accretion origin. A comparison with M54 and other Sagittarius clusters suggests that NGC 6229 could also be the remnant core of a former dwarf spheroidal galaxy.

  12. Volatile Metabolites

    Directory of Open Access Journals (Sweden)

    Daryl D. Rowan

    2011-11-01

    Full Text Available Volatile organic compounds (volatiles comprise a chemically diverse class of low molecular weight organic compounds having an appreciable vapor pressure under ambient conditions. Volatiles produced by plants attract pollinators and seed dispersers, and provide defense against pests and pathogens. For insects, volatiles may act as pheromones directing social behavior or as cues for finding hosts or prey. For humans, volatiles are important as flavorants and as possible disease biomarkers. The marine environment is also a major source of halogenated and sulfur-containing volatiles which participate in the global cycling of these elements. While volatile analysis commonly measures a rather restricted set of analytes, the diverse and extreme physical properties of volatiles provide unique analytical challenges. Volatiles constitute only a small proportion of the total number of metabolites produced by living organisms, however, because of their roles as signaling molecules (semiochemicals both within and between organisms, accurately measuring and determining the roles of these compounds is crucial to an integrated understanding of living systems. This review summarizes recent developments in volatile research from a metabolomics perspective with a focus on the role of recent technical innovation in developing new areas of volatile research and expanding the range of ecological interactions which may be mediated by volatile organic metabolites.

  13. Oxygen, $\\alpha$-element and iron abundance distributions in the inner part of the Galactic thin disc. II

    CERN Document Server

    Andrievsky, S M; Kovtyukh, V V; Korotin, S A; Lépine, J R D

    2016-01-01

    We have derived the abundances of 36 chemical elements in one Cepheid star, ASAS 181024--2049.6, located R$_{\\rm G}= 2.53$ kpc from the Galactic center. This star falls within a region of the inner thin disc poorly sampled in Cepheids. Our spectral analysis shows that iron, magnesium, silicon, calcium and titanium LTE abundances in that star support the presence of a plateau-like abundance distribution in the thin disc within 5 kpc of the Galactic center, as previously suggested by \\cite{Maret15}. If confirmed, the flattening of the abundance gradient within that region could be the result of a decrease in the star formation rate due to dynamic effects, possibly from the central Galactic bar.

  14. Galactic abundance gradients from Cepheids. α and heavy elements in the outer disk

    NARCIS (Netherlands)

    Lemasle, B.; François, P.; Genovali, K.; Kovtyukh, V. V.; Bono, G.; Inno, L.; Laney, C. D.; Kaper, L.; Bergemann, M.; Fabrizio, M.; Matsunaga, N.; Pedicelli, S.; Primas, F.; Romaniello, M.

    2013-01-01

    Context. Galactic abundance gradients set strong constraints to chemo-dynamical evolutionary models of the Milky Way. Given the period-luminosity relations that provide accurate distances and the large number of spectral lines, Cepheids are excellent tracers of the present-day abundance gradients. A

  15. Galactic abundance gradients from Cepheids : α and heavy elements in the outer disk

    NARCIS (Netherlands)

    Lemasle, B.; Francois, P.; Genovali, K.; Kovtyukh, V. V.; Bono, G.; Inno, L.; Laney, C. D.; Kaper, L.; Bergemann, M.; Fabrizio, M.; Matsunaga, N.; Pedicelli, S.; Primas, F.; Romaniello, M.

    2013-01-01

    Context. Galactic abundance gradients set strong constraints to chemo-dynamical evolutionary models of the Milky Way. Given the period-luminosity relations that provide accurate distances and the large number of spectral lines, Cepheids are excellent tracers of the present-day abundance gradients. A

  16. Abundances of Ag and Cu in mantle peridotites and the implications for the behavior of chalcophile elements in the mantle

    Science.gov (United States)

    Wang, Zaicong; Becker, Harry

    2015-07-01

    Silver abundances in mantle peridotites and the behavior of Ag during high temperature mantle processes have received little attention and, as a consequence, the abundance of Ag in the bulk silicate Earth (BSE) has been poorly constrained. In order to better understand the processes that fractionate Ag and other chalcophile elements in the mantle, abundances of Ag and Cu in mantle peridotites from different geological settings (n = 68) have been obtained by isotope dilution ICP-MS methods. In peridotite tectonites and in a few suites of peridotite xenoliths which display evidence for variable extents of melt depletion and refertilization by silicate melts, Ag and Cu abundances show positive correlations with moderately incompatible elements such as S, Se, Te and Au. The mean Cu/Ag in fertile peridotites (3500 ± 1200, 1s, n = 38) is indistinguishable from the mean Cu/Ag of mid ocean ridge basalts (MORB, 3600 ± 400, 1s, n = 338) and MORB sulfide droplets. The constant mean Cu/Ag ratios indicate similar behavior of Ag and Cu during partial melting of the mantle, refertilization and magmatic fractionation, and thus should be representative of the Earth's upper mantle. The systematic fractionation of Cu, Ag, Au, S, Se and Te in peridotites and basalts is consistent with sulfide melt-silicate melt partitioning with apparent partition coefficients of platinum group elements (PGE) > Au ⩾ Te > Cu ≈ Ag > Se ⩾ S. Because of the effects of secondary processes, the abundances of chalcophile elements, notably S, Se, but also Cu and the PGE in many peridotite xenoliths are variable and lower than in peridotite massifs. Refertilization of peridotite may change abundances of chalcophile and lithophile elements in peridotite massifs, however, this seems to mostly occur in a systematic way. Correlations with lithophile and chalcophile elements and the overlapping mean Cu/Ag ratios of peridotites and ocean ridge basalts are used to constrain abundances of Ag and Cu in the BSE

  17. Bioindication of volatile elements emission by the Puyehue-Cordón Caulle (North Patagonia) volcanic event in 2011.

    Science.gov (United States)

    Bubach, Débora; Pérez Catán, Soledad; Arribére, María; Guevara, Sergio Ribeiro

    2012-07-01

    The emission of volatile pollutants from the volcanic eruption of the Puyehue-Cordón Caulle complex (North Patagonia Andean Range) that started in June 4th, 2011, was investigated by bioindication means with the epyphytic fruticose lichen Usnea sp. The elemental composition of pooled samples made up with 10 lichen thalli were analysed by Instrumental Neutron Activation Analysis. Eleven sampling sites were selected within the impacted region at different distance from the volcanic source. Five sites were selected as they were already sampled in a previous study prior to the eruption. Two other new sampling sites were selected from outside the impacted zone to provide non-impacted baseline sites. The elements associated with the lichen incorporation of particulate matter (PM) of geological origin were identified by linear correlation with a geochemical tracer (Sm concentrations). The elements associated with PM uptake were Ce, Eu, Fe, Hf, La, Lu, Na, Nd, Sb, Sc, Se, Ta, Tb, Th, U, and Yb. Arsenic and Cs concentrations showed contributions exceeding the PM fraction in sites near the volcanic centre, also higher than the baseline concentrations, which could be associated with permanent emissions from the geothermal system of the Puyehue-Cordón Caulle complex. The lichen concentrations of Ba, Ca, Co, Hg, K, Rb, Sr, and Zn were not associated with the PM, not showing higher concentrations in the sites nearby the volcanic source or respect to the baseline values either. Therefore, there is no indication of the emission of volatile forms of these elements in the lichen records. The lichen records only identified Br volatile emissions associated with the Puyehue-Cordón Caulle complex eruption in 2011.

  18. Determination of rare earth and refractory trace element abundances in early solar system objects by ion microprobe

    Indian Academy of Sciences (India)

    S Sahijpal; K K Marhas; J N Goswami

    2003-12-01

    Experimental and analytical procedures devised for measurement of rare earth element (REE) abundances using a secondary ion mass spectrometer (ion microprobe) are described. This approach is more versatile than the conventional techniques such as neutron activation analysis and isotope dilution mass spectrometry by virtue of its high spatial resolution that allows determination of REE abundances in small domains (10-20 micron) within individual mineral phases. The ion microprobe measurements are performed at a low mass-resolving power adopting the energy-filltering technique (Zinner and Crozaz 1986) for removal and suppression of unresolved complex molecular interferences in the REE masses of interest. Synthetic standards are used for determining various instrument specific parameters needed in the data deconvolution procedure adopted for obtaining REE abundances. Results obtained from analysis of standards show that our ion microprobe may be used for determining REE abundances down to ppm range with uncertainties of ∼10 to 15%. Abundances of rare earth and several other refractory trace elements in a set of early solar system objects isolated from two primitive carbonaceous chondrites were determined using the procedures devised by us. The results suggest that some of these objects could be high temperature nebular condensates, while others are products of melting and recrystallization of precursor nebular solids in a high temperature environment.

  19. A Subaru/HDS study of Lead (Pb) abundances in eight s-process-element-rich, metal-poor stars

    CERN Document Server

    Aoki, W; Norris, J E; Beers, T C; Ando, H

    2002-01-01

    We report the abundances of neutron-capture elements in eight carbon-rich, metal-poor (-2.7=<[Fe/H]=<-1.9) stars observed with the Subaru Telescope High Dispersion Spectrograph. The derived abundance patterns indicate that the neutron-capture elements in these objects primarily originated from s-process nucleosynthesis, although the [Ba/Eu] abundance ratios in some objects are lower than that of the solar-system s-process component. The present analysis has yielded the Pb abundances for seven objects, as well as an upper limit for one object, from use of the Pb I 4057A and 3683A lines. The values of [Pb/Ba] in these objects cover a wide range, between -0.3 and +1.2. Theoretical studies of s-process nucleosynthesis at low metallicity are required to explain this large dispersion of the [Pb/Ba] values. Variations in radial velocity have been found for two of the eight objects, suggesting that, at least in these instances, the observed excess of s-process elements is due to the transfer of material across ...

  20. On the internal pollution mechanisms in the globular cluster NGC 6121 (M4): heavy-element abundances and AGB models

    CERN Document Server

    D'Orazi, Valentina; Lugaro, Maria; Lattanzio, John C; Pignatari, Marco; Carretta, Eugenio

    2013-01-01

    Globular clusters display significant variations in their light-element content, pointing to the existence of a second stellar generation formed from the ejecta of an earlier generation. The nature of these internal polluters is still a matter of debate: the two most popular scenarios indicate intermediate-mass AGB stars and fast rotating massive stars. Abundances determination for some key elements can help distinguish between these competitor candidates. We present in this paper Y abundances for a sample of 103 red giant branch stars in NGC 6121. Within measurement errors, we find that the [Y/Fe] is constant in this cluster contrary to a recent suggestion. For a subsample of six stars we also find [Rb/Fe] to be constant, consistent with previous studies showing no variation in other s-process elements. We also present a new set of stellar yields for intermediate-mass AGB stellar models of 5 and 6 solar masses, including heavy element s-process abundances. The uncertainties on the mass-loss rate, the mixing-...

  1. Evaporative fractionation of volatile stable isotopes and their bearing on the origin of the Moon.

    Science.gov (United States)

    Day, James M D; Moynier, Frederic

    2014-09-13

    The Moon is depleted in volatile elements relative to the Earth and Mars. Low abundances of volatile elements, fractionated stable isotope ratios of S, Cl, K and Zn, high μ ((238)U/(204)Pb) and long-term Rb/Sr depletion are distinguishing features of the Moon, relative to the Earth. These geochemical characteristics indicate both inheritance of volatile-depleted materials that formed the Moon and planets and subsequent evaporative loss of volatile elements that occurred during lunar formation and differentiation. Models of volatile loss through localized eruptive degassing are not consistent with the available S, Cl, Zn and K isotopes and abundance data for the Moon. The most probable cause of volatile depletion is global-scale evaporation resulting from a giant impact or a magma ocean phase where inefficient volatile loss during magmatic convection led to the present distribution of volatile elements within mantle and crustal reservoirs. Problems exist for models of planetary volatile depletion following giant impact. Most critically, in this model, the volatile loss requires preferential delivery and retention of late-accreted volatiles to the Earth compared with the Moon. Different proportions of late-accreted mass are computed to explain present-day distributions of volatile and moderately volatile elements (e.g. Pb, Zn; 5 to >10%) relative to highly siderophile elements (approx. 0.5%) for the Earth. Models of early magma ocean phases may be more effective in explaining the volatile loss. Basaltic materials (e.g. eucrites and angrites) from highly differentiated airless asteroids are volatile-depleted, like the Moon, whereas the Earth and Mars have proportionally greater volatile contents. Parent-body size and the existence of early atmospheres are therefore likely to represent fundamental controls on planetary volatile retention or loss.

  2. Possible in situ Tests of the Evolution of Elemental and Isotopic Abundances in the Solar Convection Zone

    CERN Document Server

    Turcotte, S

    2002-01-01

    Helioseismology has shown that the chemical composition of the Sun has changed over its lifetime. The surface abundance of helium and heavy elements is believed to have decreased by up to 10% relative to their initial values. However, this reduction is too small to be tested by direct observations of the photospheric chemical composition. Here, we compare the predicted variations in the solar photospheric composition with precise measurements of abundances in meteorites and the solar wind composition. Although elemental composition ratios can vary by roughly a percent (e. g. for Ca/Mg and Ca/Fe) over the Sun's lifetime, their measurements are rife with uncertainties related to uncertainties in the interpretation of meteoritic measurements, photospheric determinations, and the complex fractionation processes occurring between the upper photosphere and lower chromosphere and the corona. On the other hand, isotopic ratios can be measured much more accurately and are not expected to be affected as much by extraso...

  3. The Abundances of Light Neutron-Capture Elements in Planetary Nebulae II. s-process Enrichments and Interpretation

    CERN Document Server

    Sterling, N C

    2007-01-01

    We present the results of a large-scale survey of neutron(n)-capture elements in Galactic planetary nebulae (PNe), undertaken to study enrichments from s-process nucleosynthesis in their progenitor stars. From new K band observations of over 100 PNe supplemented by data from the literature, we have detected the emission lines [Kr III] 2.199 and/or [Se IV] 2.287 $\\mu$m in 81 of 120 objects. We determine Se and Kr elemental abundances, employing ionization correction formulae derived in the first paper of this series. We find a significant range in Se and Kr abundances, from near solar (no enrichment) to enhanced by >1.0 dex relative to solar, which we interpret as self-enrichment due to in situ s-process nucleosynthesis. Kr tends to be more strongly enriched than Se; in 18 objects exhibiting both Se and Kr emission, we find that [Kr/Se] = 0.5$\\pm$0.2. Our survey has increased the number of PNe with n-capture element abundance determinations by a factor of ten, enabling us for the first time to search for corre...

  4. High-precision abundances of Sc, Mn, Cu, and Ba in solar twins. Trends of element ratios with stellar age

    CERN Document Server

    Nissen, P E

    2016-01-01

    A previous study of correlations between element abundance ratios, [X/Fe], and ages of solar twin stars is extended to include Sc, Mn, Cu, and Ba. HARPS spectra with S/N > 600 are used to derive very precise (+/- 0.01 dex) differential abundances, and stellar ages with internal errors less than 1 Gyr are obtained by interpolation in the logg - Teff diagram between isochrones calculated with the Aarhus Stellar Evolution Code. For stars younger than 6 Gyr, [X/Fe] is tightly correlated with stellar age for all elements. For ages between 6 and 9 Gyr, the [X/Fe] - age correlations break down and the stars split up into two groups having respectively high and low [X/Fe] for the odd-Z elements. It is concluded that while stars in the solar neighborhood younger than about 6 Gyr were formed from interstellar gas with a smooth chemical evolution, older stars have originated from regions enriched by supernovae with different neutron excesses. Furthermore, the correlations between abundance ratios and stellar age suggest...

  5. Element Abundances in a Gas-rich Galaxy at z = 5: Clues to the Early Chemical Enrichment of Galaxies

    CERN Document Server

    Morrison, Sean; Som, Debopam; DeMarcy, Bryan; Quiret, Samuel; Peroux, Celine

    2016-01-01

    Element abundances in high-redshift quasar absorbers offer excellent probes of the chemical enrichment of distant galaxies, and can constrain models for population III and early population II stars. Recent observations indicate that the sub-damped Lyman-alpha (sub-DLA) absorbers are more metal-rich than the damped Lyman-alpha (DLA) absorbers at redshifts 0$$4.7. However, only 3 DLAs at $z$$>$4.5 and no sub-DLAs at $z$$>$3.5 have "dust-free" metallicity measurements of undepleted elements. We report the first measurement of element abundances in a sub-DLA at $z$=5.0, using Keck HIRES and ESI data. We obtain fairly robust abundances of C, O, Si, and Fe, using lines outside the Lyman-alpha forest. We find this absorber to be metal-poor, with [O/H]=$-2.02$$\\pm$0.12, which is $>$5$\\sigma$ below the level expected from an extrapolation of the trend for $z$$<$3.5 sub-DLAs. The C/O ratio is $1.7^{+0.4}_{-0.3}$ times lower than in the Sun. More strikingly, Si/O is $3.0^{+0.6}_{-0.5}$ times lower than in the Sun, wh...

  6. Volatilization of elemental mercury from fresh blast furnace sludge mixed with basic oxygen furnace sludge under different temperatures.

    Science.gov (United States)

    Földi, Corinna; Dohrmann, Reiner; Mansfeldt, Tim

    2015-11-01

    Blast furnace sludge (BFS) is a waste with elevated mercury (Hg) content due to enrichment during the production process of pig iron. To investigate the volatilization potential of Hg, fresh samples of BFS mixed with basic oxygen furnace sludge (BOFS; a residue of gas purification from steel making, processed simultaneously in the cleaning devices of BFS and hence mixed with BFS) were studied in sealed column experiments at different temperatures (15, 25, and 35 °C) for four weeks (total Hg: 0.178 mg kg(-1)). The systems were regularly flushed with ambient air (every 24 h for the first 100 h, followed by every 72 h) for 20 min at a flow rate of 0.25 ± 0.03 L min(-1) and elemental Hg vapor was trapped on gold coated sand. Volatilization was 0.276 ± 0.065 ng (x m: 0.284 ng) at 15 °C, 5.55 ± 2.83 ng (x m: 5.09 ng) at 25 °C, and 2.37 ± 0.514 ng (x m: 2.34 ng) at 35 °C. Surprisingly, Hg fluxes were lower at 35 than 25 °C. For all temperature variants, an elevated Hg flux was observed within the first 100 h followed by a decrease of volatilization thereafter. However, the background level of ambient air was not achieved at the end of the experiments indicating that BFS mixed with BOFS still possessed Hg volatilization potential.

  7. Elemental abundances in Milky Way-like galaxies from a hierarchical galaxy formation model

    NARCIS (Netherlands)

    De Lucia, Gabriella; Tornatore, Luca; Frenk, Carlos S.; Helmi, Amina; Navarro, Julio F.; White, Simon D. M.

    2014-01-01

    We develop a new method to account for the finite lifetimes of stars and trace individual abundances within a semi-analytic model of galaxy formation. At variance with previous methods, based on the storage of the (binned) past star formation history of model galaxies, our method projects the inform

  8. Disk Evolution, Element Abundances and Cloud Properties of Young Gas Giant Planets

    NARCIS (Netherlands)

    Helling, Christiane; Woitke, Peter; Rimmer, Paul B.; Kamp, Inga; Thi, Wing-Fai; Meijerink, Rowin

    We discuss the chemical pre-conditions for planet formation, in terms of gas and ice abundances in a protoplanetary disk, as function of time and position, and the resulting chemical composition and cloud properties in the atmosphere when young gas giant planets form, in particular discussing the

  9. VizieR Online Data Catalog: Pal1-I elemental equivalent widths and abundances (Monaco+, 2011)

    Science.gov (United States)

    Monaco, L.; Saviane, I.; Correnti, M.; Bonifacio, P.; Geisler, D.

    2010-11-01

    Table A1. reports the line list and atomic parameters adopted for the Palomar 1 giant Pal1-I and the Sun. For the Mn and Co lines we adopted the hyperfine structures (HFS) tabulated by Prochaska et al. (2000AJ....120.2513P). The measured equivalent width and the corresponding abundance obtained for each line are also reported. (1 data file).

  10. Disk Evolution, Element Abundances and Cloud Properties of Young Gas Giant Planets

    NARCIS (Netherlands)

    Helling, Christiane; Woitke, Peter; Rimmer, Paul B.; Kamp, Inga; Thi, Wing-Fai; Meijerink, Rowin

    2014-01-01

    We discuss the chemical pre-conditions for planet formation, in terms of gas and ice abundances in a protoplanetary disk, as function of time and position, and the resulting chemical composition and cloud properties in the atmosphere when young gas giant planets form, in particular discussing the ef

  11. Highly siderophile element (HSE) abundances in the mantle of Mars are due to core formation at high pressure and temperature

    Science.gov (United States)

    Righter, K.; Danielson, L. R.; Pando, K. M.; Williams, J.; Humayun, M.; Hervig, R. L.; Sharp, T. G.

    2015-04-01

    Highly siderophile elements (HSEs) can be used to understand accretion and core formation in differentiated bodies, due to their strong affinity for FeNi metal and sulfides. Coupling experimental studies of metal-silicate partitioning with analyses of HSE contents of Martian meteorites can thus offer important constraints on the early history of Mars. Here, we report new metal-silicate partitioning data for the PGEs and Au and Re across a wide range of pressure and temperature space, with three series designed to complement existing experimental data sets for HSE. The first series examines temperature effects for D(HSE) in two metallic liquid compositions—C-bearing and C-free. The second series examines temperature effects for D(Re) in FeO-bearing silicate melts and FeNi-rich alloys. The third series presents the first systematic study of high pressure and temperature effects for D(Au). We then combine our data with previously published partitioning data to derive predictive expressions for metal-silicate partitioning of the HSE, which are subsequently used to calculate HSE concentrations of the Martian mantle during continuous accretion of Mars. Our results show that at midmantle depths in an early magma ocean (equivalent to approximately 14 GPa, 2100 °C), the HSE contents of the silicate fraction are similar to those observed in the Martian meteorite suite. This is in concert with previous studies on moderately siderophile elements. We then consider model calculations that examine the role of melting, fractional crystallization, and sulfide saturation/undersaturation in establishing the range of HSE contents in Martian meteorites derived from melting of the postcore formation mantle. The core formation modeling indicates that the HSE contents can be established by metal-silicate equilibrium early in the history of Mars, thus obviating the need for a late veneer for HSE, and by extension volatile siderophile elements, or volatiles in general.

  12. Volatile Abundances and Magma Geochemistry of Recent (2006) Through Ancient Eruptions (Less Than 2100 aBP) of Augustine Volcano, Alaska

    Science.gov (United States)

    Webster, J. D.; Mandeville, C. W.; Gerard, T.; Goldoff, B.; Coombs, M. L.

    2006-12-01

    Augustine Volcano, Cook Inlet, Alaska, is a subduction-related Aleutian arc volcano located approximately 275 km southwest of Anchorage. During the past 200 years, Augustine volcano has shown explosive eruptive behavior seven times, with the most recent activity occurring in January through March 2006. Its ash and pumice eruptions pose a threat to commercial air traffic, the local fishing industry, and the inhabitants of the region. Following prior investigations on volatile abundances and processes of evolution for magmas associated with the 1976 (Johnston, 1978) and 1986 (Roman et al., 2005) eruptions of Augustine, we have analyzed phenocrysts, matrix glasses, and silicate melt inclusions in andesites formed during 5 pre-historic eruptions (ranging from 2100 to 1000 years in age) as well as the 1986 and recent 2006 eruptions. Outcrops of basaltic units on Augustine are rare, and basaltic melt inclusions are as well, so most melt inclusions studied range from andesitic to rhyolitic compositions. Comparison of the volatile abundances in felsic melt inclusion glasses shows few differences in H2O, CO2, S, and Cl, respectively, between eruptive materials of the pre- historic, 1976 (Johnston, 1978), and 1986 (Roman et al., 2005; our data) events. The magmas associated with these eruptions contained 1.6 to 8.0 wt.% H2O with 0.21 to 0.84 wt.% Cl, 100 to 1800 ppm CO2, and 100 to 400 ppm S. In contrast, preliminary research on rhyodacitic to rhyolitic melt inclusions in a single 2006 andesite sample collected from a lahar deposit indicates they contain somewhat lower H2O contents and higher Cl and S abundances than felsic melt inclusions from prior eruptions, and they exhibit geochemical trends consonant with magma mixing. Relationships involving H2O, CO2, S, and Cl in prehistoric through 1986 melt inclusions are consistent with fluid-saturated magma evolution of andesitic to rhyolitic melt compositions during closed-system ascent. The various batches of magma rose through

  13. Seasonal and spatial variation in species diversity, abundance, and element accumulation capacities of macroalgae in mangrove forests of Zhanjiang, China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yubin; LI Yuan; SHI Fei; SUN Xingli; LIN Guanghui

    2014-01-01

    The objective of this study was to investigate whether there was distinctive seasonal and zonal variation in the species diversity, biomass, and element accumulation capacities of macroalgae in two major intertidal mangrove stand types (Avicennia marina assemblage andSonneratia apetala assemblage) in the Zhanjiang region of southern China. Over a year, 31 species in 15 genera were identified in both mangrove assem-blages, of which the dominant species wereCladophoropsis zollingeriand Enteromorpha clathrat.Macroal-gal species were significantly most abundant in spring (p<0.05), followed by summer, winter, and autumn. Variation in the zonal distribution of macroalgal species was conspicuous in both intertidal mangrove as-semblages, with the greatest abundance in the middle zone, and the least in the front zone. Patterns in the seasonal and zonal variation in macroalgal biomass in theS. apetalaassemblage were similar to those of macroalgal species diversity in both mangrove assemblages. The seasonal patterns in tissue concentrations of 15 analyzed elements were not uniform among the macroalgaeC. zollingeri,E. clathrata, andGracilaria salicornia in theA. marina assemblage. All three species exhibited variation in their responses to ambient concentrations of different elements, implying their differential ability to absorb and selectively accumulate certain elements.

  14. Abundances of Baade's Window Giants from Keck/HIRES Spectra: II. The Alpha- and Light Odd Elements

    CERN Document Server

    Fulbright, J P; Rich, R M; Fulbright, Jon. P.; William, Andrew Mc

    2006-01-01

    We report detailed chemical abundance analysis of 27 RGB stars towards the Galactic bulge in Baade's Window for elements produced by massive stars: O, Na, Mg, Al, Si, Ca and Ti. All of these elements are overabundant in the bulge relative to the disk, especially Mg, indicating that the bulge is enhanced in Type~II supernova ejecta and most likely formed more rapidly than the disk. We attribute a rapid decline of [O/Fe] to metallicity-dependent yields of oxygen in massive stars, perhaps connected to the Wolf-Reyet phenomenon. he explosive nucleosynthesis alphas, Si, Ca and Ti, possess identical trends with [Fe/H], consistent with their putative common origin. We note that different behaviors of hydrostatic and explosive alpha elements can be seen in the stellar abundances of stars in Local Group dwarf galaxies. We also attribute the decline of Si,Ca and Ti relative to Mg, to metallicity- dependent yields for the explosive alpha elements from Type~II supernovae. The starkly smaller scatter of [/Fe] with [Fe/H] ...

  15. ELEMENTAL ABUNDANCES IN THE EJECTA OF OLD CLASSICAL NOVAE FROM LATE-EPOCH SPITZER SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Helton, L. Andrew; Vacca, William D. [SOFIA Science Center, USRA, NASA Ames Research Center, M.S. N232-11, Moffett Field, CA 94035 (United States); Gehrz, Robert D.; Woodward, Charles E.; Shenoy, Dinesh P. [Minnesota Institute for Astrophysics, School of Physics and Astronomy, 116 Church Street S.E., University of Minnesota, Minneapolis, MN 55455 (United States); Wagner, R. Mark [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Evans, Aneurin [Astrophysics Group, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom); Krautter, Joachim [Landessternwarte-Zentrum fuer Astronomie der Universitaet, Koenigstuhl, D-69117 Heidelberg (Germany); Schwarz, Greg J. [American Astronomical Society, 2000 Florida Avenue, NW, Suite 400, Washington, DC 20009 (United States); Starrfield, Sumner, E-mail: ahelton@sofia.usra.edu [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287 (United States)

    2012-08-10

    We present Spitzer Space Telescope mid-infrared IRS spectra, supplemented by ground-based optical observations, of the classical novae V1974 Cyg, V382 Vel, and V1494 Aql more than 11, 8, and 4 years after outburst, respectively. The spectra are dominated by forbidden emission from neon and oxygen, though in some cases, there are weak signatures of magnesium, sulfur, and argon. We investigate the geometry and distribution of the late time ejecta by examination of the emission line profiles. Using nebular analysis in the low-density regime, we estimate lower limits on the abundances in these novae. In V1974 Cyg and V382 Vel, our observations confirm the abundance estimates presented by other authors and support the claims that these eruptions occurred on ONe white dwarfs (WDs). We report the first detection of neon emission in V1494 Aql and show that the system most likely contains a CO WD.

  16. Physical conditions and element abundances in SN and GRB host galaxies at different redshifts

    CERN Document Server

    Contini, M

    2016-01-01

    We compare the physical parameters and the relative abundances calculated throughout supernova (SN) and gamma-ray burst (GRB) host galaxies by the detailed modelling of the spectra. The results show that : 1) shock velocities are lower in long period GRB (LGRB) than in SN host galaxies. 2) O/H relative abundance in SN hosts are scattered within a range 8.0 10^5 K. Ts in LGRB hosts are 3-8 10^4 K. 4) Ha increases with the ionization parameter U. We suggest that SN-host symbiosis is stronger in terms of host galaxy activity than GRB-host in the range of energies related to the near UV - optical - near IR spectra.

  17. Chlorine distribution and its isotopic composition in “rusty rock” 66095. Implications for volatile element enrichments of “rusty rock” and lunar soils, origin of “rusty” alteration, and volatile element behavior on the Moon

    Science.gov (United States)

    Shearer, C. K.; Sharp, Z. D.; Burger, P. V.; McCubbin, F. M.; Provencio, P. P.; Brearley, A. J.; Steele, A.

    2014-08-01

    An interesting characteristic of the pyroclastic glass bead deposits, select impact produced lithologies such as the “rusty rock” 66095, and unique lunar soils from the Apollo 16 landing site, is their unusual enrichments in 204Pb, Cd, Bi, Br, I, Ge, Sb, Tl, Zn, and Cl which indicates that portions of these sample contain a substantial volatile component. Sample 66095, a fine-grained, subophitic to ophitic polymict melt breccia, also hosts a pervasive low-temperature, volatile-rich, oxyhydrated mineral assemblage. The volatile element enrichments in these assorted lunar lithologies have been attributed to a variety of extra-lunar and lunar processes, whereas the oxyhydration in 66095 has long been thought to represent either terrestrial alteration of lunar chlorides and Fe-Ni metal to βFeO(OH,Cl) or indigenous lunar processes. In 66095, Cl is accommodated in FeO(OH,Cl), phosphates, and chlorides and is heterogeneously distributed. The low-temperature alteration occurs as rims around Fe-Ni metal and sulfide grains, and as dispersed grains in the adjacent matrix. Micro-Raman and transmission electron microscope (TEM) imaging indicate that akaganéite (βFeO(OH,Cl)) is the dominant FeO(OH) polymorph and is intergrown with goethite (αFeO(OH)) and hematite (αFe2O3). TEM observations indicate a well-defined “nanometer-scale” stratigraphy” to the alteration. For example, kamacite (body centered cubic) → face-centered cubic (fcc) Fe-Ni alloy → lawrencite (FeCl2) → akaganéite. The lunar lawrencite (Fe,Ni)Cl2 in 66095 does not react directly to akaganéite on Earth. Rather, lawrencite exposed to terrestrial conditions reacts to form an amorphous Fe- and Cl-bearing phase, nano-crystalline goethite, and hematite. The morphology of these terrestrial alteration products is significantly different than that of the akaganéite occurring in 66095. The chlorine isotopic compositions of these volatile-rich samples are enriched in heavy Cl. For 66095, the δ37Cl

  18. Abundance of Weak r-Process Elements of Metal-Poor Stars ˜Universality or Diversity?˜

    Science.gov (United States)

    Aoki, Misa; Ishimaru, Yuhri; Aoki, Wako; Wanajo, Shinya

    The origin of the rapid neutron-capture process is a major question in astrophysics. The key to this question is the chemical abundance patterns of very metal-poor stars (VMP), which are believed to reflect the nucleosynthesis yields of single event. Recent observations of VMP indicate that there are at least two components to r-process; "main r-process" responsible for relatively heavy neutron-capture elements and "weak r-process" [1] responsible for relatively light neutron-capture elements. The VMP with heavier neutron-capture elements are known to have similar pattern to that of solar r-process, suggesting universality in main r-process nucleosynthesis [2]. A question is whether weak r-process also show such universality. We present the abundance analysis of neutron-capture elements in five stars (HD107752, HD110184, HD85773, HD23798, BD+6 648) in the Galactic halo observed by the Subaru Telescope High Dispersion Spectrograph. Their light neutron-capture elements (e.g., Sr, Y) show overabundance, inferring contribution of weak r-process, while heavy neutron-capture elements (e.g., Ba, Eu) are deficient. The overabundance of these stars, however, is not as significant as that found in HD122563 [3] known as the weak r-process star. These results suggests that there is diversity in the nucleosynthesis of the weak r-process. In addition, we compare our results with the latest nucleosynthesis models of electron capture supernova and core collapse supernova [4, 5].

  19. Double white dwarf mergers and elemental surface abundances in extreme helium and R Coronae Borealis stars

    CERN Document Server

    Jeffery, C Simon; Saio, Hideyuki

    2011-01-01

    The surface abundances of extreme helium (EHe) and R Coronae Borealis (RCB) stars are discussed in terms of the merger of a carbon-oxygen white dwarf with a helium white dwarf. The model is expressed as a linear mixture of the individual layers of both constituent white dwarfs, taking account of the specific evolution of each star. In developing this recipe from previous versions, particular attention has been given to the inter-shell abundances of the asymptotic giant branch star which evolved to become the carbon-oxygen white dwarf. Thus the surface composition of the merged star is estimated as a function of the initial mass and metallicity of its progenitor. The question of whether additional nucleosynthesis occurs during the white dwarf merger has been examined. The high observed abundances of carbon and oxygen must either originate by dredge-up from the core of the carbon-oxygen white dwarf during a cold merger or be generated directly by alpha-burning during a hot merger. The presence of large quantiti...

  20. The abundance pattern of heavy elements in Sirius: Impact of modern observations (STIS) and improved Atomic data

    Science.gov (United States)

    Ramsay Cowley, Charles; Ayres, Thomas; Wahlgren, Glenn; Carpenter, Kenneth

    2015-08-01

    The abundance pattern of heavy elements in Sirius: Impact of modern observations (STIS) and improved atomic data. We determine abundances or upper limits for the 55 stable elements from copper to uranium for the A1 Vm star Sirius. The primary observational material consists of Hubble Space Telescope (HST) spectra taken with the Space Telescope Imaging Spectrograph (STIS) from the ASTRAL project (Ayres 2010, ApJS, 187, 149). We have also used archival material from COPERNICUS (retrieved from the MAST) and from HST/GHRS, as well as the ground-based Furenlid, Westin, and Kurucz Sirius Atlas (FWK). The GHRS observations were described by Wahlgren, et al. (1993, Bull. AAS, 25, 1321). We also used the monumental study of Sirius by Klaus Kohl (1964, Zs. f. Ap. 60, 115, 1964, see also 1964, Das Spektrum des Sirius, 3100 - 8863A, Kiel thesis). Abundance determinations are based on the photospheric model of Landstreet (2011, A&A, 528, 132). The atomic data base is significantly improved since the pioneering work by Sadakane (1988, PASP, 100, 811; 1991, 103, 355). The basic source was VALD3 (http://vald.inasan.ru/~vald3/php/vald.php), supplemented for all species by the essential NIST bibliographic data base (http://physics.nist.gov/cgi-bin/ASBib1/TransProbBib.cgi). We determine abundances and upper limits by synthesizing short wavelength regions around strong lines. Virtually all of the abundance/upper limit results show excesses over the solar composition of between 1 and 2 dex. This result is in general agreement with overall results for metallic line stars, though we have no information on possible severe depletions for most elements. We conclude that the mechanisms causing abundance anomalies in Sirius have not acted to produce the extreme excesses of 4 or more dex (Pt, Hg), or deficiencies (Zn) seen in many HgMn stars.CRC thanks Stefano Bagnulo for the UVESPOP Sirius spectrum. Robert Kurucz was most helpful with older Sirius UV and visual spectra.

  1. Transposable element distribution, abundance and role in genome size variation in the genus Oryza.

    Science.gov (United States)

    Zuccolo, Andrea; Sebastian, Aswathy; Talag, Jayson; Yu, Yeisoo; Kim, HyeRan; Collura, Kristi; Kudrna, Dave; Wing, Rod A

    2007-08-29

    The genus Oryza is composed of 10 distinct genome types, 6 diploid and 4 polyploid, and includes the world's most important food crop - rice (Oryza sativa [AA]). Genome size variation in the Oryza is more than 3-fold and ranges from 357 Mbp in Oryza glaberrima [AA] to 1283 Mbp in the polyploid Oryza ridleyi [HHJJ]. Because repetitive elements are known to play a significant role in genome size variation, we constructed random sheared small insert genomic libraries from 12 representative Oryza species and conducted a comprehensive study of the repetitive element composition, distribution and phylogeny in this genus. Particular attention was paid to the role played by the most important classes of transposable elements (Long Terminal Repeats Retrotransposons, Long interspersed Nuclear Elements, helitrons, DNA transposable elements) in shaping these genomes and in their contributing to genome size variation. We identified the elements primarily responsible for the most strikingly genome size variation in Oryza. We demonstrated how Long Terminal Repeat retrotransposons belonging to the same families have proliferated to very different extents in various species. We also showed that the pool of Long Terminal Repeat Retrotransposons is substantially conserved and ubiquitous throughout the Oryza and so its origin is ancient and its existence predates the speciation events that originated the genus. Finally we described the peculiar behavior of repeats in the species Oryza coarctata [HHKK] whose placement in the Oryza genus is controversial. Long Terminal Repeat retrotransposons are the major component of the Oryza genomes analyzed and, along with polyploidization, are the most important contributors to the genome size variation across the Oryza genus. Two families of Ty3-gypsy elements (RIRE2 and Atlantys) account for a significant portion of the genome size variations present in the Oryza genus.

  2. Transposable element distribution, abundance and role in genome size variation in the genus Oryza

    Directory of Open Access Journals (Sweden)

    Collura Kristi

    2007-08-01

    Full Text Available Abstract Background The genus Oryza is composed of 10 distinct genome types, 6 diploid and 4 polyploid, and includes the world's most important food crop – rice (Oryza sativa [AA]. Genome size variation in the Oryza is more than 3-fold and ranges from 357 Mbp in Oryza glaberrima [AA] to 1283 Mbp in the polyploid Oryza ridleyi [HHJJ]. Because repetitive elements are known to play a significant role in genome size variation, we constructed random sheared small insert genomic libraries from 12 representative Oryza species and conducted a comprehensive study of the repetitive element composition, distribution and phylogeny in this genus. Particular attention was paid to the role played by the most important classes of transposable elements (Long Terminal Repeats Retrotransposons, Long interspersed Nuclear Elements, helitrons, DNA transposable elements in shaping these genomes and in their contributing to genome size variation. Results We identified the elements primarily responsible for the most strikingly genome size variation in Oryza. We demonstrated how Long Terminal Repeat retrotransposons belonging to the same families have proliferated to very different extents in various species. We also showed that the pool of Long Terminal Repeat Retrotransposons is substantially conserved and ubiquitous throughout the Oryza and so its origin is ancient and its existence predates the speciation events that originated the genus. Finally we described the peculiar behavior of repeats in the species Oryza coarctata [HHKK] whose placement in the Oryza genus is controversial. Conclusion Long Terminal Repeat retrotransposons are the major component of the Oryza genomes analyzed and, along with polyploidization, are the most important contributors to the genome size variation across the Oryza genus. Two families of Ty3-gypsy elements (RIRE2 and Atlantys account for a significant portion of the genome size variations present in the Oryza genus.

  3. The Origin of the Metal-Poor Common Proper Motion Pair HD 134439/134440: Insights from New Elemental Abundances

    CERN Document Server

    Chen, Yu; Boesgaard, Ann M

    2014-01-01

    The low [alpha/Fe] ratio in the metal-poor ([Fe/H]= -1.50) common proper motion pair HD 134439 and HD 134440 has been variously attributed to chemical evolution in an extragalactic environment with an irregular star formation history, planetessimal accretion, and formation in an environment with an unusually high dust-to-gas ratio. We explore these various putative origins using CNO, Be, Ag, and Eu abundances derived from high-resolution near-UV Keck/HIRES spectroscopy. While we confirm a previously suggested correlation between elemental abundance ratios and condensation temperature at the 95% confidence level, these ratios lie within the continuum of values manifested by extant dSph data. We argue that the most plausible origin of our stars' distinctive abundance distribution relative to the Galactic halo field is formation in an environment chemically dominated by products of Type II SN of low progenitor mass; such a progenitor mass bias has been previously suggested as an explanation of low alpha-element ...

  4. Estimating stellar atmospheric parameters, absolute magnitudes and elemental abundances from the LAMOST spectra with Kernel-based Principal Component Analysis

    CERN Document Server

    Xiang, Maosheng; Shi, Jianrong; Yuan, Haibo; Huang, Yang; Luo, Ali; Zhang, Huawei; Zhao, Yongheng; Zhang, Jiannan; Ren, Juanjuan; Chen, Bingqiu; Wang, Chun; Li, Ji; Huo, Zhiying; Zhang, Wei; Wang, Jianling; Zhang, Yong; Hou, Yonghui; Wang, Yuefei

    2016-01-01

    Accurate determination of stellar atmospheric parameters and elemental abundances is crucial for Galactic archeology via large-scale spectroscopic surveys. In this paper, we estimate stellar atmospheric parameters -- effective temperature T_{\\rm eff}, surface gravity log g and metallicity [Fe/H], absolute magnitudes M_V and M_{Ks}, {\\alpha}-element to metal (and iron) abundance ratio [{\\alpha}/M] (and [{\\alpha}/Fe]), as well as carbon and nitrogen abundances [C/H] and [N/H] from the LAMOST spectra with amultivariate regressionmethod based on kernel-based principal component analysis, using stars in common with other surveys (Hipparcos, Kepler, APOGEE) as training data sets. Both internal and external examinations indicate that given a spectral signal-to-noise ratio (SNR) better than 50, our method is capable of delivering stellar parameters with a precision of ~100K for Teff, ~0.1 dex for log g, 0.3 -- 0.4mag for M_V and M_{Ks}, 0.1 dex for [Fe/H], [C/H] and [N/H], and better than 0.05 dex for [{\\alpha}/M] ([...

  5. Determination of elemental composition of volatile organic compounds from Chinese rose oil by spectral accuracy and mass accuracy.

    Science.gov (United States)

    Zhou, Wei; Zhang, Yaheng; Xu, Hongliang; Gu, Ming

    2011-10-30

    Elemental composition determination of volatile organic compounds through high mass accuracy and isotope pattern matching could not be routinely achieved with a unit-mass resolution mass spectrometer until the recent development of the comprehensive instrument line-shape calibration technology. Through this unique technology, both m/z values and mass spectral peak shapes are calibrated simultaneously. Of fundamental importance is that calibrated mass spectra have symmetric and mathematically known peak shapes, which makes it possible to deconvolute overlapped monoisotopes and their (13)C-isotope peaks and achieve accurate mass measurements. The key experimental requirements for the measurements are to acquire true raw data in a profile or continuum mode with the acquisition threshold set to zero. A total of 13 ions from Chinese rose oil were analyzed with internal calibration. Most of the ions produced high mass accuracy of better than 5 mDa and high spectral accuracy of better than 99%. These results allow five tested ions to be identified with unique elemental compositions and the other eight ions to be determined as a top match from multiple candidates based on spectral accuracy. One of them, a coeluted component (Nerol) with m/z 154, could not be identified by conventional GC/MS (gas chromatography/mass spectrometry) and library search. Such effective determination for elemental compositions of the volatile organic compounds with a unit-mass resolution quadrupole system is obviously attributed to the significant improvement of mass accuracy. More importantly, high spectral accuracy available through the instrument line-shape calibration enables highly accurate isotope pattern recognition for unknown identification.

  6. Survey for Ortho-to-Para Abundance Ratios (OPRs) of NH2 in Comets: Revisit to the Meaning of OPRs of Cometary Volatiles

    Science.gov (United States)

    Kawakita, Hideyo; Shinnaka, Yoshiharu; Jehin, Emmanuel; Decock, Alice; Hutsemekers, Damien; Manfroid, Jean

    2016-10-01

    Since molecules having identical protons can be classified into nuclear-spin isomers (e.g., ortho-H2O and para-H2O for water) and their inter-conversions by radiative and non-destructive collisional processes are believed to be very slow, the ortho-to-para abundance ratios (OPRs) of cometary volatiles such as H2O, NH3 and CH4 in coma have been considered as primordial characters of cometary molecules [1]. Those ratios are usually interpreted as nuclear-spin temperatures although the real meaning of OPRs is in strong debate. Recent progress in laboratory studies about nuclear-spin conversion in gas- and solid-phases [2,3] revealed short-time nuclear-spin conversions for water, and we have to reconsider the interpretation for observed OPRs of cometary volatiles. We have already performed the survey for OPRs of NH2 in more than 20 comets by large aperture telescopes with high-resolution spectrographs (UVES/VLT, HDS/Subaru, etc.) in the optical wavelength region [4]. The observed OPRs of ammonia estimated from OPRs of NH2, cluster around ~1.1 (cf. 1.0 as a high-temperature limit), indicative of ~30 K as nuclear-spin temperatures. We present our latest results for OPRs of cometary NH2 and discuss about the real meaning of OPRs of cometary ammonia, in relation to OPRs of water in cometary coma. Chemical processes in the inner coma may play an important role to achieve un-equilibrated OPRs of cometary volatiles in coma.This work was financially supported by MEXT Supported Program for the Strategic Research Foundation at Private Universities, 2014–2018 (No. S1411028) (HK) and by Graint-in-Aid for JSPS Fellows, 15J10864 (YS).References:[1] Mumma & Charnley, 2011, Annu. Rev. Astro. Astrophys. 49, 471.[2] Hama & Watanabe, 2013, Chem. Rev. 113, 8783.[3] Hama et al., 2008, Science 351, 6268.[4] Shinnaka et al., 2011, ApJ 729, 81.

  7. Super-Massive Stars as a Source of Abundance Anomalies of Proton-Capture Elements in Globular Clusters

    CERN Document Server

    Denissenkov, Pavel A

    2013-01-01

    We propose that the abundance anomalies of proton-capture elements in globular clusters, such as the C-N, Na-O, Mg-Al and Na-F anti-correlations, were produced by super-massive stars with M ~ 10,000 Msun. Such stars could form in the runaway collisions of massive stars that sank to the cluster center as a result of dynamical friction, or via the direct collapse of the low-metallicity gas cloud from which the cluster formed. To explain the observed abundance anomalies, we assume that the super-massive stars had lost significant fractions of their initial masses when only a small mass fraction of hydrogen, Delta X ~ 0.15, was transformed into helium. We speculate that the required mass loss might be caused by the super-Eddington radiation continuum-driven stellar wind or by the diffusive mode of the Jeans instability.

  8. Determination of solar wind elemental abundances from M/Q observations during three periods in 1980

    Science.gov (United States)

    Kunz, S.; Bochsler, P.; Geiss, J.; Ogilvie, K. W.; Coplan, M. A.

    1983-10-01

    Mass spectra in the range 2 ≤ M/Q ≤ 3 provided by a high resolution mode of the ISEE-3 Plasma Composition Experiment were evaluated for three selected periods during early 1980. The observed Ne/O ratios are compatible with estimated solar abundance ratios. In two of the three periods, the He/Ne-ratios agree with the Apollo foil results. Freezing-in temperatures for oxygen are similar to those obtained by other groups. Possible reasons for an unexpectedly high flux at M/Q = 2.4 are discussed.

  9. Determination of solar wind elemental abundances from M/Q observations during three periods in 1980

    Energy Technology Data Exchange (ETDEWEB)

    Kunz, S.; Bochsler, P.; Geiss, J. (Bern Univ. (Switzerland). Physikalisches Inst.); Ogilvie, K.W. (National Aeronautics and Space Administration, Greenbelt, MD (USA). Goddard Space Flight Center); Coplan, M.A. (Maryland Univ., College Park (USA). Inst. for Physical Science and Technology)

    1983-10-01

    Mass spectra in the range 2<=M/Q<=3 provided by a high resolution mode of the ISEE-3 Plasma Composition Experiment were evaluated for three selected periods during early 1980. The observed Ne/O ratios are compatible with estimated solar abundance ratios. In two of the three periods, the He/Ne-ratios agree with the Apollo foil results. Freezing-in temperatures for oxygen are similar to those obtained by other groups. Possible reasons for an unexpectedly high flux at M/Q=2.4 are discussed.

