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Sample records for lbv ag carinae

  1. On the nature of the prototype LBV AG Carinae I. Fundamental parameters during visual minimum phases and changes in the bolometric luminosity during the S-Dor cycle

    CERN Document Server

    Groh, Jose H; Damineli, Augusto; Whitelock, Patricia A; Marang, Fred; Rossi, C

    2009-01-01

    We present a detailed spectroscopic analysis of the luminous blue variable AG Carinae during the last two visual minimum phases of its S-Dor cycle (1985-1990 and 2000-2003). The analysis reveals an overabundance of He, N, and Na, and a depletion of H, C, and O, on the surface of AG Car, indicating the presence of CNO-processed material. Furthermore, the ratio N/O is higher on the stellar surface than in the nebula. We found that the minimum phases of AG Car are not equal to each other, since we derived a noticeable difference between the maximum effective temperature achieved during 1985-1990 (22,800 K) and 2000-2001 (17,000 K). While the wind terminal velocity was 300 km/s in 1985-1990, it was as low as 105 km/s in 2001. The mass-loss rate, however, was lower from 1985-1990 (1.5 x 10^(-5) Msun/yr) than from 2000-2001 (3.7 x 10^(-5) Msun/yr). We found that the wind of AG Car is significantly clumped (f=0.10 - 0.25) and that clumps must be formed deep in the wind. We derived a bolometric luminosity of 1.5 x 10...

  2. The bipolar structure of the LBV nebula around HR Carinae

    CERN Document Server

    Weis, K; Bomans, D J; Chu, Y H; Joner, M D

    1997-01-01

    HR Carinae is one of the few Luminous Blue Variables (LBVs) in the Galaxy. It has a nebula that appears bipolar. We have obtained imaging and high-dispersion, long-slit echelle data of the HR Car nebula, and confirmed that it is a bipolar nebula. Its polar axis lies along the position angle of 125 +- 5 degree; each lobe has, at a distance of 5 kpc a diameter of about 0.65 pc and a line-of-sight expansion velocity of 75-150 km/sec. Beside the expanding bipolar lobes, a number of [NII]-bright knots are detected. These knots have lower expansion velocities than the lobes and are detected only within the projected boundary of the lobes. These knots are most likely nitrogen-enriched material ejected by HR Car. On a larger scale, a funnel-shaped nebula is detected at 2.5" northwest of HR Car. The axis of the funnel is roughly aligned with the polar axis of the HR Car nebula, suggesting that HR Car may be responsible for the ionization and shaping of this nebula. Future observations of kinematics and abundances are ...

  3. Spectrophotometry of the shell around AG Carinae

    Science.gov (United States)

    Mitra, P. Mila; Dufour, Reginald J.

    1990-01-01

    Spatially-resolved long-slit spectrophotometry are presented for two regions of the shell nebula around the P-Cygni variable star AG Carinae. The spectra cover the 3700-6800 A wavelength range. Emission-line diagnostics are used to derive extinction, electron temperatures, and densities for various positions in the nebula. The chemical abundances and ionization structure are calculated and compared with other types of planetary nebulae and shells around other luminous stars. It is found that the N/O and N/S ratios of Ag Car are high compared to solar neighborhood ISM values. The O/H depletion found for the AG Car shell approaches that found in the condensations of the Eta Car system.

  4. Modelagem do vento e da fotosfera de AG Carinae

    Science.gov (United States)

    Groh, J. H.; Damineli, A.

    2003-08-01

    A trajetória evolutiva das estrelas de alta massa depende fortemente de suas taxas de perda de massa. Apesar do rápido progresso no estudo destas estrelas, a taxa de perda de massa e outros parâmetros físicos básicos, como a temperatura superficial e a velocidade terminal do vento ainda não estão bem determinados. Isto ocorre devido à presença de ventos irregulares, rápidos e fortes ao redor destas estrelas, tornando a interpretação dos seus espectros uma tarefa difícil. Assim, a modelagem do vento e da fotosfera dessas estrelas está sendo cada vez mais usada para obter tais parâmetros a partir dos espectros. O aumento da taxa de perda de massa durante a fase LBV (Variáveis Luminosas Azuis), comparado com outros tipos de estrelas, tem sido atribuído a instabilidades do tipo S Doradus. Dispomos de uma base de dados espectroscópicos cobrindo 22 anos de observações de AG Carinae, incluindo um ciclo S Doradus completo, com espectros CCD em alta resolução na faixa óptica e infravermelha. Utilizamos o programa desenvolvido por Schmutz (1997) para uma análise preliminar desse ciclo, obtendo a taxa de perda de massa a partir da linha do Ha. Não existe uma correlação clara da taxa de perda de massa com mudanças da temperatura efetiva, do raio da estrela e do fluxo na banda V. A estrela atingiu seu mínimo fotométrico (raio mínimo) em 1990 e o máximo fotométrico (raio máximo) em 1995, enquanto que o fluxo máximo da linha do Ha ocorreu em 1996. Além disso a taxa de perda de massa não segue esse ciclo, contrariamente às idéias correntes. Para fazer um modelo mais realista estamos usando o programa CMFGEN (Hillier & Miller), que trata a fotosfera e o vento estelar de forma consistente, considerando a radiação fora do equilíbrio termodinâmico (NLTE) e com blanketting total de linhas. Simulamos o espectro de AG Carinae em duas épocas extremas do ciclo S Dor para testar os resultados obtidos com o modelo mais simplificado.

  5. The S Dor phases of AG Carinae

    Science.gov (United States)

    Sterken, C.

    2003-05-01

    AG Car (HD 94910) is a Luminous Blue Variable (LBV) of the southern hemisphere. Its light curve displays episodes of fading and brightening with strongly variable amplitude, as is observed in S Doradus and some other LBVs or Hubble-Sandage variables. Van Genderen, Sterken & de Groot (1997) discussed all available photometric data covering more than one century, and introduced the concept S Dor phase: phases of brightening with a cyclic pattern of recurrence. In particular, they distinguish short S Dor phases superimposed on a much longer rhythm of brightening and fading. S Dor phases are recognised by a substantial reddening while the star migrates to the red side of the H-R diagram. Such changes, when strong, are not seldomly mistaken for eruptions. In 1995, AG Car was in one of its brightest maxima since the early 1980s, and then faded again to a more quiescent state. Recently, the star started brightening again and has now Strömgren colour indices very similar to those of 1994, though the level of brightening is less strong. The current brightening corresponds to cycle 7 after the 1995 maximum and conforms to the cycle length of 371.4 days. Financial support from the Belgian Fund for Scientific Research (FWO) and the Belgian Federal Office for Scientific, Technical and Cultural Affairs (IUAP-5/36) is acknowledged. Observing time at La Silla was provided by ESO and by the Danish Natural Science Research Council through the centre for Ground-Based Observational Astronomy.

  6. Spatially resolved spectroscopy of AG Carinae, and direct evidence for stellar evolution: The central star of NGC 2392

    Science.gov (United States)

    Altner, Bruce; Shore, Steven N.

    1993-01-01

    We have performed spatially-resolved low dispersion long-slit spectroscopy for the circumstellar shell of the luminous blue variable AG Carinae with IUE between lambda lambda 1200 - 3200 A. At all positions a strong dust-scattered stellar continuum is detected. Only a few emission lines, FE II 2600 and O I (?) 1304, have been detected; the emission is stronger on the southern side of the shell. The UV surface brightness and derived dust properties are completely consistent with the groundbased and KAO FIR observations: the grains are large (0.1 - 1 micron), warm (45 - 100 K depending on composition), highly reflecting (C(sub sca)/C(sub abs) approximately equal to 1), and tie up about 10(exp -4) to 10(exp -3) solar mass of material. We also observe similarities of the results for HR Car and LBV's to those reported here.

  7. LBVs AND THE NATURE OF THE S DOR CYCLES: THE CASE OF AG CARINAE

    Directory of Open Access Journals (Sweden)

    J. H. Groh

    2008-01-01

    Full Text Available Presentamos los resultados de un análisis espectroscópico detallado sobre 20 a~nos de observaciones de AG Carinae, usando el código de transferencia radiativa llamado CMFGEN. Entre las conclusiones de este trabajo, resaltamos la importancia de incluir efectos dependientes del tiempo en el análisis del ciclo completo de S Dor. Hemos obtenido que la tasa de pérdida de masa es aproximadamente constante durante las fases fras, implicando que las erupciones en los objetos de tipo S Dor comienzan bastante más temprano que durante el máximo observado en la curva de luz visual. Hemos determinado ademías que los ciclos S Dor son, en ultima instancia, consecuencia de un aumento/disminución del radio hidrostático en combinación con una pseudo-fotosfera.

  8. AG Carinae III. The 1990 hot phase of the star and the physical structure of the circumstellar environment

    CERN Document Server

    Viotti, R; Rossi, C

    1993-01-01

    Long slit spectra of the region around the Luminous Blue Variable AG Car obtained in June 1990, just before the onset of its new brightening phase, indicate that AG Car was in the hottest phase so far recorded. The spectrum shows strong broad emissions of He II 468.6 nm, and [Fe III] 465.8-470.1 nm, and He I, N II, Si III, Al III and Fe III with a P Cygni profile. We have also identified weak lines of C II and O II. A faint continuum emission has been detected within the whole ring nebula. We also find that the spectrum of some regions is partially due to scattered star's light. This provides evidence of the presence of dust grains, and indicates that even in present times dust is condensing from AG Car wind. The sharp outer edge of the ring suggest the presence of a shock front. We have also identified an extended low density H II $halo$, which should be associated with the residual of the stellar wind of a previous cooler evolutionary phase of AG Car. In the halo the H$\\alpha$/[N II] ratio is strengthened w...

  9. MOLECULES IN {eta} CARINAE

    Energy Technology Data Exchange (ETDEWEB)

    Loinard, Laurent; Menten, Karl M.; Guesten, Rolf [Max-Planck Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany); Zapata, Luis A.; Rodriguez, Luis F. [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 3-72, 58090 Morelia, Michoacan (Mexico)

    2012-04-10

    We report the detection toward {eta} Carinae of six new molecules, CO, CN, HCO{sup +}, HCN, HNC, and N{sub 2}H{sup +}, and of two of their less abundant isotopic counterparts, {sup 13}CO and H{sup 13}CN. The line profiles are moderately broad ({approx}100 km s{sup -1}), indicating that the emission originates in the dense, possibly clumpy, central arcsecond of the Homunculus Nebula. Contrary to previous claims, CO and HCO{sup +} do not appear to be underabundant in {eta} Carinae. On the other hand, molecules containing nitrogen or the {sup 13}C isotope of carbon are overabundant by about one order of magnitude. This demonstrates that, together with the dust responsible for the dimming of {eta} Carinae following the Great Eruption, the molecules detected here must have formed in situ out of CNO-processed stellar material.

  10. Molecules in \\eta\\ Carinae

    CERN Document Server

    Loinard, Laurent; Guesten, Rolf; Zapata, Luis A; Rodriguez, Luis F

    2012-01-01

    We report the detection toward \\eta\\ Carinae of six new molecules, CO, CN, HCO+, HCN, HNC, and N2H+, and of two of their less abundant isotopic counterparts, 13CO and H13CN. The line profiles are moderately broad (about 100 km /s) indicating that the emission originates in the dense, possibly clumpy, central arcsecond of the Homunculus Nebula. Contrary to previous claims, CO and HCO+ do not appear to be under-abundant in \\eta\\ Carinae. On the other hand, molecules containing nitrogen or the 13C isotope of carbon are overabundant by about one order of magnitude. This demonstrates that, together with the dust responsible for the dimming of eta Carinae following the Great Eruption, the molecules detected here must have formed in situ out of CNO-processed stellar material.

  11. Long-term Spectroscopic Monitoring of LBVs and LBV Candidates

    CERN Document Server

    Lobel, A; Torres, K; Gorlova, N

    2010-01-01

    We present results of a long-term spectroscopic monitoring program (since mid 2009) of Luminous Blue Variables with the new HERMES echelle spectrograph on the 1.2 m Mercator telescope at La Palma (Spain). We investigate high-resolution (R=80,000) optical spectra of two LBVs, P Cyg and HD 168607, the LBV candidates MWC 930 and HD 168625, and the LBV binary MWC 314. In P Cyg we observe flux changes in the violet wings of the Balmer H{\\alpha}, H{\\beta}, and He I lines between May and Sep 2009. The changes around 200 km/s to 300 km/s are caused by variable opacity at the base of the supersonic wind from the blue supergiant. We observe in MWC 314 broad double-peaked metal emission lines with invariable radial velocities over time. On the other hand, we measure in the photospheric S II {\\lambda}5647 absorption line, with lower excitation energy of ~14 eV, an increase of the heliocentric radial velocity centroid from 37 km/s to 70 km/s between 5 and 10 Sep 2009 (and 43 km/s on 6 Apr 2010). The increase of radial vel...

  12. Modeling the Asymmetric Wind of Massive LBV Binary MWC 314

    CERN Document Server

    Lobel, A; Dozinel, K Torres; Gorlova, N; Martayan, C; Raskin, G; Van Winckel, H; Prins, S; Pessemier, W; Waelkens, C; Frémat, Y; Hensberge, H; Dummortier, L; Jorissen, A; Van Eck, S; Lehmann, H

    2011-01-01

    Spectroscopic monitoring with Mercator-HERMES over the past two years reveals that MWC 314 is a massive binary system composed of an early B-type primary LBV star and a less-luminous supergiant companion. We determine an orbital period Porb of 60.85 d from optical S II and Ne I absorption lines observed in this single-lined spectroscopic binary. We find an orbital eccentricity of e=0.26, and a large amplitude of the radial velocity curve of 80.6 km/s. The ASAS V light-curve during our spectroscopic monitoring reveals two brightness minima (\\Delta V~0.1 mag.) over the orbital period due to partial eclipses at an orbital inclination angle of ~70 degrees. We find a clear correlation between the orbital phases and the detailed shapes of optical and near-IR P Cygni-type line profiles of He I, Si II, and double- or triple-peaked stationary cores of prominent Fe II emission lines. A preliminary 3-D radiative transfer model computed with Wind3D shows that the periodic P Cygni line profile variability results from an ...

  13. Discrete absorption components in the massive LBV Binary MWC 314

    CERN Document Server

    Lobel, A; Corcoran, M; Groh, J H; Frémat, Y

    2014-01-01

    We investigate the physical properties of large-scale wind structures around massive hot stars with radiatively-driven winds. We observe Discrete Absorption Components (DACs) in optical He I P Cygni lines of the LBV binary MWC 314 (Porb=60.8 d). The DACs are observed during orbital phases when the primary is in front of the secondary star. They appear at wind velocities between -100 km/s and -600 km/s in the P Cyg profiles of He I lam5875, lam6678, and lam4471, signaling high-temperature expanding wind regions of enhanced density and variable outflow velocity. The DACs can result from wave propagation linked to the orbital motion near the low-velocity wind base. The He I lines indicate DAC formation close to the primary's surface in high-temperature wind regions in front of its orbit, or in dynamical wind regions confined between the binary stars. We observed the DACs with Mercator-HERMES on 5 Sep 2009, 5 May 2012, and 6 May 2014 when the primary is in front of the secondary star. XMM-Newton observations of 6...

  14. Tracing back the evolution of the candidate LBV HD168625

    CERN Document Server

    Mahy, L; Royer, P; Waelkens, C

    2016-01-01

    Aims. We obtained Herschel/PACS imaging and spectroscopic observations of the nebula surrounding the candidate LBV HD168625. By combining these data with optical spectra of the star, we want to constrain the abundances in the nebula and in the star and compare them to trace back its evolution. Methods. We use CMFGEN to determine the fundamental parameters and the CNO abundances of the central star whilst the abundances of the nebula are derived from the emission lines present in the Herschel/PACS spectrum. Result. The FIR images show a nebula composed of an elliptical ring/torus of ejecta with a ESE-WNW axis and of a second perpendicular bipolar structure composed of empty caps/rings. We detect equatorial shells composed of dust and ionized material with different sizes when observed at different wavelengths, and bipolar caps more of less separated from the central star in H$\\alpha$ and mid-IR images. This complex global structure seems to show 2 different inclinations: 40{\\deg} for the equatorial torus and 6...

  15. FUSE Observations of eta Carinae

    CERN Document Server

    Iping, R C; Gull, T R

    2004-01-01

    Eta Carinae was observed by FUSE through the LWRS (30 arcsec x30 arcsec) and HIRS (1.25 arcsec x 20 arcsec) apertures in March and April 2004. There are significant differences between the two spectra. About half of the LWRS flux appears to be due to two B-type stars near the edge of the LWRS aperture, 14 arcsec from eta Carinae. The HIRS spectrum (LiF1 channel) therefore reveals the intrinsic FUV spectrum of eta Carinae without this stellar contamination. The HIRS spectrum contains strong interstellar H2 having high rotational excitation (up to J=8). Most of the atomic species with prominent ISM features (C II, Fe II, Ar I, P II, etc) also have strong blue-shifted absorption to v= ~ -580 km/s that is associated with expanding debris from the 1840 eruption.

  16. Giant Eruption of the Extremely Metal-Poor LBV in DDO 68

    Science.gov (United States)

    Perepelitsyna, Y. A.; Pustilnik, S. A.

    2017-06-01

    Understanding the evolution of massive stars with metallicities much lower than that of the Sun (e.g., Zresearch until extremely large telescopes (ELTs) are in operation. Meantime, selection of good targets for future ELT research becomes actual. Here we present one of such important targets. The unusual void galaxy DDO68 has several star-forming (SF) regions with the gas metallicity Z = Z⊙/35 [12+log(O/H)=7.14]. In 2008, we discovered a luminous blue variable (LBV) star in its HII-region Knot 3. We present the LBV's V-band lightcurve for the time range of 1988 to 2016 using both our new and published data for Knot 3 brightness as well as the archive data from eleven telescopes. The prerequisite is an accurate estimate of the ‘minimal' (non-variable) V-band light for the Knot 3 underlying HII region. Its subtraction from the variable light of Knot 3 allows us to determine the full amplitude of the LBV variability at the level of δV ≳4m. This implies that the LBV has experienced a very rare event of a giant eruption during the years 2008-2011.

  17. X-shooter, NACO, and AMBER observations of the LBV Pistol Star

    NARCIS (Netherlands)

    Martayan, C.; Blomme, R.; Bouquin, J.-B; Merand, A.; Montagnier, G.; Selman, F.; Girard, J.; Fox, A.; Baade, D.; Frémat, Y.; Lobel, A.; Martins, F.; Patru, F.; Rivinius, T.; Sana, H.A.A.; Stefl, S.; Zorec, J.; Semaan, T.

    2011-01-01

    We present multi-instrument and multi-wavelength observations of the famous LBV star Pistol Star. These observations are part of a larger program on early O stars at different metallicities. The Pistol Star has been claimed to be one of the most massive star known, with 250 solar masses. We present

  18. Arctic Ocean data in CARINA

    Directory of Open Access Journals (Sweden)

    S. Jutterström

    2009-08-01

    Full Text Available The paper describes the steps taken for quality controlling chosen parameters within the Arctic Ocean data included in the CARINA data set and checking for offsets between the individual cruises. The evaluated parameters are the inorganic carbon parameters (total dissolved inorganic carbon, total alkalinity and pH, oxygen and nutrients: nitrate, phosphate and silicate. More parameters can be found in the CARINA data product, but were not subject to a secondary quality control. The main method in determining offsets between cruises was regional multi-linear regression, after a first rough basin-wide deep-water estimate of each parameter. Lastly, the results of the secondary quality control are discussed as well as suggested adjustments.

  19. Arctic Ocean data in CARINA

    Directory of Open Access Journals (Sweden)

    S. Jutterström

    2010-02-01

    Full Text Available The paper describes the steps taken for quality controlling chosen parameters within the Arctic Ocean data included in the CARINA data set and checking for offsets between the individual cruises. The evaluated parameters are the inorganic carbon parameters (total dissolved inorganic carbon, total alkalinity and pH, oxygen and nutrients: nitrate, phosphate and silicate. More parameters can be found in the CARINA data product, but were not subject to a secondary quality control. The main method in determining offsets between cruises was regional multi-linear regression, after a first rough basin-wide deep-water estimate of each parameter. Lastly, the results of the secondary quality control are discussed as well as applied adjustments.

  20. Atlantic CFC data in CARINA

    Directory of Open Access Journals (Sweden)

    R. Steinfeldt

    2010-01-01

    Full Text Available Water column data of carbon and carbon-relevant parameters have been collected and merged into a new database called CARINA (CARbon IN the Atlantic. In order to provide a consistent data set, all data have been examined for systematic biases and adjusted if necessary (secondary quality control (QC. The CARINA data set is divided into three regions: the Arctic/Nordic Seas, the Atlantic region and the Southern Ocean. Here we present the CFC data for the Atlantic region, including the chlorofluorocarbons CFC-11, CFC-12 and CFC-113 as well as carbon tetrachloride (CCl4. The methods applied for the secondary quality control, a crossover analyses, the investigation of CFC ratios in the ocean and the CFC surface saturation are presented. Based on the results, the CFC data of some cruises are adjusted by a certain factor or given a "poor'' quality flag.

  1. A Smoking Gun in the Carina Nebula

    Science.gov (United States)

    Hamaguchi, Kenji; Corcoran, Michael F.; Ezoe, Yuichiro; Townsley, Leisa; Broos, Patrick; Gruendl, Robert; Vaidya, Kaushar; White, Stephen M.; Petre, Rob; Chu, You-Hua

    2009-01-01

    The Carina Nebula is one of thc youngest, most active sites of massive star formation in our Galaxy. In this nebula, we have discovered a bright X-ray source that has persisted for approx.30 years. The soft X-ray spectrum. consistent with kT approx.130 eV blackbody radiation with mild extinction, and no counterpart in the near- and mid-infrared wavelengths indicate that it is a, approx. 10(exp 6)-year-old neutron star housed in the Carina Nebula. Current star formation theory does not suggest that the progenitor of the neutron star and massive stars in the Carina Nebula, in particular (eta)Car, are coeval. This result demonstrates that the Carina Nebula experienced at least two major episodes of massive star formation. The neutron star would be responsible for remnants of high energy activity seen in multiple wavelengths.

  2. CARINA: nutrient data in the Atlantic Ocean

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    T. Tanhua

    2009-11-01

    Full Text Available Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from previously non-publicly available cruise data sets in the Arctic, Atlantic and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic. These data have gone through rigorous quality control (QC procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA data base were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the data products, i.e. three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; Arctic Mediterranean Seas, Atlantic and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 98 were conducted in the Atlantic Ocean and of these 84 cruises report nitrate values, 79 silicate, and 78 phosphate. Here we present details of the secondary QC for nutrients for the Atlantic Ocean part of CARINA. Procedures of quality control, including crossover analysis between cruises and inversion analysis of all crossover data are briefly described. Adjustments were applied to the nutrient values for 43 of the cruises in the Atlantic Ocean region. With these adjustments the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s (Key et al., 2004. Based on our analysis we estimate the internal accuracy of the CARINA-ATL nutrient data to be: nitrate 1.5%; phosphate 2.6%; silicate 3.1%. The CARINA data are now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation.

  3. CARINA: nutrient data in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    T. Tanhua

    2009-07-01

    Full Text Available Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from previously non-publicly available cruise data sets in the Arctic, Atlantic and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic. These data have gone through rigorous quality control (QC procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA data base were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the data products, i.e. three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; Arctic, Atlantic and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 98 were conducted in the Atlantic Ocean and of these 84 cruises report nitrate values, 79 silicate, and 78 phosphate. Here we present details of the secondary QC for nutrients for the Atlantic Ocean part of CARINA. Procedures of quality control, including crossover analysis between cruises and inversion analysis of all crossover data are briefly described. Adjustments were applied to the nutrient values for 43 of the cruises in the Atlantic Ocean region. With these adjustments the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s (Key et al., 2004. Based on our analysis we estimate the internal accuracy of the CARINA-ATL nutrient data to be: nitrate 1.5%; phosphate 2.6%; silicate 3.1%. The CARINA data are now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation.

  4. 3D modelling of the colliding winds in Eta Carinae - evidence for radiative inhibition

    CERN Document Server

    Parkin, E R; Corcoran, M F; Hamaguchi, K; Stevens, I R

    2009-01-01

    The X-ray emission from the super-massive star Eta Carinae is simulated using a three dimensional model of the wind-wind collision. In the model the intrinsic X-ray emission is spatially extended and energy dependent. Absorption due to the unshocked stellar winds and the cooled postshock material from the primary LBV star is calculated as the intrinsic emission is ray-traced along multiple sightlines through the 3D spiral structure of the circumstellar environment. The observable emission is then compared to available X-ray data, including the lightcurve observed by the Rossi X-ray Timing Explorer (RXTE) and spectra observed by XMM-Newton. The orientation and eccentricity of the orbit are explored, as are the wind parameters of the stars and the nature and physics of their close approach. Our modelling supports a viewing angle with an inclination of ~ 42 degrees, consistent with the polar axis of the Homunculus nebula (Smith 2006), and the projection of the observer's line-of-sight onto the orbital plane has ...

  5. The fossil wind structures of Eta Carinae: changes across on 5.54-year cycle

    CERN Document Server

    Gull, Theodore R; Teodoro, Mairan; Clementel, Nicola; Corcoran, Michael; Damineli, Augusto; Groh, Jose H; Hamaguchi, Kenji; Hiller, D John; Moffat, Anthony F J; Richardson, Noel D; Weigelt, Gerd; Lindler, Don; Feggans, Keith

    2016-01-01

    Eta Carinae, the closest, active, massive binary containing a highly unstable LBV, exhibits expanding, compressed wind shells, seen in emission, that are spatially and spectrally resolved by \\hst/\\stis. Starting in June 2009, these structures were mapped across its 5.54-year, highly elliptical, binary orbit to follow temporal changes in the light of [Fe~III] 4659\\AA\\ and [Fe~II] 4815\\AA. The emissions trace portions of fossil wind-shells, that were formed by wind-wind interactions across each cycle. Over the high-ionization state, dense arcs, photo-ionized by far ultraviolet radiation from the hot secondary, are seen in [Fe~III]. Other arcs, ionized by mid-ultraviolet radiation from the primary star, are seen in [Fe II]. The [Fe III] structures tend to be interior to [Fe II] structures that trace extensive, less disturbed primary wind. During the brief periastron passage when the secondary plunges deep into the primary's extremely dense wind, on the far side of primary star, high-ionization [Fe III] structure...

  6. The lbv phase of the planetary nebula lmc-n66

    Directory of Open Access Journals (Sweden)

    M. Peña

    2002-01-01

    Full Text Available Observaciones recientes de la estrella central de la nebulosa planetaria LMC-N66 muestran que el fuerte viento tipo LBV ha estado disminuyendo lentamente, despu es del violento m aximo de 1994. La magnitud actual (mV 18:1 mag y la probable tasa de p erdida de masa de la estrella son similares a los valores de 1990. A partir de espectros de rendija larga obtenidos con el espectr ografo STIS del Telescopio Espacial Hubble, se han podido analizar algunos datos nebulares.

  7. Bona-fide, strong-variable galactic Luminous Blue Variable stars are fast rotators: detection of a high rotational velocity in HR Carinae

    CERN Document Server

    Groh, Jose H; Hillier, D John; Barba, Rodolfo; Fernandez-Lajus, Eduardo; Gamen, Roberto C; Moises, Alessandro; Solivella, Gladys; Teodoro, Mairan

    2009-01-01

    We report optical observations of the Luminous Blue Variable (LBV) HR Carinae which show that the star has reached a visual minimum phase in 2009. More importantly, we detected absorptions due to Si IV 4088-4116 Angstroms. To match their observed line profiles from 2009 May, a high rotational velocity of vrot=150 +- 20 km/s is needed (assuming an inclination angle of 30 degrees), implying that HR Car rotates at ~0.88 +- 0.2 of its critical velocity for break-up (vcrit). Our results suggest that fast rotation is typical in all strong-variable, bona-fide galactic LBVs, which present S Dor-type variability. Strong-variable LBVs are located in a well-defined region of the HR diagram during visual minimum (the "LBV minimum instability strip"). We suggest this region corresponds to where vcrit is reached. To the left of this strip, a forbidden zone with vrot/vcrit>1 is present, explaining why no LBVs are detected in this zone. Since dormant/ex LBVs like P Cygni and HD 168625 have low vrot, we propose that LBVs can ...

  8. Var C: Long-term photometric and spectral variability of an LBV in M33

    CERN Document Server

    Burggraf, B; Bomans, D J; Henze, M; Meusinger, H; Sholukhova, O; Zharova, A; Pellerin, A; Becker, A

    2015-01-01

    So far the highly unstable phase of luminous blue variables (LBVs) has not been understood well. It is still uncertain why and which massive stars enter this phase. Investigating the variabilities by looking for a possible regular or even (semi-)periodic behaviour could give a hint at the underlying mechanism for these variations and might answer the question of where these variabilities originate. Finding out more about the LBV phase also means understanding massive stars better in general, which have (e.g. by enriching the ISM with heavy elements, providing ionising radiation and kinetic energy) a strong and significant influence on the ISM, hence also on their host galaxy. Photometric and spectroscopic data were taken for the LBV Var C in M33 to investigate its recent status. In addition, scanned historic plates, archival data, and data from the literature were gathered to trace Var C's behaviour in the past. Its long-term variability and periodicity was investigated. Our investigation of the variability i...

  9. The LBV HR Car has a partner: Discovery of a companion with the VLTI

    CERN Document Server

    Boffin, Henri M J; Merand, Antoine; Mehner, Andrea; LeBouquin, Jean-Baptiste; Pourbaix, Dimitri; de Wit, Willem-Jan; Martayan, Christophe; Guieu, Sylvain

    2016-01-01

    Luminous Blue Variables (LBVs) are massive stars caught in a post-main sequence phase, during which they are losing a significant amount of mass. As, on one hand, it is thought that the majority of massive stars are close binaries that will interact during their lifetime, and on the other, the most dramatic example of an LBV, Eta Car, is a binary, it would be useful to find other binary LBVs. We present here interferometric observations of the LBV HR Car done with the AMBER and PIONIER instruments attached to ESO's Very Large Telescope Interferometer (VLTI). Our observations, spanning two years, clearly reveal that HR Car is a binary star. It is not yet possible to constrain fully the orbit, and the orbital period may lie between a few years and several hundred years. We derive a radius for the primary in the system and possibly resolve as well the companion. The luminosity ratio in the H-band between the two components is changing with time, going from about 6 to 9. We also tentatively detect the presence of...

  10. Study on Soil Gleization in Subtropic Region of China Using LBV Transformed Landsat Images

    Institute of Scientific and Technical Information of China (English)

    ZENGZHIYUAN; PANXIANZHANG

    1997-01-01

    This paper describes a new type of transformed Landsat images (LBV images) and their application in discriminating soil gleization in subtropic region of China,LBV transformaition was worked out by the present author for extracting useful information from original landsat images.Using this method three black and white images,L image ,B image and V image ,were computer generated from original bans of a Landsat scene,which covers a large area of 34 528 km2 in Hubei and Hunan province in south China.Then a Color composite was produced by these three images .This kind of black-and-white and color images contained rich and definite geographic in formation.By a field work ,the relationship between the colors on the composite and the land use/cover categories on the graound wa established.37 composite colors and 70 ground feature categories an be discriminated altogether,Finally,17 land use/cover categories and 10 subregions suffering from soil gleization were detemined ,and the gleiztion area for the study area was estimated to be 731.3 km2.

  11. Discovery of an ammonia shell surrounding the LBV nebula G79.29+0.46

    CERN Document Server

    Rizzo, J R; Jimenez-Esteban, F M; Henkel, C

    2014-01-01

    The surroundings of Luminous Blue Variable (LBV) stars are excellent laboratories to study the effects of their high UV radiation, powerful winds, and strong ejection events onto the surrounding gas and dust. The LBV G79.29+0.46 powered two concentric infrared rings which may interact with the infrared dark cloud (IRDC) G79.3+0.3. The Effelsberg 100m telescope was used to observe the NH_3 (1,1), (2,2) emission surrounding G79.29+0.46 and the IRDC. In addition, we observed particular positions in the (3,3) transition toward the strongest region of the IRDC. We report here the first coherent shell-like structure of dense NH_3 gas associated with an evolved massive star. The shell, two or three orders of magnitude more tenuous than the IRDC, is well traced in both ammonia lines, and surrounds the ionized nebula. The NH_3 emission in the IRDC is characterized by a low and uniform rotational temperature (T_rot ~ 10 K) and moderately high opacities in the (1,1) line. The rest of the observed field is spotted by war...

  12. Superluminous Supernovae: No Threat from Eta Carinae

    Science.gov (United States)

    Thomas, Brian; Melott, A. L.; Fields, B. D.; Anthony-Twarog, B. J.

    2008-05-01

    Recently Supernova 2006gy was noted as the most luminous ever recorded, with a total radiated energy of 1044 Joules. It was proposed that the progenitor may have been a massive evolved star similar to η Carinae, which resides in our own galaxy at a distance of about 2.3 kpc. η Carinae appears ready to detonate. Although it is too distant to pose a serious threat as a normal supernova, and given its rotation axis is unlikely to produce a Gamma-Ray Burst oriented toward the Earth, η Carinae is about 30,000 times nearer than 2006gy, and we re-evaluate it as a potential superluminous supernova. We find that given the large ratio of emission in the optical to the X-ray, atmospheric effects are negligible. Ionization of the atmosphere and concomitant ozone depletion are unlikely to be important. Any cosmic ray effects should be spread out over 104 y, and similarly unlikely to produce any serious perturbation to the biosphere. We also discuss a new possible effect of supernovae, endocrine disruption induced by blue light near the peak of the optical spectrum. This is a possibility for nearby supernovae at distances too large to be considered "dangerous” for other reasons. However, due to reddening and extinction by the interstellar medium, η Carinae is unlikely to trigger such effects to any significant degree.

  13. Forming Planets in the Hostile Carina Nebula

    Science.gov (United States)

    Kohler, Susanna

    2016-07-01

    Can protoplanetary disks form and be maintained around low-mass stars in the harsh environment of a highly active, star-forming nebula? A recent study examines the Carina nebula to answer this question.Crowded ClustersStars are often born in clusters that contain both massive and low-mass stars. The most massive stars in these clusters emit far-ultraviolet and extreme-ultraviolet light that irradiates the region around them, turning the surrounding area into a hostile environment for potential planet formation.Planet formation from protoplanetary disks typically requires timescales of at least 12 million years. Could the harsh radiation from massive stars destroy the protoplanetary disks around low-mass stars by photoevaporation before planets even have a chance to form?Artists impression of a protoplanetary disk. Such disks can be photoevaporated by harsh ultraviolet light from nearby massive stars, causing the disk to be destroyed before planets have a chance to form within them. [ESO/L. Calada]Turning ALMA Toward CarinaA perfect case study for exploring hostile environments is the Carina nebula, located about 7500 lightyears away and home to nearly 100 O-type stars as well as tens of thousands of lower-mass young stars. The Carina population is ~14 Myr old: old enough to form planets within protoplanetary disks, but also old enough that photoevaporation could already have wreaked havoc on those disks.Due to the dense stellar populations in Carinas clusters, this is a difficult region to explore, but the Atacama Large Millimeter-submillimeter Array (ALMA) is up to the task. In a recent study, a team of scientists led by Adal Mesa-Delgado (Pontifical Catholic University of Chile) made use of ALMAs high spatial resolution to image four regions spaced throughout Carina, searching for protoplanetary disks.Detections and Non-DetectionsTwo evaporating gas globules in the Carina nebula, 104-593 and 105-600, that each contain a protoplanetary disk. The top panels are

  14. Photometric behaviour of eta Carinae, a celestial Chinese lantern: 1974-1998

    Science.gov (United States)

    van Genderen, A. M.; Sterken, C.; de Groot, M.; Burki, G.

    1999-03-01

    We discuss 24 y of optical photometry of eta Carinae, among which new Geneva photometry made between 1994 and 1998. Various conclusions from our previous photometric studies are confirmed. The core hides a normal S Dor variable (or LBV): it shows light variations on a time scale of 1-4 y, with superimposed micro oscillations whose quasi-period indicates a temperature in the order of 22 000 K. Therefore, a more complicated model for eta Car is necessary to explain its extraordinary appearance and phenomena exhibited in the past and at present. An analysis of the brightness of eta Car in the ultraviolet (UV) passbands of three photometric systems (Walraven, Strömgren and Geneva) reveals the presence of an important variable UV source, which appears to be modulated with the 5.52 y period of the spectroscopic events, related to the possible revolution of an excentric binary of the type proposed by Damineli et al. (1997). Our new data support the luminous disk model suggested by van Genderen et al. (1994, 1995). A very hot companion of the LBV would be responsible for the excitation of the disk. We suspect that the flare-like event in the X-ray flux and in the optical and near-infrared light around 1998.0 was the result of the encounter of the interface of the colliding winds of the binary with an arm-shaped density enhancement in a disk around the LBV (not necessarily ``the" luminous disk). We suppose that this encounter created an intense X-ray/hot spot region. The subsequent steep decline of the flare is ascribed to an eclipse of the X-ray/hot spot by the wind interface. The radio flux variation of the gas torus in the equatorial plane at a distance of 2arcsec from the core, could be the result of the luminous disk becoming optically thin. This would, obviously, start abruptly near the time of periastron passage and would last for a few years thereafter, so that a hot star, normally enshrouded by the disk, is able to excite the outer gas torus. The creation of the X

  15. Gravitational fragmentation of the Carina Flare supershell

    Science.gov (United States)

    Wünsch, Richard

    2015-03-01

    We study the gravitational fragmentation of a thick shell comparing the analytical theory to 3D hydrodynamic simulations and to observations of the Carina Flare supershell. We use both grid-based (AMR) and particle-based (SPH) codes to follow the idealised model of the fragmenting shell and found an excellent agreement between the two codes. Growth rates of fragments at different wavelength are well described by the pressure assisted gravitational instability (PAGI) - a new theory of the thick shell fragmentation. Using the APEX telescope we observe a part of the surface of the Carina Flare supershell (GSH287+04-17) in the 13CO(2-1) line. We apply a new clump-finding algorithm DENDROFIND to identify 50 clumps. We determine the clump mass function and we construct the minimum spanning tree connecting clumps positions to estimate the typical distance among clumps. We conclude that the observed masses and distances correspond well to the prediction of PAGI.

  16. Superluminous supernovae: No threat from Eta Carinae

    CERN Document Server

    Thomas, Brian C; Fields, Brian D; Anthony-Twarog, Barbara J

    2007-01-01

    Recently Supernova 2006gy was noted as the most luminous ever recorded, with a total radiated energy of ~10^44 Joules. It was proposed that the progenitor may have been a massive evolved star similar to Eta Carinae, which resides in our own galaxy at a (poorly determined) distance of ~2.5 kpc. Eta Carinae appears ready to detonate, and in fact had an outburst in 1843. Although it is too distant to pose a serious threat as a normal supernova, and given its rotation axis is unlikely to produce a Gamma Ray Burst oriented toward the Earth, Eta Carinae is about 30,000 times nearer than 2006gy, and we re-evaluate it as a potential superluminous supernova. We find that given the large ratio of emission in the optical to the X-ray, atmospheric effects are negligible. Ionization of the atmosphere and concomitant ozone depletion are unlikely to be important. Any cosmic ray effects should be spread out over ~10^4 y, and similarly unlikely to produce any serious perturbation to the biosphere. We also discuss a new possib...

  17. Nordic Seas nutrients data in CARINA

    Directory of Open Access Journals (Sweden)

    J. Olafsson

    2010-09-01

    Full Text Available Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 cruises in the Arctic, Atlantic, and Southern Ocean have been assembled and the collection merged into a new database: CARINA (CARbon IN the Atlantic. The data have been subject to rigorous quality control (QC in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS, the Atlantic (ATL and the Southern Ocean (SO. With the adjustments, the CARINA database is consistent both internally as well as with GLODAP (Key et al., 2004 and is suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates, and for model validation. The Arctic Mediterranean Seas is the collective term for the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. This contribution presents an account of the quality control of the nutrients (nitrate, phosphate, and silicate data from the Nordic Seas in CARINA. Out of the 35 cruises from the Nordic Seas included in CARINA, 33 had nutrients data. The nitrate data from 4 of these appeared to be of so poor quality that they should not be used, for phosphate this number is 7 and for silicate it is 3. We also recommend that the nitrate data from 4 of the cruises should be adjusted, for phosphate and silicate only data from one cruise should be adjusted. The final data appears consistent to 5% based on evaluation of deep data. For nitrate this corresponds to 0.6 μmol kg−1, and for phosphate and silicate it corresponds to 0.04 and 0.6 μmol kg−1, respectively.

  18. ANAESTHESIA FOR EVALUATION AND EXCISION OF TRACHEAL TUMOUR AT CARINA EXTENDING INTO RIGHT MAIN BRONCHUS: CASE REPORT

    Directory of Open Access Journals (Sweden)

    Deepraj Singh

    2014-04-01

    Full Text Available A tracheal tumor at carinal angle is uncommon. Presented here is an interesting case of a 22 year old, HBsAg positive female with a tracheal tumor at carina extending into the right main bronchus. The patient reported shortness of breath along with fatigue and cough. Routine and other appropriate investigations were done during which X-ray chest and CT scan revealed right lung collapse with ipsilateral shift of mediastinum. Telescopic evaluation and biopsy performed under general anesthesia using supraglottic Jet Ventilation further revealed proliferative growth arising from the anterior wall of the carina extending into the right main bronchus. Subsequently, excision of the tumor through tracheotomy under general anesthesia was carried out. The patient recovered completely with no postoperative complications.

  19. HESS observations of the Carina nebula and its enigmatic colliding wind binary Eta Carinae

    Science.gov (United States)

    HESS Collaboration; Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Balzer, A.; Barnacka, A.; Becherini, Y.; Becker, J.; Bernlöhr, K.; Birsin, E.; Biteau, J.; Bochow, A.; Boisson, C.; Bolmont, J.; Bordas, P.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Büsching, I.; Carrigan, S.; Casanova, S.; Cerruti, M.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Cologna, G.; Conrad, J.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; Drury, L. O'C.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Espigat, P.; Fallon, L.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gallant, Y. A.; Garrigoux, T.; Gast, H.; Gérard, L.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Göring, D.; Grondin, M.-H.; Häffner, S.; Hague, J. D.; Hahn, J.; Hampf, D.; Harris, J.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hofverberg, P.; Holler, M.; Horns, D.; Jacholkowska, A.; Jahn, C.; Jamrozy, M.; Jung, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Khélifi, B.; Klochkov, D.; Kluźniak, W.; Kneiske, T.; Komin, Nu.; Kosack, K.; Kossakowski, R.; Krayzel, F.; Laffon, H.; Lamanna, G.; Lenain, J.-P.; Lennarz, D.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Masbou, J.; Maurin, G.; Maxted, N.; Mayer, M.; McComb, T. J. L.; Medina, M. C.; Méhault, J.; Moderski, R.; Mohamed, M.; Moulin, E.; Naumann, C. L.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Nguyen, N.; Nicholas, B.; Niemiec, J.; Nolan, S. J.; Ohm, S.; de Oña Wilhelmi, E.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Paz Arribas, M.; Pekeur, N. W.; Pelletier, G.; Perez, J.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raue, M.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Sanchez, D. A.; Santangelo, A.; Schlickeiser, R.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Sheidaei, F.; Skilton, J. L.; Sol, H.; Spengler, G.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Szostek, A.; Tavernet, J.-P.; Terrier, R.; Tluczykont, M.; Valerius, K.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Viana, A.; Vincent, P.; Völk, H. J.; Volpe, F.; Vorobiov, S.; Vorster, M.; Wagner, S. J.; Ward, M.; White, R.; Wierzcholska, A.; Zacharias, M.; Zajczyk, A.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.; Montmerle, T.

    2012-07-01

    The massive binary system Eta Carinae and the surrounding H II complex, the Carina nebula, are potential particle acceleration sites from which very high energy (VHE; E≥ 100 GeV) γ-ray emission could be expected. This paper presents data collected during VHE γ-ray observations with the HESS telescope array from 2004 to 2010, which cover a full orbit of Eta Carinae. In the 33.1-h data set no hint of significant γ-ray emission from Eta Carinae has been found and an upper limit on the γ-ray flux of ? (99 per cent confidence level) is derived above the energy threshold of 470 GeV. Together with the detection of high energy (HE; 0.1 ≤E≤ 100 GeV) γ-ray emission by the Fermi Large Area Telescope up to 100 GeV, and assuming a continuation of the average HE spectral index into the VHE domain, these results imply a cut-off in the γ-ray spectrum between the HE and VHE γ-ray range. This could be caused either by a cut-off in the accelerated particle distribution or by severe γ-γ absorption losses in the wind collision region. Furthermore, the search for extended γ-ray emission from the Carina nebula resulted in an upper limit on the γ-ray flux of ? (99 per cent confidence level). The derived upper limit of ˜23 on the cosmic ray enhancement factor is compared with results found for the old-age mixed-morphology supernova remnant W28.

  20. η Carinae Baby Homunculus uncovered by ALMA

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, Zulema; Beaklini, Pedro P. B. [Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, R. do Matão 1226, Cidade Universitária, CEP 05508-900 São Paulo, SP (Brazil); Falceta-Gonçalves, Diego, E-mail: zulema.abraham@iag.usp.br [Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, R. Arlindo Bettio 1000, 03828-000 São Paulo, SP (Brazil)

    2014-08-20

    We report observations of η Carinae obtained with ALMA in the continuum of 100, 230, 280, and 660 GHz in 2012 November, with a resolution that varied from 2.''88 to 0.''45 for the lower and higher frequencies, respectively. The source is not resolved, even at the highest frequency; its spectrum is characteristic of thermal bremsstrahlung of a compact source, but different from the spectrum of optically thin wind. The recombination lines H42α, He42α, H40α, He40α, H50β, H28α, He28α, H21α, and He21α were also detected, and their intensities reveal non-local thermodynamic equilibrium effects. We found that the line profiles could only be fit by an expanding shell of dense and ionized gas, which produces a slow shock in the surroundings of η Carinae. Combined with fittings to the continuum, we were able to constrain the shell size, radius, density, temperature, and velocity. The detection of the He recombination lines is compatible with the high-temperature gas and requires a high-energy ionizing photon flux, which must be provided by the companion star. The mass-loss rate and wind velocity, necessary to explain the formation of the shell, are compatible with an luminous blue variable eruption. The position, velocity, and physical parameters of the shell coincide with those of the Weigelt blobs. The dynamics found for the expanding shell correspond to matter ejected by η Carinae in 1941 in an event similar to that which formed the Little Homunculus; for that reason, we called the new ejecta the 'Baby Homunculus'.

  1. He II λ4686 in η Carinae

    DEFF Research Database (Denmark)

    Teodoro, M.; Damineli, A.; Arias, J.I.

    2012-01-01

    The periodic spectroscopic events in eta Carinae are now well established and occur near the periastron passage of two massive stars in a very eccentric orbit. Several mechanisms have been proposed to explain the variations of different spectral features, such as an eclipse by the wind-wind colli...... this as a collapse of the WWC onto the "surface" of the secondary star, switching off the hard X-ray source and diminishing the WWC shock cone. The recovery from this state is controlled by the momentum balance between the secondary's wind and the clumps in the primary's wind....

  2. $\\eta$ Carinae Baby Homunculus Uncovered by ALMA

    CERN Document Server

    Abraham, Zulema; Beaklini, Pedro P B

    2014-01-01

    We report observations of $\\eta$ Carinae obtained with ALMA in the continuum of 100, 230, 280 and 660 GHz in 2012 November, with a resolution that varied from 2.88" to 0.45" for the lower and higher frequencies respectively. The source is not resolved, even at the highest frequency; its spectrum is characteristic of thermal bremsstrahlung of a compact source, but different from the spectrum of optically thin wind. The recombination lines H42$\\alpha$, He42$\\alpha$, H40$\\alpha$, He40$\\alpha$, H50$\\beta$, H28$\\alpha$, He28$\\alpha$, H21$\\alpha$ and He21$\\alpha$ were also detected and their intensities reveal non local thermodynamic equilibrium (NLTE) effects. We found that the line profiles could only be fit by an expanding shell of dense and ionized gas, which produces a slow shock in the surroundings of $\\eta$ Carinae. Combined with fittings to the continuum, we were able to constrain the shell size, radius, density, temperature and velocity. The detection of the He recombination lines is compatible with the hi...

  3. Extremely metal-poor galaxy DDO 68: the LBV, H-alpha shells and the most luminous stars

    CERN Document Server

    Pustilnik, S A; Perepelitsyna, Y A; Moiseev, A V; Makarov, D I

    2016-01-01

    The paper presents new results of the ongoing study of the unusual Lynx-Cancer void galaxy DDO 68 with record-low-metallicity regions (12+log(O/H) ~7.14) of the current star formation (SF). They include: a) a new spectrum and photometry with the 6-m SAO RAS telescope (BTA) for the Luminous Blue Variable (LBV = DDO68-V1). Photometric data sets are complemented with those based on the Sloan Digital Sky Survey (SDSS) and the Hubble Space Telescope (HST) archive images; b) the analysis of the DDO~68 supergiant shell (SGS) and the prominent smaller H-alpha arcs/shells visible at the HST image coupled with kinematics maps in H-alpha obtained with the Fabry-Perot interferometer (FPI) at the BTA; c) the list of identified at the HST images of about 50 most luminous stars (-9.1 3.7~mag for the first time. New data suggest that in 2008--2010 the LBV reached M_V = --10.5 and probably underwent a giant eruption. We argue that the structure of star-forming complexes along the SGS (`Northern Ring') perimeter provides evid...

  4. CARINA oxygen data in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    I. Stendardo

    2009-12-01

    Full Text Available In the CARINA (Carbon dioxide in the Atlantic Ocean project, a new dataset with many previously unpublished hydrographic data from the Atlantic, Arctic and Southern Ocean was assembled and subjected to careful quality control (QC procedures. Here, we present the dissolved oxygen measurements in the Atlantic region of the dataset and describe in detail the secondary QC procedures that aim to ensure that the data are internally consistent. This is achieved by a cross-over analysis, i.e. the comparison of deep ocean data at places that were sampled by different cruises at different times. Initial adjustments to the individual cruises were then determined by an inverse procedure that computes a set of adjustments that requires the minimum amount of adjustment and at the same time reduces the offsets in an optimal manner. The initial adjustments were then reviewed by the CARINA members, and only those that passed the following two criteria were adopted: (i the region is not subject to substantial temporal variability, and (ii the adjustment must be based on at least three stations from each cruise. No adjustment was recommended for cruises that did not fit these criteria. The final CARINA-Oxygen dataset has 103414 oxygen samples from 9491 stations obtained during 98 cruises covering three decades. The sampling density of the oxygen data is particularly good in the North Atlantic north of about 40° N especially after 1987. In contrast, the sample density in the South Atlantic is much lower. Some cruises appear to have poor data quality, and were subsequently omitted from the adjusted dataset. Of the data included in the adjusted dataset, 20% were adjusted with a mean adjustment of 2%. Due to the achieved internal consistency, the resulting product is well suited to produce an improved climatology or to study long-term changes in the oxygen content of the ocean. However, the adjusted dataset is not necessarily better suited than the unadjusted data to

  5. UV extinction properties of carina nebular dust

    Science.gov (United States)

    Massa, Derck

    1993-01-01

    I have performed an analysis of the UV extinction by dust along the line of sight to the young open cluster Tr 16. The observed curves are parameterized in order to extract quantitative information about the structure of the curves. Furthermore, by constructing differential extinction curves, obtained by differencing curves for stars which lie within a few arc seconds of each other on the sky, I was able to obtain a curve which is free of the effects of foreground extinction, and represents the extinction by the dust in the Tr 16 molecular cloud. I then show that this curve is nearly identical to one due to dust in the Orion molecular cloud. This result shows that dust in the Carina arm exhibits the same behavior as that in the local arm.

  6. Nordic Seas and Arctic Ocean CFC data in CARINA

    Directory of Open Access Journals (Sweden)

    E. Jeansson

    2010-02-01

    Full Text Available Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters have been retrieved from a large number of cruises and collected into a new database called CARINA (CARbon IN the Atlantic. These data have been merged into three sets of files, one for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS, the Atlantic (ATL and the Southern Ocean (SO. The first part of the CARINA database consists of three files, one for each CARINA region, containing the original, non-adjusted cruise data sets, including data quality flags for each measurement. These data have then been subject to rigorous quality control (QC in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the second part of the CARINA data product. This consists of three files, one for each CARINA region, which contain adjustments to the original data values based on recommendations from the CARINA QC procedures, along with calculated and interpolated values for some missing parameters.

    Here we present an overview of the QC of the CFC data for the AMS region, including the chlorofluorocarbons CFC-11, CFC-12 and CFC-113, as well as carbon tetrachloride (CCl4. The Arctic Mediterranean Seas is comprised of the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. For the secondary QC of the CFCs we used a combination of tools, including the evaluation of depth profiles and CFC ratios, surface saturations and a crossover analysis. This resulted in a multiplicative adjustment of data from some cruises, while other data were flagged to be of questionable quality, which excluded them from the final data product.

  7. Atlantic Ocean CARINA data: overview and salinity adjustments

    Energy Technology Data Exchange (ETDEWEB)

    Tanhua, T. [IFM-GEOMAR, Leibniz Institute for Marine Sciences, Chemical Oceanography, Kiel, Germany; Steinfeldt, R. [University of Bremen, Bremen, Germany; Key, Robert [Princeton University; Brown, P. [University of East Anglia, Norwich, United Kingdom; Gruber, N. [ETH Zurich, Switzerland; Wanninkhof, R. [Atlantic Oceanographic & Meteorological Laboratory, NOAA; Perez, F.F. [Instituto de Investigaciones Marinas de Vigo, CSIC, Vigo, Spain; Kortzinger, A. [IFM-GEOMAR, Leibniz Institute for Marine Sciences, Chemical Oceanography, Kiel, Germany; Velo, A. [Instituto de Investigaciones Marinas de Vigo, CSIC, Vigo, Spain; Schuster, U. [University of East Anglia, Norwich, United Kingdom; Van Heuven, S. [University of Groningen, The Netherlands; Bullister, J.L. [NOAA Pacific Marine Environmental Laboratory; Stendardo, I. [ETH Zurich, Switzerland; Hoppema, M. [Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany; Olsen, Are [Bjerknes Centre for Climate Research, UNIFOB AS, Bergen, Norway; Kozyr, Alexander [ORNL; Pierrot, D. [Cooperative Institute of Marine and Atmospheric Sciences, U. Miami; Schirnick, C. [IFM-GEOMAR, Leibniz Institute for Marine Sciences, Chemical Oceanography, Kiel, Germany; Wallace, D.W.R. [IFM-GEOMAR, Leibniz Institute for Marine Sciences, Chemical Oceanography, Kiel, Germany

    2010-01-01

    Water column data of carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruise data sets in the Arctic Mediterranean Seas, Atlantic and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon dioxide IN the Atlantic Ocean). The data have gone through rigorous quality control procedures to assure the highest possible quality and consistency. The data for the pertinent parameters in the CARINA database were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the three data products: merged data files with measured, calculated and interpolated data for each of the three CARINA regions, i.e. the Arctic Mediterranean Seas, the Atlantic and the Southern Ocean. These products have been corrected to be internally consistent. Ninety-eight of the cruises in the CARINA database were conducted in the Atlantic Ocean, defined here as the region south of the Greenland-Iceland-Scotland Ridge and north of about 30 S. Here we present an overview of the Atlantic Ocean synthesis of the CARINA data and the adjustments that were applied to the data product. We also report the details of the secondary QC (Quality Control) for salinity for this data set. Procedures of quality control including crossover analysis between stations and inversion analysis of all crossover data are briefly described. Adjustments to salinity measurements were applied to the data from 10 cruises in the Atlantic Ocean region. Based on our analysis we estimate the internal consistency of the CARINA-ATL salinity data to be 4.1 ppm. With these adjustments the CARINA data products are consistent both internally was well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s, and is now suitable for accurate assessments of, for example, oceanic carbon inventories

  8. High Spatial/Spectral Resolution Studies of Eta Carinae

    Science.gov (United States)

    Gull, Theodore R.; Eta Carinae HST Treasury Team

    2005-01-01

    The ejecta of Eta Carinae revealed by HST/STIS are in a large range of physical conditions. As Eta Carinae undergoes a 5.52 period changes occur in nebular emission and nebular absorption. ""Warm"" neutral regions partially ionized regions and fully ionized regions undergo significant changes. Over 2000 emission lines most of Fe-like elements have been indentified in the Weigelt blobs B and D. Over 500 emission lines have been identifed in the Strontium Filament. An ionized Little Homunculus is nestled within the neutral-shelled Homunculus. In line of sight over 500 nebular absorption lines have been identified with up to twenty velocity components. STIS is following changes in many nebular emission and absorption lines as Eta Carinae approaches the minimum predicted to be in June/July 2003 during the General Assembly. Coordinated observations with HST CHANDRA RXTE FUSE UVES/VLT Gemini and other observatories are following this minimum.

  9. Is the Ejecta of ETA Carinae Overabundant or Overexcited

    Science.gov (United States)

    Gull, Theodore; Davidson, Kris; Johansson, Sveneric; Damineli, Augusto; Ishibashi, Kaxunori; Corcoran, Michael; Hartman, Henrick; Viera, Gladys; Nielsen, Krister

    2003-01-01

    The ejecta of Eta Carinae, revealed by HST/STIS, are in a large range of physical conditions. As Eta Carinae undergoes a 5.52 period, changes occur in nebular emission and nebular absorption. "Warm" neutral regions, partially ionized regions, and fully ionized regions undergo significant changes. Over 2000 emission lines, most of Fe-like elements, have been indentified in the Weigelt blobs B and D. Over 500 emission lines have been indentified in the Strontium Filament. An ionized Little Homunculus is nestled within the neutral-shelled Homunculus. In line of sight, over 500 nebular absorption lines have been identified with up to twenty velocity components. STIS is following changes in many nebular emission and absorption lines as Eta Carinae approaches the minimum, predicted to be in June/July 2003, during the General Assembly. Coordinated observations with HST, CHANDRA, RXTE, FUSE, UVES/VLT, Gemini and other observatories are following this minimum.

  10. Is the Ejecta of Eta Carinae Overabundant or Overexcited?

    Science.gov (United States)

    Gull, Theodore; Davidson, Kris; Johansson, Sveneric; Damineli, Augusto; Ishibashi, Kazunori; Corcoran, Michael; Hartman, Henrick; Viera, Gladys; Nielsen, Krister; Eta Carinae Teams

    The ejecta of Eta Carinae revealed by HST/STIS are in a large range of physical conditions. As Eta Carinae undergoes a 5.52 period changes occur in nebular emission and nebular absorption. ""Warm"" neutral regions partially ionized regions and fully ionized regions undergo significant changes. Over 2000 emission lines most of Fe-like elements have been indentified in the Weigelt blobs B and D. Over 500 emission lines have been identifed in the Strontium Filament. An ionized Little Homunculus is nestled within the neutral-shelled Homunculus. In line of sight over 500 nebular absorption lines have been identified with up to twenty velocity components. STIS is following changes in many nebular emission and absorption lines as Eta Carinae approaches the minimum predicted to be in June/July 2003 during the General Assembly. Coordinated observations with HST CHANDRA RXTE FUSE UVES/VLT Gemini and other observatories are following this minimum.

  11. Eta Carinae -- Physics of the Inner Ejecta

    CERN Document Server

    Hamann, Fred

    2012-01-01

    Eta Carinae's inner ejecta are dominated observationally by the bright Weigelt blobs and their famously rich spectra of nebular emission and absorption lines. They are dense (n_e ~ 10^7 to 10^8 cm^-3), warm (T_e ~ 6000 to 7000 K) and slow moving (~40 km/s) condensations of mostly neutral (H^0) gas. Located within 1000 AU of the central star, they contain heavily CNO-processed material that was ejected from the star about a century ago. Outside the blobs, the inner ejecta include absorption-line clouds with similar conditions, plus emission-line gas that has generally lower densities and a wider range of speeds (reaching a few hundred km/s) compared to the blobs. The blobs appear to contain a negligible amount of dust and have a nearly dust-free view of the central source, but our view across the inner ejecta is severely affected by uncertain amounts of dust having a patchy distribution in the foreground. Emission lines from the inner ejecta are powered by photoionization and fluorescent processes. The variabl...