  10. Element Abundances in a Gas-rich Galaxy at z = 5: Clues to the Early Chemical Enrichment of Galaxies

    Science.gov (United States)

    Morrison, Sean; Kulkarni, Varsha P.; Som, Debopam; DeMarcy, Bryan; Quiret, Samuel; Péroux, Celine

    2016-10-01

    Element abundances in high-redshift quasar absorbers offer excellent probes of the chemical enrichment of distant galaxies, and can constrain models for population III and early population II stars. Recent observations indicate that the sub-damped Lyα (sub-DLA) absorbers are more metal-rich than DLA absorbers at redshifts 0 4.7. However, only three DLAs at z > 4.5 and no sub-DLAs at z > 3.5 have “dust-free” metallicity measurements of undepleted elements. We report the first quasar sub-DLA metallicity measurement at z > 3.5, from detections of undepleted elements in high-resolution data for a sub-DLA at z = 5.0. We obtain fairly robust abundances of C, O, Si, and Fe, using lines outside the Lyα forest. This absorber is metal-poor, with [O/H] = ‑2.00 ± 0.12, which is ≳4σ below the level expected from extrapolation of the trend for z Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

  11. Estimating stellar atmospheric parameters, absolute magnitudes and elemental abundances from the LAMOST spectra with Kernel-based principal component analysis

    Science.gov (United States)

    Xiang, M.-S.; Liu, X.-W.; Shi, J.-R.; Yuan, H.-B.; Huang, Y.; Luo, A.-L.; Zhang, H.-W.; Zhao, Y.-H.; Zhang, J.-N.; Ren, J.-J.; Chen, B.-Q.; Wang, C.; Li, J.; Huo, Z.-Y.; Zhang, W.; Wang, J.-L.; Zhang, Y.; Hou, Y.-H.; Wang, Y.-F.

    2017-01-01

    Accurate determination of stellar atmospheric parameters and elemental abundances is crucial for Galactic archaeology via large-scale spectroscopic surveys. In this paper, we estimate stellar atmospheric parameters - effective temperature Teff, surface gravity log g and metallicity [Fe/H], absolute magnitudes MV and MKs, α-element to metal (and iron) abundance ratio [α/M] (and [α/Fe]), as well as carbon and nitrogen abundances [C/H] and [N/H] from the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) spectra with a multivariate regression method based on kernel-based principal component analysis, using stars in common with other surveys (Hipparcos, Kepler, Apache Point Observatory Galactic Evolution Experiment) as training data sets. Both internal and external examinations indicate that given a spectral signal-to-noise ratio (SNR) better than 50, our method is capable of delivering stellar parameters with a precision of ˜100 K for Teff, ˜0.1 dex for log g, 0.3-0.4 mag for MV and MKs, 0.1 dex for [Fe/H], [C/H] and [N/H], and better than 0.05 dex for [α/M] ([α/Fe]). The results are satisfactory even for a spectral SNR of 20. The work presents first determinations of [C/H] and [N/H] abundances from a vast data set of LAMOST, and, to our knowledge, the first reported implementation of absolute magnitude estimation directly based on a vast data set of observed spectra. The derived stellar parameters for millions of stars from the LAMOST surveys will be publicly available in the form of value-added catalogues.

  12. Estimating stellar atmospheric parameters, absolute magnitudes and elemental abundances from the LAMOST spectra with Kernel-based Principal Component Analysis

    Science.gov (United States)

    Xiang, M.-S.; Liu, X.-W.; Shi, J.-R.; Yuan, H.-B.; Huang, Y.; Luo, A.-L.; Zhang, H.-W.; Zhao, Y.-H.; Zhang, J.-N.; Ren, J.-J.; Chen, B.-Q.; Wang, C.; Li, J.; Huo, Z.-Y.; Zhang, W.; Wang, J.-L.; Zhang, Y.; Hou, Y.-H.; Wang, Y.-F.

    2016-10-01

    Accurate determination of stellar atmospheric parameters and elemental abundances is crucial for Galactic archeology via large-scale spectroscopic surveys. In this paper, we estimate stellar atmospheric parameters - effective temperature Teff, surface gravity log g and metallicity [Fe/H], absolute magnitudes MV and MKs, α-element to metal (and iron) abundance ratio [α/M] (and [α/Fe]), as well as carbon and nitrogen abundances [C/H] and [N/H] from the LAMOST spectra with a multivariate regression method based on kernel-based principal component analysis, using stars in common with other surveys (Hipparcos, Kepler, APOGEE) as training data sets. Both internal and external examinations indicate that given a spectral signal-to-noise ratio (SNR) better than 50, our method is capable of delivering stellar parameters with a precision of ˜100 K for Teff, ˜0.1 dex for log g, 0.3 - 0.4 mag for MV and MKs, 0.1 dex for [Fe/H], [C/H] and [N/H], and better than 0.05 dex for [α/M] ([α/Fe]). The results are satisfactory even for a spectral SNR of 20. The work presents first determinations of [C/H] and [N/H] abundances from a vast data set of LAMOST, and, to our knowledge, the first reported implementation of absolute magnitude estimation directly based on the observed spectra. The derived stellar parameters for millions of stars from the LAMOST surveys will be publicly available in the form of value-added catalogues.

  13. High-precision abundances of Sc, Mn, Cu, and Ba in solar twins. Trends of element ratios with stellar age

    Science.gov (United States)

    Nissen, P. E.

    2016-09-01

    Aims: A previous study of correlations between element abundances and ages of solar twin stars in the solar neighborhood is extended to include Sc, Mn, Cu, and Ba to obtain new information on the nucleosynthetic history of these elements. Methods: HARPS spectra with S/N ≳ 600 are used to derive very precise (σ ~ 0.01 dex) differential abundances of Sc, Mn, Cu, and Ba for 21 solar twins and the Sun. The analysis is based on MARCS model atmospheres with parameters determined from the excitation and ionization balance of Fe lines. Stellar ages with internal errors less than 1 Gyr are obtained by interpolation in the log g - Teff diagram between isochrones based on the Aarhus Stellar Evolution Code. Results: For stars younger than 6 Gyr, [Sc/Fe], [Mn/Fe], [Cu/Fe], and [Ba/Fe] are tightly correlated with stellar age, which is also the case for the other elements previously studied; linear relations between [X/Fe] and age have χ^2red ˜ 1, and for most stars the residuals do not depend on elemental condensation temperature. For ages between 6 and 9 Gyr, the [X/Fe] - age correlations break down and the stars split up into two groups having respectively high and low [X/Fe] for the odd-Z elements Na, Al, Sc, and Cu. Conclusions: While stars in the solar neighborhood younger than ~ 6 Gyr were formed from interstellar gas with a smooth chemical evolution, older stars seem to have originated from regions enriched by supernovae with different neutron excesses. Correlations between abundance ratios and stellar age suggest that: (i) Sc is made in Type II supernovae along with the α-capture elements; (ii) the Type II to Ia yield ratio is about the same for Mn and Fe; (iii) Cu is mainly made by the weak s-process in massive stars; (iv) the Ba/Y yield ratio for asymptotic giant branch stars increases with decreasing stellar mass; (v) [Y/Mg] and [Y/Al] can be used as chemical clocks when determining ages of solar metallicity stars. Based on data products from observations made

  14. Elemental Abundances in Two High Column Density Damped Lyman Alpha Systems at z < 1.5

    CERN Document Server

    Rao, S M; Howk, J C; Wolfe, A M; Rao, Sandhya M.; Prochaska, Jason X.; Wolfe, Arthur M.

    2004-01-01

    We present Keck/HIRES abundance measurements and metal-line kinematic profiles of the damped Lyman alpha systems (DLAs) towards the quasars Q0933+733 (z_abs=1.479) and Q0948+433 (z_abs=1.233). These two DLAs have among the five highest HI column densities at any redshift: N(HI)=4.2E21 cm^{-2}. The metal-line data, presented here for the first time, reveal that these DLAs are noteworthy for several other reasons as well. 1) The Q0933+733 DLA exhibits simple kinematic structure with unusually narrow velocity widths as measured from its unsaturated metal lines (delta v=16 km/s). At 2.6% solar, it has the second lowest metallicity at z -1) and a significant alpha-enhancement. The strong metal lines of this DLA have made possible the detection of TiII1910, CoII2012, and MgI2026. 3) We find that the relative gas-phase abundances of both DLAs follow the general trend seen at high redshift, e.g., enhanced Zn/Fe and Si/Fe, and sub-solar Mn/Fe, indicating that there is little evolution in the nucleosynthetic patterns o...

  15. Disk evolution, element abundances and cloud properties of young gas giant planets

    CERN Document Server

    Helling, Ch; Rimmer, P B; Kamp, I; Thi, W -F; Meijerink, R

    2014-01-01

    We discuss the chemical pre-conditions for planet formation, in terms of gas and ice abundances in a protoplanetary disk, as function of time and position, and the resulting chemical composition and cloud properties in the atmosphere when young gas giant planets form. Large deviations between the abundances of the host star and its gas giants seem likely to occur if the planet formation follows the core-accretion scenario. These deviations stem from the separate evolution of gas and dust in the disk, where the dust forms the planet cores, followed by the final run-away accretion of the left-over gas. ProDiMo protoplanetary disk models are used to predict the chemical evolution of gas and ice in the midplane. We find that cosmic rays play a crucial role in slowly un-blocking the CO, where the liberated oxygen forms water, which then freezes out quickly. Therefore, the C/O ratio in the gas phase is found to gradually increase with time, in a region bracketed by the water and CO ice-lines. In this regions, C/O i...

  16. A Solar cycle correlation of coronal element abundances in Sun-as-a-star observations

    Science.gov (United States)

    Brooks, David H.; Baker, Deborah; van Driel-Gesztelyi, Lidia; Warren, Harry P.

    2017-08-01

    The elemental composition in the coronae of low-activity solar-like stars appears to be related to fundamental stellar properties such as rotation, surface gravity, and spectral type. Here we use full-Sun observations from the Solar Dynamics Observatory, to show that when the Sun is observed as a star, the variation of coronal composition is highly correlated with a proxy for solar activity, the F10.7 cm radio flux, and therefore with the solar cycle phase. Similar cyclic variations should therefore be detectable spectroscopically in X-ray observations of solar analogs. The plasma composition in full-disk observations of the Sun is related to the evolution of coronal magnetic field activity. Our observations therefore introduce an uncertainty into the nature of any relationship between coronal composition and fixed stellar properties. The results highlight the importance of systematic full-cycle observations for understanding the elemental composition of solar-like stellar coronae.

  17. Transport Phenomena and Light Element Abundances in the Sun and Solar Type Stars

    CERN Document Server

    Vauclair, S

    2000-01-01

    The observations of light elements in the Sun and Solar type stars givespecial clues for understanding the hydrodynamical processes at work in stellarinteriors. In the Sun 7Li is depleted by 140 while 3He has not increased bymore than 10 0n 3 Gyrs. Meanwhile the inversion of helioseismic modes lead toa precision on the sound velocity of about .1The mixing processes below thesolar convection zone are constrained by these observations. Lithium isdepleted in most Pop I solar type stars. In halo stars however, the lithiumabundance seems constant in the "spite plateau" with no observed dispersion,which is difficult to reconcile with the theory of diffusion processes. In thepresent paper, the various relevant observations will be discussed. It will beshown that the mu-gradients induced by element settling may help solving the"lithium paradox".

  18. Abundances of s-process elements in planetary nebulae: Br, Kr & Xe

    CERN Document Server

    Zhang, Y; Pellegrini, E; Cavagnolo, K; Baldwin, J A; Sharpee, B; Phillips, M; Liu, X W

    2006-01-01

    We identify emission lines of post-iron peak elements in very high signal-to-noise spectra of a sample of planetary nebulae. Analysis of lines from ions of Kr and Xe reveals enhancements in most of the PNe, in agreement with the theories of s-process in AGB star. Surprisingly, we did not detect lines from Br even though s-process calculations indicate that it should be produced with Kr at detectable levels.

  19. Effect of additives on the volatility of elements in a DC arc during the atomic emission analysis of nickel(II) oxide

    Energy Technology Data Exchange (ETDEWEB)

    Zolotareva, N.I.; Kuzyakov, Yu.Ya.; Khlystova, A.D.; Chernova, N.A.

    1986-10-20

    The authors have studied the effect of traditional halogenating additives, AgCl, CdF/sub 2/, PTFE and that of an effective additive they have selected, ZnF/sub 2/, on the volatility of impurity elements, viz. tungsten, molybdenum, titanium, and zirconium from nickel (II) oxide, and determined the constants for the average relative volatility of the elements by the method of Kantor and Pungor. The results have been used to lower the limits of detection of the impurities cited in nickel(II) oxide.

  20. Metal-rich accretion and thermohaline instabilities in exoplanets-host stars: consequences on the light elements abundances

    CERN Document Server

    Théado, Sylvie

    2011-01-01

    The early evolution of planetary systems is expected to depend on various periods of disk matter accretion onto the central star, which may include the accretion of metal-rich matter after the star settles on the main sequence. When this happens, the accreted material is rapidly mixed within the surface convective zone and induces an inverse mean-molecular-weight gradient, unstable for thermohaline convection. The induced mixing, which dilutes the metal excess, may also have important consequences on the light elements abundances. We model and analyze this process, and present the results according to various possible accretion scenarios. We give a detailed discussion of the different ways of treating thermohaline mixing, as proposed by previous authors, and we converge on a consistent view, including the most recent numerical simulations. We show how the observations of light elements in stars can be used as tracers of such events.

  1. Determining element abundances of [WC]-type Central Stars for probing stellar evolution and nucleosynthesis

    CERN Document Server

    Todt, H; Hamann, W -R; Gräfener, G

    2007-01-01

    [WC]-type CSPNs are hydrogen-deficient Central Stars of Planetary Nebulae showing strong stellar winds and a carbon-rich chemistry. We have analyzed new high-resolution spectra of [WC]-type CSPNs with the Potsdam Wolf-Rayet (PoWR) non-LTE expanding atmosphere models, using upgraded model atoms and atomic data. Previous analyses are repeated on the basis of the current models which account for iron-line blanketing. We especially focus on determining the chemical composition, including some trace elements like nitrogen which are of key importance for understanding the evolutionary origin of the hydrogen-deficient Central Stars.

  2. Observations of Heavy Element Abundances over a Broad Energy Range in 3He-rich Solar Energetic Particle Events

    Science.gov (United States)

    Wiedenbeck, M. E.; Mason, G. M.; Cohen, C. M.; Leske, R. A.; Cummings, A. C.; Dwyer, J. R.; Mazur, J. E.; Mewaldt, R. A.; Stone, E. C.; von Rosenvinge, T. T.

    2006-05-01

    During the maximum of solar cycle 23 a number of 3He-rich solar energetic particle (SEP) events with measurable intensities of heavy elements (Z≥6) at energies >10 MeV/nuc were observed with instrumentation on the Advanced Composition Explorer (ACE) spacecraft. This represents a relatively small fraction of all the 3He-rich SEP events that were detected since heavy-ion intensities at these energies were frequently too low to be measured. Using data from two ACE instruments (SIS covering ~10--60 MeV/nuc and ULEIS ~0.2--1 MeV/nuc) we have investigated heavy element abundances over a broad energy range in this special set of events. We report the average abundance ratios and the correlations between different ratios in the two energy intervals. Furthermore we compare the results from the two different energy ranges, both statistically and on an event-by-event basis. In addition, we compare the statistical properties observed in the SIS and ULEIS data sets with previously-published results obtained at intermediate energies (~1--3 MeV/nuc) from instruments on ISEE-3 during the maximum of solar cycle 21 (Mason et al. 1986, Reames et al. 1994).

  3. Fossil Imprints of Outflow from the Galactic Bulge in Elemental Abundances of Metal-Rich Disk Stars

    CERN Document Server

    Tsujimoto, Takuji

    2007-01-01

    We explore the elemental abundance features of metal-rich disk stars, highlighting the comparisons made with those of the recently revealed Galactic bulge stars. A similarity between two of the comparisons leads to a new theoretical picture of the bulge-disk connection in the Galaxy, where a supermassive black hole resides at the center. We postulate that a metal-rich outflow, triggered by feedback from a black hole, was generated and quenched the star formation, which had lasted several billion years in the bulge. The expelled gas cooled down in the Galactic halo without escaping from the gravitational potential of the Galaxy. The gas gradually started to accrete to the disk around five billion years ago, corresponding to the time of sun's birth, and replaced a low-metallicity halo gas that had been accreting over nearly ten billion years. The metal-rich infalling gas, whose elemental abundance reflects that of metal-rich bulge stars, mixed with the interstellar gas already present in the disk. Stars formed ...

  4. Subaru/HDS study of CH stars: elemental abundances for stellar neutron-capture process studies

    CERN Document Server

    Goswami, Aruna; Karinkuzhi, Drisya

    2015-01-01

    A comprehensive abundance analysis providing rare insight into the chemical history of lead stars is still lacking. We present results from high resolution (R ~ 50000), spectral analyses of three CH stars, HD 26, HD 198269, HD 224959, and, a carbon star with a dusty envelope, HD 100764. Previous studies on these objects are limited by both resolution and wavelength regions and the results differ significantly from each other. We have undertaken to re-analyse the chemical composition of these objects based on high resolution Subaru spectra covering the wavelength regions 4020 to 6775 A,. Considering local thermodynamic equilibrium and using model atmospheres, we have derived the stellar parameters, the effective temperatures Teff, surface gravities log g, and metallicities [Fe/H] for these objects. The derived parameters for HD 26, HD 100764, HD 198269 and HD 224959 are (5000, 1.6, -1.13), (4750, 2.0 -0.86), (4500, 1.5, -2.06) and (5050, 2.1, -2.44) respectively. The stars are found to exhibit large enhancemen...

  5. Elemental Abundances in Milky Way-like Galaxies from a Hierarchical Galaxy Formation Model

    CERN Document Server

    De Lucia, Gabriella; Frenk, Carlos S; Helmi, Amina; Navarro, Julio F; White, Simon D M

    2014-01-01

    We develop a new method to account for the finite lifetimes of stars and trace individual abundances within a semi-analytic model of galaxy formation. At variance with previous methods, based on the storage of the (binned) past star formation history of model galaxies, our method projects the information about the metals produced by each simple stellar population (SSP) in the future. Using this approach, an accurate accounting of the timings and properties of the individual SSPs composing model galaxies is possible. We analyse the dependence of our chemical model on various ingredients, and apply it to six simulated haloes of roughly Milky Way mass and with no massive close neighbour at z=0. For all models considered, the [Fe/H] distributions of the stars in the disc component are in good agreement with Milky Way data, while for the spheroid component (whose formation we model only through mergers) these are offset low with respect to observational measurements for the Milky Way bulge. This is a consequence o...

  6. Metallicity Distribution Functions, Radial Velocities, and Alpha Element Abundances in Three Off-Axis Bulge Fields

    CERN Document Server

    Johnson, Christian I; Kobayashi, Chiaki; Kunder, Andrea; Pilachowski, Catherine A; Koch, Andreas; De Propris, Roberto

    2013-01-01

    We present radial velocities and chemical abundance ratios of [Fe/H], [O/Fe], [Si/Fe], and [Ca/Fe] for 264 red giant branch (RGB) stars in three Galactic bulge off-axis fields located near (l,b)=(-5.5,-7), (-4,-9), and (+8.5,+9). The results are based on equivalent width and spectrum synthesis analyses of moderate resolution (R~18,000), high signal-to-noise ratio (S/N~75-300) spectra obtained with the Hydra spectrographs on the Blanco 4m and WIYN 3.5m telescopes. The targets were selected from the blue side of the giant branch to avoid cool stars that would be strongly affected by CN and TiO; however, a comparison of the color-metallicity distribution in literature samples suggests our selection of bluer targets should not present a significant bias against metal-rich stars. We find a full range in metallicity that spans [Fe/H]\\approx-1.5 to +0.5, and that, in accordance with the previously observed minor-axis vertical metallicity gradient, the median [Fe/H] also declines with increasing Galactic latitude in ...

  7. Gas composition of major volatile elements in protoplanetary discs and its implication for planet formation

    CERN Document Server

    Amaury, Thiabaud; Yann, Alibert; Ingo, Leya; Klaus, Mezger

    2014-01-01

    Direct observations of gaseous exoplanets reveals that their gas envelope is commonly enriched in C/O ratio compared to that of the host star. This has been explained by considering that the gas phase of the disc could be inhomogeneous, exceeding the stellar C/O ratio in regions where these planets formed; but few studies have considered the drift of the gas and the migration of planets. We aim to derive the gas composition in planets to evaluate if the formation of giant planets with an enriched C/O ratio is possible. The study focusses on the effects of different processes on the C/O ratio like the disc evolution, the drift of gas, and the migration of the planet. We used our previous models for computation of the chemical composition together with the planet formation model of Alibert et al. (2013), to which we added the composition and drift of the gas phase of the disc composed of major volatile species, H2 and He. The study focusses on the region where ice lines are present and influence the C/O ratio o...

  8. Volatile elements production rates in a 1.4 Gev proton-irradiated molten lead-bismuth target

    CERN Document Server

    Zanini, L; Everaerts, P; Fallot, M; Franberg, H; Gröschel, F; Jost, C; Kirchner, T; Kojima, Y; Köster, U; Lebenhaft, J; Manfrina, E; Pitcher, E J; Ravn, H L; Tall, Y; Wagner, W; Wohlmuther, M

    2005-01-01

    Production rates of volatile elements following spallation reaction of 1.4 GeV protons on a liquid Pb/Bi target have been measured. The experiment was performed at the ISOLDE facility at CERN. These data are of interest for the developments of targets for accelerator driven systems such as MEGAPIE. Additional data have been taken on a liquid Pb target. Calculations were performed using the FLUKA and MCNPX Monte Carlo codes coupled with the evolution codes ORIHET3 and FISPACT using different options for the intra-nuclear cascades and evaporation models. Preliminary results from the data analysis show good comparison with calculations for Hg and for noble gases. For other elements such as I it is apparent that only a fraction of the produced isotopes is released. The agreement with the experimental data varies depending on the model combination used. The best results are obtained using MCNPX with the INCL4/ABLA models and with FLUKA. Discrepancies are found for some isotopes produced by fission using the MCNPX ...

  9. Volatile (Cl, F and S) and major element constraints on subduction-related mantle metasomatism along the alkaline basaltic backarc, Payenia, Argentina

    DEFF Research Database (Denmark)

    Brandt, Frederik Ejvang; Holm, Paul Martin; Hansteen, Thor H.

    2017-01-01

    We present data on volatile (S, F and Cl) and major element contents in olivine-hosted melt inclusions (MIs) from alkaline basaltic tephras along the Quaternary Payenia backarc volcanic province (~34°S–38°S) of the Andean Southern Volcanic Zone (SVZ). The composition of Cr-spinel inclusions and h...

  10. A novel abundant family of retroposed elements (DAS-SINEs) in the nine-banded armadillo (Dasypus novemcinctus).

    Science.gov (United States)

    Churakov, Gennady; Smit, Arian F A; Brosius, Jürgen; Schmitz, Jürgen

    2005-04-01

    About half of the mammalian genome is composed of retroposons. Long interspersed elements (LINEs) and short interspersed elements (SINEs) are the most abundant repetitive elements and account for about 21% and 13% of the human genome, respectively. SINEs have been detected in all major mammalian lineages, except for the South American order Xenarthra, also termed Edentata (armadillos, anteaters, and sloths). Investigating this order, we discovered a novel high-copy-number family of tRNA derived SINEs in the nine-banded armadillo Dasypus novemcinctus, a species that successfully crossed the Central American land bridge to North America in the Pliocene. A specific computer algorithm was developed, and we detected and extracted 687 specific SINEs from databases. Termed DAS-SINEs, we further divided them into six distinct subfamilies. We extracted tRNA(Ala)-derived monomers, two types of dimers, and three subfamilies of chimeric fusion products of a tRNA(Ala) domain and an approximately 180-nt sequence of thus far unidentified origin. Comparisons of secondary structures of the DAS-SINEs' tRNA domains suggest selective pressure to maintain a tRNA-like D-arm structure in the respective founder RNAs, as shown by compensatory mutations. By analysis of subfamily-specific genetic variability, comparison of the proportion of direct repeats, and analysis of self-integrations as well as key events of dimerization and deletions or insertions, we were able to delineate the evolutionary history of the DAS-SINE subfamilies.

  11. Solanum lycopersicum cv. Heinz 1706 chromosome 6: distribution and abundance of genes and retrotransposable elements.

    Science.gov (United States)

    Peters, Sander A; Datema, Erwin; Szinay, Dóra; van Staveren, Marjo J; Schijlen, Elio G W M; van Haarst, Jan C; Hesselink, Thamara; Abma-Henkens, Marleen H C; Bai, Yuling; de Jong, Hans; Stiekema, Willem J; Klein Lankhorst, René M; van Ham, Roeland C H J

    2009-06-01

    We studied the physical and genetic organization of chromosome 6 of tomato (Solanum lycopersicum) cv. Heinz 1706 by combining bacterial artificial chromosome (BAC) sequence analysis, high-information-content fingerprinting, genetic analysis, and BAC-fluorescent in situ hybridization (FISH) mapping data. The chromosome positions of 81 anchored seed and extension BACs corresponded in most cases with the linear marker order on the high-density EXPEN 2000 linkage map. We assembled 25 BAC contigs and eight singleton BACs spanning 2.0 Mb of the short-arm euchromatin, 1.8 Mb of the pericentromeric heterochromatin and 6.9 Mb of the long-arm euchromatin. Sequence data were combined with their corresponding genetic and pachytene chromosome positions into an integrated map that covers approximately a third of the chromosome 6 euchromatin and a small part of the pericentromeric heterochromatin. We then compared physical length (Mb), genetic (cM) and chromosome distances (microm) for determining gap sizes between contigs, revealing relative hot and cold spots of recombination. Through sequence annotation we identified several clusters of functionally related genes and an uneven distribution of both gene and repeat sequences between heterochromatin and euchromatin domains. Although a greater number of the non-transposon genes were located in the euchromatin, the highly repetitive (22.4%) pericentromeric heterochromatin displayed an unexpectedly high gene content of one gene per 36.7 kb. Surprisingly, the short-arm euchromatin was relatively rich in repeats as well, with a repeat content of 13.4%, yet the ratio of Ty3/Gypsy and Ty1/Copia retrotransposable elements across the chromosome clearly distinguished euchromatin (2:3) from heterochromatin (3:2).

  12. Abundance of volatile organic compounds in white ash phloem and emerald ash borer larval frass does not attract Tetrastichus planipennisi in a Y-tube olfactometer.

    Science.gov (United States)

    Chen, Yigen; Ulyshen, Michael D; Poland, Therese M

    2016-10-01

    Many natural enemies employ plant- and/or herbivore-derived signals for host/prey location. The larval parasitoid Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae) is 1 of 3 biocontrol agents currently being released in an effort to control the emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coloeptera: Burprestidae) in North America. To enhance its efficiency, allelochemicals that attract it need to be assessed. In this study, ash phloem volatile organic compounds (VOCs) of black, green, and white ash, and EAB larval frass were compared. Foraging behavior of T. planipennisi females in response to VOCs of white ash or frass from EAB larvae feeding on white ash phloem was tested using a Y-tube olfactometer. Results indicated that the 3 ash species had similar VOC profiles. EAB larval frass generally contained greater levels of VOCs than phloem. Factor analysis indicated that the 11 VOCs could be broadly divided into 2 groups, with α-bisabolol, β-caryophyllene, (E)-2-hexenal, (Z)-3-hexenal, limonene, methyl benzoate, methyl indole-3-acetic acid, methyl jasmonate, methyl salicylate as the first group and the rest (i.e., methyl linoleate and methyl linolenate) as a second. Abundance of VOCs in white ash phloem tissue and frass, nevertheless, did not attract T. planipennisi females. The concealed feeding of EAB larvae might explain the selection for detectable and reliable virbrational signals, instead of undetectable and relatively unreliable VOC cues from phloem and frass, in short-range foraging by T. planipennisi. Alternatively, it is possible that T. planipennisi is not amenable to the Y-tube olfactometer assay employed.

  13. ELEMENTAL ABUNDANCES AND THEIR IMPLICATIONS FOR THE CHEMICAL ENRICHMENT OF THE BOOeTES I ULTRAFAINT GALAXY

    Energy Technology Data Exchange (ETDEWEB)

    Gilmore, Gerard [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Norris, John E.; Yong, David [Research School of Astronomy and Astrophysics, The Australian National University, Weston, ACT 2611 (Australia); Monaco, Lorenzo [European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Santiago 19 (Chile); Wyse, Rosemary F. G. [Department of Physics and Astronomy, The Johns Hopkins University, 3900 North Charles Street, Baltimore, MD 21218 (United States); Geisler, D., E-mail: gil@ast.cam.ac.uk, E-mail: jen@mso.anu.edu.au, E-mail: yong@mso.anu.edu.au, E-mail: lmonaco@eso.org, E-mail: wyse@pha.jhu.edu, E-mail: dgeisler@astro-udec.cl [Departamento de Astronomia, Universidad de Concepcion (Chile)

    2013-01-20

    We present a double-blind analysis of high-dispersion spectra of seven red giant members of the Booetes I ultrafaint dwarf spheroidal galaxy, complemented with re-analysis of a similar spectrum of an eighth-member star. The stars cover [Fe/H] from -3.7 to -1.9 and include a CEMP-no star with [Fe/H] = -3.33. We conclude from our chemical abundance data that Booetes I has evolved as a self-enriching star-forming system, from essentially primordial initial abundances. This allows us uniquely to investigate the place of CEMP-no stars in a chemically evolving system, in addition to limiting the timescale of star formation. The elemental abundances are formally consistent with a halo-like distribution, with enhanced mean [{alpha}/Fe] and small scatter about the mean. This is in accord with the high-mass stellar initial mass function in this low-stellar-density, low-metallicity system being indistinguishable from the present-day solar neighborhood value. There is a non-significant hint of a decline in [{alpha}/Fe] with [Fe/H]; together with the low scatter, this requires low star formation rates, allowing time for supernova ejecta to be mixed over the large spatial scales of interest. One star has very high [Ti/Fe], but we do not confirm a previously published high value of [Mg/Fe] for another star. We discuss the existence of CEMP-no stars, and the absence of any stars with lower CEMP-no enhancements at higher [Fe/H], a situation that is consistent with knowledge of CEMP-no stars in the Galactic field. We show that this observation requires there be two enrichment paths at very low metallicities: CEMP-no and 'carbon-normal'.

  14. Improved Precision and Accuracy of Quantification of Rare Earth Element Abundances via Medium-Resolution LA-ICP-MS

    Science.gov (United States)

    Funderburg, Rebecca; Arevalo, Ricardo; Locmelis, Marek; Adachi, Tomoko

    2017-07-01

    Laser ablation ICP-MS enables streamlined, high-sensitivity measurements of rare earth element (REE) abundances in geological materials. However, many REE isotope mass stations are plagued by isobaric interferences, particularly from diatomic oxides and argides. In this study, we compare REE abundances quantitated from mass spectra collected with low-resolution (m/Δm = 300 at 5% peak height) and medium-resolution (m/Δm = 2500) mass discrimination. A wide array of geological samples was analyzed, including USGS and NIST glasses ranging from mafic to felsic in composition, with NIST 610 employed as the bracketing calibrating reference material. The medium-resolution REE analyses are shown to be significantly more accurate and precise (at the 95% confidence level) than low-resolution analyses, particularly in samples characterized by low (ICP-MS methods, particularly those relying on mass analyzers that do not offer tuneable mass-resolution and/or collision cell technologies that can reduce oxide and/or argide formation.

  15. Major, Trace, and Volatile (CO2, H2O, S, F, and Cl) Elements from 1000+ Hawaiian Olivine-hosted Melt Inclusions Reveal the Dynamics of Crustal Recycling

    Science.gov (United States)

    Marske, J. P.; Hauri, E. H.; Trusdell, F.; Garcia, M. O.; Pietruszka, A. J.

    2015-12-01

    Global cycling of volatile elements (H2O, CO2, F, S, Cl) via subduction to deep mantle followed by entrainment and melting within ascending mantle plumes is an enigmatic process that controls key aspects of hot spot volcanism (i.e. melting rate, magma supply, degassing, eruptive style). Variations in radiogenic isotope ratios (e.g.187Os/188Os) at hot spots such as Hawaii reveal magmatic processes within deep-seated mantle plumes (e.g. mantle heterogeneity, lithology, and melt transport). Shield-stage lavas from Hawaii likely originate from a mixed plume source containing peridotite and recycled oceanic crust (pyroxenite) based on variations of radiogenic isotopes. Hawaiian lavas display correlations among isotopes, major and trace elements [1] that might be expected to have an expression in the volatile elements. To investigate this link, we present Os isotopic ratios (n=51), and major, trace, and volatile elements from 1003 olivine-hosted melt inclusions (MI) and their host minerals from tephra from Koolau, Mauna Loa, Hualalai, Kilauea, and Loihi volcanoes. The data show a strong correlation between MI volatile contents and incompatible trace element ratios (La/Yb) with Os isotopes of the same host olivines and reveal large-scale volatile heterogeneity and zonation exists within the Hawaiian plume. 'Loa' chain lavas, which are thought to originate from greater proportions of recycled oceanic crust/pyroxenite, have MIs with lower H2O, S, F, and Cl contents compared to 'Kea' chain lavas that were derived from more peridotite-rich sources. The depletion of volatile elements in the 'Loa' volcano MIs can be explained if they tapped an ancient dehydrated oceanic crust component within the Hawaiian plume. Higher extents of melting beneath 'Loa' volcanoes can also explain these depletions. The presence of dehydrated recycled mafic material in the plume source suggests that subduction effectively devolatilizes part of the oceanic crust. These results are similar to the

  16. High resolution study of the abundance pattern of the heavy elements in very metal-poor field stars

    CERN Document Server

    Spite, Monique

    2013-01-01

    The abundances of heavy elements in EMP stars are not well explained by the simple view of an initial basic "rapid" process. In a careful and homogeneous analysis of the "First stars" sample (eighty per cent of the stars have a metallicity [Fe/H]=-3.1$\\pm$0.4), it has been shown that at this metallicity [Eu/Ba] is constant, and therefore the Eu-rich stars (generally called "r-rich") are also Ba-rich. The very large variation of [Ba/Fe] (existence of "r-poor" and "r-rich" stars) induces that the early matter was not perfectly mixed. On the other hand, the distribution of the values of [Sr/Ba] vs. [Ba/Fe] appears with well defined upper and lower envelopes. No star was found with [Sr/Ba]<-0.5 and the scatter of [Sr/Ba] increases regularly when [Ba/Fe] decreases. To explain this behavior, we suggest that an early "additional" process forming mainly first peak elements would affect the initial composition of the matter. For a same quantity of accreted matter, this additional Sr production would barely affect t...

  17. Olivine-Wadsleyite-Pyroxene Epitaxy: Element and Volatile Distributions at the 410km Discontinuity

    Science.gov (United States)

    Smyth, J. R.; Miyajima, N.; Huss, G. R.; Hellebrand, E.; Rubie, D. C.; Frost, D. J.

    2010-12-01

    We have synthesized hydrous peridotite-composition samples at 13GPa and 1400C with co-existing coarse grains (~100 micrometer) of olivine, wadsleyite, clinoenstatite, and melt in a multi-anvil press. The olivine grains contain fine-scale lamellae of wadsleyite and clinoenstatite that likely resulted from small temperature fluctuations during the four-hour experiment. Major-element compositions were determined by electron microprobe and H contents by secondary ion mass spectroscopy (SIMS). The olivine is about Fo93 in composition and contains about 650 ppm by weight H2O. The wadsleyite is about Fo87 in composition and contains about 1650 weight percent H2O. The clinoenstatite is about En96 in composition and about 440 ppm H2O. High resolution transmission electron microscopy of the lamellae and host show that the olivine and wadsleyite share their close-packed oxygen planes so that the wadsleyite lamellae are nearly planar and perpendicular to the [1 0 0] of olivine. The wadsleyite lamellae thus have their [1 0 1] and [1 0 -1] directions parallel to the [1 0 0] of olivine. Additionally, a second orientation relation with the [001] of olivine parallel to [100] of wadsleyite is also found as are incoherent blebs of wadsleyite in olivine. The coexisting melt phase quenched to a feathery mass of mostly wadsleyite crystals. Neither a quenched glass phase nor a nominally hydrous phase was observed. The lamellae indicate that the olivine-wadsleyite transformation can proceed effectively by coherent mechanisms that could potentially preserve lattice preferred orientation. The observed rapid coherent inversion from olivine to wadsleyite means that a metastable preservation of olivine below 410 km is unlikely under slightly hydrous conditions. The distribution of H among the nominally anhydrous phases implies that dehydration of peridotites by partial melting is inefficient so that complete dehydration of subducting slabs is unlikely. SEM-BSE image of wadsleyite (W) blebs and

  18. Historic activity of mt. Vesuvius: major elements and volatile constituents of primary melts

    Science.gov (United States)

    Cecchetti, A.; Marianelli, P.; Metrich, N.; Sbrana, A.

    2003-04-01

    Mt. Vesuvius experienced a three-century long period of semi-persistent activity, after the 1631 eruption and is presently in a phase of rest. During this period, several eruptions displayed composite style since they started with lava effusions and evolved towards explosive activity (lava fountains, phreatomagmatic explosions and occasionally steady columns). The tephrostratigraphic sequence of post-1631 activity is well reconstructed [1] on the basis of historical chronicles and field investigations, whereas information about the feeding system is still weak. We have selected samples related to energetic lava fountain activity that occurred during the 1794, 1822 and 1872 composite-style eruptions for investigating the deep feeding systems of Mt. Vesuvius, during the 1631--1944 period. We present data on melt inclusions and their host olivines. Major elements, S, Cl and F were obtained using the electron microprobe (SX50, Camparis), CO_2 and H_2O by Fourier Transform InfraRed spectroscopy. Carbon was also analysed by nuclear reaction 12C(d,p)13C. The magma batches emitted during the 1794, 1822 and 1872 eruptions brought to the surface primitive olivines (Fo90.4-88.5) containing spinel (Cr/(Cr+Al) = 0.77--0.75). Their inclusions attest of crystallization at high pressure from K-rich (HK) parental magmas with K_2O varying from 4.3 to 6.0, high K_2O/H_2O (up to 2.4), Cl/H_2O (up to 0.25), Cl/F (up to 3) ratios, and H_2O content systematically high and variable from 2.3 to 4.9 wt.%. The most primitive compositions are recorded in melt inclusions from the oldest samples (1794 and 1822 eruptions). We propose a rather rapid transfer of HK-melts carrying olivine crystals from depth. This process is only detectable by the means of melt inclusions in Fo-rich olivines phenocrysts occurring only in the deposits related to the most powerful episodes of lava fountains while the whole rocks are cumulative with respect to clinopyroxene (± leucite). These new data, in addition to

  19. First stars XVI. STIS/HST abundances of heavy-elements in the uranium-rich star CS 31082-001

    CERN Document Server

    Mello, C Siqueira; Barbuy, B; Spite, F; Caffau, E; Hill, V; Wanajo, S; Primas, F; Plez, B; Cayrel, R; Andersen, J; Nordström, B; Sneden, C; Beers, T C; Bonifacio, P; François, P; Molaro, P

    2012-01-01

    Detailed abundances of the elements produced by r-process nucleosynthesis in various circumstances are our best observational clues to their origin, since the site(s) of r-element production is(are) still not known with certainty. A small fraction of extremely metal-poor (EMP) stars exhibit excesses of heavy neutron-capture elements produced in the r-process, and CS 31082-001 is among the 4 well-known r-process-enhanced EMP stars. Observations with HST/STIS provide abundances for elements observable only from the UV region. Here we aim to supplement the optical data with abundances from near-UV spectroscopy of the first and second peak of the r-elements, which are crucial to giving insight into the nucleosynthesis of the elements beyond iron. The UVES spectrum provided additional measurements, thereby improving the previous results. The spectra were analyzed with the OSMARCS LTE model atmosphere and with a consistent approach based on the spectrum synthesis code Turbospectrum to derive abundances of heavy ele...

  20. Chlorine and fluorine partition coefficients and abundances in sub-arc mantle xenoliths (Kamchatka, Russia): Implications for melt generation and volatile recycling processes in subduction zones

    Science.gov (United States)

    Bénard, A.; Koga, K. T.; Shimizu, N.; Kendrick, M. A.; Ionov, D. A.; Nebel, O.; Arculus, R. J.

    2017-02-01

    We report chlorine (Cl) and fluorine (F) abundances in minerals, interstitial glasses, and melt inclusions in 12 andesite-hosted, spinel harzburgite xenoliths and crosscutting pyroxenite veins exhumed from the sub-arc lithospheric mantle beneath Avacha volcano in the Kamchatka Arc (NE Russia). The data are used to calculate equilibrium mineral-melt partition coefficients (D mineral / melt) for Cl and F relevant to subduction-zone processes and unravel the history of volatile depletion and enrichment mechanisms in an arc setting. Chlorine is ∼100 times more incompatible in pyroxenes (DClmineral/melt = 0.005-0.008 [±0.002-0.003]) than F (DFmineral/melt = 0.50-0.57 [±0.21-0.24]), which indicates that partial melting of mantle sources leads to strong depletions in Cl relative to F in the residues. The data set in this study suggests a strong control of melt composition on DCl,Fpyroxene/melt, in particular H2O contents and Al/(Al + Si), which is in line with recent experiments. Fluorine is compatible in Ca-amphibole in the 'wet' sub-arc mantle (DFamphibole/melt = 3.5-3.7 [±1.5]) but not Cl (DClamphibole/melt = 0.03-0.05 [±0.01-0.03]), indicating that amphibole may fractionate F from Cl in the mantle wedge. The inter-mineral partition coefficients for Cl and F in this study are consistent amongst different harzburgite samples, whether they contain glass or not. In particular, disseminated amphibole hosts much of the Cl and F bulk rock budgets of spinel harzburgites (DClamphibole/pyroxene up to 14 and DFamphibole/pyroxene up to 40). Chlorine and fluorine are variably enriched (up to 1500 ppm Cl and 750 ppm F) in the parental arc picrite and boninite melts of primitive pyroxenite veins (and related melt inclusions) crosscutting spinel harzburgites. Based on the data in this study, the main inferences on the behaviour of Cl and F during melting and metasomatic processes in the sub-arc mantle are as follow: (i) Melting models show that most depleted mantle protoliths

  1. Early Earth differentiation investigated through 142Nd, 182W, and highly siderophile element abundances in samples from Isua, Greenland

    Science.gov (United States)

    Rizo, H.; Walker, R. J.; Carlson, R. W.; Touboul, M.; Horan, M. F.; Puchtel, I. S.; Boyet, M.; Rosing, M. T.

    2016-02-01

    We report new data for W concentrations, stable W isotopic compositions, high-precision 182W/184W ratios, highly siderophile element (HSE) abundances and 187Re-187Os systematics in a suite of 3.8-3.3 Ga mafic and ultramafic rocks from the Isua supracrustal belt, and the Paleoarchean terrane in the northwestern part of the belt. These data are compared with published data for 146Sm-142Nd systematics in the same samples. The samples from the Isua supracrustal belt show well resolved excesses of 182W/184W of up to ∼21 ppm, consistent with previous W isotopic data reported by Willbold et al. (2011). While there is abundant evidence that W was mobilized in the crust accessed by the Isua supracrustal suite, the isotopic anomalies are interpreted to primarily reflect processes that affected the mantle precursors to these rocks. The origin of the 182W excesses in these rocks remains uncertain. The Isua mantle source could represent a portion of the post-core-formation mantle that was isolated from late accretionary additions (e.g., Willbold et al., 2011). However, the combined 182W, Re-Os isotopic systematics and HSE abundances estimated for the source of the Isua basalts are difficult to reconcile with this interpretation. The W isotope variations were more likely produced as a result of fractionation of the Hf/W ratio in the mantle during the lifetime of 182Hf, i.e., during the first 50 Ma of Solar System history. This could have occurred as a result of differentiation in an early magma ocean. The Isua suite examined is also characterized by variable 142Nd/144Nd, but the variations do not correlate with the variations in 182W/184W. Further, samples with ages between 3.8 and 3.3 Ga show gradual diminution of 142Nd anomalies until these are no longer resolved from the modern mantle isotopic composition. By contrast, there is no diminishment of 182W variability with time, suggesting different mechanisms of origin and retention of isotopic variations for these two extinct

  2. Formation of the Abundance Boundaries of the Heavier Neutron-capture Elements in Metal-poor Stars

    Science.gov (United States)

    Yang, Guochao; Li, Hongjie; Liu, Nian; Zhang, Lu; Cui, Wenyuan; Liang, Yanchun; Niu, Ping; Zhang, Bo

    2017-06-01

    The abundance scatter of heavier r-process elements (Z≥slant 56) relative to Fe ([r/Fe]) in metal-poor stars preserves excellent information of the star formation history and provides important insights into the various situations of the Galactic chemical enrichment. In this respect, the upper and lower boundaries of [r/Fe] could present useful clues for investigating the extreme situations of the star formation history and the early Galactic chemical evolution. In this paper, we investigate the formation of the upper and lower boundaries of [r/Fe] for the gas clouds. We find that, for a cloud from which metal-poor stars formed, the formation of the upper limits of [r/Fe] is mainly due to the pollution from a single main r-process event. For a cloud from which metal-poor stars formed, the formation of the lower limits of [r/Fe] is mainly due to the pollution from a single SN II event that ejects primary Fe.

  3. Magnetocaloric effect in AlFe2B2: toward magnetic refrigerants from earth-abundant elements.

    Science.gov (United States)

    Tan, Xiaoyan; Chai, Ping; Thompson, Corey M; Shatruk, Michael

    2013-06-26

    AlFe2B2 was prepared by two alternative synthetic routes, arc melting and synthesis from Ga flux. In the layered crystal structure, infinite chains of B atoms are connected by Fe atoms into two-dimensional [Fe2B2] slabs that alternate with layers of Al atoms. As expected from the theoretical analysis of electronic band structure, the compound exhibits itinerant ferromagnetism, with the ordering temperature of 307 K. The measurement of magnetocaloric effect (MCE) as a function of applied magnetic field reveals isothermal entropy changes of 4.1 J kg(-1) K(-1) at 2 T and 7.7 J kg(-1) K(-1) at 5 T. These are the largest values observed near room temperature for any metal boride and for any magnetic material of the vast 122 family of layered structures. Importantly, AlFe2B2 represents a rare case of a lightweight material prepared from earth-abundant, benign reactants which exhibits a substantial MCE while not containing any rare-earth elements.

  4. Radioactive Elements on Mercury's Surface from MESSENGER: Implications for the Planet's Formation and Evolution

    National Research Council Canada - National Science Library

    Patrick N. Peplowski; Larry G. Evans; Steven A. Hauck; Timothy J. McCoy; William V. Boynton; Jeffery J. Gillis-Davis; Denton S. Ebel; John O. Goldsten; David K. Hamara; David J. Lawrence; Ralph L. McNutt; Larry R. Nittler; Sean C. Solomon; Edgar A. Rhodes; Ann L. Sprague; Richard D. Starr; Karen R. Stockstill-Cahill

    2011-01-01

    ...) in Mercury's northern hemisphere. The abundance of the moderately volatile element K, relative to Th and U, is inconsistent with physical models for the formation of Mercury requiring extreme heating of the planet or its precursor...

  5. CHEMICAL ABUNDANCES OF THE MILKY WAY THICK DISK AND STELLAR HALO. II. SODIUM, IRON-PEAK, AND NEUTRON-CAPTURE ELEMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Ishigaki, M. N. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Aoki, W. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Chiba, M., E-mail: miho.ishigaki@ipmu.jp, E-mail: aoki.wako@nao.ac.jp, E-mail: chiba@astr.tohoku.ac.jp [Astronomical Institute, Tohoku University, Aoba-ku, Sendai 980-8578 (Japan)

    2013-07-01

    We present chemical abundance analyses of sodium, iron-peak, and neutron-capture elements for 97 kinematically selected thick disk, inner halo, and outer halo stars with metallicities -3.3 < [Fe/H] <-0.5. The main aim of this study is to examine chemical similarities and differences among metal-poor stars belonging to these old Galactic components as a clue to determine their early chemodynamical evolution. In our previous paper, we obtained abundances of {alpha} elements by performing a one-dimensional LTE abundance analysis based on the high-resolution (R {approx} 50, 000) spectra obtained with the Subaru/HDS. In this paper, a similar analysis is performed to determine abundances of an additional 17 elements. We show that, in metallicities below [Fe/H] {approx}-2, the abundance ratios of many elements in the thick disk, inner halo, and outer halo subsamples are largely similar. In contrast, in higher metallicities ([Fe/H] {approx}> -1.5), differences in some of the abundance ratios among the three subsamples are identified. Specifically, the [Na/Fe], [Ni/Fe], [Cu/Fe], and [Zn/Fe] ratios in the inner and outer halo subsamples are found to be lower than those in the thick disk subsample. A modest abundance difference between the two halo subsamples in this metallicity range is also seen for the [Na/Fe] and [Zn/Fe] ratios. In contrast to that observed for [Mg/Fe] in our previous paper, [Eu/Fe] ratios are more enhanced in the two halo subsamples rather than in the thick disk subsample. The observed distinct chemical abundances of some elements between the thick disk and inner/outer halo subsamples with [Fe/H] >-1.5 support the hypothesis that these components formed through different mechanisms. In particular, our results favor the scenario that the inner and outer halo components formed through an assembly of multiple progenitor systems that experienced various degrees of chemical enrichments, while the thick disk formed through rapid star formation with an

  6. Elemental Abundances and Ionization States within the Local Interstellar Cloud Derived from HST and FUSE Observations of the Capella Line of Sight

    CERN Document Server

    Wood, B E; Linsky, J L; Sahu, M S; Wood, Brian E.; Redfield, Seth; Linsky, Jeffrey L.