  12. The periodicity of the eta Carinae events

    CERN Document Server

    Damineli, A; Hillier, D J; Stahl, O; Levenhagen, R S; Leister, N V; Groh, J H; Teodoro, M; Colombo, J F Albacete; Gonzalez, F; Arias, J; Levato, H; Grosso, M; Morrell, N; Gamen, R; Wallerstein, G; Niemela, V

    2007-01-01

    Extensive spectral observations of eta Carinae over the last cycle, and particularly around the 2003.5 low excitation event, have been obtained. The variability of both narrow and broad lines, when combined with data taken from two earlier cycles, reveal a common and well defined period. We have combined the cycle lengths derived from the many lines in the optical spectrum with those from broad-band X-rays, optical and near-infrared observations, and obtained a period length of 2022.7+-1.3 d. Spectroscopic data collected during the last 60 years yield an average period of 2020+-4 d, consistent with the present day period. The period cannot have changed by more than $\\Delta$P/P=0.0007 since 1948. This confirms the previous claims of a true, stable periodicity, and gives strong support to the binary scenario. We have used the disappearance of the narrow component of HeI 6678 to define the epoch of the Cycle 11 minimum, T_0=JD 2,452,819.8. The next event is predicted to occur on 2009 January 11 (+-2 days). The d...

  13. Nordic Seas total dissolved inorganic carbon data in CARINA

    Directory of Open Access Journals (Sweden)

    A. Olsen

    2009-11-01

    Full Text Available Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic. The data have been subject to rigorous quality control (QC in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS, the Atlantic (ATL and the Southern Ocean (SO. With the adjustments the CARINA database is consistent both internally as well as with GLODAP (Key et al., 2004 and is suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation. The Arctic Mediterranean Seas includes the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. This contribution presents an account of the quality control of the total dissolved inorganic carbon (TCO2 data from the Nordic Seas in CARINA. Out of the 35 cruises from the Nordic Seas included in CARINA, 25 had TCO2 data. The data from 7 of these were found to be of low quality and should not be used, thus the final CARINA data product contains TCO2 data from 18 cruises from the Nordic Seas. These data appear consistent to at least 4 μmol kg−1.

  14. An Introduction to the Chandra Carina Complex Project

    CERN Document Server

    Townsley, Leisa K; Corcoran, Michael F; Feigelson, Eric D; Gagné, Marc; Montmerle, Thierry; Oey, M S; Smith, Nathan; Garmire, Gordon P; Getman, Konstantin V; Povich, Matthew S; Evans, Nancy Remage; Nazé, Yaël; Parkin, E R; Preibisch, Thomas; Wang, Junfeng; Wolk, Scott J; Chu, You-Hua; Cohen, David H; Gruendl, Robert A; Hamaguchi, Kenji; King, Robert R; Mac Low, Mordecai-Mark; McCaughrean, Mark J; Moffat, Anthony F J; Oskinova, L M; Pittard, Julian M; Stassun, Keivan G; ud-Doula, Asif; Walborn, Nolan R; Waldron, Wayne L; Churchwell, Ed; Nichols, J S; Owocki, Stanley P; Schulz, N S

    2011-01-01

    The Great Nebula in Carina provides an exceptional view into the violent massive star formation and feedback that typifies giant HII regions and starburst galaxies. We have mapped the Carina star-forming complex in X-rays, using archival Chandra data and a mosaic of 20 new 60ks pointings using the Chandra X-ray Observatory's Advanced CCD Imaging Spectrometer, as a testbed for understanding recent and ongoing star formation and to probe Carina's regions of bright diffuse X-ray emission. This study has yielded a catalog of properties of >14,000 X-ray point sources; >9800 of them have multiwavelength counterparts. Using Chandra's unsurpassed X-ray spatial resolution, we have separated these point sources from the extensive, spatially-complex diffuse emission that pervades the region; X-ray properties of this diffuse emission suggest that it traces feedback from Carina's massive stars. In this introductory paper, we motivate the survey design, describe the Chandra observations, and present some simple results, pr...

  15. Detection of the compressed primary stellar wind in eta Carinae

    CERN Document Server

    Teodoro, M; Gull, T R; Corcoran, M F; Hamaguchi, K

    2013-01-01

    A series of three HST/STIS spectroscopic mappings, spaced approximately one year apart, reveal three partial arcs in [Fe II] and [Ni II] emissions moving outward from eta Carinae. We identify these arcs with the shell-like structures, seen in the 3D hydrodynamical simulations, formed by compression of the primary wind by the secondary wind during periastron passages.

  16. Atlantic Ocean CARINA data: overview and salinity adjustments

    Directory of Open Access Journals (Sweden)

    T. Tanhua

    2010-02-01

    Full Text Available Water column data of carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruise data sets in the Arctic Mediterranean Seas, Atlantic and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon dioxide IN the Atlantic Ocean. The data have gone through rigorous quality control procedures to assure the highest possible quality and consistency. The data for the pertinent parameters in the CARINA database were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the three data products: merged data files with measured, calculated and interpolated data for each of the three CARINA regions, i.e. the Arctic Mediterranean Seas, the Atlantic and the Southern Ocean. These products have been corrected to be internally consistent. Ninety-eight of the cruises in the CARINA database were conducted in the Atlantic Ocean, defined here as the region south of the Greenland-Iceland-Scotland Ridge and north of about 30° S. Here we present an overview of the Atlantic Ocean synthesis of the CARINA data and the adjustments that were applied to the data product. We also report the details of the secondary QC (Quality Control for salinity for this data set. Procedures of quality control – including crossover analysis between stations and inversion analysis of all crossover data – are briefly described. Adjustments to salinity measurements were applied to the data from 10 cruises in the Atlantic Ocean region. Based on our analysis we estimate the internal consistency of the CARINA-ATL salinity data to be 4.1 ppm. With these adjustments the CARINA data products are consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s, and is now suitable for accurate assessments of, for example

  17. The CARINA data synthesis project: introduction and overview

    Directory of Open Access Journals (Sweden)

    R. M. Key

    2010-03-01

    Full Text Available The original goal of the CARINA (Carbon in Atlantic Ocean data synthesis project was to create a merged calibrated data set from open ocean subsurface measurements by European scientists that would be generally useful for biogeochemical investigations in the North Atlantic and in particular, studies involving the carbon system. Over time the geographic extent expanded to include the entire Atlantic, the Arctic and the Southern Ocean and the international collaboration broadened significantly. In this paper we give a brief history of the project, a general overview of data included and an outline of the procedures used during the synthesis.

    The end result of this project was a set of 3 data products, one for each of the listed ocean regions. It is critical that anyone who uses any of the CARINA data products recognize that the data products are not simply concatenations of the originally measured values. Rather, the data have been through an extensive calibration procedure designed to remove measurement bias and bad data. Also a significant fraction of the individual values in the data products were derived either by direct calculation or some means of approximation. These data products were constructed for basin scale biogeochemical investigations and may be inappropriate for investigations involving small areal extent or similar detailed analyses. More information on specific parts of this project can be found in companion articles in this issue. In particular, Tanhua et al. (2010 and Tanhua (2009 describe the procedures and software used to remove measurement bias from the original data.

    The three data products and a significant volume of supporting information are available from the CARINA web site hosted by the Carbon Dioxide Information Analysis Center (CDIAC: CARINA/Carina_inv.html" target="_blank">http://cdiac.esd.ornl.gov/oceans/CARINA/Carina_inv.html. Anyone wanting to use

  18. The CARINA data synthesis project: introduction and overview

    Energy Technology Data Exchange (ETDEWEB)

    Key, Robert [Princeton University; Tanhua, T. [IFM-GEOMAR, Leibniz Institute for Marine Sciences, Chemical Oceanography, Kiel, Germany; Olsen, Are [Bjerknes Centre for Climate Research, UNIFOB AS, Bergen, Norway; Hoppema, M. [Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany; Jutterström, S. [University of Gothenburg, Sweden; Schirnick, C. [IFM-GEOMAR, Leibniz Institute for Marine Sciences, Chemical Oceanography, Kiel, Germany; Van Heuven, S. [University of Groningen, The Netherlands; Kozyr, Alexander [ORNL; Lin, X. [Princeton University; Velo, A. [Instituto de Investigaciones Marinas de Vigo, CSIC, Vigo, Spain; Wallace, D.W.R. [IFM-GEOMAR, Leibniz Institute for Marine Sciences, Chemical Oceanography, Kiel, Germany; Mintrop, L. [MARIANDA marine analytics and data, Kiel, Germany

    2010-01-01

    The original goal of the CARINA (Carbon in Atlantic Ocean) data synthesis project was to create a merged calibrated data set from open ocean subsurface measurements by European scientists that would be generally useful for biogeochemical investigations in the North Atlantic and in particular, studies involving the carbon system. Over time the geographic extent expanded to include the entire Atlantic, the Arctic and the Southern Ocean and the international collaboration broadened significantly. In this paper we give a brief history of the project, a general overview of data included and an outline of the procedures used during the synthesis. The end result of this project was a set of 3 data products, one for each of the listed ocean regions. It is critical that anyone who uses any of the CARINA data products recognize that the data products are not simply concatenations of the originally measured values. Rather, the data have been through an extensive calibration procedure designed to remove measurement bias and bad data. Also a significant fraction of the individual values in the data products were derived either by direct calculation or some means of approximation. These data products were constructed for basin scale biogeochemical investigations and may be inappropriate for investigations involving small areal extent or similar detailed analysis. More information on specific parts of this project can be found in companion articles in this issue. In particular, Tanhua et al. (2010) and Tanhua (2009) describe the procedures and software used to remove measurement bias from the original data. The three data products and a significant volume of supporting information are available from the CARINA web site hosted by the Carbon Dioxide Information Analysis Center (CDIAC: http://cdiac.esd.ornl.gov/oceans/CARINA/Carina inv.html). Anyone wanting to use the data is advised to get the highest version number of each data product. Incremental versions represent either

  19. H.E.S.S. observations of the Carina nebula and its enigmatic colliding wind binary Eta Carinae

    CERN Document Server

    Abramowski, A; Aharonian, F; Akhperjanian, A G; Anton, G; Balzer, A; Barnacka, A; Becherini, Y; Becker, J; Bernlöhr, K; Birsin, E; Biteau, J; Bochow, A; Boisson, C; Bolmont, J; Bordas, P; Brucker, J; Brun, F; Brun, P; Bulik, T; Büsching, I; Carrigan, S; Casanova, S; Cerruti, M; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Cologna, G; Conrad, J; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Egberts, K; Eger, P; Espigat, P; Fallon, L; Fegan, S; Feinstein, F; Fernandes, M V; Fiasson, A; Fontaine, G; Förster, A; Füßling, M; Gallant, Y A; Garrigoux, T; Gast, H; Gèrard, L; Giebels, B; Glicenstein, J F; Glück, B; Göring, D; Grondin, M -H; Häffner, S; Hague, J D; Hahn, J; Hampf, D; Harris, J; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hillert, A; Hinton, J A; Hofmann, W; Hofverberg, P; Holler, M; Horns, D; Jacholkowska, A; Jahn, C; Jamrozy, M; Jung, I; Kastendieck, M A; Katarzyński, K; Katz, U; Kaufmann, S; Khélifi, B; Klochkov, D; Kluźniak, W; Kneiske, T; Komin, Nu; Kosack, K; Kossakowski, R; Krayzel, F; Laffon, H; Lamanna, G; Lenain, J -P; Lennarz, D; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Masbou, J; Maurin, G; Maxted, N; Mayer, M; McComb, T J L; Medina, M C; Méhault, J; Moderski, R; Mohamed, M; Moulin, E; Naumann, C L; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nekrassov, D; Nguyen, N; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Wilhelmi, E de Oña; Opitz, B; Ostrowski, M; Oya, I; Panter, M; Arribas, M Paz; Pekeur, N W; Pelletier, G; Perez, J; Petrucci, P -O; Peyaud, B; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raue, M; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Sahakian, V; Sanchez, D A; Santangelo, A; Schlickeiser, R; Schulz, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Sheidaei, F; Skilton, J L; Sol, H; Spengler, G; Stawarz, Ł; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Szostek, A; Tavernet, J -P; Terrier, R; Tluczykont, M; Valerius, K; van Eldik, C; Vasileiadis, G; Venter, C; Viana, A; Vincent, P; Völk, H J; Volpe, F; Vorobiov, S; Vorster, M; Wagner, S J; Ward, M; White, R; Wierzcholska, A; Zacharias, M; Zajczyk, A; Zdziarski, A A; Zech, A; Zechlin, H -S; Montmerle, T

    2012-01-01

    The massive binary system Eta Carinae and the surrounding HII complex, the Carina Nebula, are potential particle acceleration sites from which very-high-energy (VHE; E > 100 GeV) \\gamma-ray emission could be expected. This paper presents data collected during VHE \\gamma-ray observations with the H.E.S.S. telescope array from 2004 to 2010, which cover a full orbit of Eta Carinae. In the 33.1-hour data set no hint of significant \\gamma-ray emission from Eta Carinae has been found and an upper limit on the \\gamma-ray flux of 7.7 x 10-13 ph cm-2 s-1 (99% confidence level) is derived above the energy threshold of 470 GeV. Together with the detection of high-energy (HE; 0.1 GeV > E > 100 GeV) \\gamma-ray emission by the Fermi-LAT up to 100 GeV, and assuming a continuation of the average HE spectral index into the VHE domain, these results imply a cut-off in the \\gamma-ray spectrum between the HE and VHE \\gamma-ray range. This could be caused either by a cut-off in the accelerated particle distribution or by severe \\...

  20. The 1981 mass-loss phase of Eta Carinae

    Science.gov (United States)

    Bidelman, William P.; Galen, Tamara A.; Wallerstein, George

    1993-07-01

    A visual-region coude spectrogram of Eta Carinae taken in 1981 May is described, and the portion of the spectrum containing H-alpha is reproduced. This was taken during one of Eta Car's 'abnormal' stages, which have been suggested by Zanella et al. (1984) to be times of large mass loss from this unique object. The 1981 spectrum is compared with the 'normal' spectrum as observed in 1985.

  1. Submillimeter and Far-Infrared Observations of the Carina Nebula

    Science.gov (United States)

    Oberst, Thomas E.; Parshley, S. C.; Nikola, T.; Stacey, G. J.; Loehr, A.; Lane, A. P.; Stark, A. A.; Kamenetzky, J.

    2011-05-01

    We present the results of a 250 arcmin2 mapping of the 205 μm [NII] fine-structure emission over the northern Carina Nebula, including the Car I and Car II HII regions. Spectra were obtained using the South Pole Imaging Fabry-Perot Interferometer (SPIFI) at the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) at South Pole. We supplement the 205 μm data with new reductions of far-IR fine-structure spectra from the Infrared Space Observatory (ISO) in 63 μm [OI], 122 μm [NII], 146 μm [OI], and 158 μm [CII]. Morphological comparisons are made with optical, radio continuum and CO maps. The 122 [NII] / 205 [NII] line ratio is used to probe the density of the low-ionization gas, and the 158 [C II] / 205 [NII] line ratio is used to probe the fraction of C+ arising from photodissociation regions (PDRs). From the [OI] and [CII] data, we construct a PDR model of Carina following Kaufman et al. (1999). When the PDR properties are compared with other sources, Carina is found to be more akin to 30 Doradus than Galactic star-forming regions such as the Orion Bar, M17, or W49; this is consistent with the view of Carina as a more evolved region, where much of the parent molecular cloud has been ionized or swept away. These data constitute the first ever ground-based detection of the 205 μm [NII] line, and only the third detection overall since those of the COBE FIRAS and the KAO in the early 1990s.

  2. Overview of the Nordic Seas CARINA data and salinity measurements

    Directory of Open Access Journals (Sweden)

    R. M. Key

    2009-07-01

    Full Text Available Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic. The data have been subject to rigorous quality control (QC in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS, the Atlantic (ATL and the Southern Ocean (SO. With the adjustments the CARINA database is consistent both internally as well as with GLODAP (Key et al., 2004 and is suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation. The Arctic Mediterranean Seas includes the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. This contribution provides an overview of the CARINA data from the Nordic Seas and summarises the findings of the QC of the salinity data. One cruise had salinity data that were of questionable quality, and these have been removed from the data product. An evaluation of the consistency of the quality controlled salinity data suggests that they are consistent to at least 0.05.

  3. Overview of the Nordic Seas CARINA data and salinity measurements

    Directory of Open Access Journals (Sweden)

    A. Olsen

    2009-11-01

    Full Text Available Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic. The data have been subject to rigorous quality control (QC in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS, the Atlantic (ATL and the Southern Ocean (SO. With the adjustments the CARINA database is consistent both internally as well as with GLODAP (Key et al., 2004 and is suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation. The Arctic Mediterranean Seas include the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. This contribution provides an overview of the CARINA data from the Nordic Seas and summarises the findings of the QC of the salinity data. One cruise had salinity data that were of questionable quality, and these have been removed from the data product. An evaluation of the consistency of the quality controlled salinity data suggests that they are consistent to at least ±0.005.

  4. Volumetric Image Guidance Using Carina vs Spine as Registration Landmarks for Conventionally Fractionated Lung Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Lavoie, Caroline; Higgins, Jane; Bissonnette, Jean-Pierre [Department of Radiation Oncology, Princess Margaret Hospital, University of Toronto, Toronto, Ontario, M5G 2M9 (Canada); Le, Lisa W. [Department of Biostatistics, Princess Margaret Hospital, Toronto, Ontario, M5G 2M9 (Canada); Sun, Alexander; Brade, Anthony; Hope, Andrew; Cho, John [Department of Radiation Oncology, Princess Margaret Hospital, University of Toronto, Toronto, Ontario, M5G 2M9 (Canada); Bezjak, Andrea, E-mail: andrea.bezjak@rmp.uhn.on.ca [Department of Radiation Oncology, Princess Margaret Hospital, University of Toronto, Toronto, Ontario, M5G 2M9 (Canada)

    2012-12-01

    Purpose: To compare the relative accuracy of 2 image guided radiation therapy methods using carina vs spine as landmarks and then to identify which landmark is superior relative to tumor coverage. Methods and Materials: For 98 lung patients, 2596 daily image-guidance cone-beam computed tomography scans were analyzed. Tattoos were used for initial patient alignment; then, spine and carina registrations were performed independently. A separate analysis assessed the adequacy of gross tumor volume, internal target volume, and planning target volume coverage on cone-beam computed tomography using the initial, middle, and final fractions of radiation therapy. Coverage was recorded for primary tumor (T), nodes (N), and combined target (T+N). Three scenarios were compared: tattoos alignment, spine registration, and carina registration. Results: Spine and carina registrations identified setup errors {>=}5 mm in 35% and 46% of fractions, respectively. The mean vector difference between spine and carina matching had a magnitude of 3.3 mm. Spine and carina improved combined target coverage, compared with tattoos, in 50% and 34% (spine) to 54% and 46% (carina) of the first and final fractions, respectively. Carina matching showed greater combined target coverage in 17% and 23% of fractions for the first and final fractions, respectively; with spine matching, this was only observed in 4% (first) and 6% (final) of fractions. Carina matching provided superior nodes coverage at the end of radiation compared with spine matching (P=.0006), without compromising primary tumor coverage. Conclusion: Frequent patient setup errors occur in locally advanced lung cancer patients. Spine and carina registrations improved combined target coverage throughout the treatment course, but carina matching provided superior combined target coverage.

  5. The Carina Project IX: on Hydrogen and helium burning variables

    CERN Document Server

    Coppola, G; Stetson, P B; Bono, G; Braga, V F; Ripepi, V; Dall'Ora, M; Musella, I; Buonanno, R; Fabrizio, M; Ferraro, I; Fiorentino, G; Iannicola, G; Monelli, M; Nonino, M; Thévenin, F; Walker, R

    2015-01-01

    We present new multi-band (UBVI) time-series data of helium burning variables in the Carina dwarf spheroidal galaxy. The current sample includes 92 RR Lyrae-six of them are new identifications-and 20 Anomalous Cepheids, one of which is new identification. The analysis of the Bailey diagram shows that the luminosity amplitude of the first overtone component in double-mode variables is located along the long-period tail of regular first overtone variables, while the fundamental component is located along the short-period tale of regular fundamental variables. This evidence further supports the transitional nature of these objects. Moreover, the distribution of Carina double-mode variables in the Petersen diagram (P_1/P_0 vs P_0) is similar to metal-poor globulars (M15, M68), to the dwarf spheroidal Draco and to the Galactic Halo. This suggests that the Carina old stellar population is metal-poor and affected by a small spread in metallicity. We use trigonometric parallaxes for five field RR Lyrae stars to provi...

  6. Flames High Resolution Spectroscopy of RGB Stars in the Carina Dwarf Spheroidal Galaxy

    NARCIS (Netherlands)

    Lemasle, B.; Hill, V.; Tolstoy, E.; Venn, K.

    2011-01-01

    Carina is a small and faint classical dwarf spheroidal galaxy in the halo of the Milky Way with a highly episodic star formation history (e.g., Hurley-Keller et al. 1998). Using VLT/FLAMES in high resolution mode, we significantly increase the sample of stars with abundance determinations in Carina,

  7. Extended VHE $\\gamma$-ray emission towards SGR1806$-$20, LBV1806$-$20, and stellar cluster Cl*1806$-$20

    CERN Document Server

    Abdalla, H; Aharonian, F; Benkhali, F Ait; Akhperjanian, A G; Angüner, E O; Arrieta, M; Aubert, P; Backes, M; Balzer, A; Barnard, M; Becherini, Y; Tjus, J Becker; Berge, D; Bernhard, S; Bernlöhr, K; Birsin, E; Blackwell, R; Böttcher, M; Boisson, C; Bolmont, J; Bordas, P; Bregeon, J; Brun, F; Brun, P; Bryan, M; Bulik, T; Capasso, M; Carr, J; Casanova, S; Chakraborty, N; Chalme-Calvet, R; Chaves, R C G; Chen, A; Chevalier, J; Chrétien, M; Colafrancesco, S; Cologna, G; Condon, B; Conrad, J; Couturier, C; Cui, Y; Davids, I D; Degrange, B; Deil, C; deWilt, P; Djannati-Ataï, A; Domainko, W; Donath, A; Drury, L O'C; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Edwards, T; Egberts, K; Eger, P; Ernenwein, J -P; Eschbach, S; Farnier, C; Fegan, S; Fernandes, M V; Fiasson, A; Fontaine, G; Förster, A; Funk, S; Füßling, M; Gabici, S; Gajdus, M; Gallant, Y A; Garrigoux, T; Giavitto, G; Giebels, B; Glicenstein, J F; Gottschall, D; Goyal, A; Grondin, M -H; Grudzińska, M; Hadasch, D; Hahn, J; Hawkes, J; Heinzelmann, G; Henri, G; Hermann, G; Hervet, O; Hillert, A; Hinton, J A; Hofmann, W; Hoischen, C; Holler, M; Horns, D; Ivascenko, A; Jacholkowska, A; Jamrozy, M; Janiak, M; Jankowsky, D; Jankowsky, F; Jingo, M; Jogler, T; Jouvin, L; Jung-Richardt, I; Kastendieck, M A; Katarzyński, K; Katz, U; Kerszberg, D; Khélifi, B; Kieffer, M; King, J; Klepser, S; Klochkov, D; Kluźniak, W; Kolitzus, D; Komin, Nu; Kosack, K; Krakau, S; Kraus, M; Krayzel, F; Krüger, P P; Laffon, H; Lamanna, G; Lau, J; Lees, J -P; Lefaucheur, J; Lefranc, V; Lemière, A; Lemoine-Goumard, M; Lenain, J -P; Leser, E; Lohse, T; Lorentz, M; Liu, R; Lypova, I; Marandon, V; Marcowith, A; Mariaud, C; Marx, R; Maurin, G; Maxted, N; Mayer, M; Meintjes, P J; Menzler, U; Meyer, M; Mitchell, A M W; Moderski, R; Mohamed, M; Morå, K; Moulin, E; Murach, T; de Naurois, M; Niederwanger, F; Niemiec, J; Oakes, L; Odaka, H; Öttl, S; Ohm, S; Ostrowski, M; Oya, I; Padovani, M; Panter, M; Parsons, R D; Arribas, M Paz; Pekeur, N W; Pelletier, G; Petrucci, P -O; Peyaud, B; Pita, S; Poon, H; Prokhorov, D; Prokoph, H; Pühlhofer, G; Punch, M; Quirrenbach, A; Raab, S; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Romoli, C; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Sahakian, V; Salek, D; Sanchez, D A; Santangelo, A; Sasaki, M; Schlickeiser, R; Schüssler, F; Schulz, A; Schwanke, U; Schwemmer, S; Seyffert, A S; Shafi, N; Shilon, I; Simoni, R; Sol, H; Spanier, F; Spengler, G; Spies, F; Stawarz, L; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Tavernet, J -P; Tavernier, T; Taylor, A M; Terrier, R; Tluczykont, M; Trichard, C; Tuffs, R; van der Walt, J; van Eldik, C; van Soelen, B; Vasileiadis, G; Veh, J; Venter, C; Viana, A; Vincent, P; Vink, J; Voisin, F; Völk, H J; Vuillaume, T; Wadiasingh, Z; Wagner, S J; Wagner, P; Wagner, R M; White, R; Wierzcholska, A; Willmann, P; Wörnlein, A; Wouters, D; Yang, R; Zabalza, V; Zaborov, D; Zacharias, M; Zdziarski, A A; Zech, A; Zefi, F; Ziegler, A; Zywucka, N

    2016-01-01

    Using the High Energy Spectroscopic System (H.E.S.S.) telescopes we have discovered a steady and extended very high-energy (VHE) $\\gamma$-ray source towards the luminous blue variable candidate LBV1806$-$20, massive stellar cluster Cl*1806$-$20, and magnetar SGR1806$-$20. The new VHE source, HESSJ1808$-$204, was detected at a statistical significance of $>6\\sigma$ (post-trial) with a photon flux normalisation $(2.9 \\pm 0.4_{\\rm stat} \\pm 0.5_{\\rm sys})\\times 10^{-13}$\\,ph\\,cm$^{-2}$\\,s$^{-1}$\\,TeV$^{-1}$ at 1\\,TeV and a power-law photon index of $2.3\\pm0.2_{\\rm stat}\\pm 0.3_{\\rm sys}$. The luminosity of this source (0.2 to 10 TeV; scaled to distance $d$=8.7\\,kpc) is $L_{\\rm VHE}\\sim1.6 \\times 10^{34}(d/{\\rm 8.7\\, kpc})^2$\\,erg\\,s$^{-1}$. The VHE $\\gamma$-ray emission is extended and is well fit by a single Gaussian with statistical standard deviation of $0.095^\\circ \\pm 0.015^\\circ$. This extension is similar to that of the synchrotron radio nebula G10.0$-$0.3, which is thought to be powered by LBV1806$-$20. ...

  8. Modelling the Radio Light Curve of Eta Carinae

    OpenAIRE

    Kashi, Amit; Soker, Noam

    2007-01-01

    We study the propagation of the ionizing radiation emitted by the secondary star in Eta Carinae. We find that a large fraction of this radiation is absorbed by the primary stellar wind, mainly after it encounters the secondary wind and passes through a shock wave. The amount of absorption depends on the compression factor of the primary wind in the shock wave. We build a model where the compression factor is limited by the magnetic pressure in the primary wind. We find that the variation of t...

  9. Protoplanetary disks in the hostile environment of Carina

    CERN Document Server

    Mesa-Delgado, A; Henney, W J; Puzia, T H; Tsamis, Y G

    2016-01-01

    We report the first direct imaging of protoplanetary disks in the star-forming region of Carina, the most distant, massive cluster in which disks have been imaged. Using the Atacama Large Millimeter/sub-millimeter Array (ALMA), disks are observed around two young stellar objects (YSOs) that are embedded inside evaporating gaseous globules and exhibit jet activity. The disks have an average size of 120 AU and total masses of 30 and 50 M_Jup. Given the measured masses, the minimum timescale required for planet formation (~1-2 Myr) and the average age of the Carina population (~1-4 Myr), it is plausible that young planets are present or their formation is currently ongoing in these disks. The non-detection of millimeter emission above the 4sigma threshold (~7 M_Jup) in the core of the massive cluster Trumpler~14, an area containing previously identified proplyd candidates, suggest evidence for rapid photo-evaporative disk destruction in the cluster's harsh radiation field. This would prevent the formation of gia...

  10. Spectroscopic and photometric observations of M supergiants in Carina.

    Science.gov (United States)

    Humphreys, R. M.; Strecker, D. W.; Ney, E. P.

    1972-01-01

    Spectroscopic study of 30 Southern-Hemisphere M supergiants mostly in Carina in the blue and near-infrared, and photometrical study of these stars from 0.4 to 18 microns. The uncertainties in the determinations of interstellar extinction are discussed, and the spatial distribution of the M supergiants in the Carina arm is shown. The presence of the 11-micron excess attributed to silicate dust is a common feature. Stars of the same spectral type and luminosity class are remarkably homogeneous in their long-wave behavior. The silicate feature becomes more prominent in the more luminous stars and in stars of later spectral type. Four composite systems show little long-wave excess. The two VV Cephei objects have excesses probably produced by gas emission, and the other two have little or no excess - supporting the suggestion that the presence of the early star prohibits the formation of a dust envelope. Three stars - VY CMa, VX Sgr, and HD 9767 - appear to be extreme examples of stars with large excesses over the entire long-wave region. It is suggested that these objects are surrounded by large amounts of particulate material over a great range of distances from the stars.

  11. Nordic Seas and Arctic Ocean CFC data in CARINA

    Directory of Open Access Journals (Sweden)

    E. Jeansson

    2009-10-01

    Full Text Available Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic. The data have been subject to rigorous quality control (QC in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS, the Atlantic (ATL and the Southern Ocean (SO. The Arctic Mediterranean Seas is comprised of the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas.

    Here we present an overview of the QC of the CFC data for the Arctic Mediterranean Seas, including the chlorofluorocarbons CFC-11, CFC-12 and CFC-113, as well as carbon tetrachloride (CCl4. For the secondary QC of the CFCs we used a combination of tools, including the evaluation of depth profiles and CFC ratios, surface saturations and a crossover analysis. This resulted in a multiplicative adjustment of some cruise data, while some other cruises were flagged with questionable quality, which excluded them from the final data product.