    2002-01-01

    We use ultraviolet spectra of Capella from the Hubble Space Telescope (HST) and Far Ultraviolet Spectroscopic Explorer (FUSE) satellites to study interstellar absorption lines from the Local Interstellar Cloud (LIC). Measurements of these lines are used to empirically determine the ionization states of carbon, nitrogen, and silicon in the LIC, for comparison with the predictions of theoretical photoionization models. We find that the observed ionization states are consistent with previously published photoionization predictions. Total abundances are determined for the elements mentioned above, and others, for comparison with solar abundances. Magnesium, aluminum, silicon, and iron are all depleted by at least a factor of 10 toward Capella. The abundances of carbon, nitrogen, and oxygen are essentially solar, although the error bars are large enough to also allow depletions of about a factor of 2 for these elements.

  7. Platinum-group element abundance and distribution in chromite deposits of the Acoje Block, Zambales Ophiolite Complex, Philippines

    Science.gov (United States)

    Bacuta, G.C.; Kay, R.W.; Gibbs, A.K.; Lipin, B.R.

    1990-01-01

    Platinum-group elements (PGE) occur in ore-grade concentration in some of the chromite deposits related to the ultramafic section of the Acoje Block of the Zambales Ophiolite Complex. The deposits are of three types: Type 1 - associated with cumulate peridotites at the base of the crust; Type 2 - in dunite pods from the top 1 km of mantle harzburgite; and Type 3 - like Type 2, but in deeper levels of the harzburgite. Most of the deposites have chromite compositions that are high in Cr with Cr/(Cr + Al) (expressed as chromium index, Cr#) > 0.6; high-Al (Cr# Pd, thought to be characteristic of PGE-barren deposits) and positive slope (Ir Platinum and Pd occur as alloy inclusions (and possibly as solid solution) in interstitial Ni-Cu sulfides and as tellurobismuthides in serpentine and altered sulfides. Variability of PGE distribution may be explained by alteration, crystal fractionation or partial melting processes. Alteration and metamorphism were ruled out, because PGE contents do not correlate with degree of serpentinization or the abundance and type (hydroxyl versus non-hydroxyl) of silicate inclusions in chromite. Preliminary Os isotopic data do not support crustal contamination as a source of the PGEs in the Acoje deposits. The anomalous PGE concentrations in Type 1 high-Cr chromite deposits are attributed to two stages of enrichment: an early enrichment of their mantle source from previous melting events and a later stage of sulfide segregation accompanying chromite crystallization. High-Al chromite deposits which crystallized from basalts derived from relatively low degrees of melting owe their low PGE content to partitioning of PGEs in sulfides and alloys that remain in the mantle. High-Cr deposits crystallized from melts that were previously enriched with PGEs during early melting events of their mantle source; Pt and Pd ore concentrations (ppm levels) are attained by segregation of magmatic sulfides. The Acoje deposits indicate that ophiolites are a

  8. p-capture reaction cycles in rotating massive stars and their impact on elemental abundances in globular cluster stars: A case study of O, Na and Al

    Science.gov (United States)

    Mahanta, Upakul; Goswami, Aruna; Duorah, Hiralal; Duorah, Kalpana

    2017-08-01

    Elemental abundance patterns of globular cluster stars can provide important clues for understanding cluster formation and early chemical evolution. The origin of the abundance patterns, however, still remains poorly understood. We have studied the impact of p-capture reaction cycles on the abundances of oxygen, sodium and aluminium considering nuclear reaction cycles of carbon-nitrogen-oxygen-fluorine, neon-sodium and magnesium-aluminium in massive stars in stellar conditions of temperature range 2×107 to 10×107 K and typical density of 102 gm cc-1. We have estimated abundances of oxygen, sodium and aluminium with respect to Fe, which are then assumed to be ejected from those stars because of rotation reaching a critical limit. These ejected abundances of elements are then compared with their counterparts that have been observed in some metal-poor evolved stars, mainly giants and red giants, of globular clusters M3, M4, M13 and NGC 6752. We observe an excellent agreement with [O/Fe] between the estimated and observed abundance values for globular clusters M3 and M4 with a correlation coefficient above 0.9 and a strong linear correlation for the remaining two clusters with a correlation coefficient above 0.7. The estimated [Na/Fe] is found to have a correlation coefficient above 0.7, thus implying a strong correlation for all four globular clusters. As far as [Al/Fe] is concerned, it also shows a strong correlation between the estimated abundance and the observed abundance for globular clusters M13 and NGC 6752, since here also the correlation coefficient is above 0.7 whereas for globular cluster M4 there is a moderate correlation found with a correlation coefficient above 0.6. Possible sources of these discrepancies are discussed.

  9. Estimation of the Primary Magma Compositions of an Igneous Rock Series Petrogenetically Associated with Fractional Crystallization with Special Reference to Element Abundance Relationships

    Institute of Scientific and Technical Information of China (English)

    汪云亮; 张万林; 等

    1994-01-01

    A primary magma not only represents the starting point of a fractional crystallization process, but also is the product of an equilibrium or fractional partial melting process in a mantle.Element abundance relationships in the primary magma obey both law of power function for fractional crystallization and the law of fractional linear function for equilibrium partial melting .Based on this double nature of the primary magma, the authors advanced a principle to restore the primary magma composition from that of an igneous rock series with petrogenesis of fractional crystallization and put forward an approach of estimating the element abundance of the primary magma, exempli-fied by the rar-earth elements in the Andes volcanic rock series.

  10. Evaluation of strontium isotope abundance ratios in combination with multi-elemental analysis as a possible tool to study the geographical origin of ciders

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Ruiz, Silvia [Department of Physical and Analytical Chemistry, University of Oviedo, Julian Claveria 8, 33006 Oviedo (Spain); Moldovan, Mariella [Department of Physical and Analytical Chemistry, University of Oviedo, Julian Claveria 8, 33006 Oviedo (Spain); Fortunato, Giuseppino [Swiss Federal Laboratories for Materials Testing and Research EMPA, 9014 St. Gallen (Switzerland); Wunderli, Samuel [Swiss Federal Laboratories for Materials Testing and Research EMPA, 9014 St. Gallen (Switzerland); Garcia Alonso, J. Ignacio [Department of Physical and Analytical Chemistry, University of Oviedo, Julian Claveria 8, 33006 Oviedo (Spain)]. E-mail: jiga@uniovi.es

    2007-05-02

    In order to evaluate alternative analytical methodologies to study the geographical origin of ciders, both multi-elemental analysis and Sr isotope abundance ratios in combination with multivariate statistical analysis were estimated in 67 samples from England, Switzerland, France and two Spanish regions (Asturias and the Basque Country). A methodology for the precise and accurate determination of the {sup 87}Sr/{sup 86}Sr isotope abundance ratio in ciders by multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) was developed. Major elements (Na, K, Ca and Mg) were measured by ICP-AES and minor and trace elements (Li, Be, B, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Y, Mo, Cd, Sn, Sb, Cs, Ba, La, Ce, W, Tl, Pb, Bi, Th and U) were measured by ICP-MS using a collision cell instrument operated in multitune mode. An analysis of variance (ANOVA test) indicated that group means for B, Cr, Fe, Ni, Cu, Se, Cd, Cs, Ce, W, Pb, Bi and U did not show any significant differences at the 95% confidence level, so these elements were rejected for further statistical analysis. Another group of elements (Li, Be, Sc, Co, Ga, Y, Sn, Sb, La, Tl, Th) was removed from the data set because concentrations were close to the limits of detection for many samples. Therefore, the remaining elements (Na, Mg, Al, K, Ca, Ti, V, Mn, Zn, As, Rb, Sr, Mo, Ba) together with {sup 87}Sr/{sup 86}Sr isotope abundance ratio were considered for principal component analysis (PCA) and linear discriminant analysis (LDA). Finally, LDA was able to classify correctly 100% of cider samples coming from different Spanish regions, France, England and Switzerland when considering Na, Mg, Al, K, Ca, Ti, V, Mn, Zn, As, Rb, Sr, Mo, Ba and {sup 87}Sr/{sup 86}Sr isotope abundance ratio as original variables.

  11. Neutron-capture element abundances in the planetary nebula NGC 5315 from deep optical and near-infrared spectrophotometry★†

    Science.gov (United States)

    Madonna, S.; García-Rojas, J.; Sterling, N. C.; Delgado-Inglada, G.; Mesa-Delgado, A.; Luridiana, V.; Roederer, I. U.; Mashburn, A. L.

    2017-10-01

    We analyse the chemical composition of the planetary nebula (PN) NGC 5315, through high-resolution (R ∼ 40000) optical spectroscopy with Ultraviolet-Visual Echelle Spectrograph at the Very Large Telescope, and medium-resolution (R ∼ 4800) near-infrared spectroscopy with Folded-port InfraRed Echellette at Magellan Baade Telescope, covering a wide spectral range from 0.31 to 2.50 μm. The main aim of this work is to investigate neutron (n)-capture element abundances to study the operation of the slow n-capture ('s-process') in the asymptotic giant branch (AGB) progenitor of NGC 5315. We detect more than 700 emission lines, including ions of the n-capture elements Se, Kr, Xe and possibly Br. We compute physical conditions from a large number of diagnostic line ratios, and derive ionic abundances for species with available atomic data. The total abundances are computed using recent ionization correction factors (ICFs) or by summing ionic abundances. Total abundances of common elements are in good agreement with previous work on this object. Based on our abundance analysis of NGC 5315, including the lack of s-process enrichment, we speculate that the most probable evolutionary scenario is that the progenitor star is in a binary system as hinted at by radial velocity studies, and interactions with its companion truncated the AGB before s-process enrichment could occur. However there are other two possible scenarios for its evolution, that cannot be ruled out: (i) the progenitor is a low-mass single star that did not undergo third dredge-up; (ii) the progenitor star of NGC 5315 had an initial mass of 3-5 M⊙, and any s-process enhancements were heavily diluted by the massive envelope during the AGB phase.

  12. Origins of volatile elements (H, C, N, noble gases) on Earth and Mars in light of recent results from the ROSETTA cometary mission

    Science.gov (United States)

    Marty, Bernard; Avice, Guillaume; Sano, Yuji; Altwegg, Kathrin; Balsiger, Hans; Hässig, Myrtha; Morbidelli, Alessandro; Mousis, Olivier; Rubin, Martin

    2016-05-01

    Recent measurements of the volatile composition of the coma of Comet 67P/Churyumov-Gerasimenko (hereafter 67P) allow constraints to be set on the origin of volatile elements (water, carbon, nitrogen, noble gases) in inner planets' atmospheres. Analyses by the ROSINA mass spectrometry system onboard the Rosetta spacecraft indicate that 67P ice has a D/H ratio three times that of the ocean value (Altwegg et al., 2015) and contains significant amounts of N2, CO, CO2, and importantly, argon (Balsiger et al., 2015). Here we establish a model of cometary composition based on literature data and the ROSINA measurements. From mass balance calculations, and provided that 67P is representative of the cometary ice reservoir, we conclude that the contribution of cometary volatiles to the Earth's inventory was minor for water (≤1%), carbon (≤1%), and nitrogen species (a few % at most). However, cometary contributions to the terrestrial atmosphere may have been significant for the noble gases. They could have taken place towards the end of the main building stages of the Earth, after the Moon-forming impact and during either a late veneer episode or, more probably, the Terrestrial Late Heavy Bombardment around 4.0-3.8 billion years (Ga) ago. Contributions from the outer solar system via cometary bodies could account for the dichotomy of the noble gas isotope compositions, in particular xenon, between the mantle and the atmosphere. A mass balance based on 36Ar and organics suggests that the amount of prebiotic material delivered by comets could have been quite considerable - equivalent to the present-day mass of the biosphere. On Mars, several of the isotopic signatures of surface volatiles (notably the high D/H ratios) are clearly indicative of atmospheric escape processes. Nevertheless, we suggest that cometary contributions after the major atmospheric escape events, e.g., during a Martian Late Heavy Bombardment towards the end of the Noachian era, could account for the

  13. Development of low-cost technology for the next generation of high efficiency solar cells composed of earth abundant elements

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Rakesh [Purdue Univ., West Lafayette, IN (United States)

    2014-09-28

    The development of renewable, affordable, and environmentally conscious means of generating energy on a global scale represents a grand challenge of our time. Due to the “permanence” of radiation from the sun, solar energy promises to remain a viable and sustainable power source far into the future. Established single-junction photovoltaic technologies achieve high power conversion efficiencies (pce) near 20% but require complicated manufacturing processes that prohibit the marriage of large-scale throughput (e.g. on the GW scale), profitability, and quality control. Our approach to this problem begins with the synthesis of nanocrystals of semiconductor materials comprising earth abundant elements and characterized by material and optoelectronic properties ideal for photovoltaic applications, namely Cu2ZnSn(S,Se)4 (CZTSSe). Once synthesized, such nanocrystals are formulated into an ink, coated onto substrates, and processed into completed solar cells in such a way that enables scale-up to high throughput, roll-to-roll manufacturing processes. This project aimed to address the major limitation to CZTSSe solar cell pce’s – the low open-circuit voltage (Voc) reported throughout literature for devices comprised of this material. Throughout the project significant advancements have been made in fundamental understanding of the CZTSSe material and device limitations associated with this material system. Additionally, notable improvements have been made to our nanocrystal based processing technique to alleviate performance limitations due to the identified device limitations. Notably, (1) significant improvements have been made in reducing intra- and inter-nanoparticle heterogeneity, (2) improvements in device performance have been realized with novel cation substitution in Ge-alloyed CZTGeSSe absorbers, (3) systematic analysis of absorber sintering has been conducted to optimize the selenization process for large grain CZTSSe absorbers, (4) novel electrical

  14. Isotopic and elemental abundances of copper and zinc in lunar samples, Zagami, Pele’s hairs, and a terrestrial basalt

    Science.gov (United States)

    Herzog, G. F.; Moynier, F.; Albarède, F.; Berezhnoy, A. A.

    2009-10-01

    We used ICP-MS to measure the elemental concentrations and isotopic abundances of Cu and Zn in: nine Ti-rich lunar basalts (10017, 10022, 10024, 10057, 70215, 71055, 74255, 75055, and 75075); size-separated samples prepared by sieving of pyroclastic black glass 74001, orange glass 74022, and the lunar soils 15021, 15231, 70181, and 79221; a basalt from the Piton des Neiges volcano, Reunion Island; two samples of Pele's hairs from the Nyiragongo volcano, Democratic Republic of Congo, and the martian meteorite Zagami. The isotopic fractionation of zinc in lunar basalts and Zagami is mass dependent relative to a terrestrial standard (JMC 400882B). These and published results imply that lunar, terrestrial, meteoritic, and perhaps martian zinc all come from one or more reservoirs linked by mass-dependent fractionation processes. Relative to terrestrial basalts, Ti-rich lunar basalts are enriched in the heavier isotopes of Cu and Zn: we find for Ti-rich lunar basalts the following ranges and averages ±1 - σ (‰): δ 65Cu/ 63Cu ≡ δ 65Cu, 0.1-1.4, 0.5 ± 0.1‰ ( N = 7); δ 66Zn/ 64Zn ≡ δ 66Zn = 0.2-1.9, 1.2 ± 0.2‰ ( N = 8; 10017 excluded). For two terrestrial samples, we find δ 66Zn ˜ +0.3‰ and δ 65Cu ˜ 0‰, which are consistent with published values. The differences between the lunar basalts and terrestrial basalts could reflect minor, planetary-scale vaporization or igneous processes on the Moon. Data for size separates of the pyroclastic glasses 74001 and 74220 confirm the well-known surface correlation of Cu and Zn, but modeling calculations reveal no sharp differences between either the elemental ratios or the isotopic composition of grain interiors and exteriors. The absence of such differences indicates that the isotopic compositions for bulk samples are dominated by a light-isotope-rich surface component. Data for size separates of lunar soils also confirm the surface correlation of Cu and Zn, but an enrichment of heavy rather than light

  15. Development of low-cost technology for the next generation of high efficiency solar cells composed of earth abundant elements

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Rakesh [Purdue Univ., West Lafayette, IN (United States)

    2014-09-28

    The development of renewable, affordable, and environmentally conscious means of generating energy on a global scale represents a grand challenge of our time. Due to the “permanence” of radiation from the sun, solar energy promises to remain a viable and sustainable power source far into the future. Established single-junction photovoltaic technologies achieve high power conversion efficiencies (pce) near 20% but require complicated manufacturing processes that prohibit the marriage of large-scale throughput (e.g. on the GW scale), profitability, and quality control. Our approach to this problem begins with the synthesis of nanocrystals of semiconductor materials comprising earth abundant elements and characterized by material and optoelectronic properties ideal for photovoltaic applications, namely Cu2ZnSn(S,Se)4 (CZTSSe). Once synthesized, such nanocrystals are formulated into an ink, coated onto substrates, and processed into completed solar cells in such a way that enables scale-up to high throughput, roll-to-roll manufacturing processes. This project aimed to address the major limitation to CZTSSe solar cell pce’s – the low open-circuit voltage (Voc) reported throughout literature for devices comprised of this material. Throughout the project significant advancements have been made in fundamental understanding of the CZTSSe material and device limitations associated with this material system. Additionally, notable improvements have been made to our nanocrystal based processing technique to alleviate performance limitations due to the identified device limitations. Notably, (1) significant improvements have been made in reducing intra- and inter-nanoparticle heterogeneity, (2) improvements in device performance have been realized with novel cation substitution in Ge-alloyed CZTGeSSe absorbers, (3) systematic analysis of absorber sintering has been conducted to optimize the selenization process for large grain CZTSSe absorbers, (4) novel electrical

  16. Investigation for the enrichment pattern of the element abundances in r+s star HE 0338-3945: a special r-II star?

    CERN Document Server

    Cui, Wenyuan; Zhu, Zizhong; Zhang, Bo; 10.1088/0004-637X/708/1/51

    2010-01-01

    The very metal-poor star HE 0338-3945 shows a double-enhanced pattern of the neutron-capture elements. The study to this sample could make people gain a better understanding of s- and r-process nucleosynthesis at low metallicity. Using a parametric model,we find that the abundance pattern of the neutron-capture elements could be best explained by a binary system formed in a molecular cloud, which had been polluted by r-process material. The observed abundance pattern of C and N can be explained by an AGB model(Karakas & Lattanzio 2007), . Combing with the parameters obtained from Cui & Zhang (2006), we suggest that the initial mass of the AGB companion is most likely to be about 2.5Msun, which excludes the possibility of forming a type-1.5 supernova. By comparing with the observational abundance pattern of CS 22892-052, we find that the dominating production of O should accompany with the production of the heavy r-process elements of r+s stars. Similar to r-II stars, the heavy r-process elements are n...

  17. Globular Cluster Abundances from High-Resolution, Integrated-Light Spectroscopy. IV. The Large Magellanic Cloud: $\\alpha$, Fe-peak, Light, and Heavy Elements

    CERN Document Server

    Colucci, J E; Cameron, S A; McWilliam, A

    2011-01-01

    We present detailed chemical abundances in 8 clusters in the Large Magellanic Cloud (LMC). We measure abundances of 22 elements for clusters spanning a range in age of 0.05 to 12 Gyr, providing a comprehensive picture of the chemical enrichment and star formation history of the LMC. The abundances were obtained from individual absorption lines using a new method for analysis of high resolution ($R\\sim$25,000) integrated light spectra of star clusters. This method was developed and presented in Papers I, II, and III of this series. In this paper, we develop an additional integrated light $\\chi^2$-minimization spectral synthesis technique to facilitate measurement of weak ($\\sim$15 m\\AA) spectral lines and abundances in low signal-to-noise ratio data (S/N$\\sim$30). Additionally, we supplement the integrated light abundance measurements with detailed abundances that we measure for individual stars in the youngest clusters (Age$+0.5$) and increases with decreasing age, indicating a strong contribution of low-meta...

  18. Detection of low Eu abundances in extremely metal-poor stars and the origin of r-process elements

    CERN Document Server

    Ishimaru, Y; Aoki, W; Ryan, S G; Aoki, Wako; Ishimaru, Yuhri; Ryan, Sean G.; Wanajo, Shinya

    2003-01-01

    We report detailed abundance analyses for three extremely metal-poor stars with [Fe/H] lesssim -3 in the Galactic halo, using the Subaru High Dispersion Spectrograph (HDS). All these stars are found to have sub-solar relative abundances of [Eu/Fe], and exhibit the lowest [Eu/H] values at their metallicities. Comparison of these low Eu abundances with our chemical evolution model of the Galactic halo implies the dominant source of Eu to be the low-mass end of the Type II supernova mass range. This suggests that collapsing O-Ne-Mg cores resulting from 8-10 Msun stars are the major r-process site.

  19. P2-type Na(x)[Fe(1/2)Mn(1/2)]O2 made from earth-abundant elements for rechargeable Na batteries.

    Science.gov (United States)

    Yabuuchi, Naoaki; Kajiyama, Masataka; Iwatate, Junichi; Nishikawa, Heisuke; Hitomi, Shuji; Okuyama, Ryoichi; Usui, Ryo; Yamada, Yasuhiro; Komaba, Shinichi

    2012-04-29

    Rechargeable lithium batteries have risen to prominence as key devices for green and sustainable energy development. Electric vehicles, which are not equipped with an internal combustion engine, have been launched in the market. Manganese- and iron-based positive-electrode materials, such as LiMn(2)O(4) and LiFePO(4), are used in large-scale batteries for electric vehicles. Manganese and iron are abundant elements in the Earth's crust, but lithium is not. In contrast to lithium, sodium is an attractive charge carrier on the basis of elemental abundance. Recently, some layered materials, where sodium can be electrochemically and reversibly extracted/inserted, have been reported. However, their reversible capacity is typically limited to 100 mAh g(-1). Herein, we report a new electrode material, P2-Na(2/3)[Fe(1/2)Mn(1/2)]O(2), that delivers 190 mAh g(-1) of reversible capacity in the sodium cells with the electrochemically active Fe(3+)/Fe(4+) redox. These results will contribute to the development of rechargeable batteries from the earth-abundant elements operable at room temperature.

  20. P2-type Nax[Fe1/2Mn1/2]O2 made from earth-abundant elements for rechargeable Na batteries

    Science.gov (United States)

    Yabuuchi, Naoaki; Kajiyama, Masataka; Iwatate, Junichi; Nishikawa, Heisuke; Hitomi, Shuji; Okuyama, Ryoichi; Usui, Ryo; Yamada, Yasuhiro; Komaba, Shinichi

    2012-06-01

    Rechargeable lithium batteries have risen to prominence as key devices for green and sustainable energy development. Electric vehicles, which are not equipped with an internal combustion engine, have been launched in the market. Manganese- and iron-based positive-electrode materials, such as LiMn2O4 and LiFePO4, are used in large-scale batteries for electric vehicles. Manganese and iron are abundant elements in the Earth’s crust, but lithium is not. In contrast to lithium, sodium is an attractive charge carrier on the basis of elemental abundance. Recently, some layered materials, where sodium can be electrochemically and reversibly extracted/inserted, have been reported. However, their reversible capacity is typically limited to 100 mAh g-1. Herein, we report a new electrode material, P2-Na2/3[Fe1/2Mn1/2]O2, that delivers 190 mAh g-1 of reversible capacity in the sodium cells with the electrochemically active Fe3+/Fe4+ redox. These results will contribute to the development of rechargeable batteries from the earth-abundant elements operable at room temperature.

  1. Volatile Concentrations and H-Isotope Composition of Unequilibrated Eucrites

    Science.gov (United States)

    Sarafian, Adam R.; Nielsen, Sune G.; Marschall, Horst R.; Gaetani, Glenn A.; Hauri, Erik H.; Righter, Kevin; Berger, Eve L.

    2017-01-01

    Eucrites are among the oldest and best studied asteroidal basalts (1). They represent magmatism that occurred on their parent asteroid, likely 4-Vesta, starting at 4563 Ma and continuing for approx. 30 Myr. Two hypotheses are debated for the genesis of eucrites, a magma ocean model (2), and a mantle partial melting model. In general, volatiles (H, C, F, Cl) have been ignored for eucrites and 4-Vesta, but solubility of wt% levels of H2O are possible at Vestan interior PT conditions. Targeted measurements on samples could aid our understanding considerably. Recent studies have found evidence of volatile elements in eucrites, but quantifying the abundance of volatiles remains problematic (6). Volatile elements have a disproportionately large effect on melt properties and phase stability, relative to their low abundance. The source of volatile elements can be elucidated by examining the hydrogen isotope ratio (D/H), as different H reservoirs have drastically different H isotope compositions. Recent studies of apatite in eucrites have shown that the D/H of 4-Vesta matches that of Earth and carbonaceous chondrites, however, the D/H of apatites may not represent the D/H of a primitive 4-Vesta melt due to the possibility of degassing prior to the crystallization of apatite. Therefore, the D/H of early crystallizing phases must be measured to determine if the D/H of 4-Vesta is equal to that of the Earth and carbonaceous chondrites.

  2. Investigation for the puzzling abundance pattern of the neutron-capture elements in the ultra metal-poor star: CS 30322-023

    CERN Document Server

    Cui, W Y; Ma, K; Zhang, L

    2007-01-01

    The s-enhanced and very metal-poor star CS 30322-023 shows a puzzling abundance pattern of the neutron-capture elements, i.e. several neutron-capture elements such as Ba, Pb etc. show enhancement, but other neutron-capture elements such as Sr, Eu etc. exhibit deficient with respect to iron. The study to this sample star could make people gain a better understanding of s- and r-process nucleosynthesis at low metallicity. Using a parametric model, we find that the abundance pattern of the neutron-capture elements could be best explained by a star that was polluted by an AGB star and the CS 30322-023 binary system formed in a molecular cloud which had never been polluted by r-process material. The lack of r-process material also indicates that the AGB companion cannot have undergone a type-1.5 supernova, and thus must have had an initial mass below 4.0M$_\\odot$, while the strong N overabundance and the absence of a strong C overabundance indicate that the companion's initial mass was larger than 2.0M$_\\odot$. Th...

  3. Comparison of element abundance between the exposed crust of the continent of China and the global averaged upper continental crust: Constraints on crustal evolution and some speculations

    Institute of Scientific and Technical Information of China (English)

    WANG Yang

    2007-01-01

    Based on the results of a study of regional element abundance in eastern China and the 1:200 000 geochemical surveys in northern Xinjiang, the element geochemical characteristics of the exposed crust in 23 tectonic units of the continent of China are summarized.Compared with the global average abundance of the upper continental crust, the exposed crust of the continent of China is compositionally more evolved than the upper crust of the island arc, but less evolved than the mature Precambrian Canadian shield. The exposed crust of the North China and Yangtze platforms has a lower SiO2 content, but markedly higher CaO and MgO contents due to the presence of widespread carbonate strata, which suggests that we should not neglect the contribution of carbonate rocks in the study of the exposed crust and the element abundance of the upper crust, in comparison with two recently published average compositional models of the global upper continental crust,the exposed crust of the continent of China is depleted in Au,Hg, Mo, Sn, and W, which suggests that their abundance in the present global models is overestimated. The exposed crust of the North China plat form and the Qinling-Dabieshan fold belt to its south has lower μ(238U/204pb) values(8), but other regions of the continent of China exhibit much higher μ values, which implies that the low μ feature of the North China platform and its adjacent regions does not have global significance. Considering the apparent lateral variation in composition of the exposed crust for the tectonic units of the continent of China, there is no adequate reason to take the average upper crust compositional model of the North China platform and its adjacent regions as a reliable composition representative for Chinese and global upper continental crust composition.

  4. Volatiles and refratories in solar analogs: no terrestial planet connection

    OpenAIRE

    Hernandez, J. I. Gonzalez; Israelian, G.; Santos,N.C.; Sousa, S.; Delgado-Mena, E.; Neves, V.; Udry, S.

    2010-01-01

    We have analysed very high-quality HARPS and UVES spectra of 95 solar analogs, 24 hosting planets and 71 without detected planets, to search for any possible signature of terrestial planets in the chemical abundances of volatile and refractory elements with respect to the solar abundances. We demonstrate that stars with and without planets in this sample show similar mean abundance ratios, in particular, a sub-sample of 14 planet-host and 14 "single" solar analogs in the metallicity range 0.14

  5. The significance of oxygen as oxides and hydroxides in controlling the abundance and residence times of elements in seawater

    Digital Repository Service at National Institute of Oceanography (India)

    DileepKumar, M.

    A model is presented which signifies the role of oxygen (as oxides and hydroxides) in controlling the composition of seawater. respective concentration and residence times for the unknown elements can be estimated. Geometric and statistical indices...

  6. Examining Moderate Volatile Loss through Lunar History

    Science.gov (United States)

    Saxena, Prabal; Killen, Rosemary M.; Airapetian, Vladimir; Petro, Noah; Mandell, Avi

    2017-06-01

    While the Moon and bulk silicate earth (BSE) share many compositional similarities, a notable difference is the apparent depletion of moderate volatiles in lunar samples. Depletion of elements such as sodium and potassium relative to BSE composition has been observed in Apollo samples. The source of these depletions is poorly understood but may be a result of preferential accretion of volatile-rich melt in the inner disk to the Earth during Moon formation.However, recent Kepler data has indicated that stellar analogues to our Sun experience enhanced flare activity early in their evolution. This implies that the Sun may have had a higher frequency and energy of flares and associated Coronal Mass Ejections (CME) in its distant past. We examine the potential impacts of this increased activity on lunar exosphere generation and specifically on potential loss of moderate volatiles including sodium and potassium.We use a surface bounded exosphere model that incorporates multiple processes including photon stimulated desorption, kinetic sputtering and impact vaporization in order to study potential moderate volatile loss under a variety of different conditions. This model is informed by appropriate solar wind and CME properties, which includes CMEs of different energies. We also incorporate regolith overturn to determine ranges of potential bulk depletion of moderate volatiles from the lunar regolith.Our work is aimed at determining the potential impact of solar activity on the depletion of moderate volatiles in the lunar regolith. Such a contribution is important to ascertain in order to isolate the depletion of volatiles due to disk processes and may thus help constrain details of the Moon's formation. Finally, we also examine the potential of lunar abundances of moderate volatiles as an observational tracer of past solar activity.

  7. APXS of First Rocks Encountered by Curiosity in Gale Crater: Geochemical Diversity and Volatile Element (K and ZN) Enrichment

    Science.gov (United States)

    Schmidt, M. E.; King, P. L.; Gellert, R.; Elliott, B.; Thompson, L.; Berger, J.; Bridges, J.; Campbell, J. L; Grotzinger, J.; Hurowitz, J.; Leshin, L.; Lewis, K. W.; McLennan, S. M.; Ming, D. W.; Perrett, G.; Pradler, I.; Stolper, E. M.; Squyres, S. W.; Greiman, A. H.

    2013-01-01

    The Alpha Particle X-ray spectrometer (APXS) on the Curiosity rover in Gale Crater [1] is the 4th such instrument to have landed on Mars [2]. Along the rover's traverse down-section toward Glenelg (through sol 102), the APXS has examined four rocks and one soil [3]. Gale rocks are geochemically diverse and expand the range of Martian rock compositions to include high volatile and alkali contents (up to 3.0 wt% K2O) with high Fe and Mn (up to 29.2% FeO*).

  8. Heavy elements in Galactic and Magellanic Cloud HII regions recombination-line versus forbidden-line abundances

    CERN Document Server

    Tsamis, Y G; Liu, X W; Danziger, I J; Storey, P J; Tsamis, Yiannis G.

    2003-01-01

    We have obtained deep optical, long-slit spectrophotometry of the Galactic HII regions M 17, NGC 3576 and of the Magellanic Cloud HII regions 30 Doradus, LMC N11B and SMC N66, recording the optical recombination lines (ORLs) of CII, NII and OII. Temperature-insensitive ORL C2+/O2+ and N2+/O2 ratios are obtained for all nebulae except SMC N66. The ORL C2+/O2+ ratios show remarkable agreement within each galactic system, while also being in agreement with the corresponding CEL ratios. For all five nebulae, the O2+/H+ abundance derived from multiple OII ORLs is found to be higher than the corresponding value derived from the strong [OIII] 4959, 5007A CELs, by factors of 1.8--2.7 for four of the nebulae. The LMC N11B nebula exhibits a more extreme discrepancy factor for the O2+ ion, ~5. Thus these HII regions exhibit ORL/CEL abundance discrepancy factors that are similar to those previously encountered amongst planetary nebulae. Our optical CEL O2+/H+ abundances agree to within 20-30 per cent with published O2+/H...

  9. The predominantly selfing plant Arabidopsis thaliana experienced a recent reduction in transposable element abundance compared to its outcrossing relative Arabidopsis lyrata

    Directory of Open Access Journals (Sweden)

    de la Chaux Nicole

    2012-02-01

    Full Text Available Abstract Background Transposable elements (TEs are major contributors to genome evolution. One factor that influences their evolutionary dynamics is whether their host reproduces through selfing or through outcrossing. According to the recombinational spreading hypothesis, for instance, TEs can spread more easily in outcrossing species through recombination, and should thus be less abundant in selfing species. We here studied the distribution and evolutionary dynamics of TE families in the predominantly selfing plant Arabidopsis thaliana and its close outcrossing relative Arabidopsis lyrata on a genome-wide scale. We characterized differences in TE abundance between them and asked which, if any, existing hypotheses about TE abundances may explain these differences. Results We identified 1,819 TE families representing all known classes of TEs in both species, and found three times more copies in the outcrossing A. lyrata than in the predominantly selfing A. thaliana, as well as ten times more TE families unique to A. lyrata. On average, elements in A. lyrata are younger than elements in A. thaliana. In particular, A. thaliana shows a marked decrease in element number that occurred during the most recent 10% of the time interval since A. thaliana split from A. lyrata. This most recent period in the evolution of A. thaliana started approximately 500,000 years ago, assuming a splitting time of 5 million years ago, and coincides with the time at which predominant selfing originated. Conclusions Our results indicate that the mating system may be important for determining TE copy number, and that selfing species are likely to have fewer TEs.

  10. Chemical abundances of the Milky Way thick disk and stellar halo II.: sodium, iron-peak and neutron-capture elements

    CERN Document Server

    Ishigaki, Miho N; Chiba, Masashi

    2013-01-01

    We present chemical abundance analyses of sodium, iron-peak and neutron-capture elements for 97 kinematically selected thick disk, inner halo and outer halo stars with metallicities -3.3-1.5), differences in some of the abundance ratios among the three subsamples are identified. Specifically, the [Na/Fe], [Ni/Fe], [Cu/Fe], and [Zn/Fe] ratios in the inner and outer halo subsamples are found to be lower than those in the thick disk subsample. In contrast to what was observed for [Mg/Fe] in our previous paper, [Eu/Fe] ratios are more enhanced in the two halo subsamples rather than in the thick disk subsample. The observed distinct chemical abundances of some elements between the thick disk and inner/outer halo subsamples with [Fe/H]>-1.5 support the hypothesis that these components formed through different mechanisms. In particular, our results favor the scenario that the inner and outer halo components formed through an assembly of multiple progenitor systems that experienced various degrees of chemical enrichm...

  11. The chemical composition of nearby young associations: s-process element abundances in AB Doradus, Carina-Near, and Ursa Major

    CERN Document Server

    D'Orazi, Valentina; Desidera, Silvano; Covino, Elvira; Andrievsky, Sergei M; Gratton, Raffaele G

    2012-01-01

    Recently, several studies have shown that young, open clusters are characterised by a considerable over-abundance in their barium content. In particular, D'Orazi et al. (2009) reported that in some younger clusters [Ba/Fe] can reach values as high as ~0.6 dex. The work also identified the presence of an anti-correlation between [Ba/Fe] and cluster age. For clusters in the age range ~4.5 Gyr-500 Myr, this is best explained by assuming a higher contribution from low-mass asymptotic giant branch stars to the Galactic chemical enrichment. The purpose of this work is to investigate the ubiquity of the barium over-abundance in young stellar clusters. We analysed high-resolution spectroscopic data, focusing on the s-process elemental abundance for three nearby young associations, i.e. AB Doradus, Carina-Near, and Ursa Major. The clusters have been chosen such that their age spread would complement the D'Orazi et al. (2009) study. We find that while the s-process elements Y, Zr, La, and Ce exhibit solar ratios in all...

  12. Neutron-capture element abundances in the planetary nebula NGC 5315 from deep high-resolution optical and near-IR spectrophotometry

    CERN Document Server

    Madonna, S; Sterling, N C; Luridiana, V

    2016-01-01

    We have done a spectroscopical analysis of the type I planetary nebula (PN) NGC 5315, through high-resolution (R$\\sim$40000) optical spectroscopy with UVES at the 8.2m Very Large Telescope, and medium-resolution (R$\\sim$4800) near-IR spectroscopy with FIRE at the 6.5m Magellan Baade telescope, covering a wide spectral range from 0.31 $\\mu$m to 2.50 $\\mu$m. The main aim of this work is to investigate the slow neutron(n)-capture process (the s-process) in the Asymptotic Giant Branch (AGB) star progenitor of a type I PNe. We detected and identified about 700 features, including lines from the n-capture elements Kr, Se, and possibly Br and Xe. We compute physical conditions using line ratios of common ions. Ionic abundances are computed for the species with available atomic data. We calculate total abundances using recent ionization correction factors (ICFs) or by summing ionic abundances. Our results for common elements are in good agreement with previous works on the same object. We do not find a substantial s-...

  13. Neutron-capture element abundances in the planetary nebula NGC 5315 from deep high-resolution optical and near-IR spectrophotometry

    Science.gov (United States)

    Madonna, S.; García-Rojas, J.; Sterling, N. C.; Luridiana, V.

    2017-03-01

    We have done a spectroscopical analysis of the type I planetary nebula (PN) NGC 5315, through high-resolution (R ˜ 40000) optical spectroscopy with UVES at the 8.2m Very Large Telescope, and medium-resolution (R ˜ 4800) near-IR spectroscopy with FIRE at the 6.5m Magellan Baade telescope, covering a wide spectral range from 0.31 μm to 2.50μm. The main aim of this work is to investigate the slow neutron(n)-capture process (the s-process) in the Asymptotic Giant Branch (AGB) star progenitor of a type I PNe. We detected and identified about 700 features, including lines from the n-capture elements Kr, Se, and possibly Br and Xe. We compute physical conditions using line ratios of common ions. Ionic abundances are computed for the species with available atomic data. We calculate total abundances using recent ionization correction factors (ICFs) or by summing ionic abundances. Our results for common elements are in good agreement with previous works on the same object. We do not find a substantial s-process enrichment in NGC 5315, which is typical for type I PNe.

  14. A deep survey of heavy element lines in planetary nebulae -- II. Recombination line abundances and evidence for ultra-cold plasma

    CERN Document Server

    Tsamis, Y G; Liu, X W; Storey, P J; Danziger, I J

    2004-01-01

    [Abridged] Deep optical observations of the spectra of 12 Galactic planetary nebulae (PNe) and 3 Magellanic Cloud PNe were presented in Paper I by Tsamis et al. (2003b), who carried out an abundance analysis using the collisionally excited forbidden lines. Here, the relative intensities of faint optical recombination lines (ORLs) from ions of carbon, nitrogen and oxygen are analysed in order to derive the abundances of these ions relative to hydrogen. We define an abundance discrepancy factor (ADF) as the ratio of the abundance derived for a heavy element ion from its recombination lines to that derived for the same ion from its ultraviolet, optical or infrared collisionally excited lines (CELs). All of the PNe in our sample are found to have ADF's that exceed unity. There is no dependence of the magnitude of the ADF upon the excitation energy of the UV, optical or IR CEL transition used, indicating that classical nebular temperature fluctuations--i.e. in a chemically homogeneous medium--are not the cause of ...

  15. Volatiles and refratories in solar analogs: no terrestial planet connection

    CERN Document Server

    Hernandez, J I Gonzalez; Santos, N C; Sousa, S; Delgado-Mena, E; Neves, V; Udry, S

    2010-01-01

    We have analysed very high-quality HARPS and UVES spectra of 95 solar analogs, 24 hosting planets and 71 without detected planets, to search for any possible signature of terrestial planets in the chemical abundances of volatile and refractory elements with respect to the solar abundances. We demonstrate that stars with and without planets in this sample show similar mean abundance ratios, in particular, a sub-sample of 14 planet-host and 14 "single" solar analogs in the metallicity range 0.14<[Fe/H]<0.36. In addition, two of the planetary systems in this sub-sample, containing each of them a super-Earth-like planet with masses in the range ~ 7-11 Earth masses, have different volatile-to-refratory abundance ratios to what would be expected from the presence of a terrestial planets. Finally, we check that after removing the Galactic chemical evolution effects any possible difference in mean abundances, with respect to solar values, of refratory and volatile elements practically dissappears.

  16. Modes of Occurrence and Abundance of Trace Elements in Pennsylvanian Coals from the Pingshuo Mine, Ningwu Coalfield, Shanxi Province, China

    Directory of Open Access Journals (Sweden)

    Ning Yang

    2016-04-01

    Full Text Available The Pingshuo Mine is an important coal mine of the Ningwu coalfield in northern Shanxi Province, China. To investigate the mineralogy and geochemistry of Pingshuo coals, core samples from the mineable No. 4 coals were collected. The minerals, major element oxides, and trace elements were analyzed by scanning electron microscopy (SEM, LTA-XRD in combination with Siroquant software, X-ray fluorescence (XRF, inductively coupled plasma mass spectrometry (ICP-MS and ICP-CCT-MS (As and Se. The minerals in the Pennsylvanian coals from the Pingshuo Mine dominantly consist of kaolinite and boehmite, with minor amounts of siderite, anatase, goyazite, calcite, apatite and florencite. Major-element oxides including SiO2 (9.54 wt %, Al2O3 (9.68 wt %, and TiO2 (0.63 wt %, as well as trace elements including Hg (449.63 ng/g, Zr (285.95 μg/g, Cu (36.72 μg/g, Ga (18.47 μg/g, Se (5.99 μg/g, Cd (0.43 μg/g, Hf (7.14 μg/g, and Pb (40.63 μg/g are enriched in the coal. Lithium and Hg present strong positive correlations with ash yield and SiO2, indicating an inorganic affinity. Elements Sr, Ba, Be, As and Ga have strong positive correlations with CaO and P2O5, indicating that most of these elements may be either associated with phosphates and carbonates or have an inorganic–organic affinity. Some of the Zr and Hf may occur in anatase due to their strong positive correlations with TiO2.

  17. A Negative Regulatory Element Controls mRNA Abundance of the Leishmania mexicana Paraflagellar Rod Gene PFR2†

    OpenAIRE

    2003-01-01

    The Leishmania mexicana PFR2 locus encodes a component of the paraflagellar rod (PFR), a flagellar structure found only in the insect stage of the life cycle. PFR2 mRNA levels are 10-fold lower in the mammalian stage than in the insect stage. Nuclear run-on experiments indicate that the change in PFR2 mRNA abundance is achieved posttranscriptionally. Deletion and block substitution analysis of the entire 1,400-nucleotide 3′ untranslated region (UTR) of PFR2C led to the identification of a reg...

  18. Determinations of rare earth element abundance and U-Pb age of zircons using multispot laser ablation-inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Yokoyama, Takaomi D; Suzuki, Toshihiro; Kon, Yoshiaki; Hirata, Takafumi

    2011-12-01

    We have developed a new calibration technique for multielement determination and U-Pb dating of zircon samples using laser ablation-inductively coupled plasma mass spectrometry (ICPMS) coupled with galvanometric optics. With the galvanometric optics, laser ablation of two or more sample materials could be achieved in very short time intervals (~10 ms). The resulting sample aerosols released from different ablation pits or different solid samples were mixed and homogenized within the sample cell and then transported into the ICP ion source. Multiple spot laser ablation enables spiking of analytes or internal standard elements directly into the solid samples, and therefore the standard addition calibration method can be applied for the determination of trace elements in solid samples. In this study, we have measured the rare earth element (REE) abundances of two zircon samples (Nancy 91500 and Prešovice) based on the standard addition technique, using a direct spiking of analytes through a multispot laser ablation of the glass standard material (NIST SRM612). The resulting REE abundance data show good agreement with previously reported values within analytical uncertainties achieved in this study (10% for most elements). Our experiments demonstrated that nonspectroscopic interferences on 14 REEs could be significantly reduced by the standard addition technique employed here. Another advantage of galvanometric devices is the accumulation of sample aerosol released from multiple spots. In this study we have measured the U-Pb age of a zircon sample (LMR) using an accumulation of sample aerosols released from 10 separate ablation pits of low diameters (~8 μm). The resulting (238)U-(206)Pb age data for the LMR zircons was 369 ± 64 Ma, which is in good agreement with previously reported age data (367.6 ± 1.5 Ma). (1) The data obtained here clearly demonstrate that the multiple spot laser ablation-ICPMS technique can become a powerful approach for elemental and isotopic

  19. Can we trust elemental abundances derived in late-type giants with the classical 1D stellar atmosphere models?

    CERN Document Server

    Kucinskas, A; Ivanauskas, A; Ludwig, H -G; Caffau, E; Blazevicius, K; Klevas, J; Prakapavicius, D

    2009-01-01

    We compare the abundances of various chemical species as derived with 3D hydrodynamical and classical 1D stellar atmosphere codes in a late-type giant characterized by T_eff=3640K, log g = 1.0, [M/H] = 0.0. For this particular set of atmospheric parameters the 3D-1D abundance differences are generally small for neutral atoms and molecules but they may reach up to 0.3-0.4 dex in case of ions. The 3D-1D differences generally become increasingly more negative at higher excitation potentials and are typically largest in the optical wavelength range. Their sign can be both positive and negative, and depends on the excitation potential and wavelength of a given spectral line. While our results obtained with this particular late-type giant model suggest that 1D stellar atmosphere models may be safe to use with neutral atoms and molecules, care should be taken if they are exploited with ions.

  20. Slab-derived halogens and noble gases illuminate closed system processes controlling volatile element transport into the mantle wedge

    Science.gov (United States)

    Kobayashi, Masahiro; Sumino, Hirochika; Nagao, Keisuke; Ishimaru, Satoko; Arai, Shoji; Yoshikawa, Masako; Kawamoto, Tatsuhiko; Kumagai, Yoshitaka; Kobayashi, Tetsuo; Burgess, Ray; Ballentine, Chris J.

    2017-01-01

    Halogen and noble gas systematics are powerful tracers of volatile recycling in subduction zones. We present halogen and noble gas compositions of mantle peridotites containing H2O-rich fluid inclusions collected at volcanic fronts from two contrasting subduction zones (the Avacha volcano of Kamchatka arc and the Pinatubo volcano of Luzon arcs) and orogenic peridotites from a peridotite massif (the Horoman massif, Hokkaido, Japan) which represents an exhumed portion of the mantle wedge. The aims are to determine how volatiles are carried into the mantle wedge and how the subducted fluids modify halogen and noble gas compositions in the mantle. The halogen and noble gas signatures in the H2O-rich fluids are similar to those of marine sedimentary pore fluids and forearc and seafloor serpentinites. This suggests that marine pore fluids in deep-sea sediments are carried by serpentine and supplied to the mantle wedge, preserving their original halogen and noble gas compositions. We suggest that the sedimentary pore fluid-derived water is incorporated into serpentine through hydration in a closed system along faults at the outer rise of the oceanic, preserving Cl/H2O and 36Ar/H2O values of sedimentary pore fluids. Dehydration-hydration process within the oceanic lithospheric mantle maintains the closed system until the final stage of serpentine dehydration. The sedimentary pore fluid-like halogen and noble gas signatures in fluids released at the final stage of serpentine dehydration are preserved due to highly channelized flow, whereas the original Cl/H2O and 36Ar/H2O ratios are fractionated by the higher incompatibility of halogens and noble gases in hydrous minerals.