  12. X-shooter, NACO, and AMBER observations of the LBV Pistol Star \\footnote{Based on ESO runs 85.D-0182A, 085.D-0625AC}

    CERN Document Server

    Martayan, Christophe; Bouquin, Jean-Baptiste Le; Merand, Antoine; Montagnier, Guillaume; Selman, Fernando; Girard, Julien; Fox, Andrew; Baade, Dietrich; Fremat, Yves; Lobel, Alex; Martins, Fabrice; Patru, Fabien; Rivinius, Thomas; Sana, Hugues; Stefl, Stan; Zorec, Jean; Semaan, Thierry

    2010-01-01

    We present multi-instruments and multi-wavelengths observations of the famous LBV star Pistol Star. These observations are part of a larger program about early O stars at different metallicities. The Pistol star has been claimed as the most massive star known, with 250 solar masses. We present the preliminary results based on X-Shooter spectra, as well as the observations performed with the VLTI-AMBER and the VLT-NACO adaptive optics. The X-shooter spectrograph allows to obtain simultaneously a spectrum from the UV to the K-band with a resolving power of $\\sim$15000. The preliminary results obtained indicate that Pistol Star has similar properties of Eta Car, including shells of matter, but also the binarity. Other objects of the program, here briefly presented, were selected for their particular nature: early O stars with mass discrepancies between stellar evolution models and observations, discrepancies with the wind momentum luminosity relation.

  13. A high-velocity transient outflow in Eta Carinae

    CERN Document Server

    Behar, Ehud; Soker, Noam

    2007-01-01

    We analyze velocity profiles of the X-ray spectral lines emitted by the Eta Carinae stellar binary at four epochs, just before the X-ray minimum (associated with periastron) and more than two years before the minimum (~apastron). The profiles are nicely resolved by the HETGS spectrometer on board Chandra. Far from periastron, we find symmetrical lines that are more or less centered at zero velocity. Closer to periastron, the lines broaden, shift towards the blue, and become visibly asymmetric. While the quiescent X-ray emission and slight (<200 km/sec) centroid shifts can be ascribed to the ordinary continuous binary wind interaction and to the orbital velocity of the secondary star, the observed high-velocity emission up to ~2,000 km/sec and the abrupt flares during which it occurs can not. This leads us to interpret the high-velocity flaring emission as due to a fast collimated outflow of ionized gas.

  14. The -145 km/S Absorption System of Eta Carinae

    Science.gov (United States)

    Vieira, G.; Gull, T. R.; Danks, A.; Johansson, S.

    2002-01-01

    With the STIS E230H mode (R-118,000) , we have identified about twenty absorption components in line of sight from Eta Carinae. Two components, one at -513 km/s and another at -145 W s , are quite different in character from the others, mostly at intermediate velocities. The -145 km/s component is significantly wider in fwhm, is seen in many more species, and the lower level can be above 20,000/cm, well above the 2000/cm noted in the -513 km/s component. In the spectral region from 2400 to 3160A, approximately 500 absorption lines have been identified. In this poster, we will present line identifications and atomic parameters of the measured lines, hopefully providing insight as to what levels are being excited and by what processes.

  15. Detection of a Hot Binary Companion of $\\eta$ Carinae

    CERN Document Server

    Iping, R C; Gull, T R; Massa, D L; Hillier, D J; Iping, Rosina C.; Sonneborn, George; Gull, Theodore R.; Massa, Derck L.

    2005-01-01

    We report the detection of a hot companion of $\\eta$ Carinae using high resolution spectra (905 - 1180 \\AA) obtained with the Far Ultraviolet Spectroscopic Explorer (\\fuse) satellite. Observations were obtained at two epochs of the 2024-day orbit: 2003 June during ingress to the 2003.5 X-ray eclipse and 2004 April several months after egress. These data show that essentially all the far-UV flux from \\etacar shortward of \\lya disappeared at least two days before the start of the X-ray eclipse (2003 June 29), implying that the hot companion, \\etaB, was also eclipsed by the dense wind or extended atmosphere of \\etaA. Analysis of the far-UV spectrum shows that \\etaB is a luminous hot star. The \

  16. The Purple Haze of Eta Carinae: Binary-Induced Variability?

    CERN Document Server

    Smith, N; Collins, N R; Gull, T R; Smith, Nathan; Morse, Jon A.; Collins, Nicholas R.; Gull, Theodore R.

    2004-01-01

    Asymmetric variability in ultraviolet images of the Homunculus obtained with the Advanced Camera for Surveys/High Resolution Camera on the Hubble Space Telescope suggests that Eta Carinae is indeed a binary system. Images obtained before, during, and after the recent ``spectroscopic event'' in 2003.5 show alternating patterns of bright spots and shadows on opposite sides of the star before and after the event, providing a strong geometric argument for an azimuthally-evolving, asymmetric UV radiation field as one might predict in some binary models. The simplest interpretation of these UV images, where excess UV escapes from the secondary star in the direction away from the primary, places the major axis of the eccentric orbit roughly perpendicular to our line of sight, sharing the same equatorial plane as the Homunculus, and with apastron for the hot secondary star oriented toward the southwest of the primary. However, other orbital orientations may be allowed with more complicated geometries. Selective UV il...

  17. The Ejecta of Eta Carinae as Studied by STIS

    Science.gov (United States)

    Gull, Theodore R.; Oegerle, William R. (Technical Monitor)

    2002-01-01

    The Space Telescope Imaging Spectrograph has been used to study the emission and absorption spectra of ejecta surrounding Eta Carinae. Discussion will be presented on the overall structure of the Homunculus, the Weigelt blobs and the Strontium filament. Three visits have been accomplished with the Position Angle precisely the same and covering the Central Source and Weigelt Blobs B and D. Deep spectra have been done at several positions to obtain the overall velocity structure of the Homunculus and the disk region. Mapping has been done with the STIS medium dispersion gratings set near H beta and H alpha. We have obtained full coverage of the strontium filament from 1640 Angstroms to 10300 Angstroms. The structure and physical properties will be described.

  18. Spatial Distribution and Kinematics of the Molecular Material Associated with eta Carinae

    Science.gov (United States)

    Loinard, Laurent; Kamiński, Tomasz; Serra, Paolo; Menten, Karl M.; Zapata, Luis A.; Rodríguez, Luis F.

    2016-12-01

    Single-dish submillimeter observations have recently revealed the existence of a substantial, chemically peculiar molecular gas component located in the innermost circumstellar environment of the very massive luminous blue variable star, η Carinae. Here, we present 5″-resolution interferometric observations of the 1\\to 0 rotational transition of hydrogen cyanide (HCN) toward this star obtained with the Australia Telescope Compact Array. The emission is concentrated in the central few arcseconds around η Carinae and shows a clear 150 km s-1 velocity gradient running from west-north-west (blue) to east-south-east (red). Given the extent, location, and kinematics of this molecular material, we associate it with the complex of dusty arcs and knots seen in mid-infrared emission near the center of the Homunculus nebula. Indeed, the shielding provided by this dust could help explain how molecules survive in the presence of the intense UV radiation field produced by η Carinae. The dust located in the central few arcseconds around η Carinae and the molecular component described here most likely formed in situ and out of material expelled by the massive interacting binary system. Thus, η Carinae offers us a rare glimpse of the processes that lead to the formation of dust and molecules around massive stars, which are relevant to the interpretation of dust and molecule detections at high redshifts.

  19. A low pre-infall mass for the Carina dwarf galaxy from disequilibrium modelling

    CERN Document Server

    Ural, Uğur; Read, Justin I; Walker, Matthew G

    2015-01-01

    Dark matter only simulations of galaxy formation predict many more subhalos around a Milky Way like galaxy than the number of observed satellites. Proposed solutions require the satellites to inhabit dark matter halos with masses between one to ten billion solar masses at the time they fell into the Milky Way. Here we use a modelling approach, independent of cosmological simulations, to obtain a preinfall mass of 360 (+380,-230) million solar masses for one of the Milky Way's satellites: Carina. This determination of a low halo mass for Carina can be accommodated within the standard model only if galaxy formation becomes stochastic in halos below ten billion solar masses. Otherwise Carina, the eighth most luminous Milky Way dwarf, would be expected to inhabit a significantly more massive halo. The implication of this is that a population of "dark dwarfs" should orbit the Milky Way: halos devoid of stars and yet more massive than many of their visible counterparts.

  20. Spatial distribution and kinematics of the molecular material associated with $\\eta$ Carinae

    CERN Document Server

    Loinard, L; Serra, P; Menten, K; Zapata, L; Rodriguez, L

    2016-01-01

    Single-dish sub-millimeter observations have recently revealed the existence of a substantial, chemically peculiar, molecular gas component located in the innermost circumstellar environment of the very massive luminous blue variable star $\\eta$ Carinae. Here, we present 5$"$-resolution interferometric observations of the 1$\\rightarrow$0 rotational transition of hydrogen cyanide (HCN) obtained with the Australia Telescope Compact Array (ATCA) toward this star. The emission is concentrated in the central few arcseconds around $\\eta$ Carinae and shows a clear 150 km s$^{-1}$ velocity gradient running from west-north-west (blue) to east-south-east (red). Given the extent and location of this molecular material, we associate it with the complex of dusty arcs and knots seen in mid-infrared emission along the equatorial plane of the Homunculus nebula. The dust located in the central few arcseconds around $\\eta$ Carinae and the molecular component described here have most likely formed in situ, out of material expel...

  1. The sub-arcsecond dusty environment of Eta Carinae

    CERN Document Server

    Chesneau, O; Herbst, T; Waters, L B F M; Hillier, D J; Leinert, C; De Koter, A; Pascucci, I; Jaffe, W; Köhler, R; Alvarez, C; Van Boekel, R; Brandner, W; Graser, U; Lagrange, A M; Lenzen, R; Morel, S; Schöller, M; Leinert, Ch

    2005-01-01

    The core of the nebula surrounding Eta Carinae has been observed with the VLT Adaptive Optics system NACO and with the interferometer VLTI/MIDI to constrain spatially and spectrally the warm dusty environment and the central object. In particular, narrow-band images at 3.74 and 4.05 micron reveal the butterfly shaped dusty environment close to the central star with unprecedented spatial resolution. A void whose radius corresponds to the expected sublimation radius has been discovered around the central source. Fringes have been obtained in the Mid-IR which reveal a correlated flux of about 100Jy situated 0.3" south-east of the photocenter of the nebula at 8.7 micron, which corresponds with the location of the star as seen in other wavelengths. This correlated flux is partly attributed to the central object, and these observations provide an upper limit for the SED of the central source from 2.2 to 13.5 micron. Moreover, we have been able to spectrally disperse the signal from the nebula itself at PA=318 degre...

  2. The Trumpler 14 photodissociation region in the Carina Nebula

    Science.gov (United States)

    Brooks, K. J.; Cox, P.; Schneider, N.; Storey, J. W. V.; Poglitsch, A.; Geis, N.; Bronfman, L.

    2003-12-01

    We report the results of observations of the fine-structure emission lines [C II] 158 μm and [O I] 63 μm using FIFI on the Kuiper Airborne Observatory (KAO) and the Long Wavelength Spectrometer (LWS) on board ISO, towards the molecular cloud associated with the stellar cluster Trumpler 14 (Tr 14) in the Carina Nebula. These data are compared with selected CO and CS transitions obtained with the SEST as well as IRAS and MSX images to produce a detailed view of the morphology and the physical conditions prevailing in the photodissociation region (PDR) at the interface between the ionized gas and the molecular dust lane. The relative intensity distribution observed for the various tracers is consistent with the stratification expected for a molecular cloud seen edge-on and exposed to a radiation field of ~ 104 G_0, which is dominated by the most massive stars of Tr 14. The grain photoelectric heating efficiency, \\epsilon, is estimated to be ~5 x 10-3 and is comparable to other galactic PDRs. The molecular gas has a complicated velocity structure with a high velocity dispersion resulting from the impact of the stellar winds arising from Tr 14. There is evidence of small-scale clumping with a very low volume filling factor. Despite the rich concentration of massive O stars in Tr 14 we find that the parameters of the PDR are much less-extreme than those of the Orion and M 17 massive star-forming regions.

  3. A multispectral view of the periodic events in eta Carinae

    CERN Document Server

    Damineli, A; Corcoran, M F; Stahl, O; Groh, J H; Arias, J; Teodoro, M; Morrell, N; Gamen, R; Gonzalez, F; Leister, N V; Levato, H; Levenhagen, R S; Grosso, M; Colombo, J F Albacete; Wallerstein, G

    2007-01-01

    A full description of the 5.5-yr low excitation events in eta Carinae is presented. We show that they are not simple and brief, as thought before, but a combination of two components. The first, the `slow variation' component, is revealed by slow changes in the ionization level of circumstellar matter across the whole cycle and is caused by the gradual immersion of the secondary star in the wind of the primary. The second, the `collapse' component, is restricted to some months around the minimum, and is due to the immersion of the secondary deep in the primary wind. During this stage there is a general collapse of the wind-wind collision shock, and the Weigelt blobs are strongly shielded from high energy photons (E > 16 eV). High energy phenomena are sensitive only to the `collapse', low energy only to the `slow variation' and that of intermediate energy to both components. Simple eclipses and mechanisms effective only near periastron (e.g., shell ejection or accretion onto the secondary star) cannot account ...

  4. The three-dimensional structure of the Eta Carinae Homunculus

    CERN Document Server

    Steffen, W; Madura, T I; Groh, J H; Gull, T R; Mehner, A; Corcoran, M F; Damineli, A; Hamaguchi, K

    2014-01-01

    We investigate, using the modeling code SHAPE, the three-dimensional structure of the bipolar Homunculus nebula surrounding Eta Carinae, as mapped by new ESO VLT/X-Shooter observations of the H2 $\\lambda=2.12125$ micron emission line. Our results reveal for the first time important deviations from the axisymmetric bipolar morphology: 1) circumpolar trenches in each lobe positioned point-symmetrically from the center and 2) off-planar protrusions in the equatorial region from each lobe at longitudinal (~55 degrees) and latitudinal (10-20 degrees) distances from the projected apastron direction of the binary orbit. The angular distance between the protrusions (~110 degrees) is similar to the angular extent of each polar trench (~130 degrees) and nearly equal to the opening angle of the wind-wind collision cavity (~110 degrees). As in previous studies, we confirm a hole near the centre of each polar lobe and no detectable near-IR H2 emission from the thin optical skirt seen prominently in visible imagery. We con...

  5. Accretion at the periastron passage of Eta Carinae

    CERN Document Server

    Kashi, Amit

    2016-01-01

    We present high resolution numerical simulations of the colliding wind system $\\eta$ Carinae, showing accretion onto the secondary star close to periastron passage. Our hydrodynamical simulations include self gravity and radiative cooling. The smooth stellar winds collide and develop instabilities, mainly the non-linear thin shell instability, and form filaments and clumps. We find that a few days before periastron passage the dense filaments and clumps flow towards the secondary as a result of its gravitational attraction, and reach the zone where we inject the secondary wind. We run our simulations for the conventional stellar masses, $M_1=120 ~\\rm{M_\\odot}$ and $M_2=30 ~\\rm{M_\\odot}$, and for a high mass model, $M_1=170 ~\\rm{M_\\odot}$ and $M_2=80 ~\\rm{M_\\odot}$, that was proposed to better fit the history of giant eruptions. As expected, the simulations results show that the accretion processes is more pronounced for a more massive secondary star.

  6. [Fe II] jets from intermediate-mass protostars in Carina

    CERN Document Server

    Reiter, Megan; Bally, John

    2016-01-01

    We present new HST/WFC3-IR narrowband [Fe II] images of protostellar jets in the Carina Nebula. Combined with 5 previously published sources, we have a sample of 18 jets and 2 HH objects. All of the jets we targeted with WFC3 show bright infrared [Fe II] emission, and a few H$\\alpha$ candidate jets are confirmed as collimated outflows based on the morphology of their [Fe II] emission. Continuum-subtracted images clearly separate jet emission from the adjacent ionization front, providing a better tracer of the collimated jet than H$\\alpha$ and allowing us to connect these jets with their embedded driving sources. The [Fe II] 1.64 $\\mu$m/H$\\alpha$ flux ratio measured in the jets is $\\gtrsim 5$ times larger than in the adjacent ionization fronts. The low-ionization jet core requires high densities to shield Fe$^+$ against further ionization by the FUV radiation from O-type stars in the H II region. High jet densities imply high mass-loss rates, consistent with the intermediate-mass driving sources we identify fo...

  7. Eta Carinae: At the Crossroads of becoming a Supernova

    Science.gov (United States)

    Gull, Theodore

    2007-01-01

    Since the 1840's, when Eta Carinae's visual magnitude rivaled Sirius, the brightest star in the night sky, astronomers have wondered what major event took place. Today with the Hubble Space Telescope Imaging Spectrograph, with CHANDRA X-ray spectroscopy and the Very Large Telescope spectrographs and interferometers, we have learned that over 12 solar masses of material was ejected at 500 to 700 km/s into interstellar space. This ejecta is quite different from the normal interstellar medium. It is rich in nitrogen, poor in oxygen and carbon. The dust properties are quite peculiar and many metals such as vanadium, strontium, cadmium are seen in both absorption against the central source, plus a number of molecules. The chemical and dust formation is likely dominated by nitrogen as we see H_2, CH, CH+, OH, NH, HCl and NH-3, but no CO. Other metals and molecules are being searched out in the FUSE, HST/STIS, VLT/UVES and VLT/CRIRES spectra. I will describe what we know about the massive binary stellar system, how it changes every 5.54 year in UV and X-ray output and how the massive ejecta responds in this astrophysical laboratory.

  8. VizieR Online Data Catalog: The populations of Carina. II. Abundances (Norris+, 2017)

    Science.gov (United States)

    Norris, J. E.; Yong, D.; Venn, K. A.; Gilmore, G.; Casagrande, L.; Dotter, A.

    2017-08-01

    Our selection of objects is based on unpublished CCD V, I observations that we have made of the Carina galaxy. High-resolution, moderate-S/N spectra were obtained of 39 Carina red giants, during 2007 November-2008 March, with the FLAMES system at the 8.2m Kueyen (VLT/UT2) telescope at Cerro Paranal. The spectra cover the wavelength ranges 4800-5750Å and 5840-6800Å. The resolving power was R=47000. Photometry has been obtained from several sources: P. B. Stetson provided us with homogenized BVI, M. J. Irwin furnished JHK from ESO VISTA survey photometry, and M. Gullieuszik supplied BVIJHKs. (12 data files).

  9. The ``Ghost Shell'': Discovery of the Forward Shock from Colliding Winds about Eta Carinae

    Science.gov (United States)

    Dorland, B. N.; Currie, D. G.; Kaufer, A.; Bacciotti, F.

    2003-01-01

    We report on the newly discovered ``Ghost Shell'' around eta Carinae. We have detected a high-velocity ( ~ - 850 km /s), spatially extended, narrow emission feature lying in front of the southeast lobe of eta Carinae's homunculus. This feature has the speed of a high-velocity shock but the spectrum of a low-velocity shock. We propose that the Ghost Shell is the forward shock between the fast stellar wind of the great eruption of 1842 and the older, slow, massive wind. This discovery is described in more detail in Currie, Dorland, & Kaufer (2002).

  10. An Aboriginal Australian Record of the Great Eruption of Eta Carinae

    CERN Document Server

    Hamacher, Duane W

    2010-01-01

    We present evidence that the Boorong Aboriginal people of northwestern Victoria observed the Great Eruption of Eta ({\\eta}) Carinae in the nineteenth century and incorporated the event into their oral traditions. We identify this star, as well as others not specifically identified by name, using descriptive material presented in the 1858 paper by William Edward Stanbridge in conjunction with early southern star catalogues. This identification of a transient astronomical event supports the assertion that Aboriginal oral traditions are dynamic and evolving, and not static. This is the only definitive indigenous record of {\\eta} Carinae's outburst identified in the literature to date.

  11. A Study of the Warm Ionized Medium Throughout the Sagittarius-Carina Arm

    CERN Document Server

    Krishnarao, Dhanesh; Benjamin, Robert A

    2016-01-01

    We present velocity-channel maps and analysis of the warm ionized medium (WIM) throughout the Sagittarius- Carina arm at Galactic longitudes 20 1000 pc along the far Carina arm. Physical conditions of the ionized gas are analyzed using the [S II]/H-alpha line ratio, which more closely traces H-alpha intensity than height above the plane, z, suggesting a stronger relationship with the in-situ electron density. We interpret this result as further evidence for the majority of the observed diffuse emission originating from in-situ ionized gas as opposed to scattered light from classical H II regions in the plane.

  12. The luminous blue variable HR Carinae has a partner. Discovery of a companion with the VLTI

    Science.gov (United States)

    Boffin, Henri M. J.; Rivinius, Thomas; Mérand, Antoine; Mehner, Andrea; LeBouquin, Jean-Baptiste; Pourbaix, Dimitri; de Wit, Willem-Jan; Martayan, Christophe; Guieu, Sylvain

    2016-09-01

    Luminous blue variables (LBVs) are massive stars caught in a post-main sequence phase, during which they lose a significant amount of mass. Since, on one hand, it is thought that the majority of massive stars are close binaries that will interact during their lifetime, and on the other, the most dramatic example of an LBV, η Car, is a binary, it would be useful to find other binary LBVs. We present here interferometric observations of the LBV HR Car done with the AMBER and PIONIER instruments attached to ESO's Very Large Telescope Interferometer (VLTI). Our observations, spanning two years, clearly reveal that HR Car is a binary star. It is not yet possible to fully constrain the orbit, and the orbital period may lie between a few years and several hundred years. We derive a radius for the primary in the system and possibly also resolve the companion. The luminosity ratio in the H-band between the two components is changing with time, going from about 6 to 9. We also tentatively detect the presence of some background flux which remained at the 2% level until January 2016, but then increased to 6% in April 2016. Our AMBER results show that the emission line-forming region of Brγ is more extended than the continuum-emitting region as seen by PIONIER and may indicate some wind-wind interaction. Most importantly, we constrain the total masses of both components, with the most likely range being 33.6 M⊙ and 45 M⊙. Our results show that the LBV HR Car is possibly an η Car analog binary system with smaller masses, with variable components, and further monitoring of this object is definitively called for. Based on data obtained with ESO programmes 092.C-0243, 092.D-0289, 092.D-0296, 094.D-0069, and 596.D-0335.

  13. Eta Carinae and the Homunculus: an Astrophysical Laboratory

    Science.gov (United States)

    Gull, T. R.

    2007-08-01

    High spatial resolution spectroscopy with HST/STIS between 1998.0 and 2004.2 has provided much exciting information about the central binary system and the physics of its N-rich, C,O-poor ejecta. Stellar He I profiles, noticeably blue-shifted relative to P Cygni H and Fe II line profiles, originate from the ionized wind region between two massive companions. Changes in profiles of He I singlet and triplet lines provide clues to the excitation mechanisms involved as the hot, UV companion moves in its highly eccentric orbit. For 90% of the 5.54-year period, the spectra of nearby Weigelt blobs and the Little Homunculus include highly excited emission lines of Ar, Ne, and Fe. During the few month-long spectroscopic minimum, these systems are deprived of Lyman continuum. Recombination, plus cooling, occurs. In the skirt region between the bipolar Homunculus, a neutral emission region, devoid of hydrogen emission, glows in Ti II, Fe I, Sr II, Sc II, etc. We find the ejecta to have Ti/Ni abundances nearly 100 times solar, not due to nuclear processing, but due to lack of oxygen. Many metals normally tied up in interstellar dust remain in gaseous phase. Much information is being obtained on the physical processes in these warm N-rich gases, whose excitation varies with time in a predictable pattern. Indeed recent GRB high dispersion spectra include signatures of circumGRB warm gases. This indicates that the early, primordial massive stars have warm massive ejecta reminiscent to that around Eta Carinae.

  14. A Catalog of New Spectroscopically Confirmed Massive OB Stars in Carina

    CERN Document Server

    Alexander, Michael J; Povich, Matthew S; McSwain, M Virginia

    2016-01-01

    The Carina star-forming region is one of the largest in the Galaxy, and its massive star population is still being unveiled. The large number of stars combined with high, and highly variable, interstellar extinction makes it inherently difficult to find OB stars in this type of young region. We present the results of a spectroscopic campaign to study the massive star population of the Carina Nebula, with the primary goal to confirm or reject previously identified Carina OB star candidates. A total of 141 known O- and B-type stars and 94 candidates were observed, of which 73 candidates had a high enough signal-to-noise ratio to classify. We find 23 new OB stars within the Carina Nebula, a 32% confirmation rate. One of the new OB stars has blended spectra and is suspected to be a double-lined spectroscopic binary (SB2). We also reclassify the spectral types of the known OB stars and discover nine new SB2s among this population. Finally, we discuss the spatial distribution of these new OB stars relative to known...

  15. Model comparison of the dark matter profiles of Fornax, Sculptor, Carina and Sextans

    NARCIS (Netherlands)

    Breddels, Maarten A.; Helmi, Amina

    2013-01-01

    Aims: We compare dark matter profile models of four dwarf spheroidal galaxies satellites of the Milky Way using Bayesian evidence. Methods: We use orbit based dynamical models to fit the 2nd and 4th moments of the line of sight velocity distributions of the Fornax, Sculptor, Carina and Sextans dwarf

  16. Nucleosynthesis and the Inhomogeneous Chemical Evolution of the Carina Dwarf Galaxy

    NARCIS (Netherlands)

    Venn, Kim A.; Shetrone, Matthew D.; Irwin, Mike J.; Hill, Vanessa; Jablonka, Pascale; Tolstoy, Eline; Lemasle, Bertrand; Divell, Mike; Starkenburg, Else; Letarte, Bruno; Baldner, Charles; Battaglia, Giuseppina; Helmi, Amina; Kaufer, Andreas; Primas, Francesca

    2012-01-01

    The detailed abundances of 23 chemical elements in nine bright red giant branch stars in the Carina dwarf spheroidal galaxy are presented based on high-resolution spectra gathered at the Very Large Telescope (VLT) and Magellan telescopes. A spherical model atmospheres analysis is applied using stand

  17. X-ray Gyrations of Eta Carinae, or, Is Presence of Evidence Evidence of Presence?

    CERN Document Server

    Corcoran, M F; Gull, T R; Damineli, A; Davidson, K

    2004-01-01

    We review the properties of the variable X-ray emission from the extremely massive star Eta Carinae concentrating on the last X-ray minimum, and briefly consider the possible role of a binary companion star on the observational properties of the system.

  18. The Carina© middle ear implant: surgical and functional outcomes.

    Science.gov (United States)

    Bruschini, Luca; Berrettini, Stefano; Forli, Francesca; Murri, Alessandra; Cuda, Domenico

    2016-11-01

    The Carina© system (Cochlear Ltd, Sydney, Australia) is a totally implantable prosthesis designed to meet the needs of acoustic amplification in adults with moderate-to-severe sensorineural or mixed hearing loss. It mechanically stimulates the ossicles or labyrinthine windows. The object of this study was to update surgical and functional results obtained in a consistent sample of Carina© recipients. The data sheets of 26 patients who underwent Carina© surgery at two ENT units [i.e., ENT Audiology and Phoniatrics Unit of the University Hospital of Pisa (Pisa, Italy) and ENT Unit of "Guglielmo da Saliceto" Hospital of Piacenza (Piacenza, Italy)] were evaluated for the surgical and audiological outcomes. Twenty patients received a unilateral device, whereas six patients were bilaterally implanted (simultaneously in one patient and sequentially in the remaining five patients). The total number of ears implanted in this study was 32. Most implanted patients expressed a high degree of satisfaction with the prosthesis, which highlights the improvement in hearing in different environmental conditions, the cosmetic advantages, and greater freedom in performing common activities in daily living. Audiological examination demonstrated valid functional gain and significant improvement in speech perception in quiet. Based on this experience, the Carina© is a valid alternative to hearing aids. Moreover, a bilateral implantation, even a simultaneous implantation, is a viable option for selected motivated patients because the intervention is generally well tolerated and the surgery time is relatively fast.

  19. Deep wide-field near-infrared survey of the Carina Nebula

    CERN Document Server

    Preibisch, Thomas; Kuderna, Benjamin; Ohlendorf, Henrike; King, Robert R; Hodgkin, Simon; Irwin, Mike; Lewis, James R; McCaughrean, Mark J; Zinnecker, Hans

    2011-01-01

    (abbreviated) We used HAWK-I at the ESO VLT to produce a near-infrared survey of the Carina Nebula that is deep enough to detect the full low-mass stellar population. The results of a recent deep X-ray survey are used to distinguish between young stars in Carina and background contaminants. We find that the ages of the low-mass stars (derived from color-magnitude diagrams of the invidual cluster in the Carina Nebula) agree with previous age estimates for the massive stars. About 3200 of the X-ray selected stars have masses >= 1 Msun; this number is in good agreement with extrapolations of the field IMF based on the number of high-mass stars and shows that there is no deficit of low-mass stars. The near-infrared excess fractions for the stellar populations in Carina are lower than typical for other, less massive clusters of similar age, suggesting a faster timescale of circumstellar disk dispersal than in the more quiescent regions, most likely due to the very high level of massive star feedback. Narrow-band i...

  20. Temperature, salinity, nutrients, carbon, and other profile data collected worldwide as part of the CARINA project (NODC Accession 0057766)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The CARINA (CARbon dioxide IN the Atlantic Ocean) data synthesis project is an international collaborative effort of the EU IP CARBOOCEAN, and US partners. It has...

  1. The sub-arcsecond dusty environment of Eta Carinae

    Science.gov (United States)

    Chesneau, O.; Min, M.; Herbst, T.; Waters, L. B. F. M.; Leinert, Ch.; Hillier, D. J.

    2005-09-01

    The core of the nebula surrounding Eta Carinae was observed with the VLT Adaptive Optics system NACO and with the interferometer VLTI/MIDI to spatially and spectrally isolate the warm dusty environment and the central object. Narrow-band images at 3.74 μm and 4.05 μm reveal a butterfly shaped dusty environment close to the central star with unprecedented spatial resolution. Fringes have been obtained in the Mid-IR and a correlated flux of about 100 Jy situated 0.3 arcsec south-east from the photocenter of the nebula at 8.7 μm is detected. This flux is partly attributed to the central object and provides an upper limit for the SED of the central source from 3.8 μm to 13.5 μm. We have been able to spectrally disperse the signal from the nebula itself at PA=318 degree, i.e. in the direction of the bipolar nebula (˜310°) within the MIDI field of view of 3 arcsec. A large amount of corundum (Al2O3) is discovered, peaking at 0.6-1.2 arcsec south-east from the star, whereas the dust content of the Weigelt blobs, in the equatorial plane, is dominated by silicates. We propose a geometry for the Butterfly nebulae assuming a similar axis for the large and little Homunculus. We suggest that the Butterfly nebulae is a consequence of the 1890 outburst and is embedded in the Little Homonculus its geometry is, mostly shaped by the local dust formation conditions which are directly affected by the latitudinal dependance of the ejection and the present wind. The dust is mostly formed in the bright rims of the Butterfly nebula. The dust condenses closer to the poles of the star owing to the larger mass-loss rate and the relative velocity between the stellar wind and the ejecta at these latitudes. In this geometry, the bright southern clump directly sees the southern pole of the central object. At intermediate latitudes, the mass-loss rate and the relative velocity of the wind are decreased and dust forms further out. We suggest that the survival and the large mass of the

  2. NUCLEOSYNTHESIS AND THE INHOMOGENEOUS CHEMICAL EVOLUTION OF THE CARINA DWARF GALAXY

    Energy Technology Data Exchange (ETDEWEB)

    Venn, Kim A.; Divell, Mike [Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 1A1 (Canada); Shetrone, Matthew D. [McDonald Observatory, University of Texas at Austin, HC75 Box 1337-McD, Fort Davis, TX 79734 (United States); Irwin, Mike J. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB03 0HA (United Kingdom); Hill, Vanessa [Laboratoire Cassiopee UMR 6202, Universite de Nice Sophia-Antipolis, CNRS, Observatoire de la Cote d' Azur (France); Jablonka, Pascale [GEPI, Observatoire de Paris, CNRS UMR 8111, Universite Paris Diderot, F-92125, Meudon, Cedex (France); Tolstoy, Eline; Lemasle, Bertrand; Starkenburg, Else; Helmi, Amina [Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen (Netherlands); Letarte, Bruno [South African Astronomical Observatory, Observatory Road, 7935 Observatory (South Africa); Baldner, Charles [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Battaglia, Giuseppina; Primas, Francesca [European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching (Germany); Kaufer, Andreas, E-mail: kvenn@uvic.ca [European Southern Observatory, Alonso de Cordova 3107, Santiago (Chile)

    2012-06-01

    The detailed abundances of 23 chemical elements in nine bright red giant branch stars in the Carina dwarf spheroidal galaxy are presented based on high-resolution spectra gathered at the Very Large Telescope (VLT) and Magellan telescopes. A spherical model atmospheres analysis is applied using standard methods (local thermodynamic equilibrium and plane-parallel radiative transfer) to spectra ranging from 380 to 680 nm. Stellar parameters are found to be consistent between photometric and spectroscopic analyses, both at moderate and high resolution. The stars in this analysis range in metallicity from -2.9 < [Fe/H] <-1.3, and adopting the ages determined by Lemasle et al., we are able to examine the chemical evolution of Carina's old and intermediate-aged populations. One of the main results from this work is the evidence for inhomogeneous mixing in Carina and therefore for a poor statistical sampling of the supernova contributions when forming stars; a large dispersion in [Mg/Fe] indicates poor mixing in the old population, an offset in the [{alpha}/Fe] ratios between the old and intermediate-aged populations (when examined with previously published results) suggests that the second star formation event occurred in {alpha}-enriched gas, and one star, Car-612, seems to have formed in a pocket enhanced in SN Ia/II products. This latter star provides the first direct link between the formation of stars with enhanced SN Ia/II ratios in dwarf galaxies to those found in the outer Galactic halo (Ivans et al.). Another important result is the potential evidence for SN II driven winds. We show that the very metal-poor stars in Carina have not been enhanced in asymptotic giant branch or SN Ia products, and therefore their very low ratios of [Sr/Ba] suggests the loss of contributions from the early SNe II. Low ratios of [Na/Fe], [Mn/Fe], and [Cr/Fe] in two of these stars support this scenario, with additional evidence from the low [Zn/Fe] upper limit for one star. It is

  3. CO(J=3-2) Observations Toward the Carina Nebula with Aste

    Science.gov (United States)

    Yamaguchi, Nobuyuki; Ezawa, Hajime; Kawabe, Ryohei; Aste Team

    We report the first 12CO (J=3-2) observations toward the Carina nebula obtained with the ASTE telescope. ASTE (Atacama Submillimeter Telescope Experiment) is a project to make submillimeter astronomical observations with a new 10-m submillemter telescope installed at Pampa la Bola (altitude 4800 m) Chile. The Carina nebula is one of the most active regions in our galaxy. Some evidences of ongoing massive star formation have been reported recently in this region. We found some CO clouds probably interacting with ionized fronts in the 12CO (J=3-2) map. A FIR source is situated near a CO peak in the interacting cloud. It suggests that the triggered star formation occured in this region.

  4. Investigating Cepheid $\\ell$ Carinae's Cycle-to-cycle Variations via Contemporaneous Velocimetry and Interferometry

    CERN Document Server

    Anderson, R I; Kervella, P; Breitfelder, J; LeBouquin, J -B; Eyer, L; Gallenne, A; Palaversa, L; Semaan, T; Saesen, S; Mowlavi, N

    2015-01-01

    Baade-Wesselink-type (BW) techniques enable geometric distance measurements of Cepheid variable stars in the Galaxy and the Magellanic clouds. The leading uncertainties involved concern projection factors required to translate observed radial velocities (RVs) to pulsational velocities and recently discovered modulated variability. We carried out an unprecedented observational campaign involving long-baseline interferometry (VLTI/PIONIER) and spectroscopy (Euler/Coralie) to search for modulated variability in the long-period (P $\\sim$ 35.5 d) Cepheid Carinae. We determine highly precise angular diameters from squared visibilities and investigate possible differences between two consecutive maximal diameters, $\\Delta_{\\rm{max}} \\Theta$. We characterize the modulated variability along the line-of-sight using 360 high-precision RVs. Here we report tentative evidence for modulated angular variability and confirm cycle-to-cycle differences of $\\ell$ Carinae's RV variability. Two successive maxima yield $\\Delta_{\\rm...

  5. 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.

  6. On the He burning phases of the Carina dSph

    CERN Document Server

    Fabrizio, M; Bono, G; Stetson, P B; Walker, A R; Buonanno, R; Cassisi, S; Ferraro, I; Iannicola, G; Monelli, M; Nonino, M; Pulone, L; Thevénin, F

    2013-01-01

    We performed a detailed comparison between predicted He burning phases and multiband photometry of the Carina dwarf spheroidal galaxy. We found a good agreement with the predictions computed assuming an {\\alpha}-enhanced chemical mixture, indicating a mean metallicity [Fe/H] ~ -1.8 with a raw observed peak-to-peak spread in iron abundance of 0.4\\pm0.2 dex.

  7. A 205 μm [N II] Map of the Carina Nebula

    Science.gov (United States)

    Oberst, T. E.; Parshley, S. C.; Nikola, T.; Stacey, G. J.; Löhr, A.; Lane, A. P.; Stark, A. A.; Kamenetzky, J.

    2011-10-01

    We present the results of a ~250 arcmin2 mapping of the 205 μm [N II] fine-structure emission over the northern Carina Nebula, including the Car I and Car II H II regions. Spectra were obtained using the South Pole Imaging Fabry-Perot Interferometer (SPIFI) at the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) at the South Pole. We supplement the 205 μm data with new reductions of far-IR fine-structure spectra from the Infrared Space Observatory (ISO) Long Wavelength Spectrometer (LWS) in 63 μm [O I], 122 μm [N II], 146 μm [O I], and 158 μm [C II]; the 146 μm [O I] data include 90 raster positions which have not been previously published. Morphological comparisons are made with optical, radio continuum, and CO maps. The 122/205 line ratio is used to probe the density of the low-ionization gas, and the 158/205 line ratio is used to probe the fraction of C+ arising from photodissociation regions (PDRs). The [O I] and [C II] lines are used to construct a PDR model of Carina. When the PDR properties are compared with other sources, Carina is found to be more akin to 30 Doradus than galactic star-forming regions such as Orion, M17, or W49; this is consistent with the view of Carina as a more evolved region, where much of the parent molecular cloud has been ionized or swept away. These data constitute the first ground-based detection of the 205 μm [N II] line, and the third detection overall since those of COBE FIRAS and the Kuiper Airborne Observatory in the early 1990s.

  8. A Comprehensive, Wide-Field Study of Pulsating Stars in the Carina Dwarf Spheroidal Galaxy

    OpenAIRE

    Vivas, A. Katherina; Mateo, Mario

    2013-01-01

    We report the detection of 388 pulsating variable stars (and some additional miscellaneous variables) in the Carina dSph galaxy over an area covering the full visible extent of the galaxy and extending a few times beyond its photometric (King) tidal radius along the direction of its major axis. Included in this total are 340 newly discovered dwarf Cepheids which are mostly located ~2.5 magnitudes below the horizontal branch and have very short periods (

  9. A Comprehensive, Wide-Field Study of Pulsating Stars in the Carina Dwarf Spheroidal Galaxy

    CERN Document Server

    Vivas, A Katherina

    2013-01-01

    We report the detection of 388 pulsating variable stars (and some additional miscellaneous variables) in the Carina dSph galaxy over an area covering the full visible extent of the galaxy and extending a few times beyond its photometric (King) tidal radius along the direction of its major axis. Included in this total are 340 newly discovered dwarf Cepheids which are mostly located ~2.5 magnitudes below the horizontal branch and have very short periods (<0.1 days) typical of their class and consistent with their location on the upper part of the extended main sequence of the younger populations of the galaxy. Several extra-tidal dwarf cepheids were found in our survey up to a distance of ~1 degree from the center of Carina. Our sample also includes RR Lyrae stars and anomalous Cepheids some of which were found outside the galaxy's tidal radius as well. This supports past works that suggests Carina is undergoing tidal disruption. We use the period-luminosity relationship for dwarf Cepheids to estimate a dist...

  10. Stellar populations in the Carina region: The Galactic plane at l = 291

    CERN Document Server

    Molina-Lera, J A; Gamen, R; Costa, E; Carraro, G

    2016-01-01

    Previous studies of the Carina region have revealed its complexity and richness as well as a significant number of early-type stars. In many cases, these studies only concentrated on the central region or were not homogeneous. This latter aspect, in particular, is crucial because very different ages and distances for key clusters have been claimed in recent years. The aim of this work is to study in detail an area of the Galactic plane in Carina. We analyze the properties of different stellar populations and focus on a sample of open clusters and their population of YSOs and highly reddened early stars. We also studied the stellar mass distribution in these clusters and the possible scenario of their formation. Finally, we outline the Galactic spiral structure in this direction. We obtained photometric data for six young open clusters located in Carina at l = 291, and their adjacent stellar fields, which we complemented with spectroscopic observations of a few selected targets. We also culled additional infor...

  11. Was the nineteenth century giant eruption of Eta Carinae a merger event in a triple system?

    CERN Document Server

    Zwart, Simon Portegies

    2015-01-01

    We discuss the events that led to the giant eruption of Eta Carinae, and find that the mid-nineteenth century (in 1838-1843) giant mass-loss outburst has the characteristics of being produced by the merger event of a massive close binary, triggered by the gravitational interaction with a massive third companion star, which is the current binary companion in the Eta Carinae system. We come to this conclusion by a combination of theoretical arguments supported by computer simulations using the Astrophysical Multipurpose Software Environment. According to this model the $\\sim 90$\\,\\MSun\\, present primary star of the highly eccentric Eta Carinae binary system is the product of this merger, and its $\\sim 30$\\,\\MSun\\, companion originally was the third star in the system. In our model the Homunculus nebula was produced by an extremely enhanced stellar wind, energized by tidal energy dissipation prior to the merger, which enormously boosted the radiation-driven wind mass-loss. The current orbital plane is then align...

  12. XMM-Newton Observations of the 2003 X-ray Minimum of Eta Carinae

    CERN Document Server

    Hamaguchi, K; Gull, T R; White, N E; Damineli, A; Davidson, K

    2004-01-01

    The XMM-Newton X-ray observatory took part in the multi-wavelength observing campaign of the massive, evolved star Eta Carinae in 2003 during its recent X-ray minimum. This paper reports on the results of these observations, mainly from the aspect of spectral change. Hard X-ray emission from the point source of Eta Carinae was detected even during the minimum. During the minimum the observed flux above 3 keV was ~3e-12 ergs cm-2 s-1, which is about one percent of the flux before the minimum. Changes in the spectral shape revealed two X-ray emission components in the central point source. One component is non-variable and has relatively cool plasma of kT~1 keV and moderate absorption, NH~5e22 cm-2. The plasma is probably located far from the star, possibly produced by the high speed polar wind from Eta Carinae. The other high temperature component has kT~5 keV and is strongly variable. This component shows an increase in the apparent column density from 5e22 cm-2 to 2e23 cm-2, probably originating near the hea...

  13. Carina® and Esteem®: a systematic review of fully implantable hearing devices.

    Directory of Open Access Journals (Sweden)

    Janaina Oliveira Bentivi Pulcherio

    Full Text Available To review the outcomes of the fully implantable middle ear devices Carina and Esteem regarding the treatment of hearing loss.PubMed, Embase, Scielo, and Cochrane Library databases were searched.Abstracts of 77 citations were screened, and 43 articles were selected for full review. From those, 22 studies and two literature reviews in English directly demonstrating the results of Carina and Esteem were included.There were a total of 244 patients ranging from 18 to 88 years. One hundred and 10 patients were implanted with Carina and with 134 Esteem. There were registered 92 males and 67 females. Five studies provided no information about patients' age or gender. From the data available, the follow-up ranged from 2 to 29.4 months.The comparison of the results about word recognition is difficult as there was no standardization of measurement. The results were obtained from various sound intensities and different frequencies. The outcomes comparing to conventional HAs were conflicting. Nevertheless, all results comparing to unaided condition showed improvement and showed a subjective improvement of quality of life.There are still some problems to be solved, mainly related to device functioning and price. Due to the relatively few publications available and small sample sizes, we must be careful in extrapolating these results to a broader population. Additionally, none of all these studies represented level high levels of evidence (i.e. randomized controlled trials.

  14. Stellar populations in the Carina region. The Galactic plane at l = 291°

    Science.gov (United States)

    Molina-Lera, J. A.; Baume, G.; Gamen, R.; Costa, E.; Carraro, G.

    2016-08-01

    Context. Previous studies of the Carina region have revealed its complexity and richness as well as a significant number of early-type stars. However, in many cases, these studies only concentrated on the central region (Trumpler 14/16) or were not homogeneous. This latter aspect, in particular, is crucial because very different ages and distances for key clusters have been claimed in recent years. Aims: The aim of this work is to study in detail an area of the Galactic plane in Carina, eastward η Carina. We analyze the properties of different stellar populations and focus on a sample of open clusters and their population of young stellar objects and highly reddened early stars. We also studied the stellar mass distribution in these clusters and the possible scenario of their formation. Finally, we outline the Galactic spiral structure in this direction. Methods: We obtained deep and homogeneous photometric data (UBVIKC) for six young open clusters: NGC 3752, Trumpler 18, NGC 3590, Hogg 10, 11, and 12, located in Carina at l ~ 291°, and their adjacent stellar fields, which we complemented with spectroscopic observations of a few selected targets. We also culled additional information from the literature, which includes stellar spectral classifications and near-infrared photometry from 2MASS. We finally developed a numerical code that allowed us to perform a homogeneous and systematic analysis of the data. Our results provide more reliable estimates of distances, color excesses, masses, and ages of the stellar populations in this direction. Results: We estimate the basic parameters of the studied clusters and find that they identify two overdensities of young stellar populations located at about 1.8 kpc and 2.8 kpc, with EB - V ~ 0.1 - 0.6. We find evidence of pre-main-sequence populations inside them, with an apparent coeval stellar formation in the most conspicuous clusters. We also discuss apparent age and distance gradients in the direction NW-SE. We study the

  15. Assessing the internal consistency of the CARINA database in the Indian sector of the Southern Ocean

    Directory of Open Access Journals (Sweden)

    C. Lo Monaco

    2010-02-01

    Full Text Available Carbon and carbon-relevant hydrographic and hydrochemical ancillary data from previously not publicly available cruises were retrieved and recently merged to a new data base, CARINA (CARbon IN the Atlantic. The initial North Atlantic project, an international effort for ocean carbon synthesis, was extended to include the Arctic Mediterranean Seas (Arctic Ocean and Nordic Seas and all three sectors of the Southern Ocean. Of a total of 188 cruises, 37 cruises are part of the Southern Ocean. The present work focuses on data collected in the Indian sector (20° S–70° S; 30° E–150° E. The Southern Indian Ocean dataset covers the period 1992–2004 and includes seasonal repeated observations. Parameters including salinity, dissolved inorganic carbon (TCO2, total alkalinity (TA, oxygen, nitrate, phosphate and silicate were examined for cruise-to-cruise and overall consistency. In addition, data from an existing, quality controlled data base (GLODAP were introduced in the CARINA analysis to improve data coverage in the Southern Ocean. A global inversion was performed to synthesize the information deduced from objective comparisons of deep measurements (>1500 m at nearby stations (generally <220 km. The corrections suggested by the inversion were allowed to vary within a fixed envelope, thus accounting for ocean interior variability. The adjustments applied to CARINA data and those recommended for GLODAP data, in order to obtain a consistent merged dataset, are presented and discussed. The final outcome of this effort is a new quality controlled data base for TCO2 and other properties of the carbon system that can now be used to investigate the natural variability or stability of ocean chemistry and the accumulation of anthropogenic carbon. This data product also offers an important new synthesis of seasonal to decadal observations to validate ocean biogeochemical models in a region where available historical data were very

  16. Changes in the distance between carina and orotracheal tube during open or videolaparoscopic bariatric surgery

    Directory of Open Access Journals (Sweden)

    Giovani de Figueiredo Locks

    2015-10-01

    Full Text Available ABSTRACTOBJECTIVE: To examine whether there are changes in the distance between the orotracheal tube and carina induced by orthostatic retractor placement or by pneumoperitoneum insufflation in obese patients undergoing gastroplasty.METHODS: 60 patients undergoing bariatric surgery by two techniques: open (G1 or videolaparoscopic (G2 gastroplasty were studied. After tracheal intubation, adequate ventilation of both hemitoraxes was confirmed by lung auscultation. The distance orotracheal tube-carina was estimated with the use of a fiber bronchoscope before and after installation of orthostatic retractors in G1 or before and after insufflation of pneumoperitoneum in patients in G2.RESULTS: G1 was composed of 22 and G2 of 38 patients. No cases of endobronchial intubation were detected in either group. The mean orotracheal tube-carina distance variation was estimated in -0.03 cm (95% CI 0.06 to -0.13 in the group of patients undergoing open gastroplasty and in -0.42 cm (95% CI -0.56 to -1.4 in the group of patients undergoing videolaparoscopic gastroplasty. The extremes of variation in each group were: 0.5 cm to -1.6 cm in patients undergoing open surgery and 0.1 cm to -2.2 cm in patients undergoing videolaparoscopic surgery.CONCLUSIONS: There was no significant change in orotracheal tube-CA distance after placement of orthostatic retractors in patients undergoing open gastroplasty. There was a reduction in orotracheal tube-CA distance after insufflation of pneumoperitoneum in patients undergoing videolaparoscopic gastroplasty. We recommend attention to lung auscultation and to signals of ventilation monitoring and reevaluation of orotracheal tube placement after peritoneal insufflation.

  17. Assessing the internal consistency of the CARINA database in the Indian sector of the Southern Ocean

    Science.gov (United States)

    Lo Monaco, C.; Álvarez, M.; Key, R. M.; Lin, X.; Tanhua, T.; Tilbrook, B.; Bakker, D. C. E.; van Heuven, S.; Hoppema, M.; Metzl, N.; Ríos, A. F.; Sabine, C. L.; Velo, A.

    2010-02-01

    Carbon and carbon-relevant hydrographic and hydrochemical ancillary data from previously not publicly available cruises were retrieved and recently merged to a new data base, CARINA (CARbon IN the Atlantic). The initial North Atlantic project, an international effort for ocean carbon synthesis, was extended to include the Arctic Mediterranean Seas (Arctic Ocean and Nordic Seas) and all three sectors of the Southern Ocean. Of a total of 188 cruises, 37 cruises are part of the Southern Ocean. The present work focuses on data collected in the Indian sector (20° S-70° S; 30° E-150° E). The Southern Indian Ocean dataset covers the period 1992-2004 and includes seasonal repeated observations. Parameters including salinity, dissolved inorganic carbon (TCO2), total alkalinity (TA), oxygen, nitrate, phosphate and silicate were examined for cruise-to-cruise and overall consistency. In addition, data from an existing, quality controlled data base (GLODAP) were introduced in the CARINA analysis to improve data coverage in the Southern Ocean. A global inversion was performed to synthesize the information deduced from objective comparisons of deep measurements (>1500 m) at nearby stations (generally accounting for ocean interior variability. The adjustments applied to CARINA data and those recommended for GLODAP data, in order to obtain a consistent merged dataset, are presented and discussed. The final outcome of this effort is a new quality controlled data base for TCO2 and other properties of the carbon system that can now be used to investigate the natural variability or stability of ocean chemistry and the accumulation of anthropogenic carbon. This data product also offers an important new synthesis of seasonal to decadal observations to validate ocean biogeochemical models in a region where available historical data were very sparse.

  18. VizieR Online Data Catalog: UBVI CCD photometry of Carina region stars (Molina-Lera+, 2016)

    Science.gov (United States)

    Molina-Lera, J. A.; Baume, G.; Gamen, R.; Costa, E.; Carraro, G.

    2016-08-01

    Photometric parameters for 62730 stars in the carina region covering 6 stellar clusters (NGC 3752, Trumpler 18, NGC 3590, Hogg 10, 11 and 12) and the surrounding field. The photometry was secured in March 2006 and March 2009 with the Y4KCAM camera attached to the Cerro Tololo Inter American Observatory (CTIO, Chile) 1.0-m telescope. (1 data file).

  19. A gigantic X-ray flare from the star Trumpler 14 Y442 in the Carina star forming complex

    Science.gov (United States)

    Hamaguchi, Kenji; Drake, Stephen A.; Corcoran, Michael F.; Richardson, Noel; Teodoro, Mairan

    2015-09-01

    XMM-Newton, NuSTAR and Swift observations of the Carina star forming complex on 2015 July 16 (ObsID - XMM:0762910401, NuSTAR:30101005002, Swift:00081578001) detected an X-ray flare at the coordinates (R.A., Dec)[J2000] = (10 44 02.80, -59 39 46.7).

  20. Inclusion of horizontal branch stars in the derivation of star formation histories of dwarf galaxies: The Carina dSph

    NARCIS (Netherlands)

    Savino, Alessandro; Salaris, Maurizio; Tolstoy, Eline

    2015-01-01

    We present a detailed analysis of the horizontal branch of the Carina dwarf spheroidal galaxy by means of synthetic modelling techniques, taking consistently into account the star formation history and metallicity evolution as determined from main sequence and red giant branch spectroscopic

  1. VLT/FLAMES spectroscopy of Red Giant Branch stars in the Carina dwarf spheroidal galaxy

    CERN Document Server

    Lemasle, B; Tolstoy, E; Venn, K A; Shetrone, M D; Irwin, M J; de Boer, T J L; Starkenburg, E; Salvadori, S

    2011-01-01

    The ages of individual Red Giant Branch stars (RGB) can range from 1 Gyr old to the age of the Universe, and it is believed that the abundances of most chemical elements in their photospheres remain unchanged with time (those that are not affected by the 1st dredge-up). This means that they trace the ISM in the galaxy at the time the star formed, and hence the chemical enrichment history of the galaxy. CMD analysis has shown the Carina dwarf spheroidal (dSph) to have had an unusually episodic star formation history (SFH) which is expected to be reflected in the abundances of different chemical elements. We use the VLT-FLAMES spectrograph in HR mode (R~20000) to measure the abundances of several chemical elements in a sample of 35 RGB stars in Carina. We also combine these abundances with photometry to derive age estimates for these stars. This allows us to determine which of two distinct star formation (SF) episodes the stars in our sample belong to, and thus to define the relationship between SF and chemical...

  2. Resolving the Hα-emitting Region in the Wind of η Carinae

    Science.gov (United States)

    Wu, Ya-Lin; Smith, Nathan; Close, Laird M.; Males, Jared R.; Morzinski, Katie M.

    2017-05-01

    The massive evolved star η Carinae is the most luminous star in the Milky Way and has the highest steady wind mass-loss rate of any known star. Radiative transfer models of the spectrum by Hillier et al. predict that Hα is mostly emitted in regions of the wind at radii of 6-60 au from the star (2.5-25 mas at 2.35 kpc). We present diffraction-limited images (FWHM ˜ 25 mas) with Magellan adaptive optics in two epochs, showing that η Carinae consistently appears ˜2.5-3 mas wider in Hα emission compared to the adjacent 643 nm continuum. This implies that the Hα line-forming region may have a characteristic emitting radius of 12 mas or ˜30 au, in very good agreement with the Hillier stellar-wind model. This provides direct confirmation that the physical wind parameters of that model are roughly correct, including the mass-loss rate of \\dot{M}={10}-3 {M}⊙ {{yr}}-1, plus the clumping factor, and the terminal velocity. Comparison of the Hα images (ellipticity and PA) to the continuum images reveals no significant asymmetries at Hα. Hence, any asymmetry induced by a companion or by the primary’s rotation do not strongly influence the global Hα emission in the outer wind.

  3. A Survey of Irradiated Pillars, Globules, and Jets in the Carina Nebul

    CERN Document Server

    Hartigan, P; Smith, N; Bally, J

    2015-01-01

    We present wide-field, deep narrowband H$_2$, Br$\\gamma$, H$\\alpha$, [S II], [O III], and broadband I and K-band images of the Carina star formation region. The new images provide a large-scale overview of all the H$_2$ and Br$\\gamma$ emission present in over a square degree centered on this signature star forming complex. By comparing these images with archival HST and Spitzer images we observe how intense UV radiation from O and B stars affects star formation in molecular clouds. We use the images to locate new candidate outflows and identify the principal shock waves and irradiated interfaces within dozens of distinct areas of star-forming activity. Shocked molecular gas in jets traces the parts of the flow that are most shielded from the intense UV radiation. Combining the H$_2$ and optical images gives a more complete view of the jets, which are sometimes only visible in H$_2$. The Carina region hosts several compact young clusters, and the gas within these clusters is affected by radiation from both the...

  4. Interaction of planetary nebulae, Eta-Carinae and supernova remnants with the Interstellar Medium

    CERN Document Server

    Zaninetti, L

    2012-01-01

    The image of planetary nebulae (PN), supernova remnant (SNR) and Eta-Carinae is made by three different physical processes. The first process is the expansion of the shell that can be modeled by the canonical laws of motion in the spherical case and by the momentum conservation when gradients of density are present in the interstellar medium. The quality of the simulations is introduced along one direction as well along many directions. The second process is the diffusion of particles that radiate from the advancing layer. The 3D diffusion from a sphere, the 1D diffusion with drift and 1D random walk are analyzed. The third process is the composition of the image through an integral operation along the line of sight. The developed framework is applied to three PN which are A39, the Ring nebula and the etched hourglass nebula MyCn 18, the hybrid object Eta-Carinae, and to two SNR which are SN 1993J and SN 1006. In all the considered cases a careful comparison between the observed and theoretical profiles in in...

  5. Eta Carinae: A Box of Puzzles...Some Solved, Others Await

    Science.gov (United States)

    Gull, Theodore

    2010-01-01

    In the l840's, Eta Carinae brightened to rival Sirius, then faded. Today we see a marginally naked-eye binary with an expanding, very dusty bipolar Homunculus. The energetics of the ejected mass (>l2 to 40 solar masses at 500-700 km/s plus outer bullets/strings up to 3000 km/s} approach that of a supernova. Extragalactic SN surveys detect near-supernovae thought to be like the Great Eruption of the 1840's. Eta Carinae presents an abundance of puzzles: rich in N, but 1/100th the solar C and O abundances; Ti, V, Sr, Sc persist in atomic states.... yet an abundance of molecules and dust exists in the Homunculus. How did molecules and dust form with low C and O? A near supernova occurred in the l840m, yet both binary companions, with total mass > 120 solar masses, survive in a very eccentric orbit. What is the near future of this system: a GRB? a SN? or just two WR stars that ultimately become two SNs? These and other puzzles will be presented

  6. The Carina Project. X. On the kinematics of old and intermediate-age stellar populations

    CERN Document Server

    Fabrizio, M; Nonino, M; Lokas, E L; Ferraro, I; Iannicola, G; Buonanno, R; Cassisi, S; Coppola, G; Dall'Ora, M; Gilmozzi, R; Marconi, M; Monelli, M; Romaniello, M; Stetson, P B; Thévenin, F; Walker, A R

    2016-01-01

    We present new radial velocity (RV) measurements of old (horizontal branch) and intermediate-age (red clump) stellar tracers in the Carina dwarf spheroidal. They are based on more than 2,200 low-resolution spectra collected with VIMOS at VLT. The targets are faint (20Carina stars. We found that the intermediate-age stellar component shows a well defined rotational pattern around the minor axis. The western and the eastern side of the galaxy differ by +5 and -4 km s-1 when compared with the main RV peak. The old stellar component is characterized by a larger RV dispersion and does not show evidence of RV pattern. We compared the observed RV distribution with N-body simulations for a former disky dwarf galaxy orbit...