  1. A window on the efficiency of the s-process in AGB stars: chemical abundances of n-capture elements in the planetary nebula NGC 3918

    CERN Document Server

    Madonna, S; Luridiana, V; Sterling, N C; Morisset, C

    2015-01-01

    The chemical content of the planetary nebula NGC 3918 is investigated through deep, high-resolution (R~40000) UVES at VLT spectrophotometric data. We identify and measure more than 750 emission lines, making ours one of the deepest spectra ever taken for a planetary nebula. Among these lines we detect very faint lines of several neutron-capture elements (Se, Kr, Rb, and Xe), which enable us to compute their chemical abundances with unprecedented accuracy, thus constraining the efficiency of the s-process and convective dredge-up in the progenitor star of NGC 3918.

  2. SNC meteorites and their implications for reservoirs of Martian volatiles

    Science.gov (United States)

    Jones, J. H.

    1993-01-01

    The SNC meteorites and the measurements of the Viking landers provide our only direct information about the abundance and isotopic composition of Martian volatiles. Indirect measurements include spectroscopic determinations of the D/H ratio of the Martian atmosphere. A personal view of volatile element reservoirs on Mars is presented, largely as inferred from the meteoritic evidence. This view is that the Martian mantle has had several opportunities for dehydration and is most likely dry, although not completely degassed. Consequently, the water contained in SNC meteorites was most likely incorporated during ascent through the crust. Thus, it is possible that water can be decoupled from other volatile/incompatible elements, making the SNC meteorites suspect as indicators of water inventories on Mars.

  3. Occurrence and abundance of a mariner-like element in freshwater and terrestrial planarians (Platyhelminthes, Tricladida from southern Brazil

    Directory of Open Access Journals (Sweden)

    Fernanda Sperb

    2009-01-01

    Full Text Available Transposable elements are DNA sequences present in all the large phylogenetic groups, both capable of changing position within the genome and constituting a significant part of eukaryotic genomes. The mariner family of transposons is one of the few which occurs in a wide variety of taxonomic groups, including freshwater planarians. Nevertheless, so far only five planarian species have been reported to carry mariner-like elements (MLEs, although several different species have been investigated. Regarding the number of copies of MLEs, Girardia tigrina is the only planarian species in which this has been evaluated, with an estimation of 8,000 copies of the element per haploid genome. Preliminary results obtained in our laboratory demonstrated that MLE is found in a large number of different species of planarians, including terrestrial. With this in mind, the aim was to evaluate the occurrence and estimate the number of MLE copies in different planarian species collected in south Brazil. Twenty-eight individuals from 15 planarian species were analyzed. By using PCR and the hybridization of nucleic acids, it was found that MLE was present in all the analyzed species, the number of copies being high, probably over 10³ per haploid genome.

  4. Volatilization mechanism of certain elements in a method of semiquantitative spectrographic analysis; Mecanismo de volatilizacion de ciertos elementos en un metodo de analisis espectrografico semicuantitativo

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Guerra, J. P.

    1972-07-01

    The efficiency of the compounds GeO{sub 2}, Li{sub 2}B{sub 4}O{sub 7}, Li{sub 2}CO{sub 3}, SiO{sub 2} and SrCO{sub 3} as spectrochemical buffers, in the development of a semiquantitative spectrographic method of analysis, that can be applied to the determination of 47 elements in different matrices, has been tested. It has been shown that trough the use of Li{sub 2}B{sub 4}O{sub 7} or Geo{sub 2} adequate accuracy is obtained, attaining with the latter the detection of much lower concentrations, specially for the elements Mo. Ti, V and W. In order to account for the different behaviour of these elements their volatilization mechanism has been studied. MoB{sub 2}, TiB{sub 2}, VB{sub 2}.{delta}WB and {epsilon}-WB were found, by x-ray diffraction analysis, to be reaction products in the case of mixtures with Li{sub 2}B{sub 4}O{sub 7}. (Author)

  5. Multi-Element Abundance Measurements from Medium-Resolution Spectra. III. Metallicity Distributions of Milky Way Dwarf Satellite Galaxies

    CERN Document Server

    Kirby, Evan N; Simon, Joshua D; Cohen, Judith G; Guhathakurta, Puragra

    2010-01-01

    We present metallicity distribution functions (MDFs) for the central regions of eight dwarf satellite galaxies of the Milky Way: Fornax, Leo I and II, Sculptor, Sextans, Draco, Canes Venatici I, and Ursa Minor. We use the published catalog of abundance measurements from the previous paper in this series. The measurements are based on spectral synthesis of iron absorption lines. For each MDF, we determine maximum likelihood fits for Leaky Box, Pre-Enriched, and Extra Gas (wherein the gas supply available for star formation increases before it decreases to zero) analytic models of chemical evolution. Although the models are too simplistic to describe any MDF in detail, a Leaky Box starting from zero metallicity gas fits none of the galaxies except Canes Venatici I well. The MDFs of some galaxies, particularly the more luminous ones, strongly prefer the Extra Gas Model to the other models. Only for Canes Venatici I does the Pre-Enriched Model fit significantly better than the Extra Gas Model. The best-fit effect...

  6. Bird Surveys at DARHT Before and During Operations: Comparison of Species Abundance and Composition and Trace Element Uptake

    Energy Technology Data Exchange (ETDEWEB)

    P. R. Fresquez, D. C. Keller, C. D. Hathcock

    2007-11-30

    The Dual-Axis Radiographic Hydrodynamic Test (DARHT) Facility Mitigation Action Plan specifies the comparison of baseline conditions in biotic and abiotic media with those collected after operations have started. Operations at DARHT at Los Alamos National Laboratory started in 2000. In this study, the abundance and composition of birds collected near the DARHT facility from 2003 through 2006 were determined and compared to a preoperational period (1999). In addition, the levels of radionuclides and other inorganic chemicals in birds were compared to regional statistical reference levels (RSRLs). The number and diversity of bird species generally increased over preoperational levels with the greatest number of birds (412) and species (46) occurring in 2005. The most common bird species collected regardless of time periods were the chipping sparrow (Spizella passerina), the Virginia's warbler (Vermivora virginiae), the western bluebird (Sialia mexicana), the broad-tailed hummingbird (Selasphorus platycercus), the sage sparrow (Amphispiza belli), and the western tanager (Piranga ludoviciana). Most radionuclides, with the exception of uranium-234 and uranium-238, in (whole body) birds collected after operations began were either not detected or below RSRLs. Uranium-234 and uranium-238 concentrations in a few samples were far below screening levels and do not pose a potential unacceptable dose to the birds. In contrast, many inorganic chemicals, particularly arsenic and silver, in birds collected before and after operations began were in higher concentrations than RSRLs. Because birds (skin plus feathers) collected in the years before operations began contained higher levels of arsenic and silver than RSRLs and because there was no evidence of these metals in soil and sediment directly around the DARHT facility, the elevated levels of these metals in birds during early operations are probably not related to DARHT operations. Arsenic and silver in birds, however

  7. The occurrence of hazardous volatile elements and nanoparticles in Bulgarian coal fly ashes and the effect on human health exposure

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Luis F.O., E-mail: lfsoliveira@univates.br [Centro Universitario Univates, Pro Reitoria de Pesquisa Estensao e Pos Graduacao, Programa de Pos Graduacao Ambiente e Desenvolvimento (Brazil); Environmental Science and Nanotechnology Department, Catarinense Institute of Environmental Research and Human Development - IPADHC, Capivari de Baixo, Santa Catarina (Brazil); DaBoit, Katia [Department of Environmental Medicine, Catarinense Institute of Environmental Research and Human Development - IPADHC, Capivari de Baixo, Santa Catarina (Brazil); Sampaio, Carlos H. [Universidade Federal do Rio Grande do Sul, Escola de Engenharia, Departamento de Metalurgia, Centro de Tecnologia, Av. Bento Goncalves, 9500, Bairro Agronomia, CEP: 91501-970, Porto Alegre - RS (Brazil); Jasper, Andre [Centro Universitario Univates, Pro Reitoria de Pesquisa Estensao e Pos Graduacao, Programa de Pos Graduacao Ambiente e Desenvolvimento (Brazil); Andrade, Maria L. [Department of Plant Biology and Soil Science, University of Vigo, 36310 Vigo (Spain); Kostova, Irena J. [Sofia University ' St. Kliment Ohridski' , Department of Geology, Paleontology and Fossil Fuels, 15, Tzar Osvoboditel Blvd., 1000 Sofia (Bulgaria); and others

    2012-02-01

    Low-rank, high-mineral matter Bulgarian coals were studied using a variety of chemical, optical, and electron beam methods. The larger fly ash carbon phases include charred carbons in contrast to coked carbons present in the fly ashes of bituminous-coal-derived fly ashes. Nanoscale carbons include multi-walled carbon nanotubes (MWCNTs) encapsulating Hg, Se, and As, among other elements. In addition to the glass which dominates the fly ash, relatively coarse 'rock fragments', consisting of an unmelted to partially melted core surrounded by a glassy rim, are present in the fly ash. Nano-scale minerals can contain hazardous elements and, along with metal-bearing multiwalled nanotubes, can be a path for the entry of hazardous particles into the lungs and other organs. Highlights: Black-Right-Pointing-Pointer We model Bulgarian power plants which have regulated minerals nanoparticles can contain hazardous elements. Black-Right-Pointing-Pointer We study changes in the level of information about nanominerals importance and the effect on human health exposure. Black-Right-Pointing-Pointer Increasing information will increase quality if power plants procedures are similar.

  8. Possible Sources of Polar Volatiles

    Science.gov (United States)

    Schultz, P. H.

    2011-12-01

    Extensive analyses of returned Apollo samples demonstrated that the Moon is extremely volatile poor. While this conclusion remains true, various measurements since the late 90's implicated the presence of water: e.g., enhanced reflection of circularly polarized radar signals and suppression of epithermal neutrons near the poles. More recently, traces of H2O have been discovered inside volcanic glass, along with more significant amounts residing in hydrous minerals (apatite) returned from both highland and mare landing sites. Three recent lunar missions (DIXI, M3, Cassini) identified hydrous phases on/near the lunar surface, whereas the LCROSS probe detected significant quantities of volatiles (OH, H2O and other volatiles) excavated by the Centaur impact. These new mission results and sample studies, however, now allow testing different hypotheses for the generation, trapping, and replenishment of these volatiles. Solar-proton implantation must contribute to the hydrous phases in the lunar regolith in order to account for the observed time-varying abundances and occurrence near the lunar equator. This also cannot be the entire story. The relatively low speed LCROSS-Centaur impact (2.5km/s) could not vaporize such hydrous minerals, yet emissions lines of OH (from the thermal disassociation of H2O), along with other compounds (CO2, NH2) were detected within the first second, before ejecta could reach sunlight. Telescopic observations by Potter and Morgan (1985) discovered a tenuous lunar atmosphere of Na, but the LCROSS UV/Vis spectrometer did not detect the Na-D line until after the ejecta reached sunlight (along with a line pair attributed to Ag). With time, other volatile species emerged (OH, CO). The LAMP instrument on the Lunar Reconnaissance Orbiter had a different viewpoint from the side (rather than from above) and detected many other atomic species release by the LCROSS-Centaur impact. Consequently, it appears that there is a stratigraphy for trapped species

  9. Rb, Sr and strontium isotopic composition, K/Ar age and large ion lithophile trace element abundances in rocks and glasses from the Wanapitei Lake impact structure

    Science.gov (United States)

    Winzer, S. R.; Lum, R. K. L.; Schuhmann, S.

    1976-01-01

    Shock metamorphosed rocks and shock-produced melt glasses from the Wanapitei Lake impact structure have been examined petrographically and by electron microprobe. Eleven clasts exhibiting varying degrees of shock metamorphism and eight impact-produced glasses have been analyzed for Rb, Sr and Sr isotopic composition. Five clasts and one glass have also been analyzed for large ion lithophile (LIL) trace element abundances including Li, Rb, Sr, and Ba and the REE's. The impact event forming the Wanapitei Lake structure occurred 37 m.y. ago based on K/Ar dating of glass and glassy whole-rock samples. Rb/Sr isotopic dating failed to provide a meaningful whole-rock or internal isochron. The isotopic composition of the glasses can be explained by impact-produced mixing and melting of metasediments.

  10. High-Resolution X-ray Spectroscopy of Hercules X-1 with the XMM-Newton RGS CNO Element Abundance Measurements and Density Diagnostics of a Photoionized Plasma

    CERN Document Server

    Jiménez-Garate, M A; Den Herder, J W A; Zane, S; Ramsay, G

    2002-01-01

    We analyze the high-resolution X-ray spectrum of Hercules X-1, an intermediate-mass X-ray binary, which was observed with the XMM-Newton Reflection Grating Spectrometer. We measure the elemental abundance ratios by use of spectral models, and we detect material processed through the CNO-cycle. The CNO abundances, and in particular the ratio N/O > 4.0 times solar, provide stringent constraints on the evolution of the binary system. The low and short-on flux states of Her X-1 exhibit narrow line emission from C VI, N VI, N VII, O VII, O VIII, Ne IX, and Ne X ions. The spectra show signatures of photoionization. We measure the electron temperature, quantify photoexcitation in the He alpha lines, and set limits on the location and density of the gas. The recombination lines may originate in the accretion disk atmosphere and corona, or on the X-ray illuminated face of the mass donor (HZ Her). The spectral variation over the course of the 35 d period provides additional evidence for the precession of the disk. Duri...

  11. The Old, Super-Metal-Rich Open Cluster, NGC 6791 - Elemental Abundances in Turn-off Stars from Keck/HIRES Spectra

    CERN Document Server

    Boesgaard, Ann Merchant; Deliyannis, Constantine P

    2014-01-01

    The study of star clusters has advanced our understanding of stellar evolution, Galactic chemical evolution and nucleosynthesis. Here we investigate the composition of turn-off stars in the intriguing open cluster, NGC 6791, which is old, but super-metal-rich with high-resolution (46,000) Keck/HIRES spectra. We find [Fe/H] = +0.30 +/-0.02 from measurements of some 40 unblended, unsaturated lines of both Fe I and Fe II in eight turn-off stars. Our O abundances come from the O I triplet near 7774 A and we do a differential analysis relative to the Sun from our Lunar spectrum also obtained with Keck/HIRES. The O results are corrected for small nLTE effects. We find consistent ratios of [O/Fe]n with a mean of $-$0.06 +/-0.02. This continues the trend of decreasing [O/Fe] with increasing [Fe/H] found in field stars that are also both old and metal-rich. The small range in our oxygen abundances is consistent with a single population of stars. Our results for the alpha elements [Mg/Fe], [Si/Fe], [Ca/Fe], and [Ti/Fe]...

  12. Splicing Regulatory Elements and mRNA-abundance of dlg1 and capt, Genetically Interacting with dFMRP in Drosophila Brain

    Directory of Open Access Journals (Sweden)

    Maria Petrova

    2014-09-01

    Full Text Available To further understand the molecular and cellular mechanisms underlying the disease, we used the Drososphila FraX model and investigated a not well studied role of Drosophila Fragile X Mental Retardation Protein (dFMRP in alternative splicing of neuronal mRNAs to which it binds via a G-quartet sequence. By means of qRT-PCR we established the relative abundance of some isoforms of the gene dlg1, resulting from alternative exon skipping nearby a G-quartet and an exonic ESE-sequence, both acting as exonic splicing enhancers. We also investigated the relative mRNA-abundance of all capt-isoforms and the pre-mRNAs of both genes. We proposed a possible involvement of dFMRP in alternative splicing of genes, interacting with dfmr1. In the absence of dFMRP in larval and pupal brains, we found a change in the mRNA-level of one of the studied isoforms of dlg1 and of its pre-mRNA.We also established previously reported splicing regulatory elements and predicted computationally novel hexamere sequences in the exonic/intronic ends of both genes with p upative regulatory roles in alternative splicing.

  13. Volatility Discovery

    DEFF Research Database (Denmark)

    Dias, Gustavo Fruet; Scherrer, Cristina; Papailias, Fotis

    The price discovery literature investigates how homogenous securities traded on different markets incorporate information into prices. We take this literature one step further and investigate how these markets contribute to stochastic volatility (volatility discovery). We formally show...... that the realized measures from homogenous securities share a fractional stochastic trend, which is a combination of the price and volatility discovery measures. Furthermore, we show that volatility discovery is associated with the way that market participants process information arrival (market sensitivity...

  14. Puzzling Origin of CEMP-r/s Stars: An Interpretation of Abundance and Enrichment of s- and r-Process Elements from Asymptotic Giant Branch Supernovae

    Indian Academy of Sciences (India)

    Jiang Zhang; Fang Zhao; Yanping Chen; Wenyuan Cui; Bo Zhang

    2013-12-01

    CEMP-r/s stars at low metallicity are known as double-enhanced stars that show enhancements of both r-process and s-process elements. The chemical abundances of these very metal-poor stars provide us a lot of information for putting new restraints on models of neutron-capture processes. In this article, we put forward an accreted scenario in which the double enrichment of r-process and s-process elements is caused by a former intermediate-mass Asymptotic Giant Branch (AGB) companion in a detached binary system. As the AGB superwind is only present at the ultimate phase of AGB stars, there is thus a lot of potential that the degenerate-core mass of an intermediate-mass AGB star reaches the Chandrasekhar limit before the AGB superwind. In these circumstances, both s-process elements produced in the AGB shell and r-process elements synthesized in the subsequent explosion would be sprayed contemporaneously and accreted by its companion. Despite similarity to physical conditions of a core-collapse supernova, a major focus in this scenario is the degenerate C–O core surrounded by an envelope of a former intermediate-mass AGB donor that may collapse and explode. Due to the existence of an outer envelope, r-process nucleosynthesis is expected to occur. Hypothesizing the material-rich europium (Eu) accreted by the secondary via the wind from the supernova to be in proportion to the geometric fraction of the companion with respect to the exploding donor star, we find that the estimated yield of Eu (as representative of r-process elements) per AGB supernova event is about 1 × 10-9⊙ ∼ 5 × 10-9⊙. Using the yields of Eu, the overabundance of r-process elements in CEMP-r/s stars can be accounted for. The calculated results show that the value of parameter , standing for efficiency of wind pollution from the AGB supernova, will reach about 104, which means that the enhanced factor is much larger than unity due to the impact of gravity of the donor and the result of the

  15. 中国南方地区水系沉积物中元素丰度%Abundance of elements in stream sediment in South China

    Institute of Scientific and Technical Information of China (English)

    程志中; 谢学锦; 潘含江; 杨榕; 商云涛

    2011-01-01

    从中国南方12个省自治区230万km2面积上所采集的水系沉积物中按每1∶5万图幅一个组合样的密度组合成5 244件组合样,采用以ICP-MS、ICP-AES和XRF为主的先进的分析测试方法和严格的质量控制方法,准确测试了其中的76种元素。统计计算了中国南方地区76种元素的平均值,给出了中国南方地区水系沉积物中76种元素的丰度值,与全国水系沉积物平均值(39种元素)、全国泛滥平原沉积物(54种元素)及全国土壤平均值进行对比。研究发现Hg、Cd高度富集,稀土元素及As、B、Co、Ni、Pb等24种元素在中国南方地区富集,Na2O、CaO、Ba、Sr等4种元素在中国南方的水系沉积物中亏损。%The stream sediment samples were collected from 12 provinces in South China covering 230 million km2.About 100 samples within each 1∶50000 map sheet were mixed to make up one composite sample.5244 composite samples were submitted for analysis.The 76 elements were analyzed including 39 elements originally analyzed in the RGNR Projects,and 37 new elements.The analytical scheme is based largely on ICP-MS,ICP-AES and XRF,supplemented with other techniques.The lowest levels of detection of all elements are less than their crustal abundances.The background values of 76 elements were calculated in Southern China and compared them with the average of national stream sediments,the flood plain sediments,and national sediments and soil.Hg,Cd are highly enriched,REE,As,B,Co,Ni,Pb and other 24 kinds of elements are enriched in Southern China,Na2O,CaO,Ba,and Sr in the sediments are depleted in Southern China.

  16. 浅议元素离子电位和丰度与巨型矿床的关系%Relationship Between Elemental Ionic Potential,Together with Elemental Abundance,and Giant Ore-Deposits

    Institute of Scientific and Technical Information of China (English)

    赵博; 王斌; 石成龙; 廖煜钟; 赵欣; 张涛; 张德会

    2015-01-01

    Both elemental quality and quantity as well as their way of permutation and combination are widely considered to be the “genes”of ore-deposits.Significantly,ionic potential and Clark value can represent the basic elemental geochemical attributes which can be divided into both of “quality”and“quantity”.Thus,we studied the relationship between such two indivisible geochemical properties of ore-elements and the tonnage accumulation index (TAI )of giant ore-deposits.There are three critical steps to achieve the formation of ore-deposits; and they are material source, transportation, and preservation. In terms of its control ability to elemental behaviors of transportation (and/or preservation?),an ionic potential must exerts a striking influence on its elemental ore-forming ability;so does the Clark value in terms of its control of material source and of some geochemical behaviors that are sensitive to elemental abundance and strongly affect the concentration in those rock-and ore-forming processes.The available and unique value of ionic potential of some individual elements was worked out;and the mathematic relationship between the numbers of TAI of global giant ore-deposits and elemental ionic potentials was subsequently depicted,which appears as an opening-up parabola.Whereas,there is a rather clear linear relationship between metal resource reserves stored in giant and supergiant ore deposits all over the world and the elemental Clark values.So,a larger value of metal abundance indicatel its regional superiority of resources.%元素的质和量及其排列组合方式被认为是矿床形成的“基因”。使用离子电位与克拉克值定量反映元素的质、量特征。成矿不外乎“源、运、储”三个环节,而离子电位通过控制金属“运”的行为影响其成矿能力,笔者给出了唯一的具有一定成因意义的元素离子电位,并发现离子电位与全球巨型矿床数目(n

  17. Galactic Cosmic Ray Origins and OB Associations: Evidence from SuperTIGER Observations of Elements $_{26}$Fe through $_{40}$Zr

    CERN Document Server

    Murphy, R P; Binns, W R; Brandt, T J; Hams, T; Israel, M H; Labrador, A W; Link, J T; Mewaldt, R A; Mitchell, J W; Rauch, B F; Sakai, K; Stone, E C; Waddington, C J; Walsh, N E; Ward, J E; Wiedenbeck, M E

    2016-01-01

    We report abundances of elements from $_{26}$Fe to $_{40}$Zr in the cosmic radiation measured by the SuperTIGER (Trans-Iron Galactic Element Recorder) instrument during 55 days of exposure on a long-duration balloon flight over Antarctica. These observations resolve elemental abundances in this charge range with single-element resolution and good statistics. These results support a model of cosmic-ray origin in which the source material consists of a mixture of 19$^{+11}_{-6}$\\% material from massive stars and $\\sim$81\\% normal interstellar medium (ISM) material with solar system abundances. The results also show a preferential acceleration of refractory elements (found in interstellar dust grains) by a factor of $\\sim$4 over volatile elements (found in interstellar gas) ordered by atomic mass (A). Both the refractory and volatile elements show a mass-dependent enhancement with similar slopes.

  18. Galactic Cosmic Ray Origins and OB Associations: Evidence from SuperTIGER Observations of Elements 26Fe through 40Zr

    Science.gov (United States)

    Murphy, R. P.; Sasaki, M.; Binns, W. R.; Brandt, T. J.; Hams, T.; Israel, M. H.; Labrador, A. W.; Link, J. T.; Mewaldt, R. A.; Mitchell, J. W.; Rauch, B. F.; Sakai, K.; Stone, E. C.; Waddington, C. J.; Walsh, N. E.; Ward, J. E.; Wiedenbeck, M. E.

    2016-11-01

    We report abundances of elements from 26Fe to 40Zr in the cosmic radiation measured by the SuperTIGER (Trans-Iron Galactic Element Recorder) instrument during 55 days of exposure on a long-duration balloon flight over Antarctica. These observations resolve elemental abundances in this charge range with single-element resolution and good statistics. These results support a model of cosmic ray origin in which the source material consists of a mixture of {19}-6+11% material from massive stars and ∼81% normal interstellar medium material with solar system abundances. The results also show a preferential acceleration of refractory elements (found in interstellar dust grains) by a factor of ∼4 over volatile elements (found in interstellar gas) ordered by atomic mass (A). Both the refractory and volatile elements show a mass-dependent enhancement with similar slopes.

  19. Volatile (Cl, F and S) and major element constraints on subduction-related mantle metasomatism along the alkaline basaltic backarc, Payenia, Argentina

    Science.gov (United States)

    Brandt, Frederik Ejvang; Holm, Paul Martin; Hansteen, Thor H.

    2017-07-01

    We present data on volatile (S, F and Cl) and major element contents in olivine-hosted melt inclusions (MIs) from alkaline basaltic tephras along the Quaternary Payenia backarc volcanic province ( 34°S-38°S) of the Andean Southern Volcanic Zone (SVZ). The composition of Cr-spinel inclusions and host olivines in Payenia are also included to constrain any variations in oxygen fugacity. The variation of potassium, fluorine and chlorine in MIs in Payenia can be modelled by partial melting (1-10%) of a variously metasomatised mantle. The high chlorine contents in MIs (up to 3200 ppm) from Northern Payenia require addition of subduction-related fluids to a mantle wedge, whereas volatile signatures in the southern Payenia are consistent with derivation from an enriched OIB source. Cl and Cl/K ratios define positive correlations with host olivine fosterite content (Fo80-90) that cannot be explained by olivine fractionation, degassing and/or degree of mantle melting. Neither can the correlation between SiO2 and TiO2 in the MIs and host olivine Fo-content be explained by magmatic differentiation processes. Instead these correlations essentially require a south to north mantle source transition from a low Mg# pyroxenite (from recycled eclogite) to a high Mg# fluid metasomatised peridotite. The Cl/K and S/K ratios in Payenia MIs extend from enriched OIB-like signatures (south) to Andean SVZ arc like signatures (north). We show that the northward increase in S, Cl and S/K is coupled to a northward increase in melt oxidation states and thus in Fe3+/Fetot ratios in the magmas. The increase in oxidation state also correlates with an increase of Mn/Fe (olivine) ratios. We calculate that 25% of the apparent north-south pyroxenite-peridotite source variation in Payenia (based on olivine Mn/Fe ratios) can be explained by the south to north variation in melt oxidation states.

  20. Origins of the thick disk of the Milky Way Galaxy as traced by the elemental abundances of metal-poor stars

    Science.gov (United States)

    Ruchti, Gregory Randal

    2010-12-01

    Understanding the formation and evolution of disks in galaxies in the early universe is very important for understanding the forms of galaxies today. Recent studies of the Milky Way Galaxy, an ideal galaxy for analyzing individual stars within its disk, indicate that the formation of the Galactic disk is very complex. Most of these studies, however, contain very few stars at low metallicities. Metal-poor stars are important, because they are potential survivors of the earliest star formation in the disk of the Milky Way Galaxy. I therefore measured elemental abundances of a statistically significant sample of metal-poor ([Fe/H] ≲ - 1.0) stars in the disk of the Galaxy, chosen from the RAVE survey in order to study the early formation history of the Galactic disk. I report on a sample of 214 red giant branch, 31 red clump/horizontal branch, and 74 dwarf/sub-giant metal-poor thick-disk candidate stars. I found that the [alpha/Fe] ratios are enhanced implying that enrichment proceeded by purely core-collapse supernovae. This requires that star formation in each star forming region had a short duration. The relative lack of scatter in the [alpha/Fe] ratios implies good mixing in the interstellar medium prior to star formation. In addition, the ratios resemble that of the halo, indicating that the halo and thick disk share a similar massive star initial mass function. I further looked for radial or vertical gradients in metallicity or alpha-enhancement for the metal-poor thick disk, never before done for such a sample. I found no radial gradient and a moderate vertical gradient in my derived iron abundance, and only minimal-amplitude gradients in [alpha/Fe]. In addition, I show that the distribution of orbital eccentricities for my metal-poor thick-disk stars requires that the thick disk was formed primarily in situ, with direct accretion being extremely minimal. I conclude that the alpha-enhancement of the metal-poor thick disk, and the lack of obvious radial or

  1. Virtual volatility

    Science.gov (United States)

    Silva, A. Christian; Prange, Richard E.

    2007-03-01

    We introduce the concept of virtual volatility. This simple but new measure shows how to quantify the uncertainty in the forecast of the drift component of a random walk. The virtual volatility also is a useful tool in understanding the stochastic process for a given portfolio. In particular, and as an example, we were able to identify mean reversion effect in our portfolio. Finally, we briefly discuss the potential practical effect of the virtual volatility on an investor asset allocation strategy.

  2. Virtual volatility

    OpenAIRE

    A. Christian Silva; Prange, Richard E.

    2006-01-01

    We introduce the concept of virtual volatility. This simple but new measure shows how to quantify the uncertainty in the forecast of the drift component of a random walk. The virtual volatility also is a useful tool in understanding the stochastic process for a given portfolio. In particular, and as an example, we were able to identify mean reversion effect in our portfolio. Finally, we briefly discuss the potential practical effect of the virtual volatility on an investor asset allocation st...

  3. Plant volatiles.

    Science.gov (United States)

    Baldwin, Ian T

    2010-05-11

    Plant volatiles are the metabolites that plants release into the air. The quantities released are not trivial. Almost one-fifth of the atmospheric CO2 fixed by land plants is released back into the air each day as volatiles. Plants are champion synthetic chemists; they take advantage of their anabolic prowess to produce volatiles, which they use to protect themselves against biotic and abiotic stresses and to provide information - and potentially disinformation - to mutualists and competitors alike. As transferors of information, volatiles have provided plants with solutions to the challenges associated with being rooted in the ground and immobile.

  4. Short interspersed nuclear elements (SINEs) are abundant in Solanaceae and have a family-specific impact on gene structure and genome organization.

    Science.gov (United States)

    Seibt, Kathrin M; Wenke, Torsten; Muders, Katja; Truberg, Bernd; Schmidt, Thomas

    2016-05-01

    Short interspersed nuclear elements (SINEs) are highly abundant non-autonomous retrotransposons that are widespread in plants. They are short in size, non-coding, show high sequence diversity, and are therefore mostly not or not correctly annotated in plant genome sequences. Hence, comparative studies on genomic SINE populations are rare. To explore the structural organization and impact of SINEs, we comparatively investigated the genome sequences of the Solanaceae species potato (Solanum tuberosum), tomato (Solanum lycopersicum), wild tomato (Solanum pennellii), and two pepper cultivars (Capsicum annuum). Based on 8.5 Gbp sequence data, we annotated 82 983 SINE copies belonging to 10 families and subfamilies on a base pair level. Solanaceae SINEs are dispersed over all chromosomes with enrichments in distal regions. Depending on the genome assemblies and gene predictions, 30% of all SINE copies are associated with genes, particularly frequent in introns and untranslated regions (UTRs). The close association with genes is family specific. More than 10% of all genes annotated in the Solanaceae species investigated contain at least one SINE insertion, and we found genes harbouring up to 16 SINE copies. We demonstrate the involvement of SINEs in gene and genome evolution including the donation of splice sites, start and stop codons and exons to genes, enlargement of introns and UTRs, generation of tandem-like duplications and transduction of adjacent sequence regions. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

  5. The Rise of the AGB in the Galactic Halo: Mg Isotopic Ratios and High Precision Elemental Abundances in M71 Giants

    CERN Document Server

    Melendez, Jorge

    2009-01-01

    High-resolution (R ~ 100 000), high signal-to-noise spectra of M71 giants have been obtained with HIRES at the KeckI Telescope in order to measure their Mg isotopic ratios, as well as elemental abundances of C, N, O, Na, Mg, Al, Si, Ca, Ti, Ni, Zr and La. We demonstrate that M71 has two populations, the first having weak CN, normal O, Na, Mg, and Al, and a low ratio of 26Mg/Mg (~4%) consistent with models of galactic chemical evolution with no contribution from AGB stars. The Galactic halo could have been formed from the dissolution of globular clusters prior to their intermediate mass stars reaching the AGB. The second population has enhanced Na and Al accompanied by lower O and by higher 26Mg/Mg (~8%), consistent with models which do incorporate ejecta from AGB stars via normal stellar winds. All the M71 giants have identical [Fe/H], [Si/Fe], [Ca/Fe], [Ti/Fe] and [Ni/Fe] to within sigma = 0.04 dex (10%). We therefore infer that the timescale for formation of the first generation of stars we see today in thi...

  6. Unstable volatility

    DEFF Research Database (Denmark)

    Casas, Isabel; Gijbels, Irène

    2012-01-01

    The objective of this paper is to introduce the break-preserving local linear (BPLL) estimator for the estimation of unstable volatility functions for independent and asymptotically independent processes. Breaks in the structure of the conditional mean and/or the volatility functions are common i...

  7. Unstable volatility

    DEFF Research Database (Denmark)

    Casas, Isabel; Gijbels, Irène

    2012-01-01

    The objective of this paper is to introduce the break-preserving local linear (BPLL) estimator for the estimation of unstable volatility functions for independent and asymptotically independent processes. Breaks in the structure of the conditional mean and/or the volatility functions are common i...

  8. A back-arc setting for mafic rocks of the Honeysuckle Beds, southeastern N.S.W.: the use of trace and rare earth element abundances determined by INAA

    Energy Technology Data Exchange (ETDEWEB)

    Dadd, K.A. [University of Technology, Sydney, NSW (Australia)

    1993-12-31

    Major, trace and rare earth elements abundance in mafic rocks of the Honeysuckle Beds was determined by x-ray fluorescence and neutron activation analysis . A comparison with typical mid-ocean ridge basalt compositions reveals an enrichment in light rare earths elements (Ba, Rb, and Th) and depletion in Nb, Ta and Ti, consistent with modifications of the source by subduction-related fluids. 9 refs., 6 figs.

  9. Measurements of gas and volatile element production rates from an irradiated molten lead and lead-bismuth spallation target with proton beams of 1 and 1.4 GeV; Mesures de taux de production d'elements gazeux et volatiles lors de reactions induites par des protons de 1 et 1,4 GeV sur des cibles epaisses de plomb et plomb-bismuth liquides

    Energy Technology Data Exchange (ETDEWEB)

    Tall, Y

    2008-03-15

    The integrated project EUROTRANS (European Research Programme for the Transmutation of High Level Nuclear Waste in an Accelerator Driven System) of the 6. EURATOM Framework Programme aims to demonstrate the transmutation of radioactive waste in ADS (Accelerator Driven Sub-critical system). It will carry out a first advanced design of an experimental facility to demonstrate the technical feasibility of transmutation, and will produce a conceptual design of an industrial facility dedicated to transmutation. An ADS consists of three fundamental elements: the accelerator of protons, the sub-critical core and the spallation target. SUBATECH (physique Sub-Atomique et des Technologies associees) laboratory is involved to the study of the chosen liquid lead-bismuth as a spallation ADS target. The irradiation of liquid lead-bismuth target with energetic proton beam generates in addition to neutrons, volatile and radioactive residues. In order to determine experimentally the production rates of gas and volatile elements following a spallation reaction in a lead-bismuth target, the experiment IS419 was performed at the ISOLDE facility at CERN (Centre Europeen de la Recherche Nucleaire). This experiment constitutes the frame of the thesis whose main objective is to assess and study the production and release rates of many gas and volatile element from the irradiated lead-bismuth target with an energetic proton beam. The obtained data are compared to Monte Carlo simulation code (MCNPX) results in order to test the intranuclear cascade model of Bertini and of Cugnon, and the evaporation options of Dresner and Schmidt. (author)

  10. First determination of s-process element abundances in pre-main sequence clusters. Y, Zr, La, and Ce in IC 2391, the Argus association, and IC 2602

    Science.gov (United States)

    D'Orazi, V.; De Silva, G. M.; Melo, C. F. H.

    2017-02-01

    Context. Several high-resolution spectroscopic studies have provided compelling observational evidence that open clusters display a decreasing trend of their barium abundances as a function of the cluster's age. Young clusters (ages ≲ 200 Myr) exhibit significant enhancement in the [Ba/Fe] ratios, at variance with solar-age clusters where the Ba content has been found to be [Ba/Fe] 0 dex. Different viable solutions have been suggested in the literature; nevertheless, a conclusive interpretation of such a peculiar trend has not been found. Interestingly, it is debated whether the other species produced with Ba via s-process reactions follow the same trend with age. Aims: Pre-main sequence clusters (≈10-50 Myr) show the most extreme behaviour in this respect: their [Ba/Fe] ratios can reach 0.65 dex, which is higher than the solar value by a factor of four. Crucially, there are no investigations of the other s-process species for these young stellar populations. In this paper we present the first determination of Y, Zr, La, and Ce in clusters IC 2391, IC 2602, and the Argus association. The main objective of our work is to ascertain whether these elements reveal the same enhancement as Ba. Methods: We have exploited high-resolution, high signal-to-noise spectra in order to derive abundances for Y, Zr, La, and Ce via spectral synthesis calculations. Our sample includes only stars with very similar atmospheric parameters so that internal errors due to star-to-star inhomogeneity are negligible. The chemical analysis was carried out in a strictly differential way, as done in all our previous investigations, to minimise the impact of systematic uncertainties. Results: Our results indicate that, at variance with Ba, all the other s-process species exhibit a solar scaled pattern; these clusters confirm a similar trend discovered in the slightly older local associations (e.g. AB Doradus, Carina-Near), where only Ba exhibit enhanced value with all other s-process species

  11. Precision Chemical Abundance Measurements

    DEFF Research Database (Denmark)

    Yong, David; Grundahl, Frank; Meléndez, Jorge;

    2012-01-01

    This talk covers preliminary work in which we apply a strictly differential line-by-line chemical abundance analysis to high quality UVES spectra of the globular cluster NGC 6752. We achieve extremely high precision in the measurement of relative abundance ratios. Our results indicate that the ob......This talk covers preliminary work in which we apply a strictly differential line-by-line chemical abundance analysis to high quality UVES spectra of the globular cluster NGC 6752. We achieve extremely high precision in the measurement of relative abundance ratios. Our results indicate...... that the observed abundance dispersion exceeds the measurement uncertainties and that many pairs of elements show significant correlations when plotting [X1/H] vs. [X2/H]. Our tentative conclusions are that either NGC 6752 is not chemically homogeneous at the ~=0.03 dex level or the abundance variations...

  12. Along-Strike Variations in the Timing of Melt Crystallization and Metamorphism Across Central and Eastern Bhutan: New Insights from LASS Monazite Geochronology and Trace-Element Abundances

    Science.gov (United States)

    Gordon, S. M.; Kauffman, R.; Gonzales-Clayton, B.; Kylander-Clark, A. R.; Agustsson, K. S.; Long, S. P.

    2014-12-01

    Continent-continent collisional systems represent the largest orogens on Earth and provide locations to study processes that drive the transition from contraction and crustal thickening to extension and collapse. The Greater Himalayan Zone (GHZ) exposed along strike of the Himalayan orogen contains exhumed mid-crustal metasedimentary rocks. To better understand the history of burial, crustal flow, and partial melting during the early stages of Himalayan tectonics in the Eocene to ~40 Myr into its orogenic evolution, monazite was analyzed from five migmatitic gneisses and five host gneisses exposed across two transects within central and eastern Bhutan. Monazite was analyzed in situ by the split-stream laser-ablation (LASS) ICPMS technique, which allows simultaneous collection of U-Th-Pb isotopes and trace-element abundances. The migmatites from the eastern Bhutan transect yield monazite dates that record melt crystallization as young as ca. 15-13 Ma. The host gneisses yield similar to younger (down to ca. 11 Ma) dates, documenting coeval to continued metamorphism of the GHZ. In comparison, melt crystallization in the central Bhutan rocks ended by ca. 18 Ma, and metamorphic monazite from a metapelite record metamorphism until ca. 14 Ma. In the migmatite and host-rock samples from both transects, the trace-element data show an inverse correlation between date and the HREE concentration. This trend likely documents the breakdown of garnet, which probably coincides with the first stages of GHZ exhumation. Thus, the LASS data showed that garnet breakdown and GHZ exhumation occurred from ca. 18 to 14 Ma in eastern Bhutan and ca. 20 to 17 Ma in central Bhutan. The new monazite data suggest different histories for the melt crystallization, metamorphism, and exhumation of the GHZ rocks between central and eastern Bhutan, even though the present day rocks from the two transects are only exposed ~60 km apart. Moreover, in comparison to other parts of the eastern Himalaya, the

  13. The mitochondrial genome of the gymnosperm Cycas taitungensis contains a novel family of short interspersed elements, Bpu sequences, and abundant RNA editing sites.

    Science.gov (United States)

    Chaw, Shu-Miaw; Shih, Arthur Chun-Chieh; Wang, Daryi; Wu, Yu-Wei; Liu, Shu-Mei; Chou, The-Yuan

    2008-03-01

    The mtDNA of Cycas taitungensis is a circular molecule of 414,903 bp, making it 2- to 6-fold larger than the known mtDNAs of charophytes and bryophytes, but similar to the average of 7 elucidated angiosperm mtDNAs. It is characterized by abundant RNA editing sites (1,084), more than twice the number found in the angiosperm mtDNAs. The A + T content of Cycas mtDNA is 53.1%, the lowest among known land plants. About 5% of the Cycas mtDNA is composed of a novel family of mobile elements, which we designated as "Bpu sequences." They share a consensus sequence of 36 bp with 2 terminal direct repeats (AAGG) and a recognition site for the Bpu 10I restriction endonuclease (CCTGAAGC). Comparison of the Cycas mtDNA with other plant mtDNAs revealed many new insights into the biology and evolution of land plant mtDNAs. For example, the noncoding sequences in mtDNAs have drastically expanded as land plants have evolved, with abrupt increases appearing in the bryophytes, and then in the seed plants. As a result, the genomic organizations of seed plant mtDNAs are much less compact than in other plants. Also, the Cycas mtDNA appears to have been exempted from the frequent gene loss observed in angiosperm mtDNAs. Similar to the angiosperms, the 3 Cycas genes nad1, nad2, and nad5 are disrupted by 5 group II intron squences, which have brought the genes into trans-splicing arrangements. The evolutionary origin and invasion/duplication mechanism of the Bpu sequences in Cycas mtDNA are hypothesized and discussed.

  14. The apogee red-clump catalog: Precise distances, velocities, and high-resolution elemental abundances over a large area of the Milky Way's disk

    Energy Technology Data Exchange (ETDEWEB)

    Bovy, Jo [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States); Nidever, David L. [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Rix, Hans-Walter [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Girardi, Léo; Rodrigues, Thaíse S. [Osservatorio Astronomico di Padova-INAF, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy); Zasowski, Gail [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Chojnowski, S. Drew; Majewski, Steven R. [Department of Astronomy, University of Virginia, Charlottesville, VA, 22904 (United States); Holtzman, Jon; Hayden, Michael R. [New Mexico State University, Las Cruces, NM 88003 (United States); Epstein, Courtney; Johnson, Jennifer A.; Pinsonneault, Marc H.; Andrews, Brett [Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States); Frinchaboy, Peter M. [Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX 76129 (United States); Stello, Dennis [Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006 (Australia); Allende Prieto, Carlos [Instituto de Astrofísica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain); Basu, Sarbani [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Beers, Timothy C. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Bizyaev, Dmitry, E-mail: bovy@ias.edu [Apache Point Observatory and New Mexico State University, P.O. Box 59, Sunspot, NM, 88349-0059 (United States); and others

    2014-08-01

    The Sloan Digital Sky Survey III's Apache Point Observatory Galactic Evolution Experiment (APOGEE) is a high-resolution near-infrared spectroscopic survey covering all of the major components of the Galaxy, including the dust-obscured regions of the inner Milky Way disk and bulge. Here we present a sample of 10,341 likely red-clump stars (RC) from the first two years of APOGEE operations, selected based on their position in color-metallicity-surface-gravity-effective-temperature space using a new method calibrated using stellar evolution models and high-quality asteroseismology data. The narrowness of the RC locus in color-metallicity-luminosity space allows us to assign distances to the stars with an accuracy of 5%-10%. The sample extends to typical distances of about 3 kpc from the Sun, with some stars out to 8 kpc, and spans a volume of approximately 100 kpc{sup 3} over 5 kpc ≲ R ≲ 14 kpc, |Z| ≲ 2 kpc, and –15° ≲ Galactocentric azimuth ≲ 30°. The APOGEE red-clump (APOGEE-RC) catalog contains photometry from the Two Micron All Sky Survey, reddening estimates, distances, line-of-sight velocities, stellar parameters and elemental abundances determined from the high-resolution APOGEE spectra, and matches to major proper motion catalogs. We determine the survey selection function for this data set and discuss how the RC selection samples the underlying stellar populations. We use this sample to limit any azimuthal variations in the median metallicity within the ≈45° azimuthal region covered by the current sample to be ≤0.02 dex, which is more than an order of magnitude smaller than the radial metallicity gradient. This result constrains coherent non-axisymmetric flows within a few kiloparsecs from the Sun.

  15. Gaseous abundances in M82

    CERN Document Server

    Ranalli, P; Origlia, L; Maiolino, R; Makishima, K; Ranalli, Piero; Comastri, Andrea; Origlia, Livia; Maiolino, Roberto; Makishima, Kazuo

    2005-01-01

    We present the preliminary analysis of a deep (100ks) XMM-Newton observation of M82. The spatial distribution of the abundances of chemical elements (Fe, O, Ne, Mg, Si, S) is investigated through narrow-band imaging analisys and spatially-resolved spectroscopy. We find that the abundances of alpha-elements follow a bipolar distribution, these elements being more abundant in the gaseous outflow than in the galaxy centre. This behaviour is found to be more marked for lighter elements (O, Ne) than for heavier elements.

  16. Investigating Planetary Volatile Accretion Mechanisms Using the Halogens

    Science.gov (United States)

    Ballentine, C. J.; Clay, P. L.; Burgess, R.; Busemann, H.; Ruzié, L.; Joachim, B.; Day, J. M.

    2014-12-01

    Depletion of the volatile elements in the Earth relative to the CI chondrites is roughly correlated with volatility, or decreasing condensation temperature. For the heavy halogen group elements (Cl, Br and I), volatility alone does not account for their apparent depletion, which early data has suggested is far greater than predicted [1-2]. Such depletion has been used to argue for the preferential loss of halogens by, amongst other processes, impact-driven erosive loss from Earth's surface [2]. Little consensus exists as to why the halogens should exhibit such preferential behavior during accretionary processes. Early efforts to constrain halogen abundance and understand their behavior in both Earth and planetary materials [3-6] have been hampered by their typically low abundance (ppb level) in most geologic materials. We present the results of halogen analysis of 23 chondrite samples, selected to represent diverse groups and petrologic type. Halogen abundances were measured by neutron irradiation noble gas mass spectrometry (NI-NGMS). Significant concentration heterogeneity is observed within some samples. However, a single Br/Cl and I/Cl ratio of 1.9 ± 0.2 (x 10-3) and 335 ± 10 (x 10-6) can be defined for carbonaceous chondrites with a good correlation between Br and Cl (R2 = 0.97) and between I and Cl (R2 = 0.84). Ratios of I/Cl overlap with terrestrial estimates of Bulk Silicate Earth and Mid Ocean Ridge Basalts. Similarly, good correlations are derived for enstatite (E) chondrites and a sulfide- and halogen- rich subset of E-chondrites. Chlorine abundances of CI (Orgueil) in this study are lower by factor of ~ 3 than the value of ~ 700 ppm Cl (compilation in [1]). Our results are similar to early discarded low values for Ivuna and Orgueil from [5,6] and agree more closely with values for CM chondrites. Halogens may not be as depleted in Earth as previously suggested, or a high degree of heterogeneity in the abundance of these volatile elements in

  17. Melt- versus fluid-induced metasomatism in spinel to garnet wedge peridotites (Ulten Zone, Eastern Italian Alps): clues from trace element and Li abundances

    Science.gov (United States)

    Scambelluri, M.; Hermann, J.; Morten, L.; Rampone, E.

    2006-04-01

    anomalies in Cs, Ba, Pb and U and moderate enrichment in Li, indicating addition of a crustal component to the mantle rocks. Amphibole hosts most of these trace elements. Clinopyroxene displays high LILE/HFSE (Pb N /Nb N =300-600), low Ce/Pb (1.4-2.7 in garnet-facies clinopyroxene compared with 2.6-24.5 in the spinel-facies one) and variable LILE and LREE enrichments. The coupled increase of modal amphibole, Sr and Pb, together with positive Pb-Sr and Pb-U correlations, further indicate that incompatible element influx in these samples was fluid-mediated. In the garnet-facies samples, amphibole and, interestingly, olivine have similarly high Li concentrations as clinopyroxene, leading to cpx/amph D Li=0.7 and cpx/ol D Li=0.7-0.8, the latter being up to ten times lower than in the spinel-facies rocks. Due to its high modal abundance, olivine is the main host of Li in the garnet-amphibole peridotites. The observed metasomatic features provide evidence for the infiltration of an aqueous fluid in the mantle wedge above a subducting slab. This fluid most likely derived from subducted crustal rocks that underwent partial melting. Successive retrograde re-equilibration during exhumation of the garnet peridotite is accompanied by garnet and clinopyroxene breakdown and amphibole formation. This process produced minor changes, such as an increase of HREE and Li in amphibole, and an increase of Li in olivine. The general trace element signature remains essentially unchanged during retrogression and further hydration, indicating that fluids with a similar composition to the one present at the garnet-amphibole peridotite formation, were responsible for increased amphibole formation. The combined evidence from the metamorphic and metasomatic evolution indicates that the peridotites experienced first corner flow in a mantle wedge, followed by subduction and finally entrapment and exhumation within a crustal slab. During their entire history the Ulten peridotites were percolated first by

  18. Chasing volatility

    DEFF Research Database (Denmark)

    Caporin, Massimiliano; Rossi, Eduardo; Santucci de Magistris, Paolo

    The realized volatility of financial returns is characterized by persistence and occurrence of unpreditable large increments. To capture those features, we introduce the Multiplicative Error Model with jumps (MEM-J). When a jump component is included in the multiplicative specification, the condi...... models, the introduction of the jump component provides a sensible improvement in the fit, as well as for in-sample and out-of-sample volatility tail forecasts....

  19. Volatility Risk

    OpenAIRE

    Zhiguang Wang

    2009-01-01

    Classical capital asset pricing theory tells us that riskaverse investors would require higher returns to compensate for higher risk on an investment. One type of risk is price (return) risk, which reflects uncertainty in the price level and is measured by the volatility (standard deviation) of asset returns. Volatility itself is also known to be random and hence is perceived as another type of risk. Investors can bear price risk in exchange for a higher return. But are investors willing to p...

  20. Volatility and mobility of some trace elements in coal from Shizuishan Power Plant%石嘴山电厂煤中微量元素的迁移释放行为

    Institute of Scientific and Technical Information of China (English)

    宋党育; 麻银娟; 秦勇; 王文峰; 郑楚光

    2011-01-01

    应用电感耦合等离子体质谱(ICP-MS)和原子荧光光谱(AFS)对中国西北部石嘴山电厂的原煤、底灰和飞灰中Hg、As、Se、Pb、Cr、Cd、Mo、Ni、Co、U和Th 11种微量元素的含量进行了测定.根据底灰和飞灰的产率,结合微量元素在底灰和飞灰中的含量计算了电厂燃煤过程中微量元素的挥发性.结果表明,Hg、Cd、Se、As四种元素在燃煤过程的挥发率均在50%以上,最高可达70%.通过对底灰和飞灰在酸性介质下的柱淋滤实验研究了底灰和飞灰中微量元素在60h内的迁移释放行为.Mn、Ni、Co、As四种元素的最大淋出率均超过2.0%,最高接近10.0%,并且还未达到淋滤平衡.根据微量元素的挥发和淋滤释放特性建立了电厂煤中有害微量元素在燃烧和淋滤过程中的释放分配模型.结果显示,燃煤过程中的挥发是微量元素释放的主要形式,部分元素的淋滤释放也可对周围水环境造成污染.%The volatility and mobility of eleven trace elements (Hg, As, Se, Ph, Cr, Cd, Mo, Ni, Co, U and Th) in coal from Shizuishan Power Plant were investigated.Column leaching tests on bottom ash and fly ash by sulfuric acid for 60 h were conducted.The contents of trace elements in input coal, bottom ash, fly ash and leaching solutions were determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic fluorescence spectroscopy (AFS).The volatility of trace elements during coal combustion was calculated based on the trace elements concentration in coal, ash and the ash yield of the raw coal.The results demonstrate that over 50% of As, Pb, and Hg volatilize to the atmosphere, leaching test results indicate that the maximum leaching proportion of As, Cd, Ni, and Mo is 1.8% ~ 6.2%.Based on the volatility and leaching characteristics, the volatilization and migration model of trace elements in the process of combustion and leaching was established.The results show that volatility of trace

  1. Elemental abundance analyses with DAO spectrograms: XXX. The middle B through early A stars ξ2 Ceti (B9 III), 21 Aquilae (B8 II-III), ι Aquilae (B5 III), and ι Delphini (A2V)

    Science.gov (United States)

    Adelman, S. J.; Westbrook, P. C.; Gulliver, A. F.

    2010-04-01

    This series of high quality elemental abundance analyses of mostly main-sequence band normal and peculiar B, A, and F stars defines their properties and provides data for the comparison with the analyses of somewhat similar stars and with theoretical predictions. Most use high dispersion and high S/N (≥ 200) spectrograms obtained with CCD detectors at the long camera of the Coudé spectrograph of the 1.22-m Dominion Astrophysical Observatory telescope. Here we reanalyze 21 Aql with better quality spectra and increase the number of stars consistently analyzed in the spectral range B5 to A2 by analyzing three new stars for this series. In the early A stars the normal and non-mCP stars have abundances with overlapping ranges. But more stars are needed especially in the B5 to B9 range. ξ2 Cet on average has a solar composition with a few abundances outside the solar range while both 21 Aql and ι Aql have abundances marginally less than solar. The abundances of ι Del are greater than solar with a few elements such as Ca being less than solar. It is an Am star. Table 3 is only available in electronic form at the CDS via http://cdsarc.u-strasbg.fr/ftp/cats/J/other/AN/331/378

  2. 186Os-187Os and highly siderophile element abundance systematics of the mantle revealed by abyssal peridotites and Os-rich alloys

    Science.gov (United States)

    Day, James M. D.; Walker, Richard J.; Warren, Jessica M.

    2017-03-01

    Abyssal peridotites are oceanic mantle fragments that were recently processed through ridges and represent residues of both modern and ancient melting. To constrain the nature and timing of melt depletion processes, and the composition of the mantle, we report high-precision Os isotope data for abyssal peridotites from three ocean basins, as well as for Os-rich alloys, primarily from Mesozoic ophiolites. These data are complemented by whole-rock highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, Re), trace- and major-element abundances for the abyssal peridotites, which are from the Southwest Indian (SWIR), Central Indian (CIR), Mid-Atlantic (MAR) and Gakkel Ridges. The results reveal a limited role for melt refertilization or secondary alteration processes in modifying abyssal peridotite HSE compositions. The abyssal peridotites examined have experienced variable melt depletion (2% to >16%), which occurred >0.5 Ga ago for some samples. Abyssal peridotites typically exhibit low Pd/Ir and, combined with high-degrees of estimated total melt extraction, imply that they were relatively refractory residues prior to incorporation into their present ridge setting. Recent partial melting processes and mid-ocean ridge basalt (MORB) generation therefore played a limited role in the chemical evolution of their precursor mantle domains. The results confirm that many abyssal peridotites are not simple residues of recent MORB source melting, having a more complex and long-lived depletion history. Peridotites from the Gakkel Ridge, SWIR, CIR and MAR indicate that the depleted MORB mantle has 186Os/188Os of 0.1198356 ± 21 (2SD). The Phanerozoic Os-rich alloys yield an average 186Os/188Os within uncertainty of abyssal peridotites (0.1198361 ± 20). Melt depletion trends defined between Os isotopes and melt extraction indices (e.g., Al2O3) allow an estimate of the primitive mantle (PM) composition, using only abyssal peridotites. This yields 187Os/188Os (0.1292 ± 25), and 186Os

  3. Sulfur and zinc abundances of red giant stars

    CERN Document Server

    Takeda, Yoichi; Harakawa, Hiroki; Sato, Bun'ei

    2016-01-01

    Sulfur and zinc are chemically volatile elements, which play significant roles as depletion-free tracers in studying galactic chemical evolution. However, regarding red giants having evolved off the main sequence, reliable abundance determinations of S and Zn seem to be difficult despite that a few studies have been reported so far. Given this situation, we tried to establish the abundances of these elements for an extensive sample of 239 field GK giants (-0.8 < [Fe/H] < +0.2), by applying the spectrum-fitting technique to S I 8694-5, S I 6757, and Zn I 6362 lines and by taking into account the non-LTE effect. Besides, similar abundance analysis was done for 160 FGK dwarfs to be used for comparison. The non-LTE corrections for the S and Zn abundances derived from these lines turned out < 0.1(-0.2) dex for most cases and not very significant. It revealed that the S I 6757 feature is more reliable as an abundance indicator than S I 8694-5 for the case of red giants, because the latter suffers blending ...

  4. First stars VI - Abundances of C, N, O, Li, and mixing in extremely metal-poor giants. Galactic evolution of the light elements

    CERN Document Server

    Spite, M; Plez, B; Hill, V; Spite, F; Depagne, E; François, P; Bonifacio, P; Barbuy, B; Beers, T; Andersen, J; Molaro, P; Nordström, B; Primas, F

    2004-01-01

    We have investigated the poorly-understood origin of nitrogen in the early Galaxy by determining N abundances in 35 extremely metal-poor halo giants (22 stars have [Fe/H]<-3.0) using the C and O abundances determined in Paper V. Because any dredge-up of CNO processed material to the surface may complicate the interpretation of CNO abundances in giants, we have also measured the surface abundance of lithium. Our sample shows a clear dichotomy between two groups of stars. The first group shows evidence of C to N conversion through CN cycling and strong Li dilution, a signature of mixing. The second group shows no evidence for C to N conversion, and Li is only moderately diluted, and we conclude that their C and N abundances are very close to those of the gas from which they formed in the early Galaxy. These "unmixed" stars reflect the abundances in the early Galaxy: the [C/Fe] ratio is constant (about +0.2 dex) and the [C/Mg] ratio is close to solar at low metallicity, favouring a high C production by massiv...

  5. The Chemical Abundances of Stars in the Halo (CASH) Project. III. A New Classification Scheme for Carbon-Enhanced Metal-poor Stars with S-process Element Enhancement

    CERN Document Server

    Hollek, Julie K; Placco, Vinicius M; Karakas, Amanda I; Shetrone, Matthew; Sneden, Christopher; Christlieb, Norbert

    2015-01-01

    We present a detailed abundance analysis of 23 elements for a newly discovered carbon-enhanced metal-poor (CEMP) star, HE 0414-0343, from the Chemical Abundances of Stars in the Halo (CASH) Project. Its spectroscopic stellar parameters are Teff = 4863 K, log g = 1.25, vmic = 2.20 km/s, and [Fe/H] = -2.24. Radial velocity measurements covering seven years indicate HE 0414-0343 to be a binary. HE 0414-0343 has [C/Fe] = 1.44 and is strongly enhanced in neutron-capture elements but its abundances cannot be reproduced by a solar-type s-process pattern alone. Traditionally, it could be classified as "CEMP-r/s" star. Based on abundance comparisons with AGB star nucleosynthesis models, we suggest a new physically-motivated origin and classification scheme for CEMP-s stars and the still poorly-understood CEMP-r/s. The new scheme describes a continuous transition between these two so-far distinctly treated subgroups: CEMP-sA, CEMP-sB, and CEMP-sC. Possible causes for a continuous transition include the number of therma...

  6. Abundances of the elements in sharp-lined early-type stars from IUE high-dispersion spectrograms; 2, the nitrogen deficiency in mercury- manganese stars

    CERN Document Server

    Roby, S W; Adelman, S J

    1999-01-01

    For pt.I see ibid., vol.419, no.1, p.276-85 (1993). The authors determine nitrogen abundances from co-added IUE high-dispersion SWP spectrograms of four HgMn stars and five normal or superficially normal main-sequence B and A stars. They find N deficiencies in the HgMn stars greater than previously reported (depletion factors of 135-400 relative to the Sun). N abundance discrepancies from UV and IR studies of normal stars are discussed in light of possible non-LTE effects. Their data set for their sample of HgMn stars (observed with a consistent strategy to maximize the benefits of co-additions) is an improvement over the single or few images previously used to derive N abundances for most of these stars. (37 refs).

  7. Volatile behavior and trace metal transport in the magmatic-geothermal system at Pūtauaki (Mt. Edgecumbe), New Zealand

    Science.gov (United States)

    Norling, B.; Rowe, M. C.; Chambefort, I.; Tepley, F. J.; Morrow, S.

    2016-05-01

    The present-day hydrothermal system beneath the Kawerau Geothermal Field, in the Taupo Volcanic Zone, New Zealand, is likely heated from the Pūtauaki (Mt. Edgecumbe) magma system. The aim of this work, as an analog for present day processes, is to identify whether or not earlier erupted Pūtauaki magmas show evidence for volatile exsolution. This may have led to the transfer of volatile components from the magmatic to hydrothermal systems. To accomplish this, minerals and melt inclusions from volcanic products were analyzed for abundances of volatile and ore-forming elements (S, Cl, Li, Cu, Sn, Mo, W, Sb, As, and Tl). The variations in abundance of these elements were used to assess magma evolution and volatile exsolution or fluxing in the magma system. Melt inclusions suggest the evolution of Pūtauaki andesite-dacite magmas is predominantly driven by crystallization processes resulting in rhyodacite-rhyolite glass compositions (although textural and geochemical evidence still indicate a role for magma mixing). Measured mineral-melt partition coefficients for trace metals of interest indicates that, with the exception of Tl in biotite, analyzed metals are all incompatible in Pūtauaki crystallization products. Excluding Li and Cu, other volatile and ore metals recorded in melt inclusions behave incompatibly, with concentrations increasing during evolution from rhyodacitic to rhyolitic melt compositions. Li and Cu appear to have increased mobility likely resulting from diffusive exchange post-crystallization, and may be related to late volatile fluxing. Although S and Cl concentrations decrease with melt evolution, no mineralogical evidence exists to indicate the exsolution and mobility of ore-forming metals from the magma at the time of crystallization. This observation cannot rule out the potential for post-crystallization volatile exsolution and ore-forming metal mobilization, which may only be recorded as diffusive re-equilibration of more rapidly diffusing

  8. The HgMn Binary Star Phi Herculis: Detection and Properties of the Secondary and Revision of the Elemental Abundances of the Primary

    CERN Document Server

    Zavala, R T; Hummel, C A; Gulliver, A F; Caliskan, H; Armstrong, J T; Hutter, D J; Johnston, K J; Pauls, T A

    2006-01-01

    Observations of the Mercury-Manganese star Phi Herculis with the Navy Prototype Optical Interferometer (NPOI) conclusively reveal the previously unseen companion in this single-lined binary system. The NPOI data were used to predict a spectral type of A8V for the secondary star Phi Her B. This prediction was subsequently confirmed by spectroscopic observations obtained at the Dominion Astrophysical Observatory. Phi Her B is rotating at 50 +/-3 km/sec, in contrast to the 8 km/sec lines of Phi Her A. Recognizing the lines from the secondary permits one to separate them from those of the primary. The abundance analysis of Phi Her A shows an abundance pattern similar to those of other HgMn stars with Al being very underabundant and Sc, Cr, Mn, Zn, Ga, Sr, Y, Zr, Ba, Ce, and Hg being very overabundant.

  9. Volatile accretion history of the Earth.

    Science.gov (United States)

    Wood, B J; Halliday, A N; Rehkämper, M

    2010-10-28

    It has long been thought that the Earth had a protracted and complex history of volatile accretion and loss. Albarède paints a different picture, proposing that the Earth first formed as a dry planet which, like the Moon, was devoid of volatile constituents. He suggests that the Earth's complement of volatile elements was only established later, by the addition of a small veneer of volatile-rich material at ∼100 Myr (here and elsewhere, ages are relative to the origin of the Solar System). Here we argue that the Earth's mass balance of moderately volatile elements is inconsistent with Albarède's hypothesis but is well explained by the standard model of accretion from partially volatile-depleted material, accompanied by core formation.

  10. Sulfur and zinc abundances of red giant stars†

    Science.gov (United States)

    Takeda, Yoichi; Omiya, Masashi; Harakawa, Hiroki; Sato, Bun'ei

    2016-10-01

    Sulfur and zinc are chemically volatile elements, which play significant roles as depletion-free tracers in studying galactic chemical evolution. However, regarding red giants having evolved off the main sequence, reliable abundance determinations of S and Zn seem to be difficult, despite the several studies that have been reported so far. Given this situation, we tried to establish the abundances of these elements for an extensive sample of 239 field GK giants ( - 0.8 ≲ [Fe/H] ≲ +0.2), by applying the spectrum-fitting technique to S I 8694-5, S I 6757, and Zn I 6362 lines and by taking into account the non-LTE effect. Besides, similar abundance analysis was done for 160 FGK dwarfs to be used for comparison. The non-LTE corrections for the S and Zn abundances derived from these lines turned out to be ≲ 0.1(-0.2) dex for most cases and not very significant. It revealed that the S I 6757 feature is more reliable as an abundance indicator than S I 8694-5 for the case of red giants, because the latter suffers blending of unidentified lines. The finally resulting [S/Fe]-[Fe/H] and [Zn/Fe]-[Fe/H] relations for GK giants were confirmed to be in good agreement with those for FGK dwarfs, indicating that S and Zn abundances of red giants are reliably determinable from the S I 6757 and Zn I 6362 lines. Accordingly, not only main-sequence stars but also evolved red giant stars are usable for tracing the chemical evolution history of S and Zn in the regime of disk metallicity by using these lines.

  11. Radioactive elements on Mercury's surface from MESSENGER: implications for the planet's formation and evolution.

    Science.gov (United States)

    Peplowski, Patrick N; Evans, Larry G; Hauck, Steven A; McCoy, Timothy J; Boynton, William V; Gillis-Davis, Jeffery J; Ebel, Denton S; Goldsten, John O; Hamara, David K; Lawrence, David J; McNutt, Ralph L; Nittler, Larry R; Solomon, Sean C; Rhodes, Edgar A; Sprague, Ann L; Starr, Richard D; Stockstill-Cahill, Karen R

    2011-09-30

    The MESSENGER Gamma-Ray Spectrometer measured the average surface abundances of the radioactive elements potassium (K, 1150 ± 220 parts per million), thorium (Th, 220 ± 60 parts per billion), and uranium (U, 90 ± 20 parts per billion) in Mercury's northern hemisphere. The abundance of the moderately volatile element K, relative to Th and U, is inconsistent with physical models for the formation of Mercury requiring extreme heating of the planet or its precursor materials, and supports formation from volatile-containing material comparable to chondritic meteorites. Abundances of K, Th, and U indicate that internal heat production has declined substantially since Mercury's formation, consistent with widespread volcanism shortly after the end of late heavy bombardment 3.8 billion years ago and limited, isolated volcanic activity since.

  12. Pricing Volatility Referenced Assets

    Directory of Open Access Journals (Sweden)

    Alan De Genaro Dario

    2006-12-01

    Full Text Available Volatility swaps are contingent claims on future realized volatility. Variance swaps are similar instruments on future realized variance, the square of future realized volatility. Unlike a plain vanilla option, whose volatility exposure is contaminated by its asset price dependence, volatility and variance swaps provide a pure exposure to volatility alone. This article discusses the risk-neutral valuation of volatility and variance swaps based on the framework outlined in the Heston (1993 stochastic volatility model. Additionally, the Heston (1993 model is calibrated for foreign currency options traded at BMF and its parameters are used to price swaps on volatility and variance of the BRL / USD exchange rate.

  13. Elemental abundance studies using the EBASIM spectrograph of the 2.1-m CASLEO Observatory telescope. I. The normal stars 5 Aqr and 30 Peg

    Science.gov (United States)

    Adelman, Saul J.; López-Garcia, Zulema; Malaroda, Stella M.; Núñez, Natalia; Grosso, Mónica

    2004-12-01

    Using data from the new EBASIM spectrograph at the 2.1-m telescope of the Complejo Astronómico El Leoncito (CASLEO), two rather sharp-lined B stars 5 Aqr (=HD 198667, B9 III) and 30 Peg (=HD 211924, B5 IV) are being studied. The measurements are compared with those from the coudé spectrograph of the 1.22-m telescope of the Dominion Astrophysical Observatory (DAO). The equivalent width scales of the EBASIM and the DAO data are similar. As we found that the line profiles of 30 Peg are variable, we are trying to determine whether this star is a slowly pulsating B star. 5 Aqr has abundances close to those of the Sun.

  14. 盐湖丰产元素与Zintl化合物(续完)%The Correlation of Abundant Elements and Zintl Phases

    Institute of Scientific and Technical Information of China (English)

    贾永忠; 景燕; 马军; 岳都元; Claude Belin; Monique Tillard

    2011-01-01

    Zintl化合物是以Edward Zintl命名的化合物,是一类由电正性的碱金属或碱土金属与电负性的13族或14族元素形成的特殊金属间化合物.其价键模式可以是离子键、金属键和共价键共存,其中的准金属可以共价键的形式形成各种形式的离子簇,因而其结构复杂多样.这类化合物的部分阴离子簇不仅具有稳定的笼状、层状和链状结构,并且具有特殊的光、电、磁等性能,使得在半导体、催化、电极材料等方面都有应用的前景和发展潜力.介绍了几个特殊Zintl化合物体系,盐湖丰产元素在Zinfi化合物中的作用,指出了含有盐湖丰产元素的Zintl化合物的应用前景和方向.%The term Zintl phase has been coined in honour of Edward Zintl,a German chemist. Zintl phases are formed by combinations of moderately electronegative post-transition elements, such as main group 13 and 14 elements with electropositive alkaline or alkaline-earth metals. In these combinations, owing to electron transfers ( total or partial) from the electropositive to the electronegative elements, anionic frameworks are formed in solid state that range from isolated anionic clusters, rings. cages and 1,2 or 3-D extended structures of which clathrates are among the most remarkable.The authors discuss the correlation of salt lake resources and Zintl phases. The potential applications of Zintl phases in salt lake resources are briefly discussed. This strategy for the synthesis of solid state compounds, which comprised light elements of salt lake resources, main group 13 and 14 elements and transition metal, have unique magnetic, electronic, thermoelectric, colossal magnetoresistance and ferromagnetic properties.

  15. Stock return, seasonality and asymmetric conditional volatility in steel & iron subsector

    Directory of Open Access Journals (Sweden)

    V. Chirila

    2015-01-01

    Full Text Available This paper presents the results obtained following the testing of five hypotheses regarding conditional return and volatility of the most listed European stocks in the steel & iron subsector. The following elements of the stocks are analysed: time variation of volatility, seasonality of return and volatility, relationship between return and volatility and volatility asymmetry. The results obtained confirm for all the analyzed stocks the existence of volatility variation in time, the lack of correlation between return and volatility, the existence of asymmetry phenomenon of volatility and the presence in some stocks of the seasonality effect both for return and volatility.

  16. Testing the ureilite projectile hypothesis for the El'gygytgyn impact: Determination of siderophile element abundances and Os isotope ratios in ICDP drill core samples and melt rocks

    Science.gov (United States)

    Goderis, S.; Wittmann, A.; Zaiss, J.; Elburg, M.; Ravizza, G.; Vanhaecke, F.; Deutsch, A.; Claeys, P.

    2013-07-01

    The geochemical nature of the impactites from International Continental Scientific Drilling Project—El'gygytgyn lake drill core 1C is compared with that of impact melt rock fragments collected near the western rim of the structure and literature data. Concentrations of major and trace elements, with special focus on siderophile metals Cr, Co, Ni, and the platinum group elements, and isotope ratios of osmium (Os), were determined to test the hypothesis of an ureilite impactor at El'gygytgyn. Least squares mixing calculations suggest that the upper volcanic succession of rhyolites, dacites, and andesites were the main contributors to the polymict impact breccias. Additions of 2-13.5 vol% of basaltic inclusions recovered from drill core intervals between 391.6 and 423.0 mblf can almost entirely account for the compositional differences observed for the bottom of a reworked fallout deposit at 318.9 mblf, a polymict impact breccia at 471.4 mblf, and three impact melt rock fragments. However, the measured Os isotope ratios and slightly elevated PGE content (up to 0.262 ng g-1 Ir) of certain impactite samples, for which the CI-normalized logarithmic PGE signature displays a relatively flat (i.e., chondritic) pattern, can only be explained by the incorporation of a small meteoritic contribution. This component is also required to explain the exceptionally high siderophile element contents and corresponding Ni/Cr, Ni/Co, and Cr/Co ratios of impact glass spherules and spherule fragments that were recovered from the reworked fallout deposits and from terrace outcrops of the Enmyvaam River approximately 10 km southeast of the crater center. Mixing calculations support the presence of approximately 0.05 wt% and 0.50-18 wt% of ordinary chondrite (possibly type-LL) in several impactites and in the glassy spherules, respectively. The heterogeneous distribution of the meteoritic component provides clues for emplacement mechanisms of the various impactite units.

  17. The Chemical Abundances of Stars in the Halo (CASH) Project. III. A New Classification Scheme for Carbon-enhanced Metal-poor Stars with s-process Element Enhancement

    Science.gov (United States)

    Hollek, Julie K.; Frebel, Anna; Placco, Vinicius M.; Karakas, Amanda I.; Shetrone, Matthew; Sneden, Christopher; Christlieb, Norbert

    2015-12-01

    We present a detailed abundance analysis of 23 elements for a newly discovered carbon-enhanced metal-poor (CEMP) star, HE 0414-0343, from the Chemical Abundances of Stars in the Halo Project. Its spectroscopic stellar parameters are Teff = 4863 K, {log}g=1.25,\\ξ = 2.20 km s-1, and [Fe/H] = -2.24. Radial velocity measurements covering seven years indicate HE 0414-0343 to be a binary. HE 0414-0343 has {{[C/Fe]}}=1.44 and is strongly enhanced in neutron-capture elements but its abundances cannot be reproduced by a solar-type s-process pattern alone. Traditionally, it could be classified as a “CEMP-r/s” star. Based on abundance comparisons with asymptotic giant branch (AGB) star nucleosynthesis models, we suggest a new physically motivated origin and classification scheme for CEMP-s stars and the still poorly understood CEMP-r/s. The new scheme describes a continuous transition between these two so-far distinctly treated subgroups: CEMP-sA, CEMP-sB, and CEMP-sC. Possible causes for a continuous transition include the number of thermal pulses the AGB companion underwent, the effect of different AGB star masses on their nucleosynthetic yields, and physics that is not well approximated in 1D stellar models such as proton ingestion episodes and rotation. Based on a set of detailed AGB models, we suggest the abundance signature of HE 0414-0343 to have arisen from a >1.3 M⊙ mass AGB star and a late-time mass transfer that transformed HE 0414-0343 into a CEMP-sC star. We also find that the [Y/Ba] ratio well parametrizes the classification and can thus be used to easily classify any future such stars. Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

  18. The fractal dimension characteristics of element abundance of the granitoid in China%中国花岗岩类化学元素组成的分维数特征

    Institute of Scientific and Technical Information of China (English)

    于蕾; 王训练; 赵博

    2011-01-01

    The data set of various elements' abundance is taken as an abundance sequence, and fractal dimension (box dimension) is used in the study of elemental abundance of the granitoid in China. In theory, the universality of fractal derives from that of randomness, and fractal dimension can indicate the inner structure of the sequence and its evolvement orientation, providing valuable information for prospecting. In practice, based on both the elemental compatible order and integrity of observed variables, characteristics of the box dimension are made effective use of. Therefore, the correlations and mechanisms between fractal dimension and evolution trend or differentiation degree of diagenetic succession, and geochemical characteristic of the research system have also been discussed in detail, according to which we can explain why some rocks have component, time and space aspects within the granitoid category while differ from one another in the metallogenic relation and ore-bearing potential. Therefore, we demonstrated a new elemental abundance method with a basis of frequency characteristics. It can be concluded that elemental abundance sequence of the granitoid may operate structur al evolution in some form, and conventional log-normal distribution fails to describe the frequency laws. However, the cumulative summation and error obey fractal distribution. Herein, descending order of the fractal dimension, which is of important geochemical significance, corresponds to the degree of chemical evolution of the observed sequence, so do the results of cluster analysis.%将各种化学元素的丰度集合视为一组丰度序列,首次将分维数(盒维数)应用于研究中国花岗岩类的化学元素组成及演化特征.原理上,分形的遍在性源于随机性的遍在性,分维数的取值可表征丰度序列的内部结 构性及演化的方向性,为矿产资源勘查提供重要信息;实践上,以观测元素相容性序列为基础分析其地球化学行

  19. Chemical classification of iron meteorites. XI - Multi-element studies of 38 new irons and the high abundance of ungrouped irons from Antarctica

    Science.gov (United States)

    Wasson, John T.; Ouyang, Xinwei; Wang, Jianmin; Jerde, Eric

    1989-01-01

    Concentrations of 14 elements in the metal of 38 iron meteorites and a pallasite are reported. Three samples are paired with previously classified irons, raising the number of well-classified, independent iron meteorites to 598. Several of the new irons are from Antarctica. Of 24 independent irons from Antarctica, eight are ungrouped, a much higher fraction than that among all classified irons. The difference is probably related to the fact that the median mass of Antarctic irons is about two orders of magnitude smaller than that of non-Antarctic irons. Smaller meteoroids may tend to sample a larger number of asteroidal source regions, perhaps because small meteoroids tend to have higher ejection velocities or because they have random-walked a greater increment of orbital semimajor axis away from that of the parent body.

  20. Abundances and distribution of minerals and elements in high-alumina coal fly ash from the Jungar Power Plant, Inner Mongolia, China

    Science.gov (United States)

    Dai, S.; Zhao, L.; Peng, S.; Chou, C.-L.; Wang, X.; Zhang, Y.; Li, D.; Sun, Y.

    2010-01-01

    The fly ash from the Jungar Power Plant, Inner Mongolia, China, is unique because it is highly enriched in alumina (Al2O3>50%). The fly ash mainly consists of amorphous glass and mullite and trace amounts of corundum, quartz, char, calcite, K-feldspar, clay minerals, and Fe-bearing minerals. The mullite content in fly ash is as high as 37.4% because of high boehmite and kaolinite contents in feed coal. Corundum is a characteristic mineral formed during the combustion of boehmite-rich coal.Samples from the economizer were sieved into six size fractions (500 mesh) and separated into magnetic, mullite+corundum+quartz (MCQ) and glass phases for mineralogical and chemical analysis. The corundum content increases but amorphous glass decreases with decreasing particle size. Fractions of small particle sizes are relatively high in mullite, probably because mullite was formed from fine clay mineral particles under high-temperature combustion condition. Similarly, fine corundum crystals formed in the boiler from boehmite in feed coal. The magnetic phase consists of hematite, magnetite, magnesioferrite, and MgFeAlO4 crystals. The MCQ phase is composed of 89% mullite, 6.1% corundum, 4.5% quartz, and 0.5% K-feldspar.Overall, the fly ash from the power plant is significantly enriched in Al2O3 with an average of 51.9%, but poor in SiO2, Fe2O3, CaO, MgO, Na2O, P2O5, and As. Arsenic, TiO2, Th, Al2O3, Bi, La, Ga, Ni, and V are high in mullite, and the magnetic matter is enriched in Fe2O3, CaO, MnO, TiO2, Cs, Co, As, Cd, Ba, Ni, Sb, MgO, Zn, and V. The remaining elements are high in the glass fraction. The concentration of K2O, Na2O, P2O5, Nb, Cr, Ta, U, W, Rb, and Ni do not clearly vary with particle size, while SiO2 and Hg decrease and the remaining elements clearly increase with decreasing particle size. ?? 2009 Elsevier B.V.

  1. Interannual variation of rare earth element abundances in corals from northern coast of the South China Sea and its relation with sea-level change and human activities

    Science.gov (United States)

    Liu, Yajing; Peng, Z.; Wei, G.; Chen, T.; Sun, W.; He, J.; Liu, Gaisheng; Chou, C.-L.; Shen, C.-C.

    2011-01-01

    Here we present interannual rare earth element (REE) records spanning the last two decades of the 20th century in two living Porites corals, collected from Longwan Bay, close to the estuarine zones off Wanquan River of Hainan Island and Hong Kong off the Pearl River Delta of Guangdong Province in the northern South China Sea. The results show that both coral REE contents (0.5-40 ng g-1 in Longwan Bay and 2-250 ng g-1 in Hong Kong for La-Lu) are characterized with a declining trend, which are significantly negative correlated with regional sea-level rise (9.4 mm a-1 from 1981 to 1996 in Longwan Bay, 13.7 mm a-1 from 1991 to 2001 in Hong Kong). The REE features are proposed to be resulted from seawater intrusion into the estuaries in response to contemporary sea-level rise. However, the tendency for the coral Er/Nd time series at Hong Kong site is absent and there is no significant relation between Er/Nd and total REEs as found for the coral at Longwan Bay site. The observations are likely attributed to changes of the water discharge and sediment load of Pearl River, which have been significantly affected by intense human activities, such as the construction of dams/reservoirs and riverbed sediment mining, in past decades. The riverine sediment load/discharge ratio of the Pearl River decreased sharply with a rate of 0.02 kg m-3 a-1, which could make significant contribution to the declining trend of coral REE. We propose that coastal corals in Longwan Bay and similar unexplored sites with little influences of river discharge and anthropogenic disruption are ideal candidates to investigate the influence of sea-level change on seawater/coral REE. ?? 2010 Elsevier Ltd.

  2. Volatile depletion in the TW Hydrae disk atmosphere

    CERN Document Server

    Du, Fujun; Hogerheijde, Michiel R

    2015-01-01

    An abundance decrease in carbon- and oxygen-bearing species relative to dust has been frequently found in planet-forming disks, which can be attributed to an overall reduction of gas mass. However, in the case of TW Hya, the only disk with gas mass measured directly with HD rotational lines, the inferred gas mass ($\\lesssim$0.005 solar mass) is significantly below the directly measured value ($\\gtrsim$0.05 solar mass). We show that this apparent conflict can be resolved if the elemental abundances of carbon and oxygen are reduced in the upper layers of the outer disk but are normal elsewhere (except for a possible enhancement of their abundances in the inner disk). The implication is that in the outer disk, the main reservoir of the volatiles (CO, water, ...) resides close to the midplane, locked up inside solid bodies that are too heavy to be transported back to the atmosphere by turbulence. An enhancement in the carbon and oxygen abundances in the inner disk can be caused by inward migration of these solid ...

  3. Evaluating the primary and/or diagenetic origin of rare earth element abundances in Ediacaran to early Cambrian phosphate deposits, Yangtze Platform (South China) by LA-ICPMS

    Science.gov (United States)

    Hippler, Dorothee; Klügel, Andreas; Biedermann, Nicole; Guo, Qingjun; Franz, Gerhard

    2014-05-01

    The Precambrian-Cambrian time interval represents one of the greatest phosphogenic episodes in Earth's history with giant and well-preserved phosphate deposits occurring on the Yangtze Platform in South China. We investigated concentrations of rare earth elements (REE) and yttrium of shallow and deep-water sedimentary phosphate deposits of the Ediacaran Doushantou Formation and the early Cambrian Zhongyicun Formation by using LA-ICP mass spectrometry. The aim is to examine the temporal and spatial variability of seawater chemistry in conjunction with the conditions of phosphate formation and the evaluation of the extent of diagenetic modification. The mineralogical and textural composition of the samples was pre-screened using SEM and XRD, and polished thick sections were prepared for subsequent high-resolution LA-ICPMS analyses. Overall concentrations in REE range between 18 and 657 ppm, with elevated concentrations (> 200 ppm) in apatite from the deep-water phosphate deposits. REE+Y patterns of shallow-water phosphate deposits exhibit the evolution from flat shale-like to gently inclined seawater-derived patterns, with the early Cambrian phosphate deposits revealing distinct negative Ce- and positive Y-anomalies indicative for oxygenated surface waters. REE+Y patterns of phosphate deposits of the deep-water facies are flat to highly enriched in MREE, which is manifested in variably pronounced concave-down patterns. In detail, these patterns display different Ce-anomalies, as well as small positive Eu-anomalies. We propose that REE+Y patterns of Ediacaran and early Cambrian sedimentary phosphate deposits can inherit both primary and secondary signatures reflecting either seawater composition or diagenetic modification and fluid flow. The combination of imaging techniques and in-situ LA-ICPMS thereby enables a more sophisticated examination of the potential sources and processes than whole rock determinations. Placing the results in stratigraphic order and assuming

  4. Forming Chondrules in Impact Splashes II Volatile Retention

    Science.gov (United States)

    Dullemond, Cornelis Petrus; Harsono, Daniel; Stammler, Sebastian Markus; Johansen, Anders

    2016-11-01

    Solving the mystery of the origin of chondrules is one of the most elusive goals in the field of meteoritics. Recently, the idea of planet(esimal) collisions releasing splashes of lava droplets, long considered out of favor, has been reconsidered as a possible origin of chondrules by several papers. One of the main problems with this idea is the lack of quantitative and simple models that can be used to test this scenario by directly comparing to the many known observables of chondrules. In Paper I of this series, we presented a simple thermal evolution model of a spherically symmetric expanding cloud of molten lava droplets that is assumed to emerge from a collision between two planetesimals. The production of lava could be either because the two planetesimals were already in a largely molten (or almost molten) state due to heating by 26Al, or due to impact jetting at higher impact velocities. In the present paper, number II of this series, we use this model to calculate whether or not volatile elements such as Na and K will remain abundant in these droplets or whether they will get depleted due to evaporation. The high density of the droplet cloud (e.g., small distance between adjacent droplets) causes the vapor to quickly reach saturation pressure and thus shuts down further evaporation. We show to what extent, and under which conditions, this keeps the abundances of these elements high, as is seen in chondrules. We find that for most parameters of our model (cloud mass, expansion velocity, initial temperature) the volatile elements Mg, Si, and Fe remain entirely in the chondrules. The Na and K abundances inside the droplets will initially stay mostly at their initial values due to the saturation of the vapor pressure, but at some point start to drop due to the cloud expansion. However, as soon as the temperature starts to decrease, most or all of the vapor recondenses again. At the end, the Na and K elements retain most of their initial abundances, albeit

  5. Evaluation of pyrolysis curves for volatile elements in aqueous standards and carbon-containing matrices in electrothermal vaporization inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Silva, A.F. [Delft University of Technology, Faculty of Applied Sciences, DelftChemTech, Julianalaan 136, 2628 BL Delft (Netherlands); Universidade Federal de Santa Catarina, Departamento de Quimica, 88040-900 Florianopolis, SC (Brazil); Welz, B. [Universidade Federal de Santa Catarina, Departamento de Quimica, 88040-900 Florianopolis, SC (Brazil); Loos-Vollebregt, M.T.C. de [Delft University of Technology, Faculty of Applied Sciences, DelftChemTech, Julianalaan 136, 2628 BL Delft (Netherlands)], E-mail: m.t.c.deloos-vollebregt@tudelft.nl

    2008-07-15

    Pyrolysis curves in electrothermal atomic absorption spectrometry (ET AAS) and electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) have been compared for As, Se and Pb in lobster hepatopancreas certified reference material using Pd/Mg as the modifier. The ET AAS pyrolysis curves confirm that the analytes are not lost from the graphite furnace up to a pyrolysis temperature of 800 deg. C. Nevertheless, a downward slope of the pyrolysis curve was observed for these elements in the biological material using ETV-ICP-MS. This could be related to a gain of sensitivity at low pyrolysis temperatures due to the matrix, which can act as carrier and/or promote changes in the plasma ionization equilibrium. Experiments with the addition of ascorbic acid to the aqueous standards confirmed that the higher intensities obtained in ETV-ICP-MS are related to the presence of organic compounds in the slurry. Pyrolysis curves for As, Se and Pb in coal and coal fly ash were also investigated using the same Pd/Mg modifier. Carbon intensities were measured in all samples using different pyrolysis temperatures. It was observed that pyrolysis curves for the three analytes in all slurry samples were similar to the corresponding graphs that show the carbon intensity for the same slurries for pyrolysis temperatures from 200 deg. C up to 1000 deg. C.

  6. Thermochromatography study of volatile polonium species in various gas atmospheres

    CERN Document Server

    Maugeri, Emilio Andrea; Eichler, Robert; Piguet,David; Mendonça, Tania Melo; Stora, Thierry; Schumann, Dorothea

    2014-01-01

    Phenomena related to the volatilization of polonium and its compounds are critical issues for the safety assessment of the innovative lead–bismuth cooled type of nuclear reactor or accelerator driven systems. The formation and volatilization of different species of polonium and their interaction with fused silica was studied by thermochromatography using carrier gases with varied redox potential. The obtained results show that under inert and reducing conditions in the absence of moisture, elemental polonium is formed. Polonium compounds more volatile than elemental polonium can be formed if traces of moisture are present in both inert and reducing carrier gas. The use of dried oxygen as carrier gas leads to the formation of polonium oxides, which are less volatile than elemental polonium. It was also found that the volatility of polonium oxides increases with increasing oxidation state. In the presence of moisture in an oxidizing carrier gas, species are formed that are more volatile than the oxides and le...

  7. Current status of fluoride volatility method development

    Energy Technology Data Exchange (ETDEWEB)

    Uhlir, J.; Marecek, M.; Skarohlid, J. [UJV - Nuclear Research Institute, Research Centre Rez, CZ-250 68 Husinec - Rez 130 (Czech Republic)

    2013-07-01

    The Fluoride Volatility Method is based on a separation process, which comes out from the specific property of uranium, neptunium and plutonium to form volatile hexafluorides whereas most of fission products (mainly lanthanides) and higher transplutonium elements (americium, curium) present in irradiated fuel form nonvolatile tri-fluorides. Fluoride Volatility Method itself is based on direct fluorination of the spent fuel, but before the fluorination step, the removal of cladding material and subsequent transformation of the fuel into a powdered form with a suitable grain size have to be done. The fluorination is made with fluorine gas in a flame fluorination reactor, where the volatile fluorides (mostly UF{sub 6}) are separated from the non-volatile ones (trivalent minor actinides and majority of fission products). The subsequent operations necessary for partitioning of volatile fluorides are the condensation and evaporation of volatile fluorides, the thermal decomposition of PuF{sub 6} and the finally distillation and sorption used for the purification of uranium product. The Fluoride Volatility Method is considered to be a promising advanced pyrochemical reprocessing technology, which can mainly be used for the reprocessing of oxide spent fuels coming from future GEN IV fast reactors.

  8. Volatile Organic Compounds (VOCs)

    Science.gov (United States)

    ... Contact Us Share Volatile Organic Compounds' Impact on Indoor Air Quality On this page: Introduction Sources Health Effects Levels in Homes Steps to Reduce Exposure Standards or Guidelines Additional Resources Introduction Volatile organic compounds ( ...

  9. Effects of Dynamical Evolution of Giant Planets on the Delivery of Atmophile Elements During Terrestrial Planet Formation

    CERN Document Server

    Matsumura, Soko; Ida, Shigeru

    2015-01-01

    Recent observations started revealing the compositions of protostellar discs and planets beyond the Solar System. In this paper, we explore how the compositions of terrestrial planets are affected by dynamical evolution of giant planets. We estimate the initial compositions of building blocks of these rocky planets by using a simple condensation model, and numerically study the compositions of planets formed in a few different formation models of the Solar System. We find that the abundances of refractory and moderately volatile elements are nearly independent of formation models, and that all the models could reproduce the abundances of these elements of the Earth. The abundances of atmophile elements, on the other hand, depend on the scattering rate of icy planetesimals into the inner disc as well as the mixing rate of the inner planetesimal disc. For the classical formation model, neither of these mechanisms are efficient and the accretion of atmophile elements during the final assembly of terrestrial plan...

  10. A fragrant neighborhood: volatile mediated bacterial interactions in soil.

    Science.gov (United States)

    Schulz-Bohm, Kristin; Zweers, Hans; de Boer, Wietse; Garbeva, Paolina

    2015-01-01

    There is increasing evidence that volatile organic compounds (VOCs) play essential roles in communication and competition between soil microorganisms. Here we assessed volatile-mediated interactions of a synthetic microbial community in a model system that mimics the natural conditions in the heterogeneous soil environment along the rhizosphere. Phylogenetic different soil bacterial isolates (Burkholderia sp., Dyella sp., Janthinobacterium sp., Pseudomonas sp., and Paenibacillus sp.) were inoculated as mixtures or monoculture in organic-poor, sandy soil containing artificial root exudates (ARE) and the volatile profile and growth were analyzed. Additionally, a two-compartment system was used to test if volatiles produced by inter-specific interactions in the rhizosphere can stimulate the activity of starving bacteria in the surrounding, nutrient-depleted soil. The obtained results revealed that both microbial interactions and shifts in microbial community composition had a strong effect on the volatile emission. Interestingly, the presence of a slow-growing, low abundant Paenibacillus strain significantly affected the volatile production by the other abundant members of the bacterial community as well as the growth of the interacting strains. Furthermore, volatiles released by mixtures of root-exudates consuming bacteria stimulated the activity and growth of starved bacteria. Besides growth stimulation, also an inhibition in growth was observed for starving bacteria exposed to microbial volatiles. The current work suggests that volatiles produced during microbial interactions in the rhizosphere have a significant long distance effect on microorganisms in the surrounding, nutrient-depleted soil.

  11. A fragrant neighborhood: Volatile mediated bacterial interactions in soil

    Directory of Open Access Journals (Sweden)

    Kristin eSchulz-Bohm

    2015-11-01

    Full Text Available There is increasing evidence that volatile organic compounds play essential roles in communication and competition between soil microorganisms. Here we assessed volatile-mediated interactions of a synthetic microbial community in a model system that mimics the natural conditions in the heterogeneous soil environment along the rhizosphere. Phylogenetic different soil bacterial isolates (Burkholderia sp., Dyella sp., Janthinobacterium sp., Pseudomonas sp., and Paenibacillus sp. were inoculated as mixtures or monoculture in organic-poor, sandy soil containing artificial root exudates and the volatile profile and growth were analyzed. Additionally, a two-compartment system was used to test if volatiles produced by inter-specific interactions in the rhizosphere can stimulate the activity of starving bacteria in the surrounding, nutrient-depleted soil. The obtained results revealed that both microbial interactions and shifts in microbial community composition had a strong effect on the volatile emission. Interestingly, the presence of a slow-growing, low abundant Paenibacillus strain significantly affected the volatile production by the other abundant members of the bacterial community as well as the growth of the interacting strains. Furthermore, volatiles released by mixtures of root-exudates consuming bacteria stimulated the activity and growth of starved bacteria. Besides growth stimulation, also an inhibition in growth was observed for starving bacteria exposed to microbial volatiles. The current work suggests that volatiles produced during microbial interactions in the rhizosphere have a significant long distance effect on microorganisms in the surrounding, nutrient-depleted soil.

  12. Silicon isotopes in angrites and volatile loss in planetesimals

    Science.gov (United States)

    Moynier, Frédéric; Savage, Paul S.; Badro, James; Barrat, Jean-Alix

    2014-01-01

    Inner solar system bodies, including the Earth, Moon, and asteroids, are depleted in volatile elements relative to chondrites. Hypotheses for this volatile element depletion include incomplete condensation from the solar nebula and volatile loss during energetic impacts. These processes are expected to each produce characteristic stable isotope signatures. However, processes of planetary differentiation may also modify the isotopic composition of geochemical reservoirs. Angrites are rare meteorites that crystallized only a few million years after calcium–aluminum-rich inclusions and exhibit extreme depletions in volatile elements relative to chondrites, making them ideal samples with which to study volatile element depletion in the early solar system. Here we present high-precision Si isotope data that show angrites are enriched in the heavy isotopes of Si relative to chondritic meteorites by 50–100 ppm/amu. Silicon is sufficiently volatile such that it may be isotopically fractionated during incomplete condensation or evaporative mass loss, but theoretical calculations and experimental results also predict isotope fractionation under specific conditions of metal–silicate differentiation. We show that the Si isotope composition of angrites cannot be explained by any plausible core formation scenario, but rather reflects isotope fractionation during impact-induced evaporation. Our results indicate planetesimals initially formed from volatile-rich material and were subsequently depleted in volatile elements during accretion. PMID:25404309

  13. Silicon isotopes in angrites and volatile loss in planetesimals.

    Science.gov (United States)

    Pringle, Emily A; Moynier, Frédéric; Savage, Paul S; Badro, James; Barrat, Jean-Alix

    2014-12-02

    Inner solar system bodies, including the Earth, Moon, and asteroids, are depleted in volatile elements relative to chondrites. Hypotheses for this volatile element depletion include incomplete condensation from the solar nebula and volatile loss during energetic impacts. These processes are expected to each produce characteristic stable isotope signatures. However, processes of planetary differentiation may also modify the isotopic composition of geochemical reservoirs. Angrites are rare meteorites that crystallized only a few million years after calcium-aluminum-rich inclusions and exhibit extreme depletions in volatile elements relative to chondrites, making them ideal samples with which to study volatile element depletion in the early solar system. Here we present high-precision Si isotope data that show angrites are enriched in the heavy isotopes of Si relative to chondritic meteorites by 50-100 ppm/amu. Silicon is sufficiently volatile such that it may be isotopically fractionated during incomplete condensation or evaporative mass loss, but theoretical calculations and experimental results also predict isotope fractionation under specific conditions of metal-silicate differentiation. We show that the Si isotope composition of angrites cannot be explained by any plausible core formation scenario, but rather reflects isotope fractionation during impact-induced evaporation. Our results indicate planetesimals initially formed from volatile-rich material and were subsequently depleted in volatile elements during accretion.

  14. Mass Spectrometry in Jupiter's Atmosphere: Vertical Variation of Volatile Vapors

    Science.gov (United States)

    Wong, Michael H.; Atreya, Sushil K.; Mahaffy, Paul R.