  7. He II 4686 in eta Carinae and the nature of the 5.538-yr cycle

    CERN Document Server

    Teodoro, M; Arias, J I; de Araújo, F X; Barbá, R H; Corcoran, M F; Fernandes, M Borges; Fernández-Lajús, E; Fraga, L; Gamen, R C; González, J F; Groh, J H; Marshall, J L; McGregor, P J; Morrell, N; Nicholls, D C; Parkin, E R; Pereira, C B; Phillips, M M; Solivella, G R; Steiner, J E; Stritzinger, M; Thompson, I; Torres, C A O; Torres, M A P; Zevallos-Herencia, M I

    2011-01-01

    The periodic minima in eta Carinae are now well defined and interpreted as due to periastron passage of two massive stars in a very eccentric orbit. Different mechanisms have been proposed to explain the light curve of different spectral features, such as eclipse, shell ejection, accretion and/or collapse of the primary wind onto the secondary star. All of them face difficulties to explain the observations in the full range of wavelengths. To better understand the nature of cyclic events, we performed a dense monitoring of eta Carinae along the 2009 spectroscopic event, focusing on the high-energy He II 4686 emission line. Our results indicate that the intensity curve of He II 4686 peaks at L~310 L_sun, has a phase-locked behaviour and shows a temporal correlation with the X-ray emission, ruling out many proposed sources of energy. The most suitable location for the He II 4686 emission region is the shocked primary wind, about 4-5 AU downstream from the apex. The 'collapse' component seen in light curves of X...

  8. SECULAR CHANGES IN ETA CARINAE'S WIND 1998-2011

    Energy Technology Data Exchange (ETDEWEB)

    Mehner, Andrea [ESO, Alonso de Cordova 3107, Vitacura, Santiago de Chile (Chile); Davidson, Kris; Humphreys, Roberta M. [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States); Ishibashi, Kazunori [Global COE, Division of Particle Physics and Astrophysics, Nagoya University, Nagoya 464-8602 (Japan); Martin, John C. [Department of Physics and Astronomy, University of Illinois Springfield, Springfield, IL 62703 (United States); Ruiz, Maria Teresa [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago de Chile (Chile); Walter, Frederick M. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States)

    2012-05-20

    Stellar wind-emission features in the spectrum of eta Carinae have decreased by factors of 1.5-3 relative to the continuum within the last 10 years. We investigate a large data set from several instruments (STIS, GMOS, UVES) obtained between 1998 and 2011 and analyze the progression of spectral changes in direct view of the star, in the reflected polar-on spectra at FOS4, and at the Weigelt knots. We find that the spectral changes occurred gradually on a timescale of about 10 years and that they are dependent on the viewing angle. The line strengths declined most in our direct view of the star. About a decade ago, broad stellar wind-emission features were much stronger in our line-of-sight view of the star than at FOS4. After the 2009 event, the wind-emission line strengths are now very similar at both locations. High-excitation He I and N II absorption lines in direct view of the star strengthened gradually. The terminal velocity of Balmer P Cyg absorption lines now appears to be less latitude dependent, and the absorption strength may have weakened at FOS4. Latitude-dependent alterations in the mass-loss rate and the ionization structure of eta Carinae's wind are likely explanations for the observed spectral changes.

  9. A deep wide-field sub-mm survey of the Carina Nebula complex

    CERN Document Server

    Preibisch, Thomas; Ohlendorf, Henrike; Pekruhl, Stephanie; Menten, Karl M; Zinnecker, Hans

    2010-01-01

    The Great Nebula in Carina is a superb location in which to study the physics of violent massive star-formation and the resulting feedback effects, including cloud dispersal and triggered star-formation. In order to reveal the cold dusty clouds in the Carina Nebula complex, we used the Large APEX Bolometer Camera LABOCA at the APEX telescope to map a 1.25 deg x 1.25 deg (= 50 x 50 pc^2) region at 870 micrometer. From a comparison to Halpha images we infer that about 6% of the 870 micrometer flux in the observed area is likely free-free emission from the HII region, while about 94% of the flux is very likely thermal dust emission. The total (dust + gas) mass of all clouds for which our map is sensitive is ~ 60 000 Msun, in good agreement with the mass of the compact clouds in this region derived from 13CO line observations. We generally find good agreement in the cloud morphology seen at 870 micrometer and the Spitzer 8 micrometer emission maps, but also identify a prominent infrared dark cloud. Finally, we co...

  10. Jet-driving protostars identified from infrared observations of the Carina Nebula complex

    CERN Document Server

    Ohlendorf, Henrike; Gaczkowski, Benjamin; Ratzka, Thorsten; Grellmann, Rebekka; McLeod, Anna F

    2012-01-01

    Aims: Jets are excellent signposts for very young embedded protostars, so we want to identify jet-driving protostars as a tracer of the currently forming generation of stars in the Carina Nebula, which is one of the most massive galactic star-forming regions and which is characterised by particularly high levels of massive-star feedback on the surrounding clouds. Methods: We used archive data to construct large (> 2 deg x 2 deg) Spitzer IRAC mosaics of the Carina Nebula and performed a spatially complete search for objects with excesses in the 4.5 micron band, typical of shock-excited molecular hydrogen emission. We also identified the mid-infrared point sources that are the likely drivers of previously discovered Herbig-Haro jets and molecular hydrogen emission line objects. We combined the Spitzer photometry with our recent Herschel far-infrared data to construct the spectral energy distributions, and used the Robitaille radiative-transfer modelling tool to infer the properties of the objects. Results: The ...

  11. The UV Scattering Halo of the Central Source Associated with Eta Carinae

    CERN Document Server

    Hillier, D J; Damineli, A; Gull, T R; Hamann, F W; Iping, R; Martin, J C; Nielsen, K; Smith, N; Sonneborn, G; Weis, K; Smith, Nathan

    2006-01-01

    We have made an extensive study of the UV spectrum of Eta Carinae, and find that we do not directly observe the star and its wind in the UV. Because of dust along our line of sight, the UV light that we observe arises from bound-bound scattering at large impact parameters. We obtain a reasonable fit to the UV spectrum by using only the flux that originates outside 0.033". This explains why we can still observe the primary star in the UV despite the large optical extinction -- it is due to the presence of an intrinsic coronagraph in the Eta Carinae system, and to the extension of the UV emitting region. It is not due to peculiar dust properties alone. We have computed the spectrum of the purported companion star, and show that it could only be directly detected in the UV spectrum preferentially in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectral region (912-1175 Ang.). However, we find no direct evidence for a companion star, with the properties indicated by X-ray studies and studies of the Weigelt b...

  12. X-ray Spectral Variation of Eta Carinae through the 2003 X-ray Minimum

    CERN Document Server

    Hamaguchi, K; Gull, T; Ishibashi, K; Pittard, J M; Hillier, D J; Damineli, A; Davidson, K; Nielsen, K E; Kober, G V; Hamaguchi, Kenji; Corcoran, Michael F.; Gull, Theodore; Ishibashi, Kazunori; Pittard, Julian M.; Damineli, Augusto; Davidson, Kris; Nielsen, Krister E.; Kober, Gladys Vieira

    2007-01-01

    We report the results of an X-ray observing campaign on the massive, evolved star Eta Carinae, concentrating on the 2003 X-ray minimum as seen by the XMM-Newton observatory. These are the first spatially-resolved X-ray monitoring observations of the stellar X-ray spectrum during the minimum. The hard X-ray emission, believed to be associated with the collision of Eta Carinae's wind with the wind from a massive companion star, varied strongly in flux on timescales of days, but not significantly on timescales of hours. The lowest X-ray flux in the 2-10 keV band seen by XMM-Newton was only 0.7% of the maximum seen by RXTE just before the X-ray minimum. The slope of the X-ray continuum above 5 keV did not vary in any observation, which suggests that the electron temperature of the hottest plasma associated with the stellar source did not vary significantly at any phase. Through the minimum, the absorption to the stellar source increased by a factor of 5-10 to NH ~3-4E23 cm-2. The thermal Fe XXV emission line show...

  13. 3D Printing Meets Computational Astrophysics: Deciphering the Structure of Eta Carinae's Inner Colliding Winds

    CERN Document Server

    Madura, Thomas I; Gull, Theodore R; Kruip, Chael J H; Paardekooper, Jan-Pieter

    2015-01-01

    We present the first 3D prints of output from a supercomputer simulation of a complex astrophysical system, the colliding stellar winds in the massive (>120 M_Sun), highly eccentric (e ~ 0.9) binary star system Eta Carinae. We demonstrate the methodology used to incorporate 3D interactive figures into a PDF journal publication and the benefits of using 3D visualization and 3D printing as tools to analyze data from multidimensional numerical simulations. Using a consumer-grade 3D printer (MakerBot Replicator 2X), we successfully printed 3D smoothed particle hydrodynamics (SPH) simulations of Eta Carinae's inner (r ~ 110 au) wind-wind collision interface at multiple orbital phases. The 3D prints and visualizations reveal important, previously unknown 'finger-like' structures at orbital phases shortly after periastron (phi ~ 1.045) that protrude radially outward from the spiral wind-wind collision region. We speculate that these fingers are related to instabilities (e.g. thin-shell, Rayleigh-Taylor) that arise a...

  14. Extended Red Objects and Stellar Wind Bow Shocks in the Carina Nebula

    CERN Document Server

    Sexton, Remington O; Smith, Nathan; Babler, Brian L; Meade, Marilyn R; Rudolph, Alexander L

    2014-01-01

    We report the results of infrared photometry on 39 extended red objects (EROs) in the Carina Nebula, observed with the Spitzer Space Telescope. Most EROs are identified by bright, extended 8.0 um emission, which ranges from 10'' to 40'' in size, but our sample also includes 4 EROs identified by extended 24 um emission. Of particular interest are nine EROs associated with late O or early B-type stars and characterized by arc-shaped morphology, suggesting dusty, stellar-wind bow shocks. These objects are preferentially oriented towards the central regions of the Carina Nebula, suggesting that these bow shocks are generally produced by the interactions of OB winds with the bulk expansion of the H II region rather than high proper motion. We identify preferred regions of mid-infrared color space occupied by our bow shock candidates, which also contain bow shock candidates in M17 and RCW 49 but are well-separated from polycyclic aromatic hydrocarbon emission or circumstellar discs. Color cuts identify an additiona...

  15. Eclipse and Collapse of the Colliding Wind X-ray Emission from Eta Carinae

    Science.gov (United States)

    Hamaguchi, Kenji; Corcoran, Michael F.

    2012-01-01

    X-ray emission from the massive stellar binary system, Eta Carinae, drops strongly around periastron passage; the event is called the X-ray minimum. We launched a focused observing campaign in early 2009 to understand the mechanism of causing the X-ray minimum. During the campaign, hard X-ray emission (<10 keV) from Eta Carinae declined as in the previous minimum, though it recovered a month earlier. Extremely hard X-ray emission between 15-25 keV, closely monitored for the first time with the Suzaku HXD/PIN, decreased similarly to the hard X-rays, but it reached minimum only after hard X-ray emission from the star had already began to recover. This indicates that the X-ray minimum is produced by two composite mechanisms: the thick primary wind first obscured the hard, 2-10 keV thermal X-ray emission from the wind-wind collision (WWC) plasma; the WWC activity then decays as the two stars reach periastron.

  16. Suzaku Observation of Diffuse X-ray Emission from the Carina Nebula

    CERN Document Server

    Hamaguchi, K; Matsumoto, H; Tsujimoto, M; Holt, S S; Ezoe, Y; Ozawa, H; Tsuboi, Y; Soong, Y; Kitamoto, S; Sekiguchi, A; Kokubun, M; Hamaguchi, Kenji; Petre, Robert; Matsumoto, Hironori; Tsujimoto, Masahiro; Holt, Stephan S.; Ezoe, Yuichiro; Ozawa, Hideki; Tsuboi, Yohko; Soong, Yang; Kitamoto, Shunji; Sekiguchi, Akiko; Kokubun, Motohide

    2006-01-01

    We studied extended X-ray emission from the Carina Nebula taken with the Suzaku CCD camera XIS on 2005 Aug. 29. The X-ray morphology, plasma temperature and absorption to the plasma are consistent with the earlier Einstein results. The Suzaku spectra newly revealed emission lines from various species including oxygen, but not from nitrogen. This result restricts the N/O ratio significantly low, compared with evolved massive stellar winds, suggesting that the diffuse emission is originated in an old supernova remnant or a super shell produced by multiple supernova remnants. The X-ray spectra from the north and south of Eta Carinae showed distinct differences between 0.3-2 keV. The south spectrum shows strong L-shell lines of iron ions and K-shell lines of silicon ions, while the north spectrum shows them weak in intensity. This means that silicon and iron abundances are a factor of 2-4 higher in the south region than in the north region. The abundance variation may be produced by an SNR ejecta, or relate to th...

  17. Gaia-ESO Survey: Gas dynamics in the Carina Nebula through optical emission lines

    CERN Document Server

    Damiani, F; Magrini, L; Prisinzano, L; Mapelli, M; Micela, G; Kalari, V; Apellaniz, J Maiz; Gilmore, G; Randich, S; Alfaro, E; Flaccomio, E; Koposov, S; Klutsch, A; Lanzafame, A C; Pancino, E; Sacco, G G; Bayo, A; Carraro, G; Casey, A R; Costado, M T; Franciosini, E; Hourihane, A; Lardo, C; Lewis, J; Monaco, L; Morbidelli, L; Worley, C; Zaggia, S; Zwitter, T; Dorda, R

    2016-01-01

    We present observations from the Gaia-ESO Survey in the lines of H$\\alpha$, [N II], [S II] and He I of nebular emission in the central part of the Carina Nebula. We investigate the properties of the two already known kinematic components (approaching and receding, respectively), which account for the bulk of emission. Moreover, we investigate the features of the much less known low-intensity high-velocity (absolute RV $>$50 km/s) gas emission. We show that gas giving rise to H$\\alpha$ and He I emission is dynamically well correlated, but not identical, to gas seen through forbidden-line emission. Gas temperatures are derived from line-width ratios, and densities from [S II] doublet ratios. The spatial variation of N ionization is also studied, and found to differ between the approaching and receding components. The main result is that the bulk of the emission lines in the central part of Carina arises from several distinct shell-like expanding regions, the most evident found around $\\eta$ Car, the Trumpler 14...

  18. 3D printing meets computational astrophysics: deciphering the structure of η Carinae's inner colliding winds

    Science.gov (United States)

    Madura, T. I.; Clementel, N.; Gull, T. R.; Kruip, C. J. H.; Paardekooper, J.-P.

    2015-06-01

    We present the first 3D prints of output from a supercomputer simulation of a complex astrophysical system, the colliding stellar winds in the massive (≳120 M⊙), highly eccentric (e ˜ 0.9) binary star system η Carinae. We demonstrate the methodology used to incorporate 3D interactive figures into a PDF (Portable Document Format) journal publication and the benefits of using 3D visualization and 3D printing as tools to analyse data from multidimensional numerical simulations. Using a consumer-grade 3D printer (MakerBot Replicator 2X), we successfully printed 3D smoothed particle hydrodynamics simulations of η Carinae's inner (r ˜ 110 au) wind-wind collision interface at multiple orbital phases. The 3D prints and visualizations reveal important, previously unknown `finger-like' structures at orbital phases shortly after periastron (φ ˜ 1.045) that protrude radially outwards from the spiral wind-wind collision region. We speculate that these fingers are related to instabilities (e.g. thin-shell, Rayleigh-Taylor) that arise at the interface between the radiatively cooled layer of dense post-shock primary-star wind and the fast (3000 km s-1), adiabatic post-shock companion-star wind. The success of our work and easy identification of previously unrecognized physical features highlight the important role 3D printing and interactive graphics can play in the visualization and understanding of complex 3D time-dependent numerical simulations of astrophysical phenomena.

  19. Diffuse X-ray Emission from the Carina Nebula Observed with Suzaku

    CERN Document Server

    Hamaguchi, Kenji

    2007-01-01

    A number of giant HII regions are associated with soft diffuse X-ray emission. Among these, the Carina nebula possesses the brightest soft diffuse emission. The required plasma temperature and thermal energy can be produced by collisions or termination of fast winds from main-sequence or embedded young O stars, but the extended emission is often observed from regions apart from massive stellar clusters. The origin of the X-ray emission is unknown. The XIS CCD camera onboard Suzaku has the best spectral resolution for extended soft sources so far, and is therefore capable of measuring key emission lines in the soft band. Suzaku observed the core and the eastern side of the Carina nebula (Car-D1) in 2005 Aug and 2006 June, respectively. Spectra of the south part of the core and Car-D1 similarly showed strong L-shell lines of iron ions and K-shell lines of silicon ions, while in the north of the core these lines were much weaker. Fitting the spectra with an absorbed thin-thermal plasma model showed kT~0.2, 0.6 k...

  20. Gaia-ESO Survey: Global properties of clusters Trumpler 14 and 16 in the Carina nebula ⋆⋆

    Science.gov (United States)

    Damiani, F.; Klutsch, A.; Jeffries, R. D.; Randich, S.; Prisinzano, L.; Maíz Apellániz, J.; Micela, G.; Kalari, V.; Frasca, A.; Zwitter, T.; Bonito, R.; Gilmore, G.; Flaccomio, E.; Francois, P.; Koposov, S.; Lanzafame, A. C.; Sacco, G. G.; Bayo, A.; Carraro, G.; Casey, A. R.; Alfaro, E. J.; Costado, M. T.; Donati, P.; Franciosini, E.; Hourihane, A.; Jofré, P.; Lardo, C.; Lewis, J.; Magrini, L.; Monaco, L.; Morbidelli, L.; Worley, C. C.; Vink, J. S.; Zaggia, S.

    2017-07-01

    Aims: We present the first extensive spectroscopic study of the global population in star clusters Trumpler 16, Trumpler 14, and Collinder 232 in the Carina nebula, using data from the Gaia-ESO Survey, down to solar-mass stars. Methods: In addition to the standard homogeneous survey data reduction, a special processing was applied here because of the bright nebulosity surrounding Carina stars. Results: We find about 400 good candidate members ranging from OB types down to slightly subsolar masses. About 100 heavily reddened early-type Carina members found here were previously unrecognized or poorly classified, including two candidate O stars and several candidate Herbig Ae/Be stars. Their large brightness makes them useful tracers of the obscured Carina population. The spectroscopically derived temperatures for nearly 300 low-mass members enables the inference of individual extinction values and the study of the relative placement of stars along the line of sight. Conclusions: We find a complex spatial structure with definite clustering of low-mass members around the most massive stars and spatially variable extinction. By combining the new data with existing X-ray data, we obtain a more complete picture of the three-dimensional spatial structure of the Carina clusters and of their connection to bright and dark nebulosity and UV sources. The identification of tens of background giants also enables us to determine the total optical depth of the Carina nebula along many sightlines. We are also able to put constraints on the star formation history of the region with Trumpler 14 stars found to be systematically younger than stars in other subclusters. We find a large percentage of fast-rotating stars among Carina solar-mass members, which provide new constraints on the rotational evolution of pre-main-sequence stars in this mass range. Based on observations collected with the FLAMES spectrograph at VLT/UT2 telescope (Paranal Observatory, ESO, Chile), for the Gaia

  1. The canonical Luminous Blue Variable AG Car and its neighbor Hen 3-519 are much closer than previously assumed

    CERN Document Server

    Smith, Nathan

    2016-01-01

    The strong mass loss of Luminous Blue Variables (LBVs) is thought to play a critical role in the evolution of massive stars, but the physics of their instability and their place in the evolutionary sequence remains uncertain and debated. A key to understanding their peculiar instability is their high observed luminosity, which for Galactic LBVs often depends on an uncertain distance estimate. Here we report direct distances and space motions of four canonical Milky Way LBVs---AG Car, HR Car, HD 168607, and (the LBV candidate) Hen 3-519---whose parallaxes and proper motions have been provided by the Gaia first data release. Whereas the distances of HR Car and HD 168607 are consistent with those previously adopted in the literature within the uncertainty, we find that the distances to Hen 3-519 and AG Car, both at $\\sim$2 kpc, are much closer than the 6--8 kpc distances previously assumed. For Hen 3-519, this moves the star far from the locus of LBVs on the HR Diagram. AG Car has been considered a defining exam...

  2. Explosions Triggered by Violent Binary-Star Collisions: Application to Eta Carinae and other Eruptive Transients

    CERN Document Server

    Smith, Nathan

    2010-01-01

    This paper discusses a model where a violent periastron collision of stars in an eccentric binary system induces an eruption or explosion seen as a brief transient source, attributed to LBVs, SN impostors, or other transients. The key ingredient is that an evolved primary increases its photospheric radius on relatively short timescales, to a point where the radius is comparable to or larger than the periastron separation in an eccentric binary. In such a configuration, a violent and sudden collision would ensue, possibly leading to substantial mass ejection instead of a binary merger. Repeated periastral grazings in an eccentric system could quickly escalate to a catastrophic encounter, wherein the companion star actually plunges deep inside the photosphere of a bloated primary during periastron, as a result of the primary star increasing its own radius. This is motivated by the case of $\\eta$~Carinae, where such a collision must have occured if conventional estimates of the present-day orbit are correct, and...

  3. Early-type massive stars in Carina Nebula within the Gaia-ESO Survey.

    Science.gov (United States)

    Berlanas, S. R.; Herrero, A.; Martins, F.; Simón-Díaz, S.; Mahy, L.; Blomme, R.; GES WG-13

    2017-03-01

    The Gaia-ESO Survey (GES) is obtaining high quality spectra of ˜ 10^5 stars in our Galaxy, providing an homogeneous and unique overview of all the main components of the Milky Way, its formation history and the evolution of young, mature and ancient Galactic populations. Our group is in charge of the early-type massive stars that define the youngest population in the survey. In this contribution, we present the results of the quantitative spectroscopic analysis of O-type stars in the Carina Nebula within the Gaia-ESO Survey. For this aim, we have used FASTWIND and CMFGEN stellar atmosphere codes, providing stellar parameters for the current sample (GES data release iDR4).

  4. Deep census of variable stars in a VLT/VIMOS field in Carina

    CERN Document Server

    Pietrukowicz, P; Fernández, J M; Pietrzynski, G; Ruiz, M T; Gieren, W; Diaz, R F; Zoccali, M; Hempel, M

    2009-01-01

    We have searched for variable stars in deep V-band images of a field towards the Galactic plane in Carina. The images were taken with VIMOS instrument at ESO VLT during 4 contiguous nights in April 2005. We detected 348 variables among 50897 stars in the magnitude range between V=15.4 and V=24.5 mag. Upon detection, we classified the variables by direct eye inspection of their light curves. All variable objects but 9 OGLE transits in the field are new discoveries. We provide a complete catalog of all variables which includes eclipsing/ellipsoidal binaries, miscellaneous pulsators (mostly delta Scuti-type variables), stars with flares and other (irregular and likely long-period) variables. Only two of the stars in our sample are known to host planets. Our result give some implications for future large variability surveys.

  5. Modelling the Central Constant Emission X-ray component of η Carinae

    Science.gov (United States)

    Russell, Christopher M. P.; Corcoran, Michael F.; Hamaguchi, Kenji; Madura, Thomas I.; Owocki, Stanley P.; Hillier, D. John

    2016-05-01

    The X-ray emission of η Carinae shows multiple features at various spatial and temporal scales. The central constant emission (CCE) component is centred on the binary and arises from spatial scales much smaller than the bipolar Homunculus nebula, but likely larger than the central wind-wind collision region between the stars as it does not vary over the ˜2-3 month X-ray minimum when it can be observed. Using large-scale 3D smoothed particle hydrodynamics (SPH) simulations, we model both the colliding-wind region between the stars, and the region where the secondary wind collides with primary wind ejected from the previous periastron passage. The simulations extend out to one hundred semimajor axes and make two limiting assumptions (strong coupling and no coupling) about the influence of the primary radiation field on the secondary wind. We perform 3D radiative transfer calculations on the SPH output to synthesize the X-ray emission, with the aim of reproducing the CCE spectrum. For the preferred primary mass-loss rate dot{M}_A≈ 8.5× 10^{-4} M_{⊙} yr-1, the model spectra well reproduce the observation as the strong- and no-coupling spectra bound the CCE observation for longitude of periastron ω ≈ 252°, and bound/converge on the observation for ω ≈ 90°. This suggests that η Carinae has moderate coupling between the primary radiation and secondary wind, that both the region between the stars and the comoving collision on the backside of the secondary generate the CCE, and that the CCE cannot place constraints on the binary's line of sight. We also discuss comparisons with common X-ray fitting parameters.

  6. XMM-Newton Observations of the 2003 X-Ray Minimum of Eta Carinae

    Science.gov (United States)

    Hamaguchi, K.; Corcoran, M. F.; White, N. E.; Damineli, A.; Davidson, K.; Gull, T. R.

    2004-01-01

    The XMM-Newton X-ray observatory took part in the multi-wavelength observing campaign of the massive, evolved star Eta Carinae in 2003 during its recent X-ray minimum in June 2003. This paper reports on the first results of these observations, which were performed (1) before the minimum (five times in January, 2003), (2) near the X-ray maximum just before the minimum (two times in June) and (3) during the minimum (four times in July-August). Hard X-ray emission from the point source of Eta Carinae was detected even during the minimum. The observed flux above 3 keV was approx. 3x10(exp -12) ergs cm(exp -2)/s, which is about one percent of the flux before the minimum. Light curves from the individual observations show no time variability on the scale of a few kilo-seconds. Changes in the spectral shape occurred, but these changes were smaller than expected if the minimum is produced solely by an increase of hydrogen column density. Fits of the hard X-Ray source by an absorbed 1T model show a constant plasma temperature at around 5 keV and an increase of column density from 5x10(exp 22) cm(exp -2) to 2x10(exp 23) cm(exp -2). The spectra below 6 keV significantly deviate from the models that fit the higher energy emission. The X-ray minimum seems to be dominated by an apparent decrease of the emission measure, suggesting that the brightest part of the X-ray emitting region is completely obscured during the minimum in the form of an eclipse. Partial covering plasma emission models might be considered for the spectral variation. The spectra also showed strong iron K line emission from both hot and cold gases, and weak line emission from Ni, Ca, Ar, S and Si.

  7. The Carina Project. X. On the Kinematics of Old and Intermediate-age Stellar Populations1,2

    Science.gov (United States)

    Fabrizio, M.; Bono, G.; Nonino, M.; Łokas, E. L.; Ferraro, I.; Iannicola, G.; Buonanno, R.; Cassisi, S.; Coppola, G.; Dall’Ora, M.; Gilmozzi, R.; Marconi, M.; Monelli, M.; Romaniello, M.; Stetson, P. B.; Thévenin, F.; Walker, A. R.

    2016-10-01

    We present new radial velocity (RV) measurements of old (horizontal branch) and intermediate-age (red clump) stellar tracers in the Carina dwarf spheroidal. They are based on more than 2200 low-resolution spectra collected with VIMOS at Very Large Telescope (VLT). The targets are faint (20 ≲ V ≲ 21.5 mag), but the accuracy at the faintest limit is ≤9 km s‑1. These data were complemented with RV measurements either based on spectra collected with FORS2 and FLAMES/GIRAFFE at VLT or available in the literature. We ended up with a sample of 2748 stars and among them, 1389 are candidate Carina stars. We found that the intermediate-age stellar component shows a well-defined rotational pattern around the minor axis. The western and the eastern side of the galaxy differ by +5 and ‑4 km s‑1 when compared with the main RV peak. The old stellar component is characterized by a larger RV dispersion and does not show evidence of the RV pattern. We compared the observed RV distribution with N-body simulations for a former disky dwarf galaxy orbiting a giant Milky Way–like galaxy. We rotated the simulated galaxy by 60° with respect to the major axis, we kept the observer on the orbital plane of the dwarf and extracted a sample of stars similar to the observed one. Observed and predicted {V}{rot}/σ ratios across the central regions are in remarkable agreement. This evidence indicates that Carina was a disky dwarf galaxy that experienced several strong tidal interactions with the Milky Way. Owing to these interactions, Carina transformed from a disky to a prolate spheroid and the rotational velocity transformed into random motions.

  8. Eta Carinae across the 2003.5 Minimum: Analysis in the visible and near infrared spectral region

    CERN Document Server

    Nielsen, K E; Weis, K; Gull, T R; Stahl, O; Bomans, D J

    2009-01-01

    We present an analysis of the visible through near infrared spectrum of Eta Carinae and its ejecta obtained during the "Eta Carinae Campaign with the UVES at the ESO VLT". This is a part of larger effort to present a complete Eta Carinae spectrum, and extends the previously presented analyses with the HST/STIS in the UV (1240-3159 A) to 10,430 A. The spectrum in the mid and near UV is characterized by the ejecta absorption. At longer wavelengths, stellar wind features from the central source and narrow emission lines from the Weigelt condensations dominate the spectrum. However, narrow absorption lines from the circumstellar shells are present. This paper provides a description of the spectrum between 3060 and 10,430 A, including line identifications of the ejecta absorption spectrum, the emission spectrum from the Weigelt condensations and the P-Cygni stellar wind features. The high spectral resolving power of VLT/UVES enables equivalent width measurements of atomic and molecular absorption lines for element...

  9. Assessing the internal consistency of the CARINA data base in the Pacific sector of the Southern Ocean

    Directory of Open Access Journals (Sweden)

    C. L. Sabine

    2010-07-01

    Full Text Available The CARINA project is aimed at gathering and providing secondary quality control checks on carbon and carbon-relevant hydrographic and geochemical data from cruises all across the Atlantic, Arctic and Southern Ocean. In total the project gathered 188 cruises that were not previously available to the public. Of these 188 cruises, 37 are part of the Southern Ocean. Parameters from the Southern Ocean cruises, including total carbon dioxide (TCO2, total alkalinity, oxygen, nitrate, phosphate and silicate, were examined for cruise-to-cruise consistency. pH and chlorofluorocarbons (CFCs are also part of the data base, but are not discussed here. This paper focuses on the quality control of the Southern Ocean data from the Pacific sector which consisted of 29 cruises of which 17 were included in a previous synthesis called GLODAP, 11 were new cruises from the CARINA dataset, and one cruise was included in GLODAP but was updated with new data and therefore also included in CARINA. The Pacific sector quality control procedures included crossover analysis between stations and inversion analysis of all crossover data. The GLODAP data were included into the analysis as reference cruises but without applying the GLODAP recommended adjustments so the corrections could be independently verified. The outcome of this effort is an internally consistent, high-quality carbon data set for all cruises, including the reference cruises.

  10. Near-Infrared properties of the X-ray emitting young stellar objects in the Carina Nebula

    CERN Document Server

    Preibisch, Thomas; Irwin, Mike; Lewis, James R; King, Robert R; McCaughrean, Mark J; Zinnecker, Hans; Townsley, Leisa; Broos, Patrick

    2011-01-01

    Abbreviated Abstract: The near-infrared study of the Carina Nebula in this paper builds on the results of the Chandra Carina Complex Project (CCCP), that detected 14368 X-ray sources in the 1.4 square-degree survey region, an automatic source classification study that classified 10714 of these as very likely young stars in Carina, and an analysis of their clustering properties. We used HAWK-I at the ESO VLT to conduct a very deep near-IR survey with sub-arcsecond angular resolution, covering about 1280 square-arcminutes. The HAWK-I images reveal more than 600000 individual infrared sources, whereby objects as faint as J ~ 23, H ~ 22, and Ks ~ 21 are detected at S/N >= 3. While less than half of the Chandra X-ray sources have counterparts in the 2MASS catalog, the ~5 mag deeper HAWK-I data reveal infrared counterparts to 6636 (= 88.8%) of the 7472 Chandra X-ray sources in the HAWK-I field. We analyze near-infrared color-color and color-magnitude diagrams to derive information about the extinctions, infrared ex...

  11. The Canonical Luminous Blue Variable AG Car and Its Neighbor Hen 3-519 are Much Closer than Previously Assumed

    Science.gov (United States)

    Smith, Nathan; Stassun, Keivan G.

    2017-03-01

    The strong mass loss of Luminous Blue Variables (LBVs) is thought to play a critical role in massive-star evolution, but their place in the evolutionary sequence remains debated. A key to understanding their peculiar instability is their high observed luminosities, which often depends on uncertain distances. Here we report direct distances and space motions of four canonical Milky Way LBVs—AG Car, HR Car, HD 168607, and (candidate) Hen 3-519—from the Gaia first data release. Whereas the distances of HR Car and HD 168607 are consistent with previous literature estimates within the considerable uncertainties, Hen 3-519 and AG Car, both at ∼2 kpc, are much closer than the 6–8 kpc distances previously assumed. As a result, Hen 3-519 moves far from the locus of LBVs on the Hertzsprung–Russell diagram, making it a much less luminous object. For AG Car, considered a defining example of a classical LBV, its lower luminosity would also move it off the S Dor instability strip. Lower luminosities allow both AG Car and Hen 3-519 to have passed through a previous red supergiant phase, lower the mass estimates for their shell nebulae, and imply that binary evolution is needed to account for their peculiarities. These results may also impact our understanding of LBVs as potential supernova progenitors and their isolated environments. Improved distances will be provided in the Gaia second data release, which will include additional LBVs. AG Car and Hen 3-519 hint that this new information may alter our traditional view of LBVs.

  12. A MegaCam Survey of Outer Halo Satellites. VI: The Spatially Resolved Star Formation History of the Carina Dwarf Spheroidal Galaxy

    CERN Document Server

    Santana, Felipe A; de Boer, T J L; Simon, Joshua D; Geha, Marla; Côté, Patrick; Guzmán, Andrés E; Stetson, Peter; Djorgovski, S G

    2016-01-01

    We present the spatially resolved star formation history (SFH) of the Carina dwarf spheroidal galaxy, obtained from deep, wide-field g,r imaging and a metallicity distribution from the literature. Our photometry covers $\\sim2$ deg$^2$, reaching up to $\\sim10$ times the half-light radius of Carina with a completeness higher than $50\\%$ at $g\\sim24.5$, more than one magnitude fainter than the oldest turnoff. This is the first time a combination of depth and coverage of this quality has been used to derive the SFH of Carina, enabling us to trace its different populations with unprecedented accuracy. We find that Carina's SFH consists of two episodes well separated by a star formation temporal gap. These episodes occurred at old ($>10$ Gyr) and intermediate ($2$-$8$ Gyr) ages. Our measurements show that the old episode comprises the majority of the population, accounting for $54\\pm5\\%$ of the stellar mass within $1.3$ times the King tidal radius, while the total stellar mass derived for Carina is $1.60\\pm0.09\\tim...

  13. OPTICAL SPECTROSCOPY OF X-RAY-SELECTED YOUNG STARS IN THE CARINA NEBULA

    Energy Technology Data Exchange (ETDEWEB)

    Vaidya, Kaushar [Physics Department, Birla Institute of Technology and Science Pilani, Pilani 333031, Rajasthan (India); Chen, Wen-Ping; Lee, Hsu-Tai [Graduate Institute of Astronomy, National Central University, 300 Zhongda Road, Zhongli 32001, Taiwan (China)

    2015-12-15

    We present low-resolution optical spectra for 29 X-ray sources identified as either massive star candidates or low-mass pre-main-sequence (PMS) star candidates in the clusters Trumpler 16 and Trumpler 14 of the Carina Nebula. Spectra of two more objects (one with an X-ray counterpart, and one with no X-ray counterpart), not originally our targets, but found close (∼3″) to two of our targets, are presented as well. Twenty early-type stars, including an O8 star, seven B1–B2 stars, two B3 stars, a B5 star, and nine emission-line stars, are identified. Eleven T Tauri stars, including eight classical T Tauri stars (CTTSs) and three weak-lined T Tauri stars, are identified. The early-type stars in our sample are more reddened compared to the previously known OB stars of the region. The Chandra hardness ratios of our T Tauri stars are found to be consistent with the Chandra hardness ratios of T Tauri stars of the Orion Nebula Cluster. Most early-type stars are found to be nonvariable in X-ray emission, except the B2 star J104518.81–594217.9, the B3 star J104507.84–594134.0, and the Ae star J104424.76–594555.0, which are possible X-ray variables. J104452.20–594155.1, a CTTS, is among the brightest and the hardest X-ray sources in our sample, appears to be a variable, and shows a strong X-ray flare. The mean optical and near-infrared photometric variability in the V and K{sub s} bands, of all sources, is found to be ∼0.04 and 0.05 mag, respectively. The T Tauri stars show significantly larger mean variation, ∼0.1 mag, in the K{sub s} band. The addition of one O star and seven B1–B2 stars reported here contributes to an 11% increase of the known OB population in the observed field. The 11 T Tauri stars are the first ever confirmed low-mass PMS stars in the Carina Nebula region.

  14. Ejecta of Eta Carinae: What We Learn about N-Rich Chemistry

    Science.gov (United States)

    Gull, Theodore

    2006-01-01

    At least one member of the binary system, Eta Carinae, is in the late stages of CNO-cycle. At least ten solar masses of ejecta make up the Homunculus, a neutral bi-polar shell ejected in the 1840s and the Little Homunculus, an internal, ionized bi-polar shell ejected in the 1890s. HST/STIS and VLTAJVES high dispersion spectroscopy revealed absorptions of multiple elements and diatomic molecules in these shells, some, such as V II and Sr II have not been seen previously in the ISM. The skirt region between the bi-lobes includes the very bright Weigelt blobs, within 0.1 to 0.3" of the central source, and the more distant, unusual Strontium Filament, a neutral emission nebula photoexcited by Balmer continuum, but shielded by Fe II from Lyman radiation. The 600+ emission lines are due to metals usually tied up in dust, but underabundances of C and O prevent precipitation as oxides onto the dust grains. Indications are that Ti/Ni is 100X solar, likely due not to nuclear processing, but the very different photo-excitation environments coupled with N-rich, C-, O-poor chemistry. In the Homunculus, level populations of the molecules indicate 60K gas; the metal absorption lines, 760K; that of the Little Homunculus 6400K during the broad spectroscopic maximum, relaxing to 5000K for the few month long minimum. Lyman radiation, including both continuum and Lyman lines, is trapped across periastron. leading to temporary relaxation of the ejecta. These ejecta are a treasure trove of information on material thrown out of massive stars in the CNO-cycle, well before the helium burning phase. Curiously, spectra of three very recent SWIFT GRBs indicate the presence of warm, photoexcited ejecta in the vicinity of the protoGRBs, but obviously of very different abundances. However, the ejecta of Eta Carinae promise to be a nearby example of massive ejecta, the study of which should lead to increased insight of earlier, very distant massive stars.

  15. Gaia-ESO Survey: Gas dynamics in the Carina nebula through optical emission lines

    Science.gov (United States)

    Damiani, F.; Bonito, R.; Magrini, L.; Prisinzano, L.; Mapelli, M.; Micela, G.; Kalari, V.; Maíz Apellániz, J.; Gilmore, G.; Randich, S.; Alfaro, E.; Flaccomio, E.; Koposov, S.; Klutsch, A.; Lanzafame, A. C.; Pancino, E.; Sacco, G. G.; Bayo, A.; Carraro, G.; Casey, A. R.; Costado, M. T.; Franciosini, E.; Hourihane, A.; Lardo, C.; Lewis, J.; Monaco, L.; Morbidelli, L.; Worley, C.; Zaggia, S.; Zwitter, T.; Dorda, R.

    2016-06-01

    Aims: We present observations from the Gaia-ESO Survey in the lines of Hα, [N II], [S II], and He I of nebular emission in the central part of the Carina nebula. Methods: We investigate the properties of the two already known kinematic components (approaching and receding), which account for the bulk of emission. Moreover, we investigate the features of the much less known low-intensity high-velocity (absolute RV >50 km s-1) gas emission. Results: We show that gas giving rise to Hα and He I emission is dynamically well correlated with but not identical to gas seen through forbidden-line emission. Gas temperatures are derived from line-width ratios, and densities from [S II] doublet ratios. The spatial variation of N ionization is also studied, and found to differ between the approaching and receding components. The main result is that the bulk of the emission lines in the central part of Carina arise from several distinct shell-like expanding regions, the most evident found around η Car, the Trumpler 14 core, and the star WR25. These "shells" are non-spherical and show distortions probably caused by collisions with other shells or colder, higher-density gas. Some of them are also partially obscured by foreground dust lanes, while very little dust is found in their interior. Preferential directions, parallel to the dark dust lanes, are found in the shell geometries and physical properties, probably related to strong density gradients in the studied region. We also find evidence that the ionizing flux emerging from η Car and the surrounding Homunculus nebula varies with polar angle. The high-velocity components in the wings of Hα are found to arise from expanding dust reflecting the η Car spectrum. Based on observations collected with the FLAMES spectrograph at VLT/UT2 telescope (Paranal Observatory, ESO, Chile), for the Gaia-ESO Large Public Survey (program 188.B-3002).Full Tables 1-3 are only available at the CDS via anonymous ftp to http

  16. The deep OB star population in Carina from the VST Photometric Hα Survey (VPHAS+)

    Science.gov (United States)

    Mohr-Smith, M.; Drew, J. E.; Napiwotzki, R.; Simón-Díaz, S.; Wright, N. J.; Barentsen, G.; Eislöffel, J.; Farnhill, H. J.; Greimel, R.; Monguió, M.; Kalari, V.; Parker, Q. A.; Vink, J. S.

    2017-02-01

    Massive OB stars are critical to the ecology of galaxies and yet our knowledge of OB stars in the Milky Way, fainter than V ∼ 12, remains patchy. Data from the VST Photometric Hα Survey (VPHAS+) permit the construction of the first deep catalogues of blue excess-selected OB stars, without neglecting the stellar field. A total of 14 900 candidates with 2MASS cross-matches are blue-selected from a 42 deg2 region in the Galactic plane, capturing the Carina Arm over the Galactic longitude range 282° ≲ ℓ ≲ 293°. Spectral energy distribution fitting is performed on these candidates' combined VPHAS+ u, g, r, i and 2MASS J, H, K magnitudes. This delivers effective temperature constraints, statistically separating O from early-B stars and high-quality extinction parameters, A0 and RV (random errors typically ∼0.1). The high-confidence O-B2 candidates number 5915 and a further 5170 fit to later B spectral type. Spectroscopy of 276 of the former confirms 97 per cent of them. The fraction of emission-line stars among all candidate B stars is 7-8 per cent. Greyer (RV > 3.5) extinction laws are ubiquitous in the region, over the distance range 2.5-3 to ∼10 kpc. Near prominent massive clusters, RV tends to rise, with particularly large and chaotic excursions to RV ∼ 5 seen in the Carina Nebula. The data reveal a hitherto unnoticed association of 108 O-B2 stars around the O5If+ star LSS 2063 (ℓ = 289.77°, b = -1.22°). Treating the OB star scaleheight as a constant within the thin disc, we find an orderly mean relation between extinction (A0) and distance in the Galactic longitude range, 287.6° < ℓ < 293.5°, and infer the subtle onset of thin-disc warping. A halo around NGC 3603, roughly a degree in diameter, of ∼500 O-B2 stars with 4 < A0(mag) < 7 is noted.

  17. AGS experiments - 1994, 1995, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Depken, J.C.

    1997-01-01

    This report contains the following information on the Brookhaven AGS Accelerator complex: FY 1996 AGS schedule as run; FY 1997 AGS schedule (working copy); AGS beams 1997; AGS experimental area FY 1994 physics program; AGS experimental area FY 1995 physics program; AGS experimental area FY 1996 physics program; AGS experimental area FY 1997 physics program (in progress); a listing of experiments by number; two-phage summaries of each experiment begin here, also ordered by number; listing of publications of AGS experiments begins here; and listing of AGS experimenters begins here.

  18. Modelling the Central Constant Emission X-ray component of eta Carinae

    CERN Document Server

    Russell, Christopher M P; Hamaguchi, Kenji; Madura, Thomas I; Owocki, Stanley P; Hillier, D John

    2016-01-01

    The X-ray emission of $\\eta$ Carinae shows multiple features at various spatial and temporal scales. The central constant emission (CCE) component is centred on the binary and arises from spatial scales much smaller than the bipolar Homunculus nebula, but likely larger than the central wind--wind collision region between the stars as it does not vary over the $\\sim$2-3 month X-ray minimum when it can be observed. Using large-scale 3D smoothed particle hydrodynamics (SPH) simulations, we model both the colliding-wind region between the stars, and the region where the secondary wind collides with primary wind ejected from the previous periastron passage. The simulations extend out to one hundred semimajor axes and make two limiting assumptions (strong coupling and no coupling) about the influence of the primary radiation field on the secondary wind. We perform 3D radiative transfer calculations on the SPH output to synthesize the X-ray emission, with the aim of reproducing the CCE spectrum. For the preferred pr...

  19. VizieR Online Data Catalog: Deep OB star population in Carina (Mohr-Smith+, 2017)

    Science.gov (United States)

    Mohr-Smith, M.; Drew, J. E.; Napiwotzki, R.; Simon-Diaz, S.; Wright, N. J.; Barentsen, G.; Eisloeffel, J.; Farnhill, H. J.; Greimel, R.; Monguio, M.; Kalari, V.; Parker, Q. A.; Vink, J. S.

    2016-11-01

    The sky positions and photometric measurements from VPHAS+ (and 2MASS) for 14900 candidate OB stars blue-selected from the Carina region of the Galactic plane are set out in the first 24 columns. The optical magnitudes are expressed in the Vega system. These are followed by the parameters and their error estimates obtained from main-sequence fits to the optical/NIR magnitudes, along with the chi-squared measure of goodness of fit (columns 25 to 33). For the 3 degrees of freedom involved, chi-squared values up to 7.82 may be regarded as 'good fits': 5915 objects are good fits in this sense and have estimated effective temperatures high enough to place them into the O-B2 range. The fitting process delivers effective temperatures, (highly uncertain) distance moduli, and the extinction parameters, A0 and RV. Subsequent columns (34 to 37) identify which candidates are: good O-B2 fits; likely to be emission line stars (based on r-Halpha excess); candidate sub-luminous stars; candidate higher-luminosity evolved objects. The 'Notes' in column 38 provide information on cross-identifications to known objects, where these exist. Columns 39 to 49 present spectroscopically-derived parameters and associated errors for the subset of 276 stars with spectra. (1 data file).

  20. X-ray Modeling of \\eta\\ Carinae and WR140 from SPH Simulations

    CERN Document Server

    Russell, Christopher M P; Okazaki, Atsuo T; Madura, Thomas I; Owocki, Stanley P

    2011-01-01

    The colliding wind binary (CWB) systems \\eta\\ Carinae and WR140 provide unique laboratories for X-ray astrophysics. Their wind-wind collisions produce hard X-rays that have been monitored extensively by several X-ray telescopes, including RXTE. To interpret these RXTE X-ray light curves, we model the wind-wind collision using 3D smoothed particle hydrodynamics (SPH) simulations. Adiabatic simulations that account for the absorption of X-rays from an assumed point source at the apex of the wind-collision shock cone by the distorted winds can closely match the observed 2-10keV RXTE light curves of both \\eta\\ Car and WR140. This point-source model can also explain the early recovery of \\eta\\ Car's X-ray light curve from the 2009.0 minimum by a factor of 2-4 reduction in the mass loss rate of \\eta\\ Car. Our more recent models relax the point-source approximation and account for the spatially extended emission along the wind-wind interaction shock front. For WR140, the computed X-ray light curve again matches the ...

  1. Multi-Wavelength Implications of the Companion Star in eta Carinae

    Science.gov (United States)

    Madura, Thomas I.; Gull, Theodore R.; Groh, Jose H.; Owocki, Stanley P.; Okazaki, Atsuo; Hillier, D. John; Russell, Christopher

    2012-01-01

    Eta-Carinae is considered to be a massive colliding wind binary system with a highly eccentric (e approximately 0.9), 5.54-yr orbit. However, the companion star continues to evade direct detection as the primary dwarfs its emission at most wavelengths. Using three-dimensional (3-D) SPH simulations of eta-Car's colliding winds and radiative transfer codes, we are able to compute synthetic observables across multiple wavebands for comparison to the observations. The models show that the presence of a companion star has a profound influence on the observed HST/STIS UV spectrum and H-alpha line profiles, as well as the ground-based photometric monitoring. Here, we focus on the Bore Hole effect, wherein the fast wind from the hot secondary star carves a cavity in the dense primary wind, allowing increased escape of radiation from the hotter/deeper layers of the primary's extended wind photosphere. The results have important implications for interpretations of eta-Car's observables at multiple wavelengths.

  2. The Clump Mass Function of the Dense Clouds in the Carina Nebula Complex

    CERN Document Server

    Pekruhl, Stephanie; Schuller, Frederic; Menten, Karl

    2012-01-01

    We want to characterize the properties of the cold dust clumps in the Carina Nebula Complex (CNC), which shows a very high level of massive star feedback. We derive the Clump Mass Function (ClMF), explore the reliability of different clump extraction algorithms, and investigate the influence of the temperatures within the clouds on the resulting shape of the ClMF. We analyze a 1.25x1.25 deg^2 wide-field sub-mm map obtained with LABOCA (APEX), which provides the first spatially complete survey of the clouds in the CNC. We use the three clump-finding algorithms CLUMPFIND (CF), GAUSSCLUMPS (GC) and SExtractor (SE) to identify individual clumps and determine their total fluxes. In addition to assuming a common `typical' temperature for all clouds, we also employ an empirical relation between cloud column densities and temperature to determine an estimate of the individual clump temperatures, and use this to determine individual clump masses. While the ClMF based on the CF extraction is very well described by a po...

  3. Exploring the multifaceted circumstellar environment of the luminous blue variable HR Carinae

    Science.gov (United States)

    Buemi, C. S.; Trigilio, C.; Leto, P.; Umana, G.; Ingallinera, A.; Cavallaro, F.; Cerrigone, L.; Agliozzo, C.; Bufano, F.; Riggi, S.; Molinari, S.; Schillirò, F.

    2017-03-01

    We present a multiwavelength study of the Galactic luminous blue variable HR Carinae, based on new high-resolution mid-infrared (IR) and radio images obtained with the Very Large Telescope (VLT) and the Australia Telescope Compact Array (ATCA), which have been complemented by far-infrared Herschel-Photodetector Array Camera and Spectrometer (PACS) observations and ATCA archive data. The Herschel images reveal the large-scale distribution of the dusty emitting nebula, which extends mainly to the north-east direction, up to 70 arcsec from the central star, and is oriented along the direction of the space motion of the star. In the mid-infrared images, the brightness distribution is characterized by two arc-shaped structures, tracing an inner envelope surrounding the central star more closely. At radio wavelengths, the ionized gas emission lies on the opposite side of the cold dust with respect to the position of the star, as if the ionized front were confined by the surrounding medium in the north-south direction. Comparison with previous data indicates significant changes in the radio nebula morphology and in the mass-loss rate from the central star, which has increased from 6.1 × 10-6 M⊙ yr-1 in 1994-1995 to 1.17 × 10-5 M⊙ yr-1 in 2014. We investigate possible scenarios that could have generated the complex circumstellar environment revealed by our multiwavelength data.

  4. Kinematics of powerful jets from intermediate-mass protostars in the Carina nebula

    CERN Document Server

    Reiter, Megan

    2014-01-01

    We present measurements of proper motions and radial velocities of four powerful Herbig-Haro (HH) jets in the Carina nebula: HH 666, HH 901, HH 902, and HH 1066. Two epochs of Hubble Space Telescope (HST) imaging separated by a time baseline of ~4.4 years provide proper motions that allow us to measure the transverse velocities of the jets, while ground-based spectra sample their Doppler velocities. Together these yield full three-dimensional space velocities. Aside from HH 666, their identification as outflows was previously inferred only from morphology in images. Proper motions now show decisively that these objects are indeed jets, and confirm that the intermediate-mass protostars identified as the candidate driving sources for HH 666 and HH 1066 are indeed the origin of these outflows. The appearance of two new knots in the HH 1066 jet suggest recent (~35 yr) changes in the accretion rate, underscoring the variable nature of accretion and outflow in the formation of intermediate-mass stars. In fact, kine...

  5. The X-ray Lightcurve of the Supermassive star eta Carinae, 1996--2014

    CERN Document Server

    Corcoran, M F; Liburd, J K; Morris, D; Gull, T R; Madura, T I; Teodoro, M; Moffat, A F J; Richardson, N D; Russell, C M P; Pollock, A M T; Owocki, S P

    2015-01-01

    Eta Carinae is the nearest example of a supermassive, superluminous, unstable star. Mass loss from the system is critical in shaping its circumstellar medium and in determining its ultimate fate. Eta Car currently loses mass via a dense, slow stellar wind and possesses one of the largest mass loss rates known. It is prone to episodes of extreme mass ejection via eruptions from some as-yet unspecified cause; the best examples of this are the large-scale eruptions which occurred in 19th century. Eta Car is a colliding wind binary in which strong variations in X-ray emission and in other wavebands are driven by the violent collision of the wind of eta Car-A and the fast, less dense wind of an otherwise hidden companion star. X-ray variations are the simplest diagnostic we have to study the wind-wind collision and allow us to measure the state of the stellar mass loss from both stars. We present the X-ray lightcurve over the last 20 years from ROSAT observations and monitoring with the Rossi X-ray Timing Explorer...

  6. Eta Carinae across the 2003.5 minimum: Spectroscopic Evidence for Massive Binary Interactions

    CERN Document Server

    Nielsen, K E; Gull, T R; Hillier, D J; Hamaguchi, K; Ivarsson, S; Lindler, D J

    2007-01-01

    We have analyzed high spatial, moderate spectral resolution observations of Eta Carinae obtained with the STIS from 1998.0 to 2004.3. The spectra show prominent P-Cygni lines in H I, Fe II and He I which are complicated by blends and contamination by nebular emission and absorption along the line-of-sight toward the observer. All lines show phase and species dependent variations in emission and absorption. For most of the cycle the He I emission is blueshifted relative to the H I and Fe II P-Cygni emission lines, which are approximately centered at system velocity. The blueshifted He I absorption varies in intensity and velocity throughout the 2024 day period. We construct radial velocity curves for the absorption component of the He I and H I lines. The He I absorption shows significant radial velocity variations throughout the cycle, with a rapid change of over 200 km/s near the 2003.5 event. The H I velocity curve is similar to that of the He I absorption, though offset in phase and reduced in amplitude. W...

  7. Discovery of CH and OH in the -513 km s-1 Ejecta of Eta Carinae

    CERN Document Server

    Verner, E; Nielsen, K E; Gull, T R; Kober, G V; Corcoran, M

    2005-01-01

    The very massive star, Eta Carinae, is enshrouded in an unusual complex of stellar ejecta, which is highly depleted in C and O, and enriched in He and N. This circumstellar gas gives rise to distinct absorption components corresponding to at least 20 different velocities along the line-of-sight. The velocity component at -513 kms-1 exhibits very low ionization with predominantly neutral species of iron-peak elements. Our statistical equilibrium/photoionization modeling indicates that the low temperature (T = 760 K) and high density (n_H=10^7 cm^-3) of the -513 kms-1 component is conducive to molecule formation including those with the elements C and O. Examination of echelle spectra obtained with the Space Telescope Imaging Spectrograph (STIS) aboard the confirms the model's predictions. The molecules, H_2, CH, and most likely OH, have been identified in the -513 kms-1 absorption spectrum. This paper presents the analysis of the HST/STIS spectra with the deduced column densities for CH, OH and C I, and upper ...

  8. Identification of Emission Lines in the Low-Ionization Strontium Filament Near Eta Carinae

    CERN Document Server

    Hartman, H; Johansson, S; Smith, N

    2004-01-01

    We have obtained deep spectra from 1640 to 10100A with the Space Telescope Imaging Spectrograph (STIS) of the Strontium Filament, a largely neutral emission nebulosity lying close to the very luminous star Eta Carinae and showing an uncommon spectrum. Over 600 emission lines, both permitted and forbidden, have been identified. The majority originates from neutral or singly-ionized iron group elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni). Sr is the only neutron capture element detected. The presence of Sr II, numerous strong Ti II and V II lines and the dominance of Fe I over Fe II are notable discoveries. While emission lines of hydrogen, helium, and nitrogen are associable with other spatial structures at other velocities within the Homunculus, no emission lines from these elements correspond to the spatial structure or velocity of the Sr Filament. Moreover, no identified Sr Filament emission line requires an ionization or excitation energy above approximately 8 eV. Ionized gas extends spatially along the apertur...

  9. Eta Carinae's Thermal X-ray Tail Measured with XMM-Newton and NuSTAR

    CERN Document Server

    Hamaguchi, Kenji; Gull, Theodore R; Takahashi, Hiromitsu; Grefenstette, Brian W; Yuasa, Takayuki; Stuhlinger, Martin; Russell, Christopher M P; Moffat, Anthony F J; Sharma, Neetika; Madura, Thomas I; Richardson, Noel D; Groh, Jose; Pittard, Julian M; Owocki, Stanley

    2016-01-01

    The evolved, massive highly eccentric binary system, eta Carinae, underwent a periastron passage in the summer of 2014. We obtained two coordinated X-ray observations with XMM-Newton and NuSTAR during the elevated X-ray flux state and just before the X-ray minimum flux state around this passage. These NuSTAR observations clearly detected X-ray emission associated with eta Car extending up to ~50 keV for the first time. The NuSTAR spectrum above 10 keV can be fit with the bremsstrahlung tail from a kT ~6 keV plasma. This temperature is Delta kT ~2 keV higher than those measured from the iron K emission line complex, if the shocked gas is in collisional ionization equilibrium. This result may suggest that the companion star's pre-shock wind velocity is underestimated. The NuSTAR observation near the X-ray minimum state showed a gradual decline in the X-ray emission by 40% at energies above 5 keV in a day, the largest rate of change of the X-ray flux yet observed in individual eta Car observations. The column de...

  10. Multi-Wavelength Implications of the Companion Star in Eta Carinae

    CERN Document Server

    Madura, Thomas I; Groh, Jose H; Owocki, Stanley P; Okazaki, Atsuo; Hillier, D John; Russell, Christopher

    2011-01-01

    Eta Carinae is considered to be a massive colliding wind binary system with a highly eccentric (e \\sim 0.9), 5.54-yr orbit. However, the companion star continues to evade direct detection as the primary dwarfs its emission at most wavelengths. Using three-dimensional (3-D) SPH simulations of Eta Car's colliding winds and radiative transfer codes, we are able to compute synthetic observables across multiple wavebands for comparison to the observations. The models show that the presence of a companion star has a profound influence on the observed HST/STIS UV spectrum and H-alpha line profiles, as well as the ground-based photometric monitoring. Here, we focus on the Bore Hole effect, wherein the fast wind from the hot secondary star carves a cavity in the dense primary wind, allowing increased escape of radiation from the hotter/deeper layers of the primary's extended wind photosphere. The results have important implications for interpretations of Eta Car's observables at multiple wavelengths.

  11. X-ray Emission from Eta Carinae near Periastron in 2009 I: A Two State Solution

    CERN Document Server

    Hamaguchi, Kenji; Russell, Christopher; Pollock, Andrew M T; Gull, Theodore R; Teodoro, Mairan; Madura, Thomas I; Damineli, Augusto; Pittard, Julian M

    2014-01-01

    X-ray emission from the supermassive binary system Eta Carinae declines sharply around periastron. This X-ray minimum has two distinct phases - the lowest flux phase in the first ~3 weeks and a brighter phase thereafter. In 2009, the Chandra X-ray Observatory monitored the first phase five times and found the lowest observed flux at ~1.9e-12 ergs cm-2 s-1 (3-8 keV). The spectral shape changed such that the hard band above ~4 keV dropped quickly at the beginning and the soft band flux gradually decreased to its lowest observed value in ~2 weeks. The hard band spectrum had begun to recover by that time. This spectral variation suggests that the shocked gas producing the hottest X-ray gas near the apex of the wind-wind collision (WWC) is blocked behind the dense inner wind of the primary star, which later occults slightly cooler gas downstream. Shocked gas previously produced by the system at earlier orbital phases is suggested to produce the faint residual X-ray emission seen when the emission near the apex is ...

  12. Latitude-dependent effects in the stellar wind of Eta Carinae

    CERN Document Server

    Smith, N; Gull, T R; Ishibashi, K; Hillier, J; Smith, Nathan; Davidson, Kris; Gull, Theodore R.; Ishibashi, Kazunori; Hillier, John

    2003-01-01

    The Homunculus reflection nebula around eta Carinae provides a rare opportunity to observe the spectrum of a star from multiple latitudes. We present STIS spectra of several positions in the Homunculus, showing directly that eta Car has an aspherical stellar wind. P Cygni absorption in Balmer lines depends on latitude, with high velocities and strong absorption near the poles. Stronger absorption at high latitudes is surprising, and it suggests higher mass flux toward the poles, perhaps resulting from radiative driving with equatorial gravity darkening on a rotating star. Reflected profiles of He I lines are more puzzling, offering clues to the wind geometry and ionization structure. During eta Car's high-excitation state in March 2000, the wind was fast and dense at the poles, with higher ionization at low latitudes. Older STIS data obtained since 1998 reveal that this global stellar-wind geometry changes during eta Car's 5.5 year cycle, and may suggest that this star's spectroscopic events are shell ejectio...