    2014-05-01

    The Galileo Probe made the first and only in situ measurements of composition in Jupiter's atmosphere, led by the Galileo Probe Mass Spectrometer, or GPMS [1]. The major contribution from this instrument was the measurement of abundances and isotope ratios of the noble gases, as well as the volatile gases CH4, NH3, H2O, and H2S [2,3]. These initial results were further refined by detailed laboratory calibrations for the noble gases [4] and the volatiles [5]. The probe measurements resulted in the first determination of the heavy element abundances (except carbon that was known previously) and He/H ratio, which provide critical constraints to models of the formation of Jupiter and the origin of its atmosphere [6,7]. The condensable volatiles, or CVs (ammonia, H2S, and water), increased with depth in the probe entry site. This vertical variation was observed at levels much deeper than the modeled cloud bases, as predicted by one-dimensional chemical equilibrium models. The discrepancy is due to the probe's entry into a dry region known as a 5-μm hot spot. The 5-μm hot spots are part of an atmospheric wave system that encircles Jupiter just north of the equator. Despite the anomalous meteorology, the bulk abundances of NH3 and H2S were measured by the probe, and found to be enriched with respect to solar composition (similarly to the non-condensable volatile CH4). The deepest water mixing ratio, however, was observed to be depleted relative to solar composition. We review an updated context for the CV vertical profiles measured by the GPMS, based on the latest results from remote sensing, simulation, and reinterpretation of Galileo Probe measurements. In particular, we find that (1) the bulk abundance of water in Jupiter's atmosphere must be greater than the subsolar abundance derived from the deepest GPMS measurements [8], and that (2) CV mixing ratios are controlled by a range of processes in addition to condensation of the ices NH3, NH4SH, and H2O [5-9]. Both

  15. Abundance analysis of Barium stars

    Institute of Scientific and Technical Information of China (English)

    Guo-Qing Liu; Yan-Chun Liang; Li-Cai Deng

    2009-01-01

    We obtain the chemical abundances of six barium stars and two CH subgiant stars based on the high signal-to-noise ratio and high resolution Echelle spectra. The neu- tron capture process elements Y, Zr, Ba, La and Eu show obvious overabundances relative to the Sun, for example, their [Ba/Fe] values are from 0.45 to 1.27. Other elements, in- cluding Na, Mg, A1, Si, Ca, Sc, Ti, V, Cr, Mn and Ni, show comparable abundances to the Solar ones, and their [Fe/H] covers a range from -0.40 to 0.21, which means they belong to the Galactic disk. The predictions of the theoretical model of wind accretion for bi- nary systems can explain the observed abundance patterns of the neutron capture process elements in these stars, which means that their overabundant heavy-elements could be caused by accreting the ejecta of AGB stars, the progenitors of present-day white dwarf companions in binary systems.

  16. Mantle Volatiles - Distribution and Consequences

    Science.gov (United States)

    Luth, R. W.

    2003-12-01

    Volatiles in the mantle have, for many years, been the subject of intensive study from a number of perspectives. They are of interest because of their potential effects on melting relationships, on transport of major and trace elements, and on the rheological and other physical properties of the mantle. By convention, "volatiles" in this context are constituents that are liquid or gaseous at normal Earth surface conditions. This review will look at the behavior of C-O-H-S-halogen volatiles, beginning with H2O and C-O volatiles.There have been tremendous strides made recently towards understanding how volatiles in general and water in particular is transported and stored in the mantle. This progress is based on research on a number of fronts: studies of mantle-derived samples have provided insight into the nature and occurrence of hydrous phases such as amphibole, mica, and chlorite, and have provided constraints on the capacity of nominally anhydrous minerals (NAMs) such as olivine, pyroxenes, and garnet to contain "water" by a variety of substitution mechanisms. Experimental studies on mantle-derived magmas have provided constraints on volatile contents in their source regions. Other studies have constrained the pressure, temperature, and composition conditions over which hydrous phases are stable in the mantle.Fundamental questions remain about the geochemical cycling of volatiles in the mantle, and between the mantle and the surface. Much attention has focused on the capability of hydrous phases such as amphibole, mica, serpentine, chlorite, and a family of "dense hydrous magnesian silicates" (DHMSs) to act as carriers of water in subducting slabs back into the mantle. It has been clear since the work of Ito et al. (1983) that there is a discrepancy between the amount of volatiles subducted into the mantle and those returned to the surface by arc magmatism. A recent overview of volatile cycling in subduction systems by Bebout (1996) suggests that 5-15% of the H2

  17. Comparison of abundances, compositions and sources of elements, inorganic ions and organic compounds in atmospheric aerosols from Xi'an and New Delhi, two megacities in China and India.

    Science.gov (United States)

    Li, Jianjun; Wang, Gehui; Aggarwal, Shankar G; Huang, Yao; Ren, Yanqin; Zhou, Bianhong; Singh, Khem; Gupta, Prabhat K; Cao, Junji; Zhang, Rong

    2014-04-01

    Wintertime TSP samples collected in the two megacities of Xi'an, China and New Delhi, India were analyzed for elements, inorganic ions, carbonaceous species and organic compounds to investigate the differences in chemical compositions and sources of organic aerosols. The current work is the first time comparing the composition of urban organic aerosols from China and India and discussing their sources in a single study. Our results showed that the concentrations of Ca, Fe, Ti, inorganic ions, EC, PAHs and hopanes in Xi'an are 1.3-2.9 times of those in New Delhi, which is ascribed to the higher emissions of dust and coal burning in Xi'an. In contrast, Cl(-), levoglucosan, n-alkanes, fatty alcohols, fatty acids, phthalates and bisphenol A are 0.4-3.0 times higher in New Delhi than in Xi'an, which is attributed to strong emissions from biomass burning and solid waste incineration. PAHs are carcinogenic while phthalates and bisphenol A are endocrine disrupting. Thus, the significant difference in chemical compositions of the above TSP samples may suggest that residents in Xi'an and New Delhi are exposed to environmental hazards that pose different health risks. Lower mass ratios of octadecenoic acid/octadecanoic acid (C18:1/C18:0) and benzo(a)pyrene/benzo(e)pyrene (BaP/BeP) demonstrate that aerosol particles in New Delhi are photochemically more aged. Mass closure reconstructions of the wintertime TSP indicate that crustal material is the most abundant component of ambient particles in Xi'an and New Delhi, accounting for 52% and 48% of the particle masses, respectively, followed by organic matter (24% and 23% in Xi'an and New Delhi, respectively) and secondary inorganic ions (sulfate, nitrate plus ammonium, 16% and 12% in Xi'an and New Delhi, respectively). Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Removal Of Volatile Impurities From Copper Concentrates

    Energy Technology Data Exchange (ETDEWEB)

    Winkel, L.; Schuler, A.; Frei, A.; Sturzenegger, M.

    2005-03-01

    To study the removal of volatile impurities from two different copper concentrates they have been heated on a thermo balance to temperatures between 900 and 1500 C. This sample treatment revealed that both concentrates undergo strong weight losses at 500 and 700 C. They were attributed to the removal of sulfur. Elemental analyses of the residues by ICP spectrometry have shown that the thermal treatment efficiently removes the volatile impurities. Already below 900 C most of the arsenic is removed by evaporation, the largest fraction of lead and zinc is removed in the temperature interval of 1300-1500 C. It was observed that quartz in the concentrate leads to the formation of a silicon-enriched phase besides a metal rich sulfide phase. The former is interpreted as an early stage of a silicate slag. Elemental analysis showed that the formation of this distinct slag phase does not hinder the efficient removal of volatile impurities. (author)

  19. Emerging Equity Market Volatility

    OpenAIRE

    Geert Bekaert; Harvey, Campbell R.

    1995-01-01

    Returns in emerging capital markets are very different from returns in developed markets. While most previous research has focused on average returns, we analyze the volatility of the returns in emerging equity markets. We characterize the time-series of volatility in emerging markets and explore the distributional foundations of the variance process. Of particular interest is evidence of asymmetries in volatility and the evolution of the variance process after periods of capital market refor...

  20. Volatility in Equilibrium

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Sizova, Natalia; Tauchen, George

    Stock market volatility clusters in time, carries a risk premium, is fractionally inte- grated, and exhibits asymmetric leverage effects relative to returns. This paper develops a first internally consistent equilibrium based explanation for these longstanding empirical facts. The model is cast......, and the dynamic cross-correlations of the volatility measures with the returns calculated from actual high-frequency intra-day data on the S&P 500 aggregate market and VIX volatility indexes....

  1. Volatile components and continental material of planets

    Science.gov (United States)

    Florenskiy, K. P.; Nikolayeva, O. V.

    1986-01-01

    It is shown that the continental material of the terrestrial planets varies in composition from planet to planet according to the abundances and composition of true volatiles (H20, CO2, etc.) in the outer shells of the planets. The formation of these shells occurs very early in a planet's evolution when the role of endogenous processes is indistinct and continental materials are subject to melting and vaporizing in the absence of an atmosphere. As a result, the chemical properties of continental materials are related not only to fractionation processes but also to meltability and volatility. For planets retaining a certain quantity of true volatile components, the chemical transformation of continental material is characterized by a close interaction between impact melting vaporization and endogeneous geological processes.

  2. Volatile Composition of Smoked and Non-Smoked Iranian Rice

    Directory of Open Access Journals (Sweden)

    Leontina Lipan

    2016-11-01

    Full Text Available In this work, the volatile profiles of smoked and non-smoked Iranian rice were identified, and their relative abundance was calculated and compared. Headspace solid-phase microextraction together with gas chromatography-mass spectrometry (SPME-GC-MS were used to extract and identify the volatile compounds. The main groups of volatiles in Iranian rice were aldehydes, ketones, phenol derivatives, furans, linear hydrocarbons, esters and terpenes. The chemical family aldehydes was the most abundant one in the profile of non-smoked rice, while phenol derivatives and furans predominated in smoked samples. This study is the first one reporting comparative data of volatile compounds between smoked and non-smoked Iranian rice.

  3. Understanding Financial Market Volatility

    NARCIS (Netherlands)

    A. Opschoor (Anne)

    2014-01-01

    markdownabstract__Abstract__ Volatility has been one of the most active and successful areas of research in time series econometrics and economic forecasting in recent decades. Loosely speaking, volatility is defined as the average magnitude of fluctuations observed in some phenomenon over time. Wi

  4. Improving Garch Volatility Forecasts

    NARCIS (Netherlands)

    Klaassen, F.J.G.M.

    1998-01-01

    Many researchers use GARCH models to generate volatility forecasts. We show, however, that such forecasts are too variable. To correct for this, we extend the GARCH model by distinguishing two regimes with different volatility levels. GARCH effects are allowed within each regime, so that our model

  5. Understanding Financial Market Volatility

    NARCIS (Netherlands)

    A. Opschoor (Anne)

    2014-01-01

    markdownabstract__Abstract__ Volatility has been one of the most active and successful areas of research in time series econometrics and economic forecasting in recent decades. Loosely speaking, volatility is defined as the average magnitude of fluctuations observed in some phenomenon over

  6. Volatile metabolites from actinomycetes

    DEFF Research Database (Denmark)

    Scholler, C.E.G.; Gurtler, H.; Pedersen, R.

    2002-01-01

    Twenty-six Streptomyces spp. were screened for their volatile production capacity on yeast starch agar. The volatile organic compounds (VOCs) were concentrated on a porous polymer throughout an 8-day growth period. VOCs were analyzed by gas chromatography with flame ionization detection and ident...

  7. Natural wetland emissions of methylated trace elements

    NARCIS (Netherlands)

    Vriens, B.; Lenz, M.; Charlet, L.; Berg, M.; Winkel, L.H.E.

    2014-01-01

    Natural wetlands are well known for their significant methane emissions. However, trace element emissions via biomethylation and subsequent volatilization from pristine wetlands are virtually unstudied, even though wetlands constitute large reservoirs for trace elements. Here we show that the averag

  8. Raccoon abundance inventory report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes the results of a raccoon abundance inventory on Clarence Cannon National Wildlife Refuge in 2012. Determining raccoon abundance allows for...

  9. Homogeneous abundance analysis of dwarf, subgiant and giant FGK stars with and without giant planets

    CERN Document Server

    da Silva, R; Rocha-Pinto, H J

    2015-01-01

    We have analyzed high-resolution and high signal-to-noise ratio optical spectra of nearby FGK stars with and without detected giant planets in order to homogeneously measure their photospheric parameters, mass, age, and the abundances of volatile (C, N, and O) and refractory (Na, Mg, Si, Ca, Ti, V, Mn, Fe, Ni, Cu, and Ba) elements. Our sample contains 309 stars from the solar neighborhood (up to the distance of 100 pc), out of which 140 are dwarfs, 29 are subgiants, and 140 are giants. The photospheric parameters are derived from the equivalent widths of Fe I and Fe II lines. Masses and ages come from the interpolation in evolutionary tracks and isochrones on the HR diagram. The abundance determination is based on the equivalent widths of selected atomic lines of the refractory elements and on the spectral synthesis of C_2, CN, C I, O I, and Na I features. We apply a set of statistical methods to analyze the abundances derived for the three subsamples. Our results show that: i) giant stars systematically exhi...

  10. Magmatic gas flux emissions from Gorelyi volcano, Kamchatka, and implications for volatile recycling in the NW Pacific

    Science.gov (United States)

    Aiuppa, A.; Bagnato, E.; Calabrese, S.; Giudice, G.; Liuzzo, M.; Tamburello, G.; Allard, P.; Chaplygin, I.; Taran, Y.

    2012-04-01

    The Kamchatka peninsula, in the north-western part of the Pacific 'Ring of Fire', is one of the most active volcanic realms on Earth, with 29 historically erupting volcanoes along its ~700 km-long Eastern Volcanic Belt (EVB). This notwithstanding, volatile input and output fluxes along this arc sector have remained poorly characterised until very recently. We here report on the very first assessment of volatile flux emissions from Gorelyi, a large (25 km3, 1830 m high) and most active shield-like Holocene volcano located on the southern segment of the Kamchatka EVB. By combing results from a variety of in situ and remote sensing techniques (MultiGAS, filter packs, and UV camera), we determine the bulk plume molar concentrations of major (H2O 93.5%, CO2 2.6%, SO2 2.2%, HCl 1.1%, HF 0.3%, H2 0.2%) to trace-halogens (Br, I) and trace-element volatile species, and we estimate a total gas release of ~11,000 t/day from Gorelyi during ~900°C non-eruptive degassing. Using this observation, we derive new constraints on the abundances and origins of volatiles in the subduction-modified mantle source feeding magmatism in Kamchatka.

  11. Nucleosynthesis: Stellar and Solar Abundances and Atomic Data

    CERN Document Server

    Cowan, J J; Sneden, C; Den Hartog, E A; Collier, J L; Cowan, John J.; Lawler, James E.; Sneden, Christopher; Collier, Jason

    2006-01-01

    Abundance observations indicate the presence of often surprisingly large amounts of neutron capture (i.e., s- and r-process) elements in old Galactic halo and globular cluster stars. These observations provide insight into the nature of the earliest generations of stars in the Galaxy -- the progenitors of the halo stars -- responsible for neutron-capture synthesis. Comparisons of abundance trends can be used to understand the chemical evolution of the Galaxy and the nature of heavy element nucleosynthesis. In addition age determinations, based upon long-lived radioactive nuclei abundances, can now be obtained. These stellar abundance determinations depend critically upon atomic data. Improved laboratory transition probabilities have been recently obtained for a number of elements. These new gf values have been used to greatly refine the abundances of neutron-capture elemental abundances in the solar photosphere and in very metal-poor Galactic halo stars. The newly determined stellar abundances are surprisingl...

  12. Idiosyncratic Volatility Puzzle

    DEFF Research Database (Denmark)

    Aslanidis, Nektarios; Christiansen, Charlotte; Lambertides, Neophytos;

    from a large pool of macroeconomic and Önancial variables. Cleaning for macro-Önance e§ects reverses the puzzling negative relation between returns and idiosyncratic volatility documented previously. Portfolio analysis shows that the e§ects from macro-Önance factors are economically strong......In this paper, we scrutinize the cross-sectional relation between idiosyncratic volatility and stock returns. As a novelty, the idiosyncratic volatility is obtained by conditioning upon macro-Önance factors as well as upon traditional asset pricing factors. The macro-Önance factors are constructed...

  13. ALH85085: a unique volatile-poor carbonaceous chondrite with possible implications for nebular fractionation processes

    Science.gov (United States)

    Grossman, J.N.; Rubin, A.E.; MacPherson, G.J.

    1988-01-01

    Allan Hills 85085 is a unique chondrite with affinities to the Al Rais-Renazzo clan of carbonaceous chondrites. Its constituents are less than 50 ??m in mean size. Chondrules and microchondrules of all textures are present; nonporphyritic chondrules are unusually abundant. The mean compositions of porphyritic, nonporphyritic and barred olivine chondrules resemble those in ordinary chondrites except that they are depleted in volatile elements. Ca-, Al-rich inclusions are abundant and largely free of nebular alteration; they comprise types similar to those in CM and CO chondrites, as well as unique types. Calcium dialuminate occurs in several inclusions. Metal, silicate and sulfide compositions are close to those in CM-CO chondrites and Al Rais and Renazzo. C1-chondrite clasts and metal-rich "reduced" clasts are present, but opaque matrix is absent. Siderophile abundances in ALH85085 are extremely high (e.g., Fe Si = 1.7 ?? solar), and volatiles are depleted (e.g., Na Si = 0.25 ?? solar, S Si = 0.03 ?? solar). Nonvolatile lithophile abundances are similar to those in Al Rais, Renazzo, and CM and CO chondrites. ALH85085 agglomerated when temperatures in the nebula were near 1000 K, in the same region where Renazzo, Al Rais and the CI chondrites formed. Agglomeration of high-temperature material may thus be a mechanism by which the fractionation of refractory lithophiles occurred in the nebula. Chondrule formation must have occurred at high temperatures when clumps of precursors were small. After agglomeration, ALH85085 was annealed and lightly shocked. C1 and other clasts were subsequently incorporated during late-stage brecciation. ?? 1988.

  14. Gd Transition Probabilities and Abundances

    CERN Document Server

    Den Hartog, E A; Sneden, C; Cowan, J J

    2006-01-01

    Radiative lifetimes, accurate to +/- 5%, have been measured for 49 even-parity and 14 odd-parity levels of Gd II using laser-induced fluorescence. The lifetimes are combined with branching fractions measured using Fourier transform spectrometry to determine transition probabilities for 611 lines of Gd II. This work is the largest-scale laboratory study to date of Gd II transition probabilities and the first using a high performance Fourier transform spectrometer. This improved data set has been used to determine a new solar photospheric Gd abundance, log epsilon = 1.11 +/- 0.03. Revised Gd abundances have also been derived for the r-process-rich metal-poor giant stars CS 22892-052, BD+17 3248, and HD 115444. The resulting Gd/Eu abundance ratios are in very good agreement with the solar-system r-process ratio. We have employed the increasingly accurate stellar abundance determinations, resulting in large part from the more precise laboratory atomic data, to predict directly the Solar System r-process elemental...

  15. On guidance and volatility

    NARCIS (Netherlands)

    Billings, M.B.; Jennings, R.; Lev, B.

    2013-01-01

    Survey evidence suggests that managers voluntarily disclose information, particularly earnings guidance, with an aim toward dampening share price volatility. Yet, consultants and influential institutions advise against providing guidance — citing fears of litigation and market penalties associated w

  16. Dynamic Volatility Arbitrage

    DEFF Research Database (Denmark)

    Dorn, Jochen

    profit on well-developed markets. Dynamic participation features on cross asset portfolios are at rst sight a remedy to that dilemma. Based on volatility thresholds and portfolio re-balancing, the fund engineers try to create a "volatility guaranteed" investment opportunity by surfing on the unusual high...... concepts, next to nothing is known about position reverting strategies and how, and -even more important- in which context they are applied in practice. In the recent market downturn only one sector generated signicant profits for the leading investment banks: Volatility trading activities, namely on Forex......, interest rates and commodities. If an investor positions himself on the (volatility) market within a long/short trading framework, he typically bets on a traditional mispricing arbitrage. However as this corresponds to a call spread with equal exercise prices, this strategy alone would not generate enough...

  17. It’s all about volatility of volatility

    DEFF Research Database (Denmark)

    Grassi, Stefano; Santucci de Magistris, Paolo

    2015-01-01

    for the realized volatility series. It emerges that during the recent financial crisis the relative weight of the daily component dominates over the monthly term. The estimates of the two factor stochastic volatility model suggest that the change in the dynamic structure of the realized volatility during...... the financial crisis is due to the increase in the volatility of the persistent volatility term. A set of Monte Carlo simulations highlights the robustness of the methodology adopted in tracking the dynamics of the parameters....

  18. Non-volatile memories

    CERN Document Server

    Lacaze, Pierre-Camille

    2014-01-01

    Written for scientists, researchers, and engineers, Non-volatile Memories describes the recent research and implementations in relation to the design of a new generation of non-volatile electronic memories. The objective is to replace existing memories (DRAM, SRAM, EEPROM, Flash, etc.) with a universal memory model likely to reach better performances than the current types of memory: extremely high commutation speeds, high implantation densities and retention time of information of about ten years.

  19. La citometría de flujo en el estudio de tumores mediastinales ricos en elementos linfoides Flow cytometry for the study of mediastinal tumors with abundant lymphoid elements

    Directory of Open Access Journals (Sweden)

    Gerardo Vides Almonacid

    2008-02-01

    Full Text Available El mediastino anterior es un sitio frecuente de localización de tumores ricos en elementos linfoides. La identificación correcta de cada entidad es de importancia en el tratamiento de los pacientes. En ocasiones puede plantearse el diagnóstico diferencial entre timoma y linfoma linfoblástico con fenotipo de precursor T (LLB-T. La Citometría de Flujo (CF es una técnica complementaria útil para estos tumores de la cual se obtiene información cualitativa y cuantitativa. Revisamos 38 tumores mediastinales que tenían estudio de CF. Además comparamos los resultados de CF de timomas y tejido tímico normal con 42 casos de LLB-T de otras localizaciones anatómicas. De los 38 tumores mediastinales 6 eran lesiones benignas, 9 linfomas difusos de células grandes con fenotipo B (LDCG-B, 10 linfomas de Hodgkin (LH, 11 timomas y 2 LLB-T. En 24 casos la CF aportó información positiva, definiendo el inmunofenotipo de las células linfoides neoplásicas, o los linfocitos característicos que acompañan a los timomas. La CF en los 10 casos de LH y en 4 lesiones benignas permitió descartar otros tipos de linfoma (LDCG-B, LLB-T, etc.. Las marcaciones para CD3, CD4 y CD8 fueron las más útiles para el diagnóstico diferencial entre timomas y LLB-T. En conclusión, la CF es una técnica complementaria de utilidad que aporta información en lesiones mediastinales de manera rápida, requiriendo cantidades pequeñas de material, tanto para el diagnóstico inicial como para el monitoreo de estas enfermedades.The anterior mediastinum is a common site of tumors with abundant lymphoid elements. Flow cytometry is a useful complementary technique to analyze this type of tumors, which provides qualitative and quantitative information. A differential diagnosis can be sometimes made between thymoma and precursor T-lymphoblastic lymphoma (T-LBL. Correct identification is of utmost importance for patient treatment. A total of 38 mediastinal tumors were analyzed, and

  20. Different methods for volatile sampling in mammals.

    Science.gov (United States)

    Kücklich, Marlen; Möller, Manfred; Marcillo, Andrea; Einspanier, Almuth; Weiß, Brigitte M; Birkemeyer, Claudia; Widdig, Anja

    2017-01-01

    Previous studies showed that olfactory cues are important for mammalian communication. However, many specific compounds that convey information between conspecifics are still unknown. To understand mechanisms and functions of olfactory cues, olfactory signals such as volatile compounds emitted from individuals need to be assessed. Sampling of animals with and without scent glands was typically conducted using cotton swabs rubbed over the skin or fur and analysed by gas chromatography-mass spectrometry (GC-MS). However, this method has various drawbacks, including a high level of contaminations. Thus, we adapted two methods of volatile sampling from other research fields and compared them to sampling with cotton swabs. To do so we assessed the body odor of common marmosets (Callithrix jacchus) using cotton swabs, thermal desorption (TD) tubes and, alternatively, a mobile GC-MS device containing a thermal desorption trap. Overall, TD tubes comprised most compounds (N = 113), with half of those compounds being volatile (N = 52). The mobile GC-MS captured the fewest compounds (N = 35), of which all were volatile. Cotton swabs contained an intermediate number of compounds (N = 55), but very few volatiles (N = 10). Almost all compounds found with the mobile GC-MS were also captured with TD tubes (94%). Hence, we recommend TD tubes for state of the art sampling of body odor of mammals or other vertebrates, particularly for field studies, as they can be easily transported, stored and analysed with high performance instruments in the lab. Nevertheless, cotton swabs capture compounds which still may contribute to the body odor, e.g. after bacterial fermentation, while profiles from mobile GC-MS include only the most abundant volatiles of the body odor.

  1. Different methods for volatile sampling in mammals

    Science.gov (United States)

    Möller, Manfred; Marcillo, Andrea; Einspanier, Almuth; Weiß, Brigitte M.

    2017-01-01

    Previous studies showed that olfactory cues are important for mammalian communication. However, many specific compounds that convey information between conspecifics are still unknown. To understand mechanisms and functions of olfactory cues, olfactory signals such as volatile compounds emitted from individuals need to be assessed. Sampling of animals with and without scent glands was typically conducted using cotton swabs rubbed over the skin or fur and analysed by gas chromatography-mass spectrometry (GC-MS). However, this method has various drawbacks, including a high level of contaminations. Thus, we adapted two methods of volatile sampling from other research fields and compared them to sampling with cotton swabs. To do so we assessed the body odor of common marmosets (Callithrix jacchus) using cotton swabs, thermal desorption (TD) tubes and, alternatively, a mobile GC-MS device containing a thermal desorption trap. Overall, TD tubes comprised most compounds (N = 113), with half of those compounds being volatile (N = 52). The mobile GC-MS captured the fewest compounds (N = 35), of which all were volatile. Cotton swabs contained an intermediate number of compounds (N = 55), but very few volatiles (N = 10). Almost all compounds found with the mobile GC-MS were also captured with TD tubes (94%). Hence, we recommend TD tubes for state of the art sampling of body odor of mammals or other vertebrates, particularly for field studies, as they can be easily transported, stored and analysed with high performance instruments in the lab. Nevertheless, cotton swabs capture compounds which still may contribute to the body odor, e.g. after bacterial fermentation, while profiles from mobile GC-MS include only the most abundant volatiles of the body odor. PMID:28841690

  2. Sm Transition Probabilities and Abundances

    CERN Document Server

    Lawler, J E; Sneden, C; Cowan, J J

    2005-01-01

    Radiative lifetimes, accurate to +/- 5%, have been measured for 212 odd-parity levels of Sm II using laser-induced fluorescence. The lifetimes are combined with branching fractions measured using Fourier-transform spectrometry to determine transition probabilities for more than 900 lines of Sm II. This work is the largest-scale laboratory study to date of Sm II transition probabilities using modern methods. This improved data set has been used to determine a new solar photospheric Sm abundance, log epsilon = 1.00 +/- 0.03, from 26 lines. The spectra of three very metal-poor, neutron-capture-rich stars also have been analyzed, employing between 55 and 72 Sm II lines per star. The abundance ratios of Sm relative to other rare earth elements in these stars are in agreement, and are consistent with ratios expected from rapid neutron-capture nucleosynthesis (the r-process).

  3. Chemical abundance analysis of 19 barium stars

    CERN Document Server

    Yang, G C; Spite, M; Chen, Y Q; Zhao, G; Zhang, B; Liu, G Q; Liu, Y J; Liu, N; Deng, L C; Spite, F; Hill, V; Zhang, C X

    2016-01-01

    We aim at deriving accurate atmospheric parameters and chemical abundances of 19 barium (Ba) stars, including both strong and mild Ba stars, based on the high signal-to-noise ratio and high resolution Echelle spectra obtained from the 2.16 m telescope at Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences. The chemical abundances of the sample stars were obtained from an LTE, plane-parallel and line-blanketed atmospheric model by inputting the atmospheric parameters (effective temperatures, surface gravities, metallicity and microturbulent velocity) and equivalent widths of stellar absorption lines. These samples of Ba stars are giants indicated by atmospheric parameters, metallicities and kinematic analysis about UVW velocity. Chemical abundances of 17 elements were obtained for these Ba stars. Their light elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn and Ni) are similar to the solar abundances. Our samples of Ba stars show obvious overabundances of neutron-capture (n-ca...

  4. Volatile Constituents of Different Plant Parts and Populations of Malabaila aurea Boiss. from Montenegro

    OpenAIRE

    Ivan Vučković; Ljubodrag Vujisić; Marina Todosijević; Danijela Stešević; Slobodan Milosavljević; Sne žana Trifunović

    2014-01-01

    The volatile constituents of different plant parts and populations of Malabaila aurea Boiss. from Montenegro were obtained by simultaneous distillation-extraction and analyzed by GC-FID and GC-MS. A total of 12 samples were examined and 45 compounds were identified. The volatile content of different M. aurea populations was very similar, while the volatile fractions obtained from different plant parts showed significant qualitative and quantitative differences. The most abundant compounds fou...

  5. Highly siderophile and chalcogen element constraints on the origin of components of the Allende and Murchison meteorites

    Science.gov (United States)

    Kadlag, Yogita; Becker, Harry

    2016-06-01

    187Re-187Os systematics, abundances of highly siderophile elements (HSE: Re, PGE, and Au), chalcogen elements (Te, Se, and S), and some major and minor elements were determined in physically separated components of the Allende (CV3) and Murchison (CM2) carbonaceous chondrites. Substantial differences exist in the absolute and relative abundances of elements in the components, but the similarity of calculated and literature bulk rock abundances of HSE and chalcogens indicate that chemical complementarity exists among the components, with CI chondrite-like ratios for many elements. Despite subsequent alteration and oxidation, the overall cosmochemical behavior of most moderately to highly siderophile elements during high-temperature processing has been preserved in components of Allende at the sampling scale of the present study. The 187Re-187Os systematics and element variations of Allende are less disturbed compared with Murchison, which reflects different degrees of oxidation and alteration of these meteorites. The HSE systematics (with the exception of Au) is controlled by two types of materials: Pd-depleted condensates and CI chondrite-like material. Enrichment and heterogeneous distribution of Au among the components is likely the result of hydrothermal alteration. Chalcogen elements are depleted compared with HSE in all components, presumably due to their higher volatility. Small systematic variations of S, Se, and Te in components bear the signature of fractional condensation/partial evaporation and metal-sulfide-silicate partitioning.

  6. Oil and stock market volatility: A multivariate stochastic volatility perspective

    Energy Technology Data Exchange (ETDEWEB)

    Vo, Minh, E-mail: minh.vo@metrostate.edu

    2011-09-15

    This paper models the volatility of stock and oil futures markets using the multivariate stochastic volatility structure in an attempt to extract information intertwined in both markets for risk prediction. It offers four major findings. First, the stock and oil futures prices are inter-related. Their correlation follows a time-varying dynamic process and tends to increase when the markets are more volatile. Second, conditioned on the past information, the volatility in each market is very persistent, i.e., it varies in a predictable manner. Third, there is inter-market dependence in volatility. Innovations that hit either market can affect the volatility in the other market. In other words, conditioned on the persistence and the past volatility in their respective markets, the past volatility of the stock (oil futures) market also has predictive power over the future volatility of the oil futures (stock) market. Finally, the model produces more accurate Value-at-Risk estimates than other benchmarks commonly used in the financial industry. - Research Highlights: > This paper models the volatility of stock and oil futures markets using the multivariate stochastic volatility model. > The correlation between the two markets follows a time-varying dynamic process which tends to increase when the markets are more volatile. > The volatility in each market is very persistent. > Innovations that hit either market can affect the volatility in the other market. > The model produces more accurate Value-at-Risk estimates than other benchmarks commonly used in the financial industry.

  7. Volatile and Isotopic Imprints of Ancient Mars

    Science.gov (United States)

    Mahaffy, Paul R.; Conrad, Pamela G.

    2015-01-01

    The science investigations enabled by Curiosity rover's instruments focus on identifying and exploring the habitability of the Martian environment. Measurements of noble gases, organic and inorganic compounds, and the isotopes of light elements permit the study of the physical and chemical processes that have transformed Mars throughout its history. Samples of the atmosphere, volatiles released from soils, and rocks from the floor of Gale Crater have provided a wealth of new data and a window into conditions on ancient Mars.

  8. Understanding Interest Rate Volatility

    DEFF Research Database (Denmark)

    Volker, Desi

    This thesis is the result of my Ph.D. studies at the Department of Finance of the Copenhagen Business School. It consists of three essays covering topics related to the term structure of interest rates, monetary policy and interest rate volatility. The rst essay, \\Monetary Policy Uncertainty...... and Interest Rates", examines the role of monetary policy uncertainty on the term structure of interest rates. The second essay, \\A Regime-Switching A ne Term Structure Model with Stochastic Volatility" (co-authored with Sebastian Fux), investigates the ability of the class of regime switching models...... with and without stochastic volatility to capture the main stylized features of U.S. interest rates. The third essay, \\Variance Risk Premia in the Interest Rate Swap Market", investigates the time-series and cross-sectional properties of the compensation demanded for holding interest rate variance risk. The essays...

  9. Stochastic volatility selected readings

    CERN Document Server

    Shephard, Neil

    2005-01-01

    Neil Shephard has brought together a set of classic and central papers that have contributed to our understanding of financial volatility. They cover stocks, bonds and currencies and range from 1973 up to 2001. Shephard, a leading researcher in the field, provides a substantial introduction in which he discusses all major issues involved. General Introduction N. Shephard. Part I: Model Building. 1. A Subordinated Stochastic Process Model with Finite Variance for Speculative Prices, (P. K. Clark). 2. Financial Returns Modelled by the Product of Two Stochastic Processes: A Study of Daily Sugar Prices, 1961-7, S. J. Taylor. 3. The Behavior of Random Variables with Nonstationary Variance and the Distribution of Security Prices, B. Rosenberg. 4. The Pricing of Options on Assets with Stochastic Volatilities, J. Hull and A. White. 5. The Dynamics of Exchange Rate Volatility: A Multivariate Latent Factor ARCH Model, F. X. Diebold and M. Nerlove. 6. Multivariate Stochastic Variance Models. 7. Stochastic Autoregressive...

  10. Volatile compounds of dry beans (Phaseolus vulgaris L.).

    Science.gov (United States)

    Oomah, B Dave; Liang, Lisa S Y; Balasubramanian, Parthiba

    2007-12-01

    Volatile compounds of uncooked dry bean (Phaseolus vulgaris L.) cultivars representing three market classes (black, dark red kidney and pinto) grown in 2005 were isolated with headspace solid phase microextraction (HS-SPME), and analyzed with gas chromatography mass spectrometry (GC-MS). A total of 62 volatiles consisting of aromatic hydrocarbons, aldehydes, alkanes, alcohols and ketones represented on average 62, 38, 21, 12, and 9 x 10(6) total area counts, respectively. Bean cultivars differed in abundance and profile of volatiles. The combination of 18 compounds comprising a common profile explained 79% of the variance among cultivars based on principal component analysis (PCA). The SPME technique proved to be a rapid and effective method for routine evaluation of dry bean volatile profile.

  11. Chemical fractionation of siderophile elements in impactites from Australian meteorite craters

    Science.gov (United States)

    Attrep, A., Jr.; Orth, C. J.; Quintana, L. R.; Shoemaker, C. S.; Shoemaker, E. M.; Taylor, S. R.

    1991-01-01

    The abundance pattern of siderophile elements in terrestrial and lunar impact melt rocks was used extensively to infer the nature of the impacting projectiles. An implicit assumption made is that the siderophile abundance ratios of the projectiles are approximately preserved during mixing of the projectile constituents with the impact melts. As this mixture occurs during flow of strongly shocked materials at high temperatures, however there are grounds for suspecting that the underlying assumption is not always valid. In particular, fractionation of the melted and partly vaporized material of the projectile might be expected because of differences in volatility, solubility in silicate melts, and other characteristics of the constituent elements. Impactites from craters with associated meteorites offer special opportunities to test the assumptions on which projectile identifications are based and to study chemical fractionation that occurred during the impact process.

  12. Pricing Volatility of Stock Returns with Volatile and Persistent Components

    DEFF Research Database (Denmark)

    Zhu, Jie

    2009-01-01

    This paper introduces a two-component volatility model based on first moments of both components to describe the dynamics of speculative return volatility. The two components capture the volatile and the persistent part of volatility, respectively. The model is applied to 10 Asia-Pacific stock...... markets. Their in-mean effects on returns are tested. The empirical results show that the persistent component is much more important for the volatility dynamic process than is the volatile component. However, the volatile component is found to be a significant pricing factor of asset returns for most...... markets. A positive or risk-premium effect exists between the return and the volatile component, yet the persistent component is not significantly priced for the return dynamic process....

  13. On the Solar Nickel and Oxygen Abundances

    Science.gov (United States)

    Scott, Pat; Asplund, Martin; Grevesse, Nicolas; Sauval, A. Jacques

    2009-02-01

    Determinations of the solar oxygen content relying on the neutral forbidden transition at 630 nm depend upon the nickel abundance, due to a Ni I blend. Here, we rederive the solar nickel abundance, using the same ab initio three-dimensional hydrodynamic model of the solar photosphere employed in the recent revision of the abundances of C, N, O, and other elements. Using 17 weak, unblended lines of Ni I together with the most accurate atomic and observational data available, we find log epsilonNi = 6.17 ± 0.02(statistical) ± 0.05(systematic), a downward shift of 0.06-0.08 dex relative to previous abundances based on one-dimensional model atmospheres. We investigate the implications of the new nickel abundance for studies of the solar oxygen abundance based on the [O I] 630 nm line in the quiet Sun. Furthermore, we demonstrate that the oxygen abundance implied by the recent sunspot spectropolarimetric study of Centeno & Socas-Navarro needs to be revised downward from log epsilonO = 8.86 ± 0.07 to 8.71 ± 0.10. This revision is based on the new nickel abundance, the application of the best available gf value for the 630 nm forbidden oxygen line, and a more transparent treatment of CO formation. Determinations of the solar oxygen content relying on forbidden lines now appear to converge around log epsilonO = 8.7.

  14. Volatile hydrocarbons inhibit methanogenic crude oil degradation

    Directory of Open Access Journals (Sweden)

    Angela eSherry

    2014-04-01

    Full Text Available Methanogenic degradation of crude oil in subsurface sediments occurs slowly, but without the need for exogenous electron acceptors, is sustained for long periods and has enormous economic and environmental consequences. Here we show that volatile hydrocarbons are inhibitory to methanogenic oil biodegradation by comparing degradation of an artificially weathered crude oil with volatile hydrocarbons removed, with the same oil that was not weathered. Volatile hydrocarbons (nC5-nC10, methylcyclohexane, benzene, toluene and xylenes were quantified in the headspace of microcosms. Aliphatic (n-alkanes nC12-nC34 and aromatic hydrocarbons (4-methylbiphenyl, 3-methylbiphenyl, 2-methylnaphthalene, 1-methylnaphthalene were quantified in the total hydrocarbon fraction extracted from the microcosms. 16S rRNA genes from key microorganisms known to play an important role in methanogenic alkane degradation (Smithella and Methanomicrobiales were quantified by quantitative PCR. Methane production from degradation of weathered oil in microcosms was rapid (1.1 ± 0.1 µmol CH4/g sediment/day with stoichiometric yields consistent with degradation of heavier n-alkanes (nC12-nC34. For non-weathered oil, degradation rates in microcosms were significantly lower (0.4 ± 0.3 µmol CH4/g sediment/day. This indicated that volatile hydrocarbons present in the non-weathered oil inhibit, but do not completely halt, methanogenic alkane biodegradation. These findings are significant with respect to rates of biodegradation of crude oils with abundant volatile hydrocarbons in anoxic, sulphate-depleted subsurface environments, such as contaminated marine sediments which have been entrained below the sulfate-reduction zone, as well as crude oil biodegradation in petroleum reservoirs and contaminated aquifers.

  15. Pricing Volatility of Stock Returns with Volatile and Persistent Components

    DEFF Research Database (Denmark)

    Zhu, Jie

    In this paper a two-component volatility model based on the component's first moment is introduced to describe the dynamic of speculative return volatility. The two components capture the volatile and persistent part of volatility respectively. Then the model is applied to 10 Asia-Pacific stock m......, a positive or risk-premium effect exists between return and the volatile component, yet the persistent component is not significantly priced for return dynamic process.......In this paper a two-component volatility model based on the component's first moment is introduced to describe the dynamic of speculative return volatility. The two components capture the volatile and persistent part of volatility respectively. Then the model is applied to 10 Asia-Pacific stock...... markets. Their in-mean effects on return are also tested. The empirical results show that the persistent component accounts much more for volatility dynamic process than the volatile component. However the volatile component is found to be a significant pricing factor of asset returns for most markets...

  16. Chemical abundances and kinematics of barium stars

    CERN Document Server

    de Castro, D B; Roig, F; Jilinski, E; Drake, N A; Chavero, C; Silva, J V Sales

    2016-01-01

    In this paper we present an homogeneous analysis of photospheric abundances based on high-resolution spectroscopy of a sample of 182 barium stars and candidates. We determined atmospheric parameters, spectroscopic distances, stellar masses, ages, luminosities and scale height, radial velocities, abundances of the Na, Al, $alpha$-elements, iron-peak elements, and s-process elements Y, Zr, La, Ce, and Nd. We employed the local-thermodynamic-equilibrium model atmospheres of Kurucz and the spectral analysis code {\\sc moog}. We found that the metallicities, the temperatures and the surface gravities for barium stars can not be represented by a single gaussian distribution. The abundances of $alpha$-elements and iron peak elements are similar to those of field giants with the same metallicity. Sodium presents some degree of enrichment in more evolved stars that could be attributed to the NeNa cycle. As expected, the barium stars show overabundance of the elements created by the s-process. By measuring the mean heav...

  17. OXYGEN ABUNDANCES IN CEPHEIDS

    Energy Technology Data Exchange (ETDEWEB)

    Luck, R. E.; Andrievsky, S. M. [Department of Astronomy, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-7215 (United States); Korotin, S. N.; Kovtyukh, V. V., E-mail: luck@fafnir.astr.cwru.edu, E-mail: serkor@skyline.od.ua, E-mail: val@deneb1.odessa.ua, E-mail: scan@deneb1.odessa.ua [Department of Astronomy and Astronomical Observatory, Odessa National University, Isaac Newton Institute of Chile, Odessa Branch, Shevchenko Park, 65014 Odessa (Ukraine)

    2013-07-01

    Oxygen abundances in later-type stars, and intermediate-mass stars in particular, are usually determined from the [O I] line at 630.0 nm, and to a lesser extent, from the O I triplet at 615.7 nm. The near-IR triplets at 777.4 nm and 844.6 nm are strong in these stars and generally do not suffer from severe blending with other species. However, these latter two triplets suffer from strong non-local thermodynamic equilibrium (NLTE) effects and thus see limited use in abundance analyses. In this paper, we derive oxygen abundances in a large sample of Cepheids using the near-IR triplets from an NLTE analysis, and compare those abundances to values derived from a local thermodynamic equilibrium (LTE) analysis of the [O I] 630.0 nm line and the O I 615.7 nm triplet as well as LTE abundances for the 777.4 nm triplet. All of these lines suffer from line strength problems making them sensitive to either measurement complications (weak lines) or to line saturation difficulties (strong lines). Upon this realization, the LTE results for the [O I] lines and the O I 615.7 nm triplet are in adequate agreement with the abundance from the NLTE analysis of the near-IR triplets.

  18. Dynamic Volatility Arbitrage

    DEFF Research Database (Denmark)

    Dorn, Jochen

    concepts, next to nothing is known about position reverting strategies and how, and -even more important- in which context they are applied in practice. In the recent market downturn only one sector generated signicant profits for the leading investment banks: Volatility trading activities, namely on Forex...

  19. The solar photospheric abundance of zirconium

    CERN Document Server

    Caffau, Elisabetta; Ludwig, Hans-Günter; Bonifacio, Piercarlo; Steffen, Matthias

    2010-01-01

    Zirconium (Zr), together with strontium and yttrium, is an important element in the understanding of the Galactic nucleosynthesis. In fact, the triad Sr-Y-Zr constitutes the first peak of s-process elements. Despite its general relevance not many studies of the solar abundance of Zr were conducted. We derive the zirconium abundance in the solar photosphere with the same CO5BOLD hydrodynamical model of the solar atmosphere that we previously used to investigate the abundances of C-N-O. We review the zirconium lines available in the observed solar spectra and select a sample of lines to determine the zirconium abundance, considering lines of neutral and singly ionised zirconium. We apply different line profile fitting strategies for a reliable analysis of Zr lines that are blended by lines of other elements. The abundance obtained from lines of neutral zirconium is very uncertain because these lines are commonly blended and weak in the solar spectrum. However, we believe that some lines of ionised zirconium are...

  20. Signatures of volatiles in the lunar proton albedo

    Science.gov (United States)

    Schwadron, N. A.; Wilson, J. K.; Looper, M. D.; Jordan, A. P.; Spence, H. E.; Blake, J. B.; Case, A. W.; Iwata, Y.; Kasper, J. C.; Farrell, W. M.; Lawrence, D. J.; Livadiotis, G.; Mazur, J.; Petro, N.; Pieters, C.; Robinson, M. S.; Smith, S.; Townsend, L. W.; Zeitlin, C.

    2016-07-01

    We find evidence for hydrated material in the lunar regolith using "albedo protons" measured with the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO). Fluxes of these albedo protons, which are emitted from the regolith due to steady bombardment by high energy radiation (Galactic Cosmic Rays), are observed to peak near the poles, and are inconsistent with the latitude trends of heavy element enrichment (e.g., enhanced Fe abundance). The latitudinal distribution of albedo protons anti-correlates with that of epithermal or high energy neutrons. The high latitude enhancement may be due to the conversion of upward directed secondary neutrons from the lunar regolith into tertiary protons due to neutron-proton collisions in hydrated regolith that is more prevalent near the poles. The CRaTER instrument may thus provide important measurements of volatile distributions within regolith at the Moon and potentially, with similar sensors and observations, at other bodies within the Solar System.

  1. Signatures of Volatiles in the Lunar Proton Albedo

    Science.gov (United States)

    Schwadron, N. A.; Wilson, J. K.; Looper, M. D.; Jordan, A. P.; Spence, H. E.; Blake, J. B.; Case, A. W.; Iwata, Y.; Kasper, J. C.; Farrell, W. M.; hide

    2015-01-01

    We find evidence for hydrated material in the lunar regolith using "albedo protons" measured with the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO). Fluxes of these albedo protons, which are emitted from the regolith due to steady bombardment by high energy radiation (Galactic Cosmic Rays), are observed to peak near the poles, and are inconsistent with the latitude trends of heavy element enrichment (e.g., enhanced Fe abundance). The latitudinal distribution of albedo protons anti-correlates with that of epithermal or high energy neutrons. The high latitude enhancement may be due to the conversion of upward directed secondary neutrons from the lunar regolith into tertiary protons due to neutron-proton collisions in hydrated regolith that is more prevalent near the poles. The CRaTER instrument may thus provide important measurements of volatile distributions within regolith at the Moon and potentially, with similar sensors and observations, at other bodies within the Solar System.

  2. Signatures of Volatiles in the Lunar Proton Albedo

    Science.gov (United States)

    Schwadron, N. A.; Wilson, J. K.; Looper, M. D.; Jordan, A. P.; Spence, H. E.; Blake, J. B.; Case, A. W.; Iwata, Y.; Kasper, J. C.; Farrell, W. M.; Petro, N.

    2015-01-01

    We find evidence for hydrated material in the lunar regolith using "albedo protons" measured with the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO). Fluxes of these albedo protons, which are emitted from the regolith due to steady bombardment by high energy radiation (Galactic Cosmic Rays), are observed to peak near the poles, and are inconsistent with the latitude trends of heavy element enrichment (e.g., enhanced Fe abundance). The latitudinal distribution of albedo protons anti-correlates with that of epithermal or high energy neutrons. The high latitude enhancement may be due to the conversion of upward directed secondary neutrons from the lunar regolith into tertiary protons due to neutron-proton collisions in hydrated regolith that is more prevalent near the poles. The CRaTER instrument may thus provide important measurements of volatile distributions within regolith at the Moon and potentially, with similar sensors and observations, at other bodies within the Solar System.

  3. Forming chondrules in impact splashes - II Volatile retention

    CERN Document Server

    Dullemond, Cornelis Petrus; Stammler, Sebastian Markus; Johansen, Anders

    2016-01-01

    Solving the mystery of the origin of chondrules is one of the most elusive goals in the field of meteoritics. Recently the idea of planet(esimal) collisions releasing splashes of lava droplets, long considered out of favor, has been reconsidered as a possible origin of chondrules by several papers. One of the main problems with this idea is the lack of quantitative and simple models that can be used to test this scenario by directly comparing to the many known observables of chondrules. In Paper I of this series we presented a simple thermal evolution model of a spherically symmetric expanding cloud of molten lava droplets that is assumed to emerge from a collision between two planetesimals. In the present paper, number II of this series, we use this model to calculate whether or not volatile elements such as Na and K will remain abundant in these droplets or whether they will get depleted due to evaporation. The high density of the droplet cloud (e.g. small distance between adjacent droplets) causes the vapo...

  4. Stock markets liberalization affects volatility?

    OpenAIRE

    Ioan Alin NISTOR; Maria-Lenuţa CIUPAC-ULICI; GHERMAN Mircea-Cristian

    2012-01-01

    Regarding the impact of liberalization, the results show that, in general, market opening is accompanied by a significant increase in market volatility. In particular, volatility tends to decrease due to large capital inflows and domestic growth.The study analyzes the impact of stock market liberalization on volatility in six emerging stock markets by using GARCH methodology. Theory on the effects of financial liberalization on volatility has been ambiguous, and empirical work has yielded con...

  5. Volatile carbon locking and release in protoplanetary disks. A study of TW Hya and HD 100546

    CERN Document Server

    Kama, M; van Dishoeck, E F; Hogerheijde, M; Folsom, C P; Miotello, A; Fedele, D; Belloche, A; Güsten, R; Wyrowski, F

    2016-01-01

    The composition of planetary solids and gases is largely rooted in the processing of volatile elements in protoplanetary disks. To shed light on the key processes, we carry out a comparative analysis of the gas-phase carbon abundance in two systems with a similar age and disk mass, but different central stars: HD 100546 and TW Hya. We combine our recent detections of C$^{0}$ in these disks with observations of other carbon reservoirs (CO, C$^{+}$, C$_{2}$H) and gas mass and warm gas tracers (HD, O$^{0}$), as well as spatially resolved ALMA observations and the spectral energy distribution. The disks are modelled with the DALI 2D physical-chemical code. Stellar abundances for HD 100546 are derived from archival spectra. Upper limits on HD emission from HD 100546 place an upper limit on the total disk mass of $\\leq0.1\\,M_{\\odot}$. The gas-phase carbon abundance in the atmosphere of this warm Herbig disk is at most moderately depleted compared to the interstellar medium, with [C]/[H]$_{\\rm gas}=(0.1-1.5)\\times 1...

  6. Ammonia volatilization from coated urea forms

    Directory of Open Access Journals (Sweden)

    Carlos Antonio Costa do Nascimento

    2013-08-01

    Full Text Available Nitrogen fertilization is a major component of the cost of agricultural production, due to the high cost and low efficiency of fertilizers. In the case of urea, the low efficiency is mainly due to losses by volatilization, which are more pronounced in cultivation systems in which plant residues are left on the soil. The objective of this work was to compare the influence of urea coated with sulfur or boric acid and copper sulfate with conventional N fertilizers on N volatilization losses in sugar cane harvested after stubble burning. The sources urea, sulfur-coated urea, urea coated with boric acid and copper sulfate, as well as nitrate and ammonium sulfate, were tested at amounts containing N rates of 120 kg ha-1 N. The integration of new technologies in urea fertilization can reduce N losses by volatilization. These losses were most reduced when using nitrate and ammonium sulfate. The application of a readily acidified substance (boric acid to urea was more efficient in reducing volatilization losses and nutrient removal by sugar cane than that of a substance with gradual acidification (elemental sulfur.

  7. Changes in volatiles and glycosides during fruit maturation of two contrasted tomato ( Solanum lycopersicum ) lines.

    Science.gov (United States)

    Birtić, Simona; Ginies, Christian; Causse, Mathilde; Renard, Catherine M G C; Page, David

    2009-01-28

    The relationship between fruit maturation and volatile contents was investigated in two contrasted Cervil (CER) and Levovil (LEV) tomato ( Solanum lycopersicum ) lines. As fruits ripened, their volatile contents mainly increased. Although some compounds displayed contrasting patterns, overall, volatiles were clearly more abundant and conferred stronger aromas to CER than to LEV fruits. This intervarietal difference in volatile contents yielding much lower volatile contents in LEV was further investigated to determine whether it is due to a higher capacity of volatile glycosylation within LEV as compared to CER. Again, glycosides mainly increased during fruit maturation and were more abundant within CER than within LEV. Overall glycoside findings were indicative of a superior capacity to biosynthesize rather than an inferior capacity to glycosylate volatiles of CER. Eugenol and 2-methoxyphenol volatiles were exceptional compounds as they remained at higher levels in maturing LEV than in CER. 2-Methylthioacetaldehyde was for the first time identified as putatively related to differences of aroma between lines, as it was abundant in Cervil but absent in Levovil. Considering the described odor value of these three products, they should contribute differently to the particular olfactive features of LEV and CER fruits.

  8. The exploitation of volatile oil

    Institute of Scientific and Technical Information of China (English)

    MENG Teng; ZHANG Da; TENG Xiangjin; LINing; HAO Zaibin

    2007-01-01

    Rose is a kind of favorite ornamental plant. This article briefly introduced the cultivation and the use of rose around the world both in ancient time and nowadays. Today, volatile oil becomes the mainstream of the rose industry. People pay attention to the effect of volatile oil; meanwhile, they speed up their research on extracting volatile oil and the ingredients.

  9. Plant volatiles and the environment

    NARCIS (Netherlands)

    Loreto, F.; Dicke, M.; Schnitzler, J.P.; Turlings, T.C.J.

    2014-01-01

    Volatile organic compounds emitted by plants represent the largest part of biogenic volatile organic compounds (BVOCs) released into our atmosphere. Plant volatiles are formed through many biochemical pathways, constitutively and after stress induction. In recent years, our understanding of the func

  10. Latent Integrated Stochastic Volatility, Realized Volatility, and Implied Volatility: A State Space Approach

    DEFF Research Database (Denmark)

    Bach, Christian; Christensen, Bent Jesper

    We include simultaneously both realized volatility measures based on high-frequency asset returns and implied volatilities backed out of individual traded at the money option prices in a state space approach to the analysis of true underlying volatility. We model integrated volatility as a latent...... fi…rst order Markov process and show that our model is closely related to the CEV and Barndorff-Nielsen & Shephard (2001) models for local volatility. We show that if measurement noise in the observable volatility proxies is not accounted for, then the estimated autoregressive parameter in the latent...... process is downward biased. Implied volatility performs better than any of the alternative realized measures when forecasting future integrated volatility. The results are largely similar across the stock market (S&P 500), bond market (30-year U.S. T-bond), and foreign currency exchange market ($/£ )....

  11. Comparison of Hygroscopicity, Volatility, and Mixing State of Submicrometer Particles between Cruises over the Arctic Ocean and the Pacific Ocean.

    Science.gov (United States)

    Kim, Gibaek; Cho, Hee-Joo; Seo, Arom; Kim, Dohyung; Gim, Yeontae; Lee, Bang Yong; Yoon, Young Jun; Park, Kihong

    2015-10-20

    Ship-borne measurements of ambient aerosols were conducted during an 11 937 km cruise over the Arctic Ocean (cruise 1) and the Pacific Ocean (cruise 2). A frequent nucleation event was observed during cruise 1 under marine influence, and the abundant organic matter resulting from the strong biological activity in the ocean could contribute to the formation of new particles and their growth to a detectable size. Concentrations of particle mass and black carbon increased with increasing continental influence from polluted areas. During cruise 1, multiple peaks of hygroscopic growth factor (HGF) of 1.1-1.2, 1.4, and 1.6 were found, and higher amounts of volatile organic species existed in the particles compared to that during cruise 2, which is consistent with the greater availability of volatile organic species caused by the strong oceanic biological activity (cruise 1). Internal mixtures of volatile and nonhygroscopic organic species, nonvolatile and less-hygroscopic organic species, and nonvolatile and hygroscopic nss-sulfate with varying fractions can be assumed to constitute the submicrometer particles. On the basis of elemental composition and morphology, the submicrometer particles were classified into C-rich mixture, S-rich mixture, C/S-rich mixture, Na-rich mixture, C/P-rich mixture, and mineral-rich mixture. Consistently, the fraction of biological particles (i.e., P-containing particles) increased when the ship traveled along a strongly biologically active area.

  12. Determination of non-volatile and volatile organic acids in Korean traditional fermented soybean paste (Doenjang).

    Science.gov (United States)

    Shukla, Shruti; Choi, Tae Bong; Park, Hae-Kyong; Kim, Myunghee; Lee, In Koo; Kim, Jong-Kyu

    2010-01-01

    Organic acids are formed in food as a result of metabolism of large molecular mass compounds. These organic acids play an important role in the taste and aroma of fermented food products. Doenjang is a traditional Korean fermented soybean paste product that provides a major source of protein. The quantitative data for volatile and non-volatile organic acid contents of 18 samples of Doenjang were determined by comparing the abundances of each peak by gas (GC) and high performance liquid chromatography (HPLC). The mean values of volatile organic acids (acetic acid, butyric acid, propionic acid and 3-methyl butanoic acid), determined in 18 Doenjang samples, were found to be 91.73, 29.54, 70.07 and 19.80 mg%, respectively, whereas the mean values of non-volatile organic acids, such as oxalic acid, citric acid, lactic acid and succinic acid, were noted to be 14.69, 5.56, 9.95 and 0.21 mg%, respectively. Malonic and glutaric acids were absent in all the tested samples of Doenjang. The findings of this study suggest that determination of organic acid contents by GC and HPLC can be considered as an affective approach to evaluate the quality characteristics of fermented food products.

  13. Behaviour of elements from lithium to europium in stars with and without planets

    Science.gov (United States)

    Mishenina, T.; Kovtyukh, V.; Soubiran, C.; Adibekyan, V. Zh.

    2016-10-01

    We conducted an analysis of the distribution of elements from lithium to europium in 200 dwarfs in the solar neighbourhood (˜20 pc) with temperatures in the range 4800-6200 K and metallicities [Fe/H] higher than -0.5 dex. Determinations of atmospheric parameters and the chemical compositions of the dwarfs were taken from our previous studies. We found that the lithium abundances in the planet-hosting solar-analogue stars of our sample were lower than those in the stars without planetary systems. Our results reveal no significant differences exceeding the determination errors for the abundances of investigated elements, except for aluminium and barium, which are more and less abundant in the planet-hosting stars, respectively. We did not find confident dependences of the lithium, aluminium and barium abundances on the ages of our target stars (which is probably because of the small number of stars). Furthermore, we found no correlation between the abundance differences in [El/Fe] and the condensation temperature (Tcond) for stars in the 16 Cyg binary system, unlike the case for 51 Peg (HD 217014), for which a slight excess of volatile elements and a deficit of refractories were obtained relative to those of solar twins. We found that one of the components of 16 Cyg exhibits a slightly higher average abundance than its counterpart ( = 0.08 ±0.02 dex); however, no significant abundance trend versus Tcond was observed. Owing to the relatively large errors, we cannot provide further constraints for this system.

  14. Scaling Foreign Exchange Volatility

    OpenAIRE

    Jonathan Batten; Craig Ellis

    2001-01-01

    When asset returns are normally distributed the risk of an asset over a long return interval may be estimated by scaling the risk from shorter return intervals. While it is well known that asset returns are not normally distributed a key empirical question concerns the effect that scaling the volatility of dependent processes will have on the pricing of related financial assets. This study provides an insight into this issue by investigating the return properties of the most important currenc...

  15. Exploring heterogeneous market hypothesis using realized volatility

    Science.gov (United States)

    Chin, Wen Cheong; Isa, Zaidi; Mohd Nor, Abu Hassan Shaari

    2013-04-01

    This study investigates the heterogeneous market hypothesis using high frequency data. The cascaded heterogeneous trading activities with different time durations are modelled by the heterogeneous autoregressive framework. The empirical study indicated the presence of long memory behaviour and predictability elements in the financial time series which supported heterogeneous market hypothesis. Besides the common sum-of-square intraday realized volatility, we also advocated two power variation realized volatilities in forecast evaluation and risk measurement in order to overcome the possible abrupt jumps during the credit crisis. Finally, the empirical results are used in determining the market risk using the value-at-risk approach. The findings of this study have implications for informationally market efficiency analysis, portfolio strategies and risk managements.

  16. Deuterium abundance and cosmology

    CERN Document Server

    Vidal-Madjar, A; Lemoine, M

    1996-01-01

    We review the status of the measurements of the deuterium abundance from the local interstellar medium to the solar system and high redshifts absorbers toward quasars. We present preliminary results toward a white dwarf and a QSO. We conclude that the deuterium evolution from the Big-Bang to now is still not properly understood.

  17. An Intelligent Analysis Model for Multisource Volatile Memory

    Directory of Open Access Journals (Sweden)

    Xiaolu Zhang

    2013-09-01

    Full Text Available For the rapidly development of network and distributed computing environment, it make researchers harder to do analysis examines only from one or few pieces of data source in persistent data-oriented approaches, so as the volatile memory analysis either. Therefore, mass data automatically analysis and action modeling needs to be considered for reporting entire network attack process. To model multiple volatile data sources situation can help understand and describe both thinking process of investigator and possible action step for attacker. This paper presents a Game model for multisource volatile data and applies it to main memory images analysis with the definition of space-time feature for volatile element information. Abstract modeling allows the lessons gleaned in performing intelligent analysis, evidence filing and automating presentation. Finally, a test demo based on the model is also present to illustrate the whole procedure

  18. Analysis of 26 Barium Stars I. Abundances

    CERN Document Server

    Allen, D M; Allen, Dinah M.; Barbuy, Beatriz

    2006-01-01

    We present a detailed analysis of 26 barium stars, including dwarf barium stars, providing their atmospheric parameters (Teff, log g, [Fe/H], vt) and elemental abundances. We aim at deriving gravities and luminosity classes of the sample stars, in particular to confirm the existence of dwarf barium stars. Accurate abundances of chemical elements were derived. Abundance ratios between nucleosynthetic processes, by using Eu and Ba as representatives of the r- and s-processes are presented. High-resolution spectra with the FEROS spectrograph at the ESO-1.5m Telescope, and photometric data with Fotrap at the Zeiss telescope at the LNA were obtained. The atmospheric parameters were derived in an iterative way, with temperatures obtained from colour-temperature calibrations. The abundances were derived using spectrum synthesis for Li, Na, Al, alpha-, iron peak, s- and r-elements atomic lines, and C and N molecular lines. Atmospheric parameters in the range 4300 < Teff < 6500, -1.2 < [Fe/H] < 0.0 and 1.4...

  19. An Analysis of the Condensation Temperature of Elements of Extrasolar Planetary Systems

    Institute of Scientific and Technical Information of China (English)

    Cong Huang; Gang Zhao; Hua-Wei Zhang; Yu-Qin Chen

    2005-01-01

    Using high signal-to-noise ratio spectra of extrasolar planet-hosting stars, we obtained the atmospheric parameters, accurate metallicities and the differential abundance for 15 elements (C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn,Ni and Ba). In a search for possible signatures of metal-rich material accreting onto the parent stars, we found that, for a given element, there is no significant trend of increasing [X/H] with increasing condensation temperature Tc. In our sample of planet-harboring stars, the volatile and refractory elements behave similarly, and we can not confirm if there exists any significant dependence on the condensation temperature Tc.

  20. Planetary nebulae abundances and stellar evolution

    CERN Document Server

    Pottasch, S R

    2006-01-01

    A summary is given of planetary nebulae abundances from ISO measurements. It is shown that these nebulae show abundance gradients (with galactocentric distance), which in the case of neon, argon, sulfur and oxygen (with four exceptions) are the same as HII regions and early type star abundance gradients. The abundance of these elements predicted from these gradients at the distance of the Sun from the center are exactly the solar abundance. Sulfur is the exception to this; the reason for this is discussed. The higher solar neon abundance is confirmed; this is discussed in terms of the results of helioseismology. Evidence is presented for oxygen destruction via ON cycling having occurred in the progenitors of four planetary nebulae with bilobal structure. These progenitor stars had a high mass, probably greater than 5 solar masses. This is deduced from the high values of He/H and N/H found in these nebulae. Formation of nitrogen, helium and carbon are discussed. The high mass progenitors which showed oxygen de...

  1. TEA: A Code Calculating Thermochemical Equilibrium Abundances

    Science.gov (United States)

    Blecic, Jasmina; Harrington, Joseph; Bowman, M. Oliver

    2016-07-01

    We present an open-source Thermochemical Equilibrium Abundances (TEA) code that calculates the abundances of gaseous molecular species. The code is based on the methodology of White et al. and Eriksson. It applies Gibbs free-energy minimization using an iterative, Lagrangian optimization scheme. Given elemental abundances, TEA calculates molecular abundances for a particular temperature and pressure or a list of temperature-pressure pairs. We tested the code against the method of Burrows & Sharp, the free thermochemical equilibrium code Chemical Equilibrium with Applications (CEA), and the example given by Burrows & Sharp. Using their thermodynamic data, TEA reproduces their final abundances, but with higher precision. We also applied the TEA abundance calculations to models of several hot-Jupiter exoplanets, producing expected results. TEA is written in Python in a modular format. There is a start guide, a user manual, and a code document in addition to this theory paper. TEA is available under a reproducible-research, open-source license via https://github.com/dzesmin/TEA.

  2. Changes in volatile compounds from sliced Havarti cheese during storage analyzed by dynamic headspace GC/MS

    DEFF Research Database (Denmark)

    Lund, Pia; Sørensen, J.; Hansen, L.F.;

    2002-01-01

    , esters, lactones, and hydrocarbons) were identified and their relative abundance was followed during storage. The complete data set of volatiles of all Havarti cheeses was subjected to partial least squares regression (PLSR) analyses. During storage an increase in the content of some of the volatiles...

  3. Origin of Cosmic Chemical Abundances

    CERN Document Server

    Maio, Umberto

    2015-01-01

    Cosmological N-body hydrodynamic computations following atomic and molecular chemistry (e$^-$, H, H$^+$, H$^-$, He, He$^+$, He$^{++}$, D, D$^+$, H$_2$, H$_2^+$, HD, HeH$^+$), gas cooling, star formation and production of heavy elements (C, N, O, Ne, Mg, Si, S, Ca, Fe, etc.) from stars covering a range of mass and metallicity are used to explore the origin of several chemical abundance patterns and to study both the metal and molecular content during simulated galaxy assembly. The resulting trends show a remarkable similarity to up-to-date observations of the most metal-poor damped Lyman-$\\alpha$ absorbers at redshift $z\\gtrsim 2$. These exhibit a transient nature and represent collapsing gaseous structures captured while cooling is becoming effective in lowering the temperature below $\\sim 10^4\\,\\rm K$, before they are disrupted by episodes of star formation or tidal effects. Our theoretical results agree with the available data for typical elemental ratios, such as [C/O], [Si/Fe], [O/Fe], [Si/O], [Fe/H], [O/...

  4. Abundances of metals in five nearby open clusters

    CERN Document Server

    Hui-Bon-Hoa, A

    1998-01-01

    Abundances of Mg, Ca, Sc, Cr, Fe, and Ni are derived for A stars of five nearby open clusters of various ages using high resolution spectroscopy. We point out a correlation between the abundance of Ca and that of Sc, suggesting that the abundance anomalies of these elements arise from the same physical process. Pronounced Am patterns are rather found in the oldest cluster stars whereas younger targets show weaker Am anomalies and atypical patterns for some of them.

  5. A Method for Software Requirement Volatility Analysis Using QFD

    Directory of Open Access Journals (Sweden)

    Yunarso Anang

    2016-10-01

    Full Text Available Changes of software requirements are inevitable during the development life cycle. Rather than avoiding the circumstance, it is easier to just accept it and find a way to anticipate those changes. This paper proposes a method to analyze the volatility of requirement by using the Quality Function Deployment (QFD method and the introduced degree of volatility. Customer requirements are deployed to software functions and subsequently to architectural design elements. And then, after determining the potential for changes of the design elements, the degree of volatility of the software requirements is calculated. In this paper the method is described using a flow diagram and illustrated using a simple example, and is evaluated using a case study.

  6. Option Pricing using Realized Volatility

    DEFF Research Database (Denmark)

    Stentoft, Lars Peter

    In the present paper we suggest to model Realized Volatility, an estimate of daily volatility based on high frequency data, as an Inverse Gaussian distributed variable with time varying mean, and we examine the joint properties of Realized Volatility and asset returns. We derive the appropriate...... benchmark model estimated on return data alone. Hence the paper provides evidence on the value of using high frequency data for option pricing purposes....

  7. Option Pricing using Realized Volatility

    DEFF Research Database (Denmark)

    Stentoft, Lars Peter

    In the present paper we suggest to model Realized Volatility, an estimate of daily volatility based on high frequency data, as an Inverse Gaussian distributed variable with time varying mean, and we examine the joint properties of Realized Volatility and asset returns. We derive the appropriate d...... benchmark model estimated on return data alone. Hence the paper provides evidence on the value of using high frequency data for option pricing purposes....

  8. Abundance analysis of the slow nova PW Vulpeculae 1984

    CERN Document Server

    Schwarz, G J; Shore, S N; Hauschildt, P H; Schwarz, Greg J.; Shore, Steven N.; Hauschildt, Peter H.

    1997-01-01

    We determine the elemental abundances for the ejecta of the slow nova PW Vul 1984. Our technique uses a minimization of the emission line fits of a photoionization model to available ultraviolet, optical and infrared spectra. We find the following abundances (by number) with respect to solar: He/H = 1.0 $^{+7}_{-2}$. In addition, there is weak evidence for solar Ne and Mg and twice solar Fe. Previous studies (Saizar et al. 1991 and Andreã et al. 1991, 1994) of PW Vul have yielded considerable differences in their derived elemental abundances for the ejecta. Our abundances fall in between the previous studies. To explain the discrepant abundances, we analyze in detail the data and methods used to obtain the previous results. The abundances of Saizar et al. (1991) are significantly smaller then our values because of the lower electron temperature used by Saizar et al. in deriving elemental abundances from ion abundances. Andreã et al. (1991) used an ionization correction method to obtain their abundances and ...

  9. VLT\\/UVES Abundances in Four Nearby Dwarf Spheroidal Galaxies I. Nucleosynthesis and Abundance Ratios

    CERN Document Server

    Shetrone, M; Tolstoy, E; Primas, F; Hill, V; Kaufer, A

    2003-01-01

    We have used UVES on VLT-UT2 to take spectra of 15 red giants in the Sculptor, Fornax, Carina and Leo I dwarf spheroidal galaxies. We measure the abundances of alpha, iron peak, s and r-process elements. No dSph giants in our sample show the deep mixing abundance pattern seen in nearly all globular clusters. At a given metallicity, the dSph giants exhibit lower [el/Fe] abundance ratios for the alpha elements than stars in the Galactic halo. This can be caused by a slow star formation rate and contribution from Type Ia SN, and/or a small star formation event (low total mass) and mass dependent Type II SN yields. Differences in the even-Z [el/Fe] ratios between these galaxies, as well as differences in the evolution of the s&r-process elements are interpreted in terms of their star formation histories. Comparison of the dSph abundances with those of the Galactic halo reveals some consistencies. In particular, we find stars that mimic the abundance pattern found by Nissen & Shuster (1997) for metal-rich,...

  10. Infrared Spectroscopy of Parent Volatiles in Comets: Implications for Astrobiology

    Science.gov (United States)

    DiSanti, Michael A.

    2010-01-01

    Current cometary orbits provide information on their recent dynamical history. However, determining a given comet's formation region from its current dynamical state alone is complicated by radial migration in the proto-planetary disk and by dynamical interactions with the growing giant planets. Because comets reside for long periods of time in the outer Solar System, the ices contained in their nuclei (native ices) retain a relatively well-preserved footprint of when and where they formed, and this in turn can provide clues to conditions in the formation epoch. As a comet approaches the Sun, sublimation of its native ices releases parent volatiles into the coma where they can be measured spectroscopically. The past to - 15 years have seen the advent of infrared spectrometers with high sensitivity between about 2.8 and 5.0 micron, enabling a taxonomy among comets based on abundances of parent volatiles (e.g., H2O, CO, CH4, C2H6, HCN, CH30H, H2CO, NH3). Such molecules are of keen interest to Astrobiology, as they include important pre-biotic species that likely were required for the emergence of life on Earth and perhaps elsewhere. Approximately 20 comets have thus far been characterized, beginning with C/1996 82 (Hyakutake) in 1996. Molecular production rates are established through comparison of observed emission line intensities with those predicted by quantum mechanical fluorescence models. Abundances of parent volatiles (relative to H2O) vary among even the relatively small number of comets sampled, with the most volatile species (CO and CH4) displaying the largest variations. Techniques developed for measuring parent volatile abundances in comets will be discussed, as will possible implications for their formation.

  11. Infrared Spectroscopy of Parent Volatiles in Comets: Implications for Astrobiology

    Science.gov (United States)

    DiSanti, Michael A.

    2010-01-01

    Current cometary orbits provide information on their recent dynamical history. However, determining a given comet's formation region from its current dynamical state alone is complicated by radial migration in the proto-planetary disk and by dynamical interactions with the growing giant planets. Because comets reside for long periods of time in the outer Solar System, the ices contained in their nuclei (native ices) retain a relatively well-preserved footprint of when and where they formed, and this in turn can provide clues to conditions in the formation epoch. As a comet approaches the Sun, sublimation of its native ices releases parent volatiles into the coma where they can be measured spectroscopically. The past to - 15 years have seen the advent of infrared spectrometers with high sensitivity between about 2.8 and 5.0 micron, enabling a taxonomy among comets based on abundances of parent volatiles (e.g., H2O, CO, CH4, C2H6, HCN, CH30H, H2CO, NH3). Such molecules are of keen interest to Astrobiology, as they include important pre-biotic species that likely were required for the emergence of life on Earth and perhaps elsewhere. Approximately 20 comets have thus far been characterized, beginning with C/1996 82 (Hyakutake) in 1996. Molecular production rates are established through comparison of observed emission line intensities with those predicted by quantum mechanical fluorescence models. Abundances of parent volatiles (relative to H2O) vary among even the relatively small number of comets sampled, with the most volatile species (CO and CH4) displaying the largest variations. Techniques developed for measuring parent volatile abundances in comets will be discussed, as will possible implications for their formation.

  12. Self-assembled three-dimensional non-volatile memories

    NARCIS (Netherlands)

    Abelmann, Leon; Tas, Niels; Berenschot, Erwin; Elwenspoek, Miko

    2010-01-01

    The continuous increase in capacity of non-volatile data storage systems will lead to bit densities of one bit per atom in 2020. Beyond this point, capacity can be increased by moving into the third dimension. We propose to use self-assembly of nanosized elements, either as a loosely organised assoc

  13. Volatile signals during pregnancy.

    Science.gov (United States)

    Vaglio, Stefano

    2010-01-01

    Scents play a key role in mediating reproductive interactions in many vertebrates including mammals. Nowadays, several studies indicate that humans seem to use remarkably olfactory communication and are even able to produce and perceive pheromones. Furthermore, over the past several years, it became increasingly clear that pheromone-like chemical signals probably play a role in offspring identification and mother recognition. Recently developed technical procedures (solid-phase microextraction and dynamic headspace extraction) now allow investigators to characterize volatile compounds with high reliability. We analyzed the volatile compounds in sweat patch samples collected from the para-axillary and nipple-areola regions of women during pregnancy and after childbirth. We hypothesized that, at the time of birth and during the first weeks of life, the distinctive olfactory pattern of the para-axillary area is probably useful to newborn babies for recognizing and distinguishing their own mother, whereas the characteristic pattern of the nipple-areola region is probably useful as a guide to nourishment.

  14. Molecular plant volatile communication.

    Science.gov (United States)

    Holopainen, Jarmo K; Blande, James D

    2012-01-01

    Plants produce a wide array of volatile organic compounds (VOCs) which have multiple functions as internal plant hormones (e.g., ethylene, methyl jasmonate and methyl salicylate), in communication with conspecific and heterospecific plants and in communication with organisms of second (herbivores and pollinators) and third (enemies of herbivores) trophic levels. Species specific VOCs normally repel polyphagous herbivores and those specialised on other plant species, but may attract specialist herbivores and their natural enemies, which use VOCs as host location cues. Attraction of predators and parasitoids by VOCs is considered an evolved indirect defence, whereby plants are able to indirectly reduce biotic stress caused by damaging herbivores. In this chapter we review these interactions where VOCs are known to play a crucial role. We then discuss the importance of volatile communication in self and nonself detection. VOCs are suggested to appear in soil ecosystems where distinction of own roots from neighbours roots is essential to optimise root growth, but limited evidence of above-ground plant self-recognition is available.

  15. Chemical Fractionation and Abundances in Coronal Plasma

    CERN Document Server

    Drake, J J

    2003-01-01

    Much of modern astrophysics is grounded on the observed chemical compositions of stars and the diffuse plasma that pervades the space between stars, galaxies and clusters of galaxies. X-ray and EUV spectra of the hot plasma in the outer atmospheres of stars have demonstrated that these environments are subject to chemical fractionation in which the abundances of elements can be enhanced and depleted by an order of magnitude or more. These coronal abundance anomalies are discussed and some of the physical mechanisms that might be responsible for producing them are examined. It is argued that coronal abundances can provide important new diagnostics on physical processes at work in solar and stellar coronae. It seems likely that other hot astrophysical plasmas will be subject to similar effects.

  16. Plume composition and volatile flux from Nyamulagira volcano

    Science.gov (United States)

    Calabrese, Sergio; Bobrowski, Nicole; Giuffrida, Giovanni Bruno; Scaglione, Sarah; Liotta, Marcello; Brusca, Lorenzo; D'Alessandro, Walter; Arellano, Santiago; Yalire, Matiew; Galle, Bo; Tedesco, Dario

    2015-04-01

    Nyamulagira, in the Virunga volcanic province (VVP), Democratic Republic of Congo, is one of the most active volcanoes in Africa. The volcano is located about 25 km north-northwest of Lake Kivu in the Western Branch of the East African Rift System (EARS). The activity is characterized by frequent eruptions (on average, one eruption every 2-4 years) which occur both from the summit crater and from the flanks (31 flank eruptions over the last 110 years). Due to the peculiar low viscosity of its lava and its location in the floor of the rift, Nyamulagira morphology is characterized by a wide lava field that covers over 1100 km2 and contains more than 100 flank cones. Indeed, Nyamulagira is a SiO2- undersaturated and alkali-rich basaltic shield volcano with a 3058 m high summit caldera with an extension of about 2 km in diameter. In November 2014 a field expedition was carried out at Nyamulagira volcano and we report here the first assessment of the plume composition and volatile flux from Nyamulagira volcano. Helicopter flights and field observations allowed us to recognize the presence of lava fountains inside an about 350-meter wide pit crater. The lava fountains originated from an extended area of about 20 to 40 m2, in the northeast sector of the central caldera. A second smaller source, close to the previous described one, was clearly visible with vigorous spattering activity. There was no evidence of a lave lake but the persistence of intense activity and the geometry of the bottom of the caldera might evolve in a new lava lake. Using a variety of in situ and remote sensing techniques, we determined the bulk plume concentrations of major volatiles, halogens and trace elements. We deployed a portable MultiGAS station at the rim of Nyamulagira crater, measuring (at 0.5 Hz for about 3 hours) the concentrations of major volcanogenic gas species in the plume (H2O, CO2, SO2, H2S). Simultaneously, scanning differential optical absorption spectroscopy instruments were

  17. Queen volatiles as a modulator of Tetragonisca angustula drone behavior.

    Science.gov (United States)

    Fierro, Macario M; Cruz-López, Leopoldo; Sánchez, Daniel; Villanueva-Gutiérrez, Rogel; Vandame, Remy

    2011-11-01

    Tetragonisca angustula mating occurs during the virgin queen nuptial flight, usually in the presence of a drone congregation area (DCA). The presence of virgin queen pheromone is considered the trigger for DCA establishment, although this has not been demonstrated experimentally. We established meliponaries, in different habitats, with T. angustula virgin queens during the main drone reproduction period. Eight DCAs were observed in urban areas, and all established outside or near colonies containing at least one virgin queen. The accumulation of drones in the DCAs occurred from 08:00 to 18:00 h and over 3-35 days. The number of drones in DCAs ranged from 60 to 2,000. In field trials, drones were attracted to virgin queens and also, unexpectedly, to physogastric queens. Volatiles collected from both virgin and physogastric queens elicited strong electoantennogram (EAG) responses from drones. Virgin and physogastric queen volatiles were qualitatively similar, but quantitatively different, in chemical composition. The queen's abdomen was the principal source of these compounds. Isopropyl hexanoate (IPH), the most abundant compound in virgin queen volatiles and one of the most abundant in physogastric queen volatiles, was identified as one of the compounds that elicited EAG responses and was demonstrated to attract drones in a field test.

  18. Chemical composition and non-volatile components of three wild edible mushrooms collected from northwest Tunisia

    Directory of Open Access Journals (Sweden)

    ibtissem Kacem Jedidi

    2016-04-01

    Full Text Available In Tunisia, many people collect wild edible mushrooms as pickers for their own consumption. The present work aims at contributing to the determination of the chemical composition, non volatile components content (soluble sugars, free amino acids and minerals and trace elements of three popular Tunisian wild edible mushrooms species collected from the northwest of Tunisia (Agaricus campestris, Boletus edulis and Cantharellus cibarius.All investigated mushrooms revealed that these species are rich sources of proteins (123.70 – 374.10 g kg-1 dry weight (DW and carbohydrates (403.3 – 722.40 g kg-1 DW, and low content of fat (28.2 – 39.9 g kg-1 DW; the highest energetic contribution was guaranteed by C. cibarius (1542.71 kJ / 100 g. A. compestris (33.14 mg/g DW showed the highest concentration of essential amino acids. The composition in individual sugars was also determined, mannitol and trehalose being the most abundant sugars. C. cibarius revealed the highest concentrations of carbohydrates (722.4 g kg-1 DW and A. compestris the lowest concentration (403.3 g kg-1 DW. Potassium (K and sodium (Na are the most abundant minerals in analyzed samples (A. compestris showed the highest concentrations of K and Na, 49141.44 and 9263.886 µg/g DW respectively.

  19. Consistent ranking of volatility models

    DEFF Research Database (Denmark)

    Hansen, Peter Reinhard; Lunde, Asger

    2006-01-01

    We show that the empirical ranking of volatility models can be inconsistent for the true ranking if the evaluation is based on a proxy for the population measure of volatility. For example, the substitution of a squared return for the conditional variance in the evaluation of ARCH-type models can...

  20. Political institutions and economic volatility

    NARCIS (Netherlands)

    Klomp, Jeroen; de Haan, Jakob

    2009-01-01

    We examine the effect of political 'institutions' on economic growth volatility, using data from more than 100 countries over the period 1960 to 2005, taking into account various control variables as suggested in previous studies. Our indicator of volatility is the relative standard deviation of the

  1. Relative Abundance Measurements in Plumes and Interplumes

    CERN Document Server

    Guennou, Chloé; Savin, Daniel Wolf

    2015-01-01

    We present measurements of relative elemental abundances in plumes and interplumes. Plumes are bright, narrow structures in coronal holes that extend along open magnetic field lines far out into the corona. Previous work has found that in some coronal structures the abundances of elements with a low first ionization potential (FIP) 10 eV). We have used EIS spectroscopic observations made on 2007 March 13 and 14 over an ~24 hour period to characterize abundance variations in plumes and interplumes. To assess their elemental composition, we have used a differential emission measure (DEM) analysis, which accounts for the thermal structure of the observed plasma. We have used lines from ions of iron, silicon, and sulfur. From these we have estimated the ratio of the iron and silicon FIP bias relative to that for sulfur. From the results, we have created FIP-bias-ratio maps. We find that the FIP-bias ratio is sometimes higher in plumes than in interplumes and that this enhancement can be time dependent. These res...

  2. Flare Plasma Iron Abundance

    Science.gov (United States)

    Dennis, Brian R.; Dan, Chau; Jain, Rajmal; Schwartz, Richard A.; Tolbert, Anne K.

    2008-01-01

    The equivalent width of the iron-line complex at 6.7 keV seen in flare X-ray spectra suggests that the iron abundance of the hottest plasma at temperatures >approx.10 MK may sometimes be significantly lower than the nominal coronal abundance of four times the photospheric value that is commonly assumed. This conclusion is based on X-ray spectral observations of several flares seen in common with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Solar X-ray Spectrometer (SOXS) on the second Indian geostationary satellite, GSAT-2. The implications of this will be discussed as it relates to the origin of the hot flare plasma - either plasma already in the corona that is directly heated during the flare energy release process or chromospheric plasma that is heated by flare-accelerated particles and driven up into the corona. Other possible explanations of lower-than-expected equivalent widths of the iron-line complex will also be discussed.

  3. Emerging non-volatile memories

    CERN Document Server

    Hong, Seungbum; Wouters, Dirk

    2014-01-01

    This book is an introduction to the fundamentals of emerging non-volatile memories and provides an overview of future trends in the field. Readers will find coverage of seven important memory technologies, including Ferroelectric Random Access Memory (FeRAM), Ferromagnetic RAM (FMRAM), Multiferroic RAM (MFRAM), Phase-Change Memories (PCM), Oxide-based Resistive RAM (RRAM), Probe Storage, and Polymer Memories. Chapters are structured to reflect diffusions and clashes between different topics. Emerging Non-Volatile Memories is an ideal book for graduate students, faculty, and professionals working in the area of non-volatile memory. This book also: Covers key memory technologies, including Ferroelectric Random Access Memory (FeRAM), Ferromagnetic RAM (FMRAM), and Multiferroic RAM (MFRAM), among others. Provides an overview of non-volatile memory fundamentals. Broadens readers' understanding of future trends in non-volatile memories.

  4. Abundance differences among G and K giants

    Science.gov (United States)

    Challener, Sharon Lynn Montgomery

    Effective temperatures and surface gravities were derived for 52 G and K giants using model atmosphere. Of these, 33 were called very strong-lined (or VSL) stars primarily because of their CN line strength. We find that when compared to normal stars, the VSL stars show a mean iron overabundance of 0.15 dex. Contrary to earlier suggestions, none of the heavier elements (Z greater than 10) appear selectively enhanced. Red giants are believed to undergo mixing, thereby driving the surface abundances towards those of the stellar interior. Carbon, nitrogen, and oxygen abundances are most sensitive to mixing as they are produced through nucleosynthesis at various depths beneath the star's surface. The CNO abundances (normalized to the iron abundances) of the VSLs appear on average to be normal for G and K giants. This result suggests that the strong CN absorption seen in VSLs is not the result of unusual mixing. Their general overabundance of metal appears instead to be innate, presumably reflecting the metallicity of the gaseous clouds from which they formed. This should be settled once the appropriate number of VSL dwarfs is found. The deviations from the normal population of giants are rather small, however, and certainly not of the magnitude envisioned by Spinrad and Taylor (1969). It is likely that VSLs are merely the stars lying in the tail of the normal abundance distribution.

  5. Governmentally amplified output volatility

    Science.gov (United States)

    Funashima, Yoshito

    2016-11-01

    Predominant government behavior is decomposed by frequency into several periodic components: updating cycles of infrastructure, Kuznets cycles, fiscal policy over business cycles, and election cycles. Little is known, however, about the theoretical impact of such cyclical behavior in public finance on output fluctuations. Based on a standard neoclassical growth model, this study intends to examine the frequency at which public investment cycles are relevant to output fluctuations. We find an inverted U-shaped relationship between output volatility and length of cycle in public investment. This implies that periodic behavior in public investment at a certain frequency range can cause aggravated output resonance. Moreover, we present an empirical analysis to test the theoretical implication, using the U.S. data in the period from 1968 to 2015. The empirical results suggest that such resonance phenomena change from low to high frequency.

  6. Volatility Exposure for Strategic Asset Allocation

    OpenAIRE

    Briere, Marie; Burgues, Alexandre; Signori, Ombretta

    2010-01-01

    The authors examine the advantages of incorporating strategic exposure to equity volatility into the investment opportunity set of a long-term equity investor. They consider two standard volatility investments: implied volatility and volatility risk premium strategies. An analytical framework, which offers pragmatic solutions for long-term investors who seek exposure to volatility, is used to calibrate and assess the risk-return profiles of portfolios. The benefit of volatility exposure for a...

  7. Reduced Heart Rate Volatility

    Science.gov (United States)

    Grogan, Eric L.; Morris, John A.; Norris, Patrick R.; France, Daniel J.; Ozdas, Asli; Stiles, Renée A.; Harris, Paul A.; Dawant, Benoit M.; Speroff, Theodore

    2004-01-01

    Objective: To determine if using dense data capture to measure heart rate volatility (standard deviation) measured in 5-minute intervals predicts death. Background: Fundamental approaches to assessing vital signs in the critically ill have changed little since the early 1900s. Our prior work in this area has demonstrated the utility of densely sampled data and, in particular, heart rate volatility over the entire patient stay, for predicting death and prolonged ventilation. Methods: Approximately 120 million heart rate data points were prospectively collected and archived from 1316 trauma ICU patients over 30 months. Data were sampled every 1 to 4 seconds, stored in a relational database, linked to outcome data, and de-identified. HR standard deviation was continuously computed over 5-minute intervals (CVRD, cardiac volatility–related dysfunction). Logistic regression models incorporating age and injury severity score were developed on a test set of patients (N = 923), and prospectively analyzed in a distinct validation set (N = 393) for the first 24 hours of ICU data. Results: Distribution of CVRD varied by survival in the test set. Prospective evaluation of the model in the validation set gave an area in the receiver operating curve of 0.81 with a sensitivity and specificity of 70.1 and 80.0, respectively. CVRD predict death as early as 24 hours in the validation set. Conclusions: CVRD identifies a subgroup of patients with a high probability of dying. Death is predicted within first 24 hours of stay. We hypothesize CVRD is a surrogate for autonomic nervous system dysfunction. PMID:15319726

  8. The Detailed Chemical Abundance Patterns of M31 Globular Clusters

    CERN Document Server

    Colucci, J E; Cohen, J

    2012-01-01

    We present detailed chemical abundances for $>$20 elements in $\\sim$30 globular clusters in M31. These results have been obtained using high resolution ($\\lambda/\\Delta\\lambda\\sim$24,000) spectra of their integrated light and analyzed using our original method. The globular clusters have galactocentric radii between 2.5 kpc and 117 kpc, and therefore provide abundance patterns for different phases of galaxy formation recorded in the inner and outer halo of M31. We find that the clusters in our survey have a range in metallicity of $-2.2$20 kpc have a small range in abundance of [Fe/H]$=-1.6 \\pm 0.10$. We also measure abundances of alpha, r- and s-process elements. These results constitute the first abundance pattern constraints for old populations in M31 that are comparable to those known for the Milky Way halo.

  9. THE ATOMIC WEIGHTS COMMISSION AND ISOTOPIC ABUNDANCE RATIO DETERMINATIONS.

    Energy Technology Data Exchange (ETDEWEB)

    HOLDEN, N.E.

    2005-08-07

    Following Thomson's discovery of stable isotopes in non-radioactive chemical elements, the derivation of atomic weight values from mass spectrometric measurements of isotopic abundance ratios moved very slowly. Forty years later, only 3 1/2 % of the recommended values were based on mass spectrometric measurements and only 38% in the first half century. It might be noted that two chemical elements (tellurium and mercury) are still based on chemical measurements, where the atomic weight value calculated from the relative isotopic abundance measurement either agrees with the value from the chemical measurement or the atomic weight value calculated from the relative isotopic abundance measurement falls within the uncertainty of the chemical measurement of the atomic weight. Of the 19 chemical elements, whose atomic weight is based on non-corrected relative isotopic abundance measurements, five of these are two isotope systems (indium, iridium, lanthanum, lutetium and tantalum) and one is a three-isotope system (oxygen).

  10. Non-random species loss in bacterial communities reduces antifungal volatile production.

    Science.gov (United States)

    Hol, W H Gera; Garbeva, Paolina; Hordijk, Cornelis; Hundscheid, P J; Gunnewiek, Paulien J A Klein; Van Agtmaal, Maaike; Kuramae, Eiko E; De Boer, Wietse

    2015-08-01

    The contribution of low-abundance microbial species to soil ecosystems is easily overlooked because there is considerable overlap between metabolic abilities (functional redundancy) of dominant and subordinate microbial species. Here we studied how loss of less abundant soil bacteria affected the production of antifungal volatiles, an important factor in the natural control of soil-borne pathogenic fungi. We provide novel empirical evidence that the loss of soil bacterial species leads to a decline in the production of volatiles that suppress root pathogens. By using dilution-to-extinction for seven different soils we created bacterial communities with a decreasing number of species and grew them under carbon-limited conditions. Communities with high bacterial species richness produced volatiles that strongly reduced the hyphal growth of the pathogen Fusarium oxysporum. For most soil origins loss of bacterial species resulted in loss of antifungal volatile production. Analysis of the volatiles revealed that several known antifungal compounds were only produced in the more diverse bacterial communities. Our results suggest that less abundant bacterial species play an important role in antifungal volatile production by soil bacterial communities and, consequently, in the natural suppression of soil-borne pathogens.

  11. Abundance, Excess, Waste

    Directory of Open Access Journals (Sweden)

    Rox De Luca

    2016-02-01

    Her recent work focuses on the concepts of abundance, excess and waste. These concerns translate directly into vibrant and colourful garlands that she constructs from discarded plastics collected on Bondi Beach where she lives. The process of collecting is fastidious, as is the process of sorting and grading the plastics by colour and size. This initial gathering and sorting process is followed by threading the components onto strings of wire. When completed, these assemblages stand in stark contrast to the ease of disposability associated with the materials that arrive on the shoreline as evidence of our collective human neglect and destruction of the environment around us. The contrast is heightened by the fact that the constructed garlands embody the paradoxical beauty of our plastic waste byproducts, while also evoking the ways by which those byproducts similarly accumulate in randomly assorted patterns across the oceans and beaches of the planet.

  12. Evolution of Martian atmospheric argon: Implications for sources of volatiles

    Science.gov (United States)

    Hutchins, Kevin S.; Jakosky, Bruce M.

    We have examined processes affecting isotopes of argon (36Ar, 38Ar, 40Ar) in order to determine important atmospheric sources and sinks. Our simple model for argon evolution incorporates production of radiogenic argon in the mantle, outgassing of all argon species by extrusive and intrusive volcanism, and loss to space by knock-on sputtering above the exobase. Sputtering has been shown previously to be an important loss process for atmospheric species, especially isotopes of noble gases, which have few other mechanisms of escape. The integrated evolution of argon (36Ar, 38Ar, and 40Ar, respectively) is modeled in terms of these variables: (1) the planetary concentration of potassium, (2) the fraction of juvenile argon released catastrophically during the first 600 Myr., (3) potential variation in the time-history of sputtering loss from that suggested by Luhmann et al. [1992], and (4) the volume of total outgassing to the surface as compared to outgassing contributed by volcanic release. Our results indicate that Mars has lost between 85-95% of 36Ar and 70-88% of outgassed 40Ar. Due to this substantial loss, the planet must have outgassed the equivalent of between 10 and 100 times the total volume of gases released by extrusive and intrusive volcanics. This indicates that volcanic outgassing, alone, is insufficient to explain the present-day abundances of 36Ar and 40Ar in the Martian atmosphere. Similar calculations for 20Ne suggest outgassed volumes of between 100 and 1800 times in excess of that due to volcanism. This results in a distinct Ne/Ar elemental fractionation, with a preference for outgassing argon, of the order of 10 to 17. Although the results must be evaluated within the model uncertainties, the results are compelling in that they unequivocally show the existence of additional sources of atmospheric volatiles and helps define a means to identify them.

  13. Earth's Volatiles History and Cycles: the Case of Iodine

    Science.gov (United States)

    Bureau, H.; Marocchi, M.; Munsch, P.; Auzende, A.; Raepsaet, C.; Mezouar, M.; Testemale, D.; Kubsky, S.; Carriere, M.; Ricolleau, A.; Fiquet, G.

    2011-12-01

    Among the volatile elements present in our solar system, iodine is involved in mechanisms of primary importance during planet's evolution. The different isotopic signatures of 129Xe/132Xe for mantle and atmosphere between the Earth and Mars may reflect an early fractionation of xenon with respect to iodine. The role of fluids and more especially water is seriously envisaged to generate such a fractionation because whereas iodine is hydrophilic, xenon is not. Therefore iodine's early degassing with a water-rich fluid from a magma ocean is a good hypothesis to explain iodine, but also chlorine and bromine losses during early differentiation stages of the Earth. It was also shown that iodine is involved in natural ozone destruction in the Earth's atmosphere. Today we are able to detect iodine in volcanic emissions. The intensive subduction-zones volcanic degassing may explain the presence of iodine in the atmosphere if degassed together with water. The combination of synchrotron X-Ray characterization with diamond anvil cells, applied as magmatic and mantelic reactors to simulate pressure and temperature conditions of the planet interiors allows: (1) the characterization of fluids (aqueous, melt, supercritic) existing in the Earth; (2) element transfers via such fluids from depths to planets surfaces. Here, we have experimentally monitored iodine degassing from high pressure hydrous melts in situ in diamond anvil cells DAC by measuring iodine partitioning between aqueous fluids and hydrous melts during decompression. DAC experiments have been combined with high energy Synchrotron X-Ray Fluorescence at the beam lines Id27 and FAME from ESRF. Partition coefficients (D(I)fluid/melt = (I)fluid/(I)melt ) have been measured in situ from 500 to 900 °C and from 0.1 to 1.8 GPa. First results show that they are ranging from 1.9 (1.4 GPa) to 60 (0.1 GPa) and seem to tend to unity close to total miscibility between melts and aqueous fluids. At low pressure conditions (lower than

  14. La and Eu Abundances in Metal-poor Halo Stars

    Science.gov (United States)

    Cardillo, Harrison; Burris, Debra L.

    2016-01-01

    Elements with atomic number greater than Z=26 (the Iron Peak) cannot be formed through fusion in a star's core; the majority of these elements are produced through one of two neutron-capture processes. Early in the history of the Galaxy, the rapid neutron-capture process (r-process) is believed to be responsible for the production of elements Z=56 and beyond. These elements require at least one generation of stars to have completed their life cycle in order to be synthesized. Therefore, if we observe the heavy metal abundances in what are called Population II stars (metal-poor stars), then we can begin to make inferences about the chemistry of the earliest stars in the Galaxy. To contribute to this picture of the early universe, the Lanthanum and Europium abundances of low-metallicity stars will be measured and trends in these abundances based on comparisons to existing related literature will be sought.

  15. TEA: A Code for Calculating Thermochemical Equilibrium Abundances

    CERN Document Server

    Blecic, Jasmina; Bowman, M Oliver

    2015-01-01

    We present an open-source Thermochemical Equilibrium Abundances (TEA) code that calculates the abundances of gaseous molecular species. The code is based on the methodology of White et al. (1958) and Eriksson (1971). It applies Gibbs free-energy minimization using an iterative, Lagrangian optimization scheme. Given elemental abundances, TEA calculates molecular abundances for a particular temperature and pressure or a list of temperature-pressure pairs. We tested the code against the method of Burrows & Sharp (1999), the free thermochemical equilibrium code CEA (Chemical Equilibrium with Applications), and the example given by White et al. (1958). Using their thermodynamic data, TEA reproduces their final abundances, but with higher precision. We also applied the TEA abundance calculations to models of several hot-Jupiter exoplanets, producing expected results. TEA is written in Python in a modular format. There is a start guide, a user manual, and a code document in addition to this theory paper. TEA is ...

  16. Two-component mantle melting-mixing model for the generation of mid-ocean ridge basalts: Implications for the volatile content of the Pacific upper mantle

    Science.gov (United States)

    Shimizu, Kei; Saal, Alberto E.; Myers, Corinne E.; Nagle, Ashley N.; Hauri, Erik H.; Forsyth, Donald W.; Kamenetsky, Vadim S.; Niu, Yaoling

    2016-03-01

    volatile and trace element contents. Our results are consistent with previously proposed geodynamical processes acting at mid-ocean ridges and with the generation of the E-DMM. Our observations indicate that the D-DMM and E-DMM have (1) a relatively constant CO2/Cl ratio of ∼57 ± 8, and (2) volatile and ITE element abundance patterns that can be related by a simple melting event, supporting the hypothesis that the E-DMM is a recycled oceanic lithosphere mantle metasomatized by low degree melts. Our calculation and model give rise to a Pacific upper mantle with volatile content of CO2 = 235 ppm, H2O = 191 ppm, F = 13 ppm, Cl = 5 ppm, and S = 114 ppm.

  17. Primordial Deuterium Abundance Measurements

    CERN Document Server

    Levshakov, S A; Takahara, F; Levshakov, Sergei A.; Kegel, Wilhelm H.; Takahara, Fumio

    1997-01-01

    Deuterium abundances measured recently from QSO absorption-line systems lie in the range from 3 10^{-5} to 3 10^{-4}, which shed some questions on standard big bang theory. We show that this discordance may simply be an artifact caused by inadequate analysis ignoring spatial correlations in the velocity field in turbulent media. The generalized procedure (accounting for such correlations) is suggested to reconcile the D/H measurements. An example is presented based on two high-resolution observations of Q1009+2956 (low D/H) [1,2] and Q1718+4807 (high D/H) [8,9]. We show that both observations are compatible with D/H = 4.1 - 4.6 10^{-5}, and thus support SBBN. The estimated mean value = 4.4 10^{-5} corresponds to the baryon-to-photon ratio during SBBN eta = 4.4 10^{-10} which yields the present-day baryon density Omega_b h^2 = 0.015.

  18. Volatile fluxes through the Big Bend section of the San Andreas Fault, California: helium and carbon-dioxide systematics

    Science.gov (United States)

    Kulongoski, Justin T.; Hilton, David R.; Barry, Peter H.; Esser, Bradley K.; Hillegonds, Darren; Belitz, Kenneth

    2013-01-01

    To investigate the source of volatiles and their relationship to the San Andreas Fault System (SAFS), 18 groundwater samples were collected from wells near the Big Bend section of the SAFS in southern California and analyzed for helium and carbon abundance and isotopes. Concentrations of 4He, corrected for air-bubble entrainment, vary from 4.15 to 62.7 (× 10− 8) cm3 STP g− 1 H2O. 3He/4He ratios vary from 0.09 to 3.52 RA (where RA = air 3He/4He), consistent with up to 44% mantle helium in samples. A subset of 10 samples was analyzed for the major volatile phase (CO2) — the hypothesized carrier phase of the helium in the mantle–crust system: CO2/3He ratios vary from 0.614 to 142 (× 1011), and δ13C (CO2) values vary from − 21.5 to − 11.9‰ (vs. PDB). 3He/4He ratios and CO2 concentrations are highest in the wells located in the Mil Potrero and Cuddy valleys adjacent to the SAFS. The elevated 3He/4He ratios are interpreted to be a consequence of a mantle volatile flux though the SAFS diluted by radiogenic He produced in the crust. Samples with the highest 3He/4He ratios also had the lowest CO2/3He ratios. The combined helium isotope, He–CO2 elemental relationships, and δ13C (CO2) values of the groundwater volatiles reveal a mixture of mantle and deep crustal (metamorphic) fluid origins. The flux of fluids into the seismogenic zone at high hydrostatic pressure may cause fault rupture, and transfer volatiles into the shallow crust. We calculate an upward fluid flow rate of 147 mm a− 1 along the SAFS, up to 37 times higher than previous estimates (Kennedy et al., 1997). However, using newly identified characteristics of the SAFS, we calculate a total flux of 3He along the SAFS of 7.4 × 103 cm3 STP a− 1 (0.33 mol 3He a− 1), and a CO2 flux of 1.5 × 1013 cm3STP a− 1 (6.6 × 108 mol a− 1), ~ 1% of previous estimates. Lower fluxes along the Big Bend section of the SAFS suggest that the flux of mantle volatiles alone is insufficient to cause the

  19. EFFECTS OF DYNAMICAL EVOLUTION OF GIANT PLANETS ON THE DELIVERY OF ATMOPHILE ELEMENTS DURING TERRESTRIAL PLANET FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Soko [School of Engineering, Physics, and Mathematics, University of Dundee, DD1 4HN, Scotland (United Kingdom); Brasser, Ramon; Ida, Shigeru, E-mail: s.matsumura@dundee.ac.uk [Earth-Life Science Institute, Tokyo Institute of Technology, Meguro-ku, Tokyo, 152-8550 (Japan)

    2016-02-10

    Recent observations started revealing the compositions of protostellar disks and planets beyond the solar system. In this paper, we explore how the compositions of terrestrial planets are affected by the dynamical evolution of giant planets. We estimate the initial compositions of the building blocks of these rocky planets by using a simple condensation model, and numerically study the compositions of planets formed in a few different formation models of the solar system. We find that the abundances of refractory and moderately volatile elements are nearly independent of formation models, and that all the models could reproduce the abundances of these elements of the Earth. The abundances of atmophile elements, on the other hand, depend on the scattering rate of icy planetesimals into the inner disk, as well as the mixing rate of the inner planetesimal disk. For the classical formation model, neither of these mechanisms are efficient and the accretion of atmophile elements during the final assembly of terrestrial planets appears to be difficult. For the Grand Tack model, both of these mechanisms are efficient, which leads to a relatively uniform accretion of atmophile elements in the inner disk. It is also possible to have a “hybrid” scenario where the mixing is not very efficient but the scattering is efficient. The abundances of atmophile elements in this case increase with orbital radii. Such a scenario may occur in some of the extrasolar planetary systems, which are not accompanied by giant planets or those without strong perturbations from giants. We also confirm that the Grand Tack scenario leads to the distribution of asteroid analogues where rocky planetesimals tend to exist interior to icy ones, and show that their overall compositions are consistent with S-type and C-type chondrites, respectively.

  20. Abundance correlations in mildly metal-poor stars

    CERN Document Server

    Jehin, E; Neuforge, C; Noels, A; Parmentier, G; Thoul, A A

    1999-01-01

    Accurate relative abundances have been obtained for a sample of 21 mildly metal-poor stars from the analysis of high resolution and high signal-to-noise spectra. With these accurate results, correlations between relative abundances have been searched for, with a special emphasis on the neutron capture elements. This analysis shows that the r elements are closely correlated to the alpha elements, which is in agreement with the generally accepted idea that the r-process takes place during the explosion of massive stars. The situation is more complex as far as the s elements are concerned. Their relation with the alpha elements is not linear. In a first group of stars, the relative abundance of the s elements increases only slightly with the alpha elements overabundance until the latter reaches a maximum value. For the second group, the s elements show a rather large range of enhancement and a constant (and maximum) value of the alpha elements overabundance. This peculiar behaviour leads us to distinguish betwee...

  1. Unifying elemental stoichiometry and metabolic theory in predicting species abundances

    NARCIS (Netherlands)

    Ott, David; Digel, Christoph; Rall, Björn Christian; Maraun, Mark; Scheu, Stefan; Brose, Ulrich

    2014-01-01

    While metabolic theory predicts variance in population density within communities depending on population average body masses, the ecological stoichiometry concept relates density variation across communities to varying resource stoichiometry. Using a data set including biomass densities of 4959

  2. Element abundances and distributions in the crab nebula

    Directory of Open Access Journals (Sweden)

    G. M. MacAlpine

    2001-01-01

    Full Text Available La Nebulosa del Cangrejo proporciona oportunidades unicas para investigar diversos aspectos de la nucleos ntesis y del enriquecimiento de elementos relativos a la estrella progenitora y a la estrella de neutrones joven. Se pueden combinar datos espectrosc opicos e im agenes para conocer la distribuci on de abundancias. Nuestros conocimientos sobre esta remanente de supernova han aumentado de manera considerable en los ultimos a~nos.

  3. Unifying elemental stoichiometry and metabolic theory in predicting species abundances

    NARCIS (Netherlands)

    Ott, David; Digel, Christoph; Rall, Björn Christian; Maraun, Mark; Scheu, Stefan; Brose, Ulrich

    2014-01-01

    While metabolic theory predicts variance in population density within communities depending on population average body masses, the ecological stoichiometry concept relates density variation across communities to varying resource stoichiometry. Using a data set including biomass densities of 4959 pop

  4. Unifying elemental stoichiometry and metabolic theory in predicting species abundances.

    Science.gov (United States)

    Ott, David; Digel, Christoph; Rall, Björn C; Maraun, Mark; Scheu, Stefan; Brose, Ulrich

    2014-10-01

    While metabolic theory predicts variance in population density within communities depending on population average body masses, the ecological stoichiometry concept relates density variation across communities to varying resource stoichiometry. Using a data set including biomass densities of 4959 populations of soil invertebrates across 48 forest sites we combined these two frameworks. We analyzed how the scaling of biomass densities with population-averaged body masses systematically interacts with stoichiometric variables. Simplified analyses employing either only body masses or only resource stoichiometry are highly context sensitive and yield variable and often misleading results. Our findings provide strong evidence that analyses of ecological state variables should integrate allometric and stoichiometric variables to explain deviations from predicted allometric scaling and avoid erroneous conclusions. In consequence, our study provides an important step towards unifying two prominent ecological theories, metabolic theory and ecological stoichiometry.

  5. Unifying elemental stoichiometry and metabolic theory in predicting species abundances

    NARCIS (Netherlands)

    Ott, David; Digel, Christoph; Rall, Björn Christian; Maraun, Mark; Scheu, Stefan; Brose, Ulrich

    2014-01-01

    While metabolic theory predicts variance in population density within communities depending on population average body masses, the ecological stoichiometry concept relates density variation across communities to varying resource stoichiometry. Using a data set including biomass densities of 4959 pop

  6. Abundances in Stars with Debris Disks

    CERN Document Server

    Ritchey, Adam M; Stone, Myra; Wallerstein, George

    2013-01-01

    We present preliminary results of a detailed chemical abundance analysis for a sample of solar-type stars known to exhibit excess infrared emission associated with dusty debris disks. Our sample of 28 stars was selected based on results from the Formation and Evolution of Planetary Systems (FEPS) Spitzer Legacy Program, for the purpose of investigating whether the stellar atmospheres have been polluted with planetary material, which could indicate that the metallicity enhancement in stars with planets is due to metal-rich infall in the later stages of star and planet formation. The preliminary results presented here consist of precise abundances for 15 elements (C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Fe, Co, and Ni) for half of the stars in our sample. We find that none of the stars investigated so far exhibit the expected trend of increasing elemental abundance with increasing condensation temperature, which would result from the stars having accreted planetary debris. Rather, the slopes of linear least...

  7. Stochastic volatility and stochastic leverage

    DEFF Research Database (Denmark)

    Veraart, Almut; Veraart, Luitgard A. M.

    This paper proposes the new concept of stochastic leverage in stochastic volatility models. Stochastic leverage refers to a stochastic process which replaces the classical constant correlation parameter between the asset return and the stochastic volatility process. We provide a systematic...... treatment of stochastic leverage and propose to model the stochastic leverage effect explicitly, e.g. by means of a linear transformation of a Jacobi process. Such models are both analytically tractable and allow for a direct economic interpretation. In particular, we propose two new stochastic volatility...... models which allow for a stochastic leverage effect: the generalised Heston model and the generalised Barndorff-Nielsen & Shephard model. We investigate the impact of a stochastic leverage effect in the risk neutral world by focusing on implied volatilities generated by option prices derived from our new...

  8. The origin of volatiles in the Earth's mantle

    Science.gov (United States)

    Hier-Majumder, Saswata; Hirschmann, Marc M.

    2017-08-01

    The Earth's deep interior contains significant reservoirs of volatiles such as H, C, and N. Due to the incompatible nature of these volatile species, it has been difficult to reconcile their storage in the residual mantle immediately following crystallization of the terrestrial magma ocean (MO). As the magma ocean freezes, it is commonly assumed that very small amounts of melt are retained in the residual mantle, limiting the trapped volatile concentration in the primordial mantle. In this article, we show that inefficient melt drainage out of the freezing front can retain large amounts of volatiles hosted in the trapped melt in the residual mantle while creating a thick early atmosphere. Using a two-phase flow model, we demonstrate that compaction within the moving freezing front is inefficient over time scales characteristic of magma ocean solidification. We employ a scaling relation between the trapped melt fraction, the rate of compaction, and the rate of freezing in our magma ocean evolution model. For cosmochemically plausible fractions of volatiles delivered during the later stages of accretion, our calculations suggest that up to 77% of total H2O and 12% of CO2 could have been trapped in the mantle during magma ocean crystallization. The assumption of a constant trapped melt fraction underestimates the mass of volatiles in the residual mantle by more than an order of magnitude.Plain Language SummaryThe Earth's deep interior contains substantial amounts of volatile elements like C, H, and N. How these elements got sequestered in the Earth's interior has long been a topic of debate. It is generally assumed that most of these elements escaped the interior of the Earth during the first few hundred thousand years to create a primitive atmosphere, leaving the mantle reservoir nearly empty. In this work, we show that the key to this paradox involves the very early stages of crystallization of the mantle from a global magma ocean. Using numerical models, we show

  9. On forecasting Exchange Rate Volatility.

    OpenAIRE

    Hafner, Christian

    2003-01-01

    In an efficient market, foreign exchange rates have to guarantee absence of triangular arbitrage. This note shows that the no-arbitrage condition can be exploited for forecasting the volatility of a single rate by using the information contained in the other rates. Linearly transforming the volatility forecasts of a bivariate model is shown to be more efficient than using a univariate model for the cross-rate.

  10. Shock-induced volatile loss from a carbonaceous chondrite Implications for planetary accretion

    Science.gov (United States)

    Tyburczy, James A.; Frisch, Benjamin; Ahrens, Thomas J.

    1986-01-01

    Solid recovery impact-induced volatile loss experiments on the Murchison C2M meteorite indicate that for an impact of a given velocity, H2O and total volatiles are driven from the sample in the same proportion as present initially. The primitive surface volatile budget of a planet growing by accretion would have the same bulk elemental composition as the volatiles in the incident planetesimals. Incipient devolatilization of Murchison occurs at an initial shock pressure of about 11 GPa and complete devolatilization occurs at a pressure of about 30 GPa. For the earth, incipient and complete devolatilization of accreting planetesimals would occur when the planet reached approximately 12 percent and 27 percent, respectively, of its present-day radius. Impact-induced devolatilization would profoundly affect the volatile distribution within the accreting planet. Prior to metallic core formation and internal differentiation the growing planet would have a very small core with the same volatile content as the incident material, a volatile depleted mantle, and an extremely volatile rich surface. In the case of the earth, 99.4 wt pct of the total incident volatile material would end up on or near the planetary surface.

  11. Shock-induced volatile loss from a carbonaceous chondrite: Implications for planetary accretion

    Science.gov (United States)

    Tyburczy, J. A.; Frisch, B.; Ahrens, T. J.

    1986-01-01

    Solid recovery impact-induced volatile loss experiments on the Murchison C2M meteorite indicate that for an impact of a given velocity, H2O and total volatiles are driven from the sample in the same proportion as present initially. The primitive surface volatile budget of a planet growing by accretion would have the same bulk elemental composition as the volatiles in the incident planetesimals. Incipient devolatilization of Murchison occurs at an initial shock pressure of about 11 GPa and complete devolatilization occurs at a pressure of about 30 GPa. For the Earth, incipient and complete devolatilization of accreting planetesimals would occur when the planet reached approximately 12% and 27%, respectively, of its present-day radius. Impact-induced devolatilization would profoundly affect the volatile distribution within the accreting planet. Prior to metallic core formation and internal differentiation the growing planet would have a very small core with the same volatile content as the incident material, a volatile depleted mantle, and an extremely volatile rich surface. In the case of the Earth, 99.4 wt% of the total incident volatile material would end up on or near the planetary surface.

  12. The solar element

    DEFF Research Database (Denmark)

    Kragh, Helge

    2009-01-01

    Apart from hydrogen, helium is the most abundant chemical element in the universe, and yet it was only discovered on the Earth in 1895. Its early history is unique because it encompasses astronomy as well as chemistry, two sciences which the spectroscope brought into contact during the second half...... of the nineteenth century. In the modest form of a yellow spectral line known as D3, 'helium' was sometimes supposed to exist in the Sun's atmosphere, an idea which is traditionally ascribed to J. Norman Lockyer. Did Lockyer discover helium as a solar element? How was the suggestion received by chemists, physicists...... elements might be different. The complex story of how helium became established as both a solar and terrestrial element involves precise observations as well as airy speculations. It is a story that is unique among the discovery histories of the chemical elements....

  13. Recent Advances in Volatiles of Teas

    Directory of Open Access Journals (Sweden)

    Xin-Qiang Zheng

    2016-03-01

    Full Text Available Volatile compounds are important components of tea aroma, a key attribute of sensory quality. The present review examines the formation of aromatic volatiles of various kinds of teas and factors influencing the formation of tea volatiles, including tea cultivar, growing environment and agronomic practices, processing method and storage of tea. The determination of tea volatiles and the relationship of active-aroma volatiles with the sensory qualities of tea are also discussed in the present paper.

  14. Measurements of Absolute Abundances in Solar Flares

    CERN Document Server

    Warren, Harry P

    2013-01-01

    We present measurements of elemental abundances in solar flares with the EUV Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO). EVE observes both high temperature Fe emission lines (Fe XV-Fe XXIV) and continuum emission from thermal bremsstrahlung that is proportional to the abundance of H. By comparing the relative intensities of line and continuum emission it is possible to determine the enrichment of the flare plasma relative to the composition of the photosphere. This is the first ionization potential or FIP bias ($f$). Since thermal bremsstrahlung at EUV wavelengths is relatively insensitive to the electron temperature, it is important to account for the distribution of electron temperatures in the emitting plasma. We accomplish this by using the observed spectra to infer the differential emission measure distribution and FIP bias simultaneously. In each of the 21 flares that we analyze we find that the observed composition is close to photospheric. The mean FIP bias in our sample is $...

  15. FAMA: An automatic code for stellar parameter and abundance determination

    CERN Document Server

    Magrini, Laura; Friel, Eileen; Spina, Lorenzo; Jacobson, Heather; Cantat-Gaudin, Tristan; Donati, Paolo; Baglioni, Roberto; Maiorca, Enrico; Bragaglia, Angela; Sordo, Rosanna; Vallenari, Antonella

    2013-01-01

    The large amount of spectra obtained during the epoch of extensive spectroscopic surveys of Galactic stars needs the development of automatic procedures to derive their atmospheric parameters and individual element abundances. Starting from the widely-used code MOOG by C. Sneden, we have developed a new procedure to determine atmospheric parameters and abundances in a fully automatic way. The code FAMA (Fast Automatic MOOG Analysis) is presented describing its approach to derive atmospheric stellar parameters and element abundances. The code, freely distributed, is written in Perl and can be used on different platforms. The aim of FAMA is to render the computation of the atmospheric parameters and abundances of a large number of stars using measurements of equivalent widths as automatic and as independent of any subjective approach as possible. It is based on the simultaneous search for three equilibria: excitation equilibrium, ionization balance, and the relationship between \\fei\\ and the reduced equivalent ...

  16. Beagle 2 the Moon: An Experimental Package to Measure Polar Ice and Volatiles in Permanently Shadowed Areas or Beneath the Lunar Surface

    Science.gov (United States)

    Gibson, E. K.; McKay, D. S.; Pillinger, C. T.; Wright, I. P.; Sims, M. R.; Richter, L.

    2008-03-01

    The Gas Analysis Package and associated instruments from Beagle 2 is the ideal payload to measure the abundances and isotopic compositions of ice and volatiles found in the polar regions of the Moon. The hardware has already been flight qualified.

  17. Quantifying the volatility of organic aerosol in the southeastern US

    Science.gov (United States)

    Saha, Provat K.; Khlystov, Andrey; Yahya, Khairunnisa; Zhang, Yang; Xu, Lu; Ng, Nga L.; Grieshop, Andrew P.

    2017-01-01

    The volatility of organic aerosols (OA) has emerged as a property of primary importance in understanding their atmospheric life cycle, and thus abundance and transport. However, quantitative estimates of the thermodynamic (volatility, water solubility) and kinetic parameters dictating ambient-OA gas-particle partitioning, such as saturation concentrations (C∗), enthalpy of evaporation (ΔHvap), and evaporation coefficient (γe), are highly uncertain. Here, we present measurements of ambient-OA volatility at two sites in the southeastern US, one at a rural setting in Alabama dominated by biogenic volatile organic compounds (BVOCs) as part of the Southern Oxidant and Aerosol Study (SOAS) in June-July 2013, and another at a more anthropogenically influenced urban location in North Carolina during October-November 2013. These measurements applied a dual-thermodenuder (TD) system, in which temperature and residence times are varied in parallel to constrain equilibrium and kinetic aerosol volatility properties. Gas-particle partitioning parameters were determined via evaporation kinetic model fits to the dual-TD observations. OA volatility parameter values derived from both datasets were similar despite the fact that measurements were collected in distinct settings and seasons. The OA volatility distributions also did not vary dramatically over the campaign period or strongly correlate with OA components identified via positive matrix factorization of aerosol mass spectrometer data. A large portion (40-70 %) of measured ambient OA at both sites was composed of very-low-volatility organics (C∗ ≤ 0.1 µg m-3). An effective ΔHvap of bulk OA of ˜ 80-100 kJ mol-1 and a γe value of ˜ 0.5 best describe the evaporation observed in the TDs. This range of ΔHvap values is substantially higher than that typically assumed for simulating OA in atmospheric models (30-40 kJ mol-1). TD data indicate that γe is on the order of 0.1 to 0.5, indicating that repartitioning

  18. Development of an ion source for volatile elements at DREAMS

    Energy Technology Data Exchange (ETDEWEB)

    Pavetich, Stefan; Akhmadaliev, Shavkat; Merchel, Silke; Rugel, Georg [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Ion Beam Physics and Materials Research, Dresden (Germany)

    2012-07-01

    After successful measurements of {sup 10}Be, {sup 26}Al and {sup 41}Ca at DREAMS (DResden Accelerator Mass Spectrometry), extensive test measurements of {sup 36}Cl started. Besides the challenge of separating the stable isobar {sup 36}S, which at DREAMS is accomplished by post-stripping and a split-anode-ionization-chamber, the problem of ion source memory must be solved. To characterize this effect we use {sup 35}Cl/{sup 37}Cl samples of natural composition and {sup 35}Cl-enriched samples with a {sup 35}Cl/{sup 37}Cl-ratio >100. Similar measurements at the French AMS facility ASTER showed differences of 2-4% in the {sup 35}Cl/{sup 37}Cl ratios of the highly enriched samples after 24 h of sputtering samples with natural isotopic ratios. To minimize the long-term-memory effect, two modified designs of the original source (HVEE) were constructed at DREAMS. A more open geometry was used to improve the vacuum level, and parts of the target loading system were modified to allow the exchange of the individual cathode aperture with each target.

  19. Trace element emissions from coal

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-09-15

    Trace elements are emitted during coal combustion. The quantity, in general, depends on the physical and chemical properties of the element itself, the concentration of the element in the coal, the combustion conditions and the type of particulate control device used, and its collection efficiency as a function of particle size. Some trace elements become concentrated in certain particle streams following combustion such as bottom ash, fly ash, and flue gas particulate matter, while others do not. Various classification schemes have been developed to describe this partitioning behaviour. These classification schemes generally distinguish between: Class 1: elements that are approximately equally concentrated in the fly ash and bottom ash, or show little or no fine particle enrichment, examples include Mn, Be, Co and Cr; Class 2: elements that are enriched in the fly ash relative to bottom ash, or show increasing enrichment with decreasing particle size, examples include As, Cd, Pb and Sb; Class 3: elements which are emitted in the gas phase (primarily Hg (not discussed in this review), and in some cases, Se). Control of class 1 trace elements is directly related to control of total particulate matter emissions, while control of the class 2 elements depends on collection of fine particulates. Due to the variability in particulate control device efficiencies, emission rates of these elements can vary substantially. The volatility of class 3 elements means that particulate controls have only a limited impact on the emissions of these elements.

  20. Superheavy Elements Challenge Experimental and Theoretical Chemistry

    CERN Document Server

    Zvára, I

    2003-01-01

    When reflecting on the story of superheavy elements, the an experimenter, acknowledges the role, which the predictions of nuclear and chemical theories have played in ongoing studies. Today, the problems of major interest for experimental chemistry are the studies of elements 112 and 114 including their chemical identification. Advanced quantum chemistry calculations of atoms and molecules would be of much help. First experiments with element 112 evidence that the metal is much more volatile and inert than mercury.

  1. Morphological and elemental properties of urban aerosols among PM events and different traffic systems.

    Science.gov (United States)

    Maskey, Shila; Chae, Hoseung; Lee, Kwangyul; Dan, Nguyen Phuoc; Khoi, Tran Tien; Park, Kihong

    2016-11-05

    Morphology and elemental composition of individual fine ambient particles varied among types of PM events and between two different urban environments having different major transportation systems (gasoline/diesel vehicles versus motorcycles). Carbonaceous particles were the most dominant in PM events, whereas S-rich particles were the highest in non-events at urban Gwangju in Korea. The aged soot, semi-volatile organic (SVO), and non-volatile organic (NVO) particles were more abundant in the polluted-long range transport (LTP) event than those in the dust-LTP event and non-event. In the dust-LTP event, the aged mineral dust particles outnumbered the fresh ones, suggesting the mineral dust particles were aged during their long-range transport. At HoChiMinh (HCM) in Vietnam, the fraction of carbonaceous particles was much higher than Gwangju (66% versus 30%) possibly due to more abundant two-stroke motor vehicles at HCM. Of the carbonaceous particles, combustion soot (19%) was the highest, followed by NVO (18%), SVO (17%), and biological particles (11%) at HCM, whereas SVO (11%) and NVO (10%) particles were the highest, followed by combustion soot particles (8%) at Gwangju. The higher fraction of mineral dust particles was also observed at HCM, indicating the sampling site was influenced by dust from unpaved roads and construction sites.

  2. Chlorine and Sulfur Volatiles from in Situ Measurements of Martian Surface Materials

    Science.gov (United States)

    Clark, B. C.

    2014-12-01

    A sentinel discovery by the first in situ measurements on Mars was the high sulfur and chlorine content of global-wide soils. A variety of circumstantial evidence led to the conclusion that soil S is in the form of sulfate, and the Cl is probably chloride. An early hypothesis states that these volatiles are emitted as gases from magmas, and quickly react with dust, soil, and exposed rocks. Subsequent determination that SNC meteorites are also samples of the martian crust revealed a significantly higher S content, as sulfide, than terrestrial igneous rocks but substantially less than in soils. The ensuing wet chemical analyses by the high-latitude Phoenix mission discovered not only chloride but also perchlorate and possibly chlorate. MSL data now also implicate perchlorate at low latitudes. Gaseous interactions may have produced amorphous material on grain surfaces without forming stoichiometric salts. Yet, when exposed to liquid water, Phoenix samples released electrolytes, indicating that the soils have not been leached by rain or fresh groundwater. Sulfate occurrences at many locations on Mars, as well as some chloride enrichments, have now been discovered by remote sensing, Landed missions have discovered Cl-enrichments and ferric, Mg, Ca and more complex sulfates as duricrust, subsurface soil horizons, sandstone evaporites, and rock coatings - most of which cannot be detected from orbit. Salt-forming volatiles affect habitability wherever they are in physical contact: physicochemical parameters (ionic strength, freezing point, water activity); S is an essential element for terrestrial organisms; perchlorate is an oxidant which can degrade some organics but also can be utilized as an energy source; the entire valence range of S-compounds has been exploited by diverse microbiota on Earth. Whether such salt-induced conditions are "extremes" of habitability depends on the relative abundance of liquid H2O.

  3. An Investigation into the Parametric Model for the Elemental Abundances in the s-and r-rich Metal-poor Star CS 31062-050%s-过程与r-过程元素均超丰的贫金属星CS 31062-050的参数化研究

    Institute of Scientific and Technical Information of China (English)

    马坤; 吴海滨

    2012-01-01

    利用参数化模型研究了s-过程与r-过程元素均超丰的贫金属星(s+r星)CS 31062-050的观测丰度.计算得到,原AGB星的重叠因子取值为0.35,其初始质量应小于3~4 M⊙.s-过程分量系数Cs为0.002 7,r-过程分量系数Cr为70.5,Cs与Cr取值较高,这是对CS 31062-050形成于AIC机制的一个有力支持.%In this paper,the authors use the parametric model to fit the elemental abundances observed in the s-and r-rich,very metal-poor star(s+r star) CS 31062-050.The value of overlap factor in the AGB star is 0.35;this value could possibly be explained by the binary system with low-mass AGB star(M3~4 M⊙).The component coefficient of the s-process is 0.002 7.The component coefficient of the r-process is 70.5.The high value of Cs and Cr provides strong support for the scenario that the r-process material in CS 31062-050 comes from an AIC.

  4. Abundance Survey of M and K Dwarf Stars

    Energy Technology Data Exchange (ETDEWEB)

    Woolf, Vincent M. [Astronomy Department, University of Washington, Seattle, WA 98133 (United States); Wallerstein, George [Astronomy Department, University of Washington, Seattle, WA 98133 (United States)

    2005-07-25

    We report the measurement of chemical abundances in 35 low-mass main sequence (M and K dwarf) stars. We have measured the abundance of 12 elements in Kapteyn's Star, a nearby halo M subdwarf. The abundances indicate an iron abundance of [Fe/H] = -0.98, which is about 0.5 dex smaller than that measured in the only previous published measurement using atomic absorption lines. We have measured Fe and Ti abundances in 35 M and K dwarfs with -2.39 [Fe/H] +0.21 using atomic absorption lines, mostly in the 8000A <{lambda} < 8850A range. These will be used to calibrate photometric and low-resolution spectrum metallicity indices for low mass dwarfs, which will make metallicity estimates for these stars more certain. We also describe some difficulties encountered which are not normally necessary to consider when studying warmer stars.

  5. Ionized Gaseous Nebulae Abundance Determination from the Direct Method

    Science.gov (United States)

    Pérez-Montero, Enrique

    2017-04-01

    This tutorial explains the procedure used to analyze an optical emission-line spectrum produced by a nebula ionized by massive star formation. Particularly, the methodology used to derive physical properties, such as electron density and temperature, and the ionic abundances of the most representative elements whose emission lines are present in the optical spectrum is described. The main focus is on the direct method, which is based on the measurement of the electron temperature to derive the abundances, given that the ionization and thermal equilibrium of the ionized gas is dominated by the metallicity. The ionization correction factors used to obtain total abundances from the abundances of some of their ions are also given. Finally, some strong-line methods to derive abundances are described. Such methods are used when no estimation of the temperature can be derived, but which can be consistent with the direct method if they are empirically calibrated.

  6. Abundance sensitive points of line profiles in the stellar spectra

    CERN Document Server

    Sheminova, V A

    2014-01-01

    Many abundance studies are based on spectrum synthesis and $\\chi$-squared differences between the synthesized and an observed spectrum. Much of the spectra so compared depend only weakly on the elemental abundances. Logarithmic plots of line depths rather than relative flux make this more apparent. We present simulations that illustrate a simple method for finding regions of the spectrum most sensitive to abundance, and also some caveats for using such information. As expected, we find that weak features are the most sensitive. Equivalent widths of weak lines are ideal features, because of their sensitivity to abundances, and insensitivity to factors that broaden the line profiles. The wings of strong lines can also be useful, but it is essential that the broadening mechanisms be accurately known. The very weakest features, though sensitive to abundance, should be avoided or used with great caution because of uncertainty of continuum placement as well as numerical uncertainties associated with the subtraction...

  7. Spiral mining for lunar volatiles

    Science.gov (United States)

    Schmitt, H. H.; Kulcinski, G. L.; Sviatoslavsky, I. N.; Carrier, W. D., III

    Lunar spiral mining, extending outward from a periodically mobile central power and processing station represents an alternative for comparison with more traditional mining schemes. In this concept, a mining machine would separate regolith fines and extract the contained volatiles. Volatiles then would be pumped along the miner's support arm to the central station for refining and for export or storage. The basic architecture of the central processing station would be cylindrical. A central core area could house the power subsystem of hydrogen-oxygen engines or fuel cells. Habitat sections and other crew occupied areas could be arranged around the power generation core. The outer cylinder could include all volatile refining subsystems. Solar thermal power collectors and reflectors would be positioned on top of the central station. Long term exploitation of a volatile resource region would begin with establishment of a support base at the center of a long boundary of the region. The mining tract for each spiral mining system would extend orthogonal to this boundary. New spiral mining systems would be activated along parallel tracts as demand for lunar He-3 and other solar wind volatiles increased.

  8. The role of volatiles in the genesis of cenozoic magmatism in Northern Victoria Land (NVL), Antarctica

    Science.gov (United States)

    Giacomoni, Pier Paolo; Coltorti, Massimo; Bonadiman, Costanza; Ferlito, Carmelo; Zanetti, Alberto; Ottolini, Luisa

    2017-04-01

    This study offers an innovative view of the petrogenetic processes responsible for the magmas erupted in the Western Antarctic Rift System (WARS) by studying the chemical composition and the volatiles content of basic lavas and olivine-hosted melt inclusions (MI). Lavas come from three localities: Shield Nunatak (Mt. Melbourne), Eldridge Bluff and Handler Ridge. They are olivine-phyric basanites (42.41-44.80 SiO2 wt%; 3.11-6.19 Na2O+K2O wt%) and basalts (44.91-48.73 SiO2 wt%; 2.81-4.55 Na2O+K2O wt%) with minor clinopyroxene and plagioclase. Samples from Handler Ridge clearly differ by having the highest TiO2 (3.55-3.65 wt%), Rb, Ba, Nb, La, Zr despite their more primitive features (60.83-44.87 Mg#, MgO/(MgO+FeO) %mol). Olivine-hosted melt inclusions (MI) were analyzed for major element and volatiles (H2O. CO2, S, F, and Cl) after HT (1300°C) and HP (6 kbar) homogenization. Despite a larger variability, MI are compositionally comparable with the host lavas and are characterized by two distinct trends (high-Fe-Ti-K and low-Fe-Ti-K). The H2O content in MI ranges from 0.70 wt% to 2.64 wt% and CO2 from 25 ppm to 341 ppm (H2O/CO2 1). At comparable H2O contents, few samples show a higher CO2 values (1322 ppm to 3905 ppm) with a H2O/CO2 molar ratio down to 0.8. F and Cl content varies from 1386 ppm to 10 ppm and from 1336 ppm to 38 ppm respectively. Concentration of volatiles show a good correlation with alkalies, especially with K2O; Handler Ridge presents the highest total value of F and Cl (2675 ppm). Chondrite-normalized trace elements concentration in MI show an intraplate pattern with negative anomalies in Rb, K, Ti. Accordingly, to the lava contents, MI from Handler Ridge have a significantly higher concentration in Rb (12-45 ppm), Sr (700-834 ppm), Ba (433-554) and Nb (48.8-83.4 ppm) with respect to the other localities at comparable Mg#. Mantle melting mass balance calculations simulate the observed H2O, CO2 and Cl concentration by melting a spinel lhezolite from

  9. RICE PRICE VOLATILITY IN EAST JAVA

    Directory of Open Access Journals (Sweden)

    Wati R.Y.E.

    2017-09-01

    Full Text Available The purpose of the research is analyzing the volatility and volatility spillover of monthly price of paddy at the level of farmers and consumers in 2010-2016. ARCH/GARCH used to analyze volatility and GARCH BEKK-model is used to analyze the volatility spillover. The results of the analysis show that price volatility at the farmer level is very high (extremely high volatility, price volatility at the consumer level is low (low volatility, and volatility spillover does not occur between the farmers and the consumers market. The need to guarantee an effective floor price as well as information disclosure related to the market commodity prices so that the pattern of prices transmission among interrelated markets can be symmetrical.

  10. The price of fixed income market volatility

    CERN Document Server

    Mele, Antonio

    2015-01-01

    Fixed income volatility and equity volatility evolve heterogeneously over time, co-moving disproportionately during periods of global imbalances and each reacting to events of different nature. While the methodology for options-based "model-free" pricing of equity volatility has been known for some time, little is known about analogous methodologies for pricing various fixed income volatilities. This book fills this gap and provides a unified evaluation framework of fixed income volatility while dealing with disparate markets such as interest-rate swaps, government bonds, time-deposits and credit. It develops model-free, forward looking indexes of fixed-income volatility that match different quoting conventions across various markets, and uncovers subtle yet important pitfalls arising from naïve superimpositions of the standard equity volatility methodology when pricing various fixed income volatilities. The ultimate goal of the authors´ efforts is to make interest rate volatility standardization a valuable...

  11. Dust formation in a galaxy with primitive abundances.

    Science.gov (United States)

    Sloan, G C; Matsuura, M; Zijlstra, A A; Lagadec, E; Groenewegen, M A T; Wood, P R; Szyszka, C; Bernard-Salas, J; van Loon, J Th

    2009-01-16

    Interstellar dust plays a crucial role in the evolution of galaxies. It governs the chemistry and physics of the interstellar medium. In the local universe, dust forms primarily in the ejecta from stars, but its composition and origin in galaxies at very early times remain controversial. We report observational evidence of dust forming around a carbon star in a nearby galaxy with a low abundance of heavy elements, 25 times lower than the solar abundance. The production of dust by a carbon star in a galaxy with such primitive abundances raises the possibility that carbon stars contributed carbonaceous dust in the early universe.

  12. Geochemical Constraints for Mechanisms of Planetary Differentiation and Volatile Depletion

    OpenAIRE

    Dhaliwal, Jasmeet Kaur

    2016-01-01

    The evolution of the terrestrial planets involved a range of complex processes, including accretion, core formation, post-core formation accretion, mantle differentiation and volatile depletion. The earliest processes of accretion and core formation have largely been overprinted on Earth and Mars, but can be investigated using geochemical measurements of extraterrestrial materials. Highly siderophile elements (HSE; Os, Ir, Ru, Rh, Pt, Pd, Re, Au) preferentially partition into metal phases an...

  13. Performance of commercial non-methane hydrocarbon analyzers in monitoring polar volatile organic compounds

    Science.gov (United States)

    Quantifying non-methane hydrocarbons (NMHC) from animal feeding operations (AFOs) is challenging due to the broad spectrum of compounds and the polar nature of the most abundant compounds. The purpose of this study was to determine the performance of commercial NMHC analyzers for measuring volatile ...

  14. Observability of market daily volatility

    Science.gov (United States)

    Petroni, Filippo; Serva, Maurizio

    2016-02-01

    We study the price dynamics of 65 stocks from the Dow Jones Composite Average from 1973 to 2014. We show that it is possible to define a Daily Market Volatility σ(t) which is directly observable from data. This quantity is usually indirectly defined by r(t) = σ(t) ω(t) where the r(t) are the daily returns of the market index and the ω(t) are i.i.d. random variables with vanishing average and unitary variance. The relation r(t) = σ(t) ω(t) alone is unable to give an operative definition of the index volatility, which remains unobservable. On the contrary, we show that using the whole information available in the market, the index volatility can be operatively defined and detected.

  15. Consistent ranking of volatility models

    DEFF Research Database (Denmark)

    Hansen, Peter Reinhard; Lunde, Asger

    2006-01-01

    result in an inferior model being chosen as "best" with a probability that converges to one as the sample size increases. We document the practical relevance of this problem in an empirical application and by simulation experiments. Our results provide an additional argument for using the realized...... variance in out-of-sample evaluations rather than the squared return. We derive the theoretical results in a general framework that is not specific to the comparison of volatility models. Similar problems can arise in comparisons of forecasting models whenever the predicted variable is a latent variable.......We show that the empirical ranking of volatility models can be inconsistent for the true ranking if the evaluation is based on a proxy for the population measure of volatility. For example, the substitution of a squared return for the conditional variance in the evaluation of ARCH-type models can...

  16. A holistic abundance analysis of r-rich stars

    CERN Document Server

    Zhang, Jiang; Zhang, Bo; 10.1111/j.1365-2966.2010.17374.x

    2010-01-01

    The chemical abundances of metal-poor stars are an excellent test bed by which to set new constraints on models of neutron-capture processes at low metallicity. Some r-process-rich (hereafter r-rich) metal-poor stars, such as HD221170, show an overabundance of the heavier neutron-capture elements and excesses of lighter neutron-capture elements. The study of these r-rich stars could give us a better understanding of weak and main r-process nucleosynthesis at low metallicity. Based on conclusions from the observation of metal-poor stars and neutron-capture element nucleosynthesis theory, we set up a model to determine the relative contributions from weak and main r-processes to the heavy-element abundances in metal-poor stars. Using this model, we find that the abundance patterns of light elements for most sample stars are close to the pattern of weak r-process stars, and those of heavier neutron-capture elements very similar to the pattern of main r-process stars, while the lighter neutron-capture elements ca...

  17. Oil Volatility Risk and Expected Stock Returns

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Pan, Xuhui (Nick)

    After the financialization of commodity futures markets in 2004-05 oil volatility has become a strong predictor of returns and volatility of the overall stock market. Furthermore, stocks' exposure to oil volatility risk now drives the cross-section of expected returns. The difference in average...... return between the quintile of stocks with low exposure and high exposure to oil volatility is significant at 0.66% per month, and oil volatility risk carries a significant risk premium of -0.60% per month. In the post-financialization period, oil volatility risk is strongly related with various measures...

  18. The specificity of herbivore-induced plant volatiles in attracting herbivore enemies.

    Science.gov (United States)

    Clavijo McCormick, Andrea; Unsicker, Sybille B; Gershenzon, Jonathan

    2012-05-01

    Plants respond to herbivore attack by emitting complex mixtures of volatile compounds that attract herbivore enemies, both predators and parasitoids. Here, we explore whether these mixtures provide significant value as information cues in herbivore enemy attraction. Our survey indicates that blends of volatiles released from damaged plants are frequently specific depending on the type of herbivore and its age, abundance and feeding guild. The sensory perception of plant volatiles by herbivore enemies is also specific, according to the latest evidence from studies of insect olfaction. Thus, enemies do exploit the detailed information provided by plant volatile mixtures in searching for their prey or hosts, but this varies with the diet breadth of the enemy.

  19. Rhenium volatilization in waste glasses

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Kai; Pierce, David A. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Hrma, Pavel, E-mail: pavel.hrma@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Schweiger, Michael J. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Kruger, Albert A. [U.S. Department of Energy, Office of River Protection, Richland, WA 99352 (United States)

    2015-09-15

    Highlights: • Re did not volatilize from a HLW feed until 1000 °C. • Re began to volatilize from LAW feeds at ∼600 °C. • The vigorous foaming and generation of gases from salts enhanced Re evaporation in LAW feeds. • The HLW glass with less foaming and salts is a promising medium for Tc immobilization. - Abstract: We investigated volatilization of rhenium (Re), sulfur, cesium, and iodine during the course of conversion of high-level waste melter feed to glass and compared the results for Re volatilization with those in low-activity waste borosilicate glasses. Whereas Re did not volatilize from high-level waste feed heated at 5 K min{sup −1} until 1000 °C, it began to volatilize from low-activity waste borosilicate glass feeds at ∼600 °C, a temperature ∼200 °C below the onset temperature of evaporation from pure KReO{sub 4}. Below 800 °C, perrhenate evaporation in low-activity waste melter feeds was enhanced by vigorous foaming and generation of gases from molten salts as they reacted with the glass-forming constituents. At high temperatures, when the glass-forming phase was consolidated, perrhenates were transported to the top surface of glass melt in bubbles, typically together with sulfates and halides. Based on the results of this study (to be considered preliminary at this stage), the high-level waste glass with less foaming and salts appears a promising medium for technetium immobilization.

  20. APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy

    Science.gov (United States)

    Hasselquist, Sten; Shetrone, Matthew; Smith, Verne; Holtzman, Jon; McWilliam, Andrew; Fernández-Trincado, J. G.; Beers, Timothy C.; Majewski, Steven R.; Nidever, David L.; Tang, Baitian; Tissera, Patricia B.; Fernández Alvar, Emma; Allende Prieto, Carlos; Almeida, Andres; Anguiano, Borja; Battaglia, Giuseppina; Carigi, Leticia; Delgado Inglada, Gloria; Frinchaboy, Peter; García-Hernández, D. A.; Geisler, Doug; Minniti, Dante; Placco, Vinicius M.; Schultheis, Mathias; Sobeck, Jennifer; Villanova, Sandro

    2017-08-01

    The Apache Point Observatory Galactic Evolution Experiment provides the opportunity of measuring elemental abundances for C, N, O, Na, Mg, Al, Si, P, K, Ca, V, Cr, Mn, Fe, Co, and Ni in vast numbers of stars. We analyze thechemical-abundance patterns of these elements for 158 red giant stars belonging to the Sagittarius dwarf galaxy (Sgr). This is the largest sample of Sgr stars with detailed chemical abundances, and it is the first time that C, N, P, K, V, Cr, Co, and Ni have been studied at high resolution in this galaxy. We find that the Sgr stars with [Fe/H] ≳ -0.8 are deficient in all elemental abundance ratios (expressed as [X/Fe]) relative to the Milky Way, suggesting that the Sgr stars observed today were formed from gas that was less enriched by Type II SNe than stars formed in the Milky Way. By examining the relative deficiencies of the hydrostatic (O, Na, Mg, and Al) and explosive (Si, P, K, and Mn) elements, our analysis supports the argument that previous generations of Sgr stars were formed with a top-light initial mass function, one lacking the most massive stars that would normally pollute the interstellar medium with the hydrostatic elements. We use a simple chemical-evolution model, flexCE, to further support our claim and conclude that recent stellar generations of Fornax and the Large Magellanic Cloud could also have formed according to a top-light initial mass function.