  13. The Optical Wind Line Variability of $\\eta$ Carinae During the 2009.0 Event

    CERN Document Server

    Richardson, Noel D; Gull, Theodore R; Moffat, Anthony F J; St-Jean, Lucas

    2015-01-01

    We report on high-resolution spectroscopy of the 2009.0 spectroscopic event of $\\eta$ Carinae collected via SMARTS observations using the CTIO 1.5 m telescope and echelle spectrograph. Our observations were made almost every night over a two-month interval around the photometric minimum of $\\eta$ Car associated with the periastron passage of a hot companion. The photoionizing flux of the companion and heating related to colliding winds causes large changes in the wind properties of the massive primary star. Here we present an analysis of temporal variations in a sample of spectral lines that are clearly formed in the wind of the primary star. These lines are affected by a changing illumination of the flux of the secondary star during the periastron passage. We document the sudden onset of blue-shifted absorption that occurred in most of the lines near or slightly after periastron, and we argue that these absorption components are seen when we view the relatively undisturbed wind of the foreground primary star...

  14. 3D hydrodynamical and radiative transfer modeling of Eta Carinae's colliding winds

    CERN Document Server

    Madura, Thomas I; Gull, Theodore R; Kruip, Chael J H; Paardekooper, Jan-Pieter; Icke, Vincent

    2015-01-01

    We present results of full 3D hydrodynamical and radiative transfer simulations of the colliding stellar winds in the massive binary system Eta Carinae. We accomplish this by applying the SimpleX algorithm for 3D radiative transfer on an unstructured Voronoi-Delaunay grid to recent 3D smoothed particle hydrodynamics (SPH) simulations of the binary colliding winds. We use SimpleX to obtain detailed ionization fractions of hydrogen and helium, in 3D, at the resolution of the original SPH simulations. We investigate several computational domain sizes and Luminous Blue Variable primary star mass-loss rates. We furthermore present new methods of visualizing and interacting with output from complex 3D numerical simulations, including 3D interactive graphics and 3D printing. While we initially focus on Eta Car, the methods employed can be applied to numerous other colliding wind (WR 140, WR 137, WR 19) and dusty 'pinwheel' (WR 104, WR 98a) binary systems. Coupled with 3D hydrodynamical simulations, SimpleX simulatio...

  15. [TiII] and [NiII] emission from the strontium filament of eta Carinae

    CERN Document Server

    Bautista, M A; Gull, T R; Smith, N; Lodders, K

    2006-01-01

    We study the nature of the [TiII] and [NiII] emission from the so-called strontium filament found in the ejecta of eta Carinae. To this purpose we employ multilevel models of the TiII and NiII systems which are used to investigate the physical condition of the filament and the excitation mechanisms of the observed lines. For the TiII ion, for which no atomic data was previously available, we carry out ab initio calculations of radiative transition rates and electron impact excitation rate coefficients. It is found that the observed spectrum is consistent with the lines being excited in a mostly neutral region with an electron density of the order of $10^7$ cm$^{-3}$ and a temperature around 6000 K. In analyzing three observations with different slit orientations recorded between March~2000 and November~2001 we find line ratios that change among various observations, in a way consistent with changes of up to an order of magnitude in the strength of the continuum radiation field. These changes result from diffe...

  16. Ancient eruptions of Eta Carinae: A tale written in proper motions

    CERN Document Server

    Kiminki, Megan M; Smith, Nathan

    2016-01-01

    We analyze eight epochs of Hubble Space Telescope H$\\alpha$+[N II] imaging of Eta Carinae's outer ejecta. Proper motions of nearly 800 knots reveal that the detected ejecta are divided into three apparent age groups, dating to around 1250 A.D., to around 1550 A.D., and to during or shortly before the Great Eruption of the 1840s. Ejecta from these groups reside in different locations and provide a firm constraint that Eta Car experienced multiple major eruptions prior to the 19th century. The 1250 and 1550 events did not share the same axisymmetry as the Homunculus; the 1250 event was particularly asymmetric, even one-sided. In addition, the ejecta in the S ridge, which have been associated with the Great Eruption, appear to predate the ejection of the Homunculus by several decades. We detect essentially ballistic expansion across multiple epochs. We find no evidence for large-scale deceleration of the observed knots that could power the soft X-ray shell by plowing into surrounding material, suggesting that th...

  17. n CARINAE: THE NATURE OF THE 5.54-YR CYCLE

    Directory of Open Access Journals (Sweden)

    A. Damineli

    2008-01-01

    Full Text Available Los eventos de baja excitación en eta Carinae son conocidos desde hace más de cien años, pero nunca han sido completamente caracterizados. Hemos derivado el período de aquellos, Ppres = 2022.7± 1.3 d, y mostramos que el mismo no puede haber cambiado por más de P/P = 0.0007 durante los últimos 60 a¿nos. Esto otorga una base fuerte para el escenario de binaridad. El así llamado evento de baja excitación es gobernado por el paso del periastro, cuando la estrella secundaria está profundamente inmersa en el viento de la primaria. Mostramos que los eventos en las líneas de excitación intensas están provocados por un blanketing en el campo de radiación de la estrella secundaria (la fuente ionizante. Descartamos la mayoría de los mecanismos propuestos previamente, tales como eyección del shell, colapso de la colisión viento-viento, o eclipse. Mostramos una serie de curvas de luz, ejemplificando las peculiaridades de cada rasgo, útil para planear campañas de monitoreo para el próximo mínimo, predicho a iniciarse el 11 de enero de 2009.

  18. Discovery of Five Candidate Analogs for $\\eta\\,$Carinae in Nearby Galaxies

    CERN Document Server

    Khan, Rubab; Stanek, K Z; Kochanek, C S; Sonneborn, G

    2015-01-01

    The late-stage evolution of very massive stars such as $\\eta\\,$Carinae may be dominated by poorly understood episodic mass ejections which may later lead to superluminous supernovae. However, as long as $\\eta\\,$Car is one of a kind, it is nearly impossible to quantitatively evaluate these possibilities. Here we announce the discovery of five objects in the nearby ($\\sim4-8\\,$Mpc) massive star-forming galaxies M$51$, M$83$, M$101$ and NGC$6946$ that have optical through mid-infrared photometric properties consistent with the hitherto unique $\\eta\\,$Car. We identified these $L_{bol}\\simeq3-8\\times10^{6}\\,L_\\odot$ objects through a systematic search of archival Spitzer and HST data. Their Spitzer mid-infrared spectral energy distributions rise steeply in the $3.6-8\\,\\mu$m bands, then turn over between $8$ and $24\\,\\mu$m, indicating the presence of warm ($\\sim400-600\\,$K) circumstellar dust. Their optical counterparts or flux limits from deep HST images are $\\sim1.5-2\\,$dex fainter than their mid-IR peaks and req...

  19. VizieR Online Data Catalog: Radio spectra of globulettes in Carina nebula (Haikala+, 2017)

    Science.gov (United States)

    Haikala, L. K.; Gahm, G. F.; Grenman, T.; Makela, M. M.; Persson, C. M.

    2017-04-01

    Radio spectral lines of globulettes in the Carina nebula are presented. The spectra were obtained with the Atacama Pathfinder Experiment (APEX), Llano Chajnantor, Chile (O-091.F-9316A and O-094.F-9312A) The observed molecular lines were 12CO(3-2), 12CO(2-1), 13CO(3-2), and 13CO (2-1). The APEX 350 and 230GHz single sideband heterodyne APEX-1 and APEX-2 SIS receivers and the 32768 channel RPG eXtended bandwidth Fast Fourier Transform Spectrometer (XFFTS) with a bandwidth of 2.5 GHz were used. The channel spacing 76.3kHz corresponds to velocity spacing of 0.1 and 0.07km/s at 230 and 345GHz, respectively. All observations were performed in position-switching mode. The telescope FWHM is 27" at 230GHz, and 18" at 345GHz, and the corresponding main beam efficiencies are 0.75 and 0.73. Second order baseline was subtracted from the spectra. The temperature scale is in Ta* units, i.e. corrected to outside of the atmosphere but not for beam coupling. The spectra are presented in one binary table FITS file. (2 data files).

  20. Suzaku Observation of Diffuse X-ray Emission from the Carina Nebula

    Science.gov (United States)

    Hamaguchi, Kenji; Petre, Robert; Matsumoti, Hironori; Tsujimoto, Masahiro; Holt, Stephan S.; Ezoe, Yuichiro; Ozawa, Hideki; Tsuboi, Yohko; Soong, Yang; Kitamoto, Shunji; Sekiguchi, Akiko; Kokubun, Motohide

    2007-01-01

    We studied extended X-ray emission from the Carina Nebula taken with the Suzaku CCD camera XIS on 2005 Aug. 29. The X-ray morphology, plasma temperature and absorption to the plasma are consistent with the earlier Einstein results. The Suzaku spectra newly revealed emission lines from various spices including oxygen, but not from nitrogen. This result restricts the N/O ratio significantly low, compared with evolved massive stellar winds, suggesting that the diffuse emission is originated in an old supernova remnant or a super shell produced by multiple supernova remnants. The X-ray spectra from the north and south of eta Car showed distinct differences between 0.3-2 keV. The south spectrum shows strong L-shell lines of iron ions and K-shell lines of silicon ions, while the north spectrum shows them weak in intensity. This means that silicon and iron abundances are a factor of 2-4 higher in the south region than in the north region. The abundance variation may be produced by an SNR ejecta, or relate to the dust formation around the star forming core.

  1. Astrophysical Lasers Operating in optical Fe II Lines Lines in Stellar Ejecta of Eta Carinae

    CERN Document Server

    Johansson, S

    2004-01-01

    After the discovery of space masers based on OH radicals (Weaver et al, 1965) and H2O (Cheung et al, 1969) such microwave lasers have been found to work in more than 100 molecular species (Elitzur, 1992; Townes, 1997), as well as in highly excited H atoms (Strelnitski et al,1996). In the IR region (10 microns), the effect of stimulated emission of radiation in the CO2 molecule has been discovered in the Martian and Venus' atmospheres (Betz et al, 1976; Mumma et al, 1981). We report here on the discovery of laser action in the range 0.9-2 micr. in several spectral lines of Fe II, which are associated with transitions from "pseudo-metastable" states populated by spontaneous transitions from Ly-alpha pumped Fe II levels. The intense Ly-alpha radiation is formed in the HII region of gas condensations close to the star Eta Carinae. The laser transitions form together with spontaneous transitions closed radiative cycles, one of which includes the extremely bright 2507/09 A lines. Closed radiative cycles, together w...

  2. The deep OB star population in Carina from the VST Photometric H$\\alpha$ Survey (VPHAS+)

    CERN Document Server

    Mohr-Smith, M; Napiwotzki, R; Simón-Díaz, S; Wright, N J; Barentsen, G; Eislöffel, J; Farnhill, H J; Greimel, R; Monguió, M; Kalari, V; Parker, Q A; Vink, J S

    2016-01-01

    Massive OB stars are critical to the ecology of galaxies, and yet our knowledge of OB stars in the Milky Way, fainter than $V \\sim 12$, remains patchy. Data from the VST Photometric H$\\alpha$ Survey (VPHAS+) permit the construction of the first deep catalogues of blue excess-selected OB stars, without neglecting the stellar field. A total of 14900 candidates with 2MASS cross-matches are blue-selected from a 42 square-degree region in the Galactic Plane, capturing the Carina Arm over the Galactic longitude range $282^{\\circ} \\lesssim \\ell \\lesssim 293^{\\circ}$. Spectral energy distribution fitting is performed on these candidates' combined VPHAS+ $u,g,r,i$ and 2MASS $J,H,K$ magnitudes. This delivers: effective temperature constraints, statistically separating O from early-B stars; high-quality extinction parameters, $A_0$ and $R_V$ (random errors typically $ 3.5$) extinction laws are ubiquitous in the region, over the distance range 2.5--3 kpc to $\\sim$10~kpc. Near prominent massive clusters, $R_V$ tends to ri...

  3. New OB star candidates in the Carina Arm around Westerlund 2 from VPHAS+

    CERN Document Server

    Mohr-Smith, M; Barentsen, G; Wright, N J; Napiwotzki, R; Corradi, R L M; Eislöffel, J; Groot, P; Kalari, V; Parker, Q A; Raddi, R; Sale, S E; Unruh, Y C; Vink, J S; Wesson, R

    2015-01-01

    O and early B stars are at the apex of galactic ecology, but in the Milky Way, only a minority of them may yet have been identified. We present the results of a pilot study to select and parametrise OB star candidates in the Southern Galactic plane, down to a limiting magnitude of $g=20$. A 2 square-degree field capturing the Carina Arm around the young massive star cluster, Westerlund 2, is examined. The confirmed OB stars in this cluster are used to validate our identification method, based on selection from the $(u-g, g-r)$ diagram for the region. Our Markov Chain Monte Carlo fitting method combines VPHAS+ $u, g, r, i$ with published $J, H, K$ photometry in order to derive posterior probability distributions of the stellar parameters $\\log(\\rm T_{\\rm eff})$ and distance modulus, together with the reddening parameters $A_0$ and $R_V$. The stellar parameters are sufficient to confirm OB status while the reddening parameters are determined to a precision of $\\sigma(A_0)\\sim0.09$ and $\\sigma(R_V)\\sim0.08$. The...

  4. Dust in the SN1987A-analog SBW1 in Carina

    Science.gov (United States)

    Smith, Nathan

    2009-02-01

    Last year Smith et al. (2007) reported the discovery of a new equatorial ring nebula, called SBW1, around a blue supergiant seen in the Carina Nebula. It has morphology and physical dimensions almost identical to the ring around SN1987A and it surrounds an early B supergiant that is a virtual twin ofthe progenitor of SN1987A. However, it is more than 20 times closer than SN1987A, and therefore shows the detailed structure of this unusual type of ring nebula in much greater detail, before the star explodes. Resolving the structure in this nebula will inform our understanding of non-spherical mass loss from supernova progenitor stars in general, and will constrain models of SN1987A as its blast wave continues to interact with its circumstellar ring. This proposal aims to obtain mid-IR images and spectroscopy of SBW1 with T-ReCS on Gemini South in order to determine the dust properties in the nebula, such as its physical location, temperature, mass, and composition, for comparison with the dust properties of SN1987A's ring and also with the circumstellar dust properties of other blue supergiants like B[e] stars. These IR data are also needed to understand the relationship between warm dust and the ionized gas structures that will be resolved in our accepted program to obtain WFC3 and STIS data with HST.

  5. Submillimeter spectroscopy of the Carina Nebula: Observations, operations and upgrades of the South Pole Imaging Fabry-Perot Interferometer

    Science.gov (United States)

    Oberst, Thomas Edward

    2009-06-01

    We present the results of a ~ 250 arcmin 2 mapping of the 205 μm [NII] fine- structure line emission over the northern Carina Nebula, including the Car I and Car II HII regions. Spectra were obtained using the South Pole Imaging Fabry-Perot Interferometer (SPIFI) at the Antarctic Telescope and Remote Observatory (AST/RO) at South Pole. New upgrades and modifications to the SPIFI instrument are discussed, and full details of SPIFI-AST/RO integration and calibration are provided. At the time of these observations, SPIFI had a spectral resolving power of ~ 4250, a FWHM beam size of ~ 54'', and a noise equivalent power (NEP) referred to the front end of the receiver of ~ 2.5 × 10 -15 W Hz -1/2 (~ 1.4 times the background limit). These data constitute the first ground-based detection of the 205 μm [NII] line, and only the third detection overall since those of the Cosmic Background Explorer (COBE) Far Infrared Absolute Spectrophotometer (FIRAS) and the Kuiper Airborne Observatory (KAO) in the early 1990s. We supplement the 205 μm data with new reductions of far-infrared fine- structure spectra from the Infrared Space Observatory (ISO) in 63 μm [OI], 122 m [NII], 146 μm [OI], and 158 μm [CII]; the 146 μm [OI] data include 90 raster positions which have not been previously published. Morphological comparisons are made with optical, radio continuum and CO maps. The 122/205 [NII] line ratio is used to probe the density of the low-ionization gas, and the 158/205 [CII]/[NII] line ratio is used to probe the fraction of C + arising from photodissociation regions (PDRs). The [OI] and [CII] lines are used to construct a PDR model of Carina following Kaufman et al. (1999). When the PDR properties are compared with other sources, Carina is found to be more akin to 30 Doradus than galactic star-forming regions such as Orion, M17, or W49. This is consistent with the view of Carina as a more evolved region, where much of the parent molecular cloud has been ionized or swept

  6. The role of Ag precipitates in Cu-12 wt% Ag

    Energy Technology Data Exchange (ETDEWEB)

    Yao, D.W.; Song, L.N. [Department of Materials Science and Engineering, Zhejiang University, Zheda Road No.38, Hangzhou, Zhejiang 310027 (China); Dong, A.P.; Wang, L.T. [China Railway Construction Electrification Bureau Group Co.,Ltd., Beijing 100036 (China); Zhang, L. [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Meng, L., E-mail: mengliang@zju.edu.cn [Department of Materials Science and Engineering, Zhejiang University, Zheda Road No.38, Hangzhou, Zhejiang 310027 (China)

    2012-12-15

    The Cu-12 wt% Ag was prepared to investigate the role of Ag precipitates on the properties of the alloy. Two kinds of heat treatment procedures were adopted to produce different amount of Ag precipitates in the Cu-12 wt% Ag. The microstructure of Ag precipitates was systematically observed by optical microscopy and electron microscopy. The Cu-12 wt% Ag with more Ag precipitates exhibits higher strength and lower electrical conductivity. More Ag precipitates results in more phase interface and less Ag atoms dissolved in Cu matrix. By comparing the strengthening effect and electron scattering effect of phase interface and dissolved Ag atoms, it is conclude that the interface between Cu matrix and Ag precipitates could significantly block dislocation movement and enhance electron scattering in Cu-Ag alloys.

  7. The clump mass function of the dense clouds in the Carina nebula complex

    Science.gov (United States)

    Pekruhl, S.; Preibisch, T.; Schuller, F.; Menten, K.

    2013-02-01

    Context. The question how the initial conditions in a star-forming region affect the resulting mass function of the forming stars is one of the most fundamental open topics in star formation theory. Aims: We want to characterize the properties of the cold dust clumps in the Carina nebula complex, which is one of the most massive star forming regions in our Galaxy and shows a very high level of massive star feedback. We derive the clump mass function (ClMF), explore the reliability of different clump extraction algorithms, and investigate the influence of the temperatures within the clouds on the resulting shape of the ClMF. Methods: We analyze a 1.25° × 1.25° wide-field submillimeter map obtained with LABOCA at the APEX telescope, which provides the first spatially complete survey of the clouds in the Carina nebula complex. We use the three clump-finding algorithms CLUMPFIND, GAUSSCLUMPS and SExtractor to identify individual clumps and determine their total fluxes. In addition to assuming a common "typical" temperature for all clouds, we also employ an empirical relation between cloud column densities and temperature to determine an estimate of the individual clump temperatures, and use this to determine individual clump masses. Results: We find that the ClMFs resulting from the different extraction methods show considerable differences in their shape. While the ClMF based on the CLUMPFIND extraction is very well described by a power-law (for clump masses well above the completeness limit), the ClMFs based on the extractions with GAUSSCLUMPS and SExtractor are better represented by a log-normal distribution. We also find that the use of individual clump temperatures leads to a shallower ClMF slope than the (often used) assumption of a common temperature (e.g. 20 K) of all clumps. Conclusions: The power-law of dN/dM ∝ M-1.95 we find for the CLUMPFIND sample is in good agreement with ClMF slopes found in previous studies of the ClMFs of other regions. The

  8. DISCOVERY OF FIVE CANDIDATE ANALOGS FOR η CARINAE IN NEARBY GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Rubab [NASA Goddard Space Flight Center, MC 665, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Adams, Scott M.; Stanek, K. Z.; Kochanek, C. S. [Department of Astronomy, The Ohio State University, 140 W. 18th Avenue, Columbus, OH 43210 (United States); and others

    2015-12-20

    The late-stage evolution of very massive stars such as η Carinae may be dominated by episodic mass ejections that may later lead to Type II superluminous supernova (SLSN-II; e.g., SN 2006gy). However, as long as η Car is one of a kind, it is nearly impossible to quantitatively evaluate these possibilities. Here, we announce the discovery of five objects in the nearby (∼4–8 Mpc) massive star-forming galaxies M51, M83, M101, and NGC 6946 that have optical through mid-infrared (mid-IR) photometric properties consistent with the hitherto unique η Car. The Spitzer mid-IR spectral energy distributions of these L{sub bol} ≃ 3–8 × 10{sup 6} L{sub ⊙} objects rise steeply in the 3.6–8 μm bands and then turn over between 8 and 24 μm, indicating the presence of warm (∼400–600 K) circumstellar dust. Their optical counterparts in HST images are ∼1.5–2 dex fainter than their mid-IR peaks and require the presence of ∼5–10 M{sub ⊙} of obscuring material. Our finding implies that the rate of η Car–like events is a fraction f = 0.094 (0.040 < f < 0.21 at 90% confidence) of the core-collapse supernova (ccSN) rate. If there is only one eruption mechanism and Type II superluminous supernovae are due to ccSNe occurring inside these dense shells, then the ejection mechanism is likely associated with the onset of carbon burning (∼10{sup 3}–10{sup 4} years), which is also consistent with the apparent ages of massive Galactic shells.

  9. THE OPTICAL WIND LINE VARIABILITY OF η CARINAE DURING THE 2009.0 EVENT

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, N. D.; Moffat, A. F. J.; St-Jean, L. [Département de physique and Centre de Recherche en Astrophysique du Québec (CRAQ), Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, Québec, H3C 3J7 (Canada); Gies, D. R. [Center for High Angular Resolution Astronomy, Department of Physics and Astronomy, Georgia State University, P.O. Box 5060, Atlanta, GA 30302-5060 (United States); Gull, T. R., E-mail: richardson@astro.umontreal.ca [Astrophysics Science Division, Code 667, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2015-10-15

    We report on high-resolution spectroscopy of the 2009.0 spectroscopic event of η Carinae collected via SMARTS observations using the CTIO 1.5 m telescope and echelle spectrograph. Our observations were made almost every night over a two-month interval around the photometric minimum of η Car associated with the periastron passage of a hot companion. The photoionizing flux of the companion and heating related to colliding winds causes large changes in the wind properties of the massive primary star. Here we present an analysis of temporal variations in a sample of spectral lines that are clearly formed in the wind of the primary star. These lines are affected by a changing illumination of the flux of the secondary star during the periastron passage. We document the sudden onset of blueshifted absorption that occurred in most of the lines near or slightly after periastron, and we argue that these absorption components are seen when we view the relatively undisturbed wind of the foreground primary star. We present time series measurements of the net equivalent width of the wind lines and of the radial velocities of the absorption trough minima and the emission peak midpoints. Most lines decrease in emission strength around periastron, and those high excitation lines formed close to the primary exhibit a red-ward velocity excursion. We show how these trends can be explained using an illuminated hemisphere model that is based on the idea that the emission originates primarily from the side of the primary facing the hot companion.

  10. The Ultraviolet Spectrum of η Carinae: Investigation of the Ejecta Absorption

    Science.gov (United States)

    Nielsen, K. E.; Gull, T. R.; Vieira Kober, G.

    2005-03-01

    We have investigated the far- through mid-UV (1150-2360 Å) spectrum of η Carinae during the late stages of its broad maximum using the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) moderate dispersion echelle modes. The η Car spectrum is a mixture of absorption and emission lines from the surrounding nebula superimposed on broad stellar wind features. This paper provides a description of the observed spectrum including the wind features, the interstellar absorption, and the emission spectrum from the surrounding nebula, but with the emphasis on the absorption spectrum formed in the foreground ejecta. The ejecta absorption spectrum has a complicated velocity structure in which two velocity structures, at -146 and -513 km s-1, are easily distinguished. These two velocity components, formed in different regions of the η Car nebula, have in an earlier analysis been identified and demonstrated to have very different spectral characteristics. The slower velocity component is time variable over the spectroscopic period and is characterized by spectral lines from mainly singly ionized iron-peak elements, while the faster one shows transitions from neutral and singly ionized elements in addition to molecular lines from the hydrogen Lyman bands. The high-velocity H2 lines dominate great parts of the spectrum with over 800 identified transitions from energy levels up to 30,000 cm-1. The STIS MAMA data provide the tool for spatial investigations of the central parts of η Car. H I Lyα pumped and semiforbidden emission lines are observed to be formed east of the central source toward Weigelt blobs B and C, located up to 0.2" from the central source. The complete spectrum, with nebular and interstellar line identifications, is available in the electronic edition of the paper. Laboratory for Astronomy and Solar Physics, Code 681, Goddard Space Flight Center, Greenbelt, MD 20771.

  11. The 2014 X-Ray Minimum of η Carinae as Seen by Swift

    Science.gov (United States)

    Corcoran, M. F.; Liburd, J.; Morris, D.; Russell, C. M. P.; Hamaguchi, K.; Gull, T. R.; Madura, T. I.; Teodoro, M.; Moffat, A. F. J.; Richardson, N. D.; Hillier, D. J.; Damineli, A.; Groh, J. H.

    2017-03-01

    We report on Swift X-ray Telescope observations of Eta Carinae (η Car), an extremely massive, long-period, highly eccentric binary obtained during the 2014.6 X-ray minimum/periastron passage. These observations show that η Car may have been particularly bright in X-rays going into the X-ray minimum state, while the duration of the 2014 X-ray minimum was intermediate between the extended minima seen in 1998.0 and 2003.5 by Rossi X-Ray Timing Explorer (RXTE), and the shorter minimum in 2009.0. The hardness ratios derived from the Swift observations showed a relatively smooth increase to a peak value occurring 40.5 days after the start of the X-ray minimum, though these observations cannot reliably measure the X-ray hardness during the deepest part of the X-ray minimum when contamination by the “central constant emission” component is significant. By comparing the timings of the RXTE and Swift observations near the X-ray minima, we derive an updated X-ray period of P X = 2023.7 ± 0.7 days, in good agreement with periods derived from observations at other wavelengths, and we compare the X-ray changes with variations in the He ii 4686 emission. The middle of the “Deep Minimum” interval, as defined by the Swift column density variations, is in good agreement with the time of periastron passage derived from the He ii λ4686 line variations.

  12. New OB star candidates in the Carina Arm around Westerlund 2 from VPHAS+

    Science.gov (United States)

    Mohr-Smith, M.; Drew, J. E.; Barentsen, G.; Wright, N. J.; Napiwotzki, R.; Corradi, R. L. M.; Eislöffel, J.; Groot, P.; Kalari, V.; Parker, Q. A.; Raddi, R.; Sale, S. E.; Unruh, Y. C.; Vink, J. S.; Wesson, R.

    2015-07-01

    O and early B stars are at the apex of galactic ecology, but in the Milky Way, only a minority of them may yet have been identified. We present the results of a pilot study to select and parametrize OB star candidates in the Southern Galactic plane, down to a limiting magnitude of g = 20. A 2 deg2 field capturing the Carina Arm around the young massive star cluster, Westerlund 2, is examined. The confirmed OB stars in this cluster are used to validate our identification method, based on selection from the (u - g, g - r) diagram for the region. Our Markov Chain Monte Carlo fitting method combines VPHAS+ u, g, r, i with published J, H, K photometry in order to derive posterior probability distributions of the stellar parameters log (Teff) and distance modulus, together with the reddening parameters A0 and RV. The stellar parameters are sufficient to confirm OB status while the reddening parameters are determined to a precision of σ(A0) ˜ 0.09 and σ(RV) ˜ 0.08. There are 489 objects that fit well as new OB candidates, earlier than ˜B2. This total includes 74 probable massive O stars, 5 likely blue supergiants and 32 reddened subdwarfs. This increases the number of previously known and candidate OB stars in the region by nearly a factor of 10. Most of the new objects are likely to be at distances between 3 and 6 kpc. We have confirmed the results of previous studies that, at these longer distances, these sight lines require non-standard reddening laws with 3.5 < RV < 4.

  13. H.E.S.S. constraints on Dark Matter annihilations towards the Sculptor and Carina Dwarf Galaxies

    CERN Document Server

    Abramowski, A; Aharonian, F; Akhperjanian, A G; Anton, G; Barnacka, A; de Almeida, U Barres; Bazer-Bachi, A R; Becherini, Y; Becker, J; Behera, B; Bernlöhr, K; Bochow, A; Boisson, C; Bolmont, J; Bordas, P; Borrel, V; Brucker, J; Brun, F; Brun, P; Bulik, T; Büsching, I; Carrigan, S; Casanova, S; Cerruti, M; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Chounet, L -M; Clapson, A C; Coignet, G; Conrad, J; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubois, F; Dubus, G; Dyks, J; Dyrda, M; Egberts, K; Eger, P; Espigat, P; Fallon, L; Farnier, C; Fegan, S; Feinstein, F; Fernandes, M V; Fiasson, A; Frster, A; Fontaine, G; Füßling, M; Gallant, Y A; Gast, H; Gérard, L; Gerbig, D; Giebels, B; Glicenstein, J F; Glück, B; Goret, P; Göring, D; Hague, J D; Hampf, D; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hoffmann, A; Hofmann, W; Hofverberg, P; Horns, D; Jacholkowska, A; de Jager, O C; Jahn, C; Jamrozy, M; Jung, I; Kastendieck, M A; Katarzyński, K; Katz, U; Kaufmann, S; Keogh, D; Kerschhaggl, M; Khangulyan, D; Khélifi, B; Klochkov, D; Kluźniak, W; Kneiske, T; Komin, Nu; Kosack, K; Kossakowski, R; Laffon, H; Lamanna, G; Lennarz, D; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Masbou, J; Maurin, D; Maxted, N; McComb, T J L; Medina, M C; Méhault, J; Moderski, R; Moulin, E; Naumann, C L; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nekrassov, D; Nguyen, N; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Olive, J-F; Wilhelmi, E de Oña; Opitz, B; Ostrowski, M; Panter, M; Arribas, M Paz; Pedaletti1, G; Pelletier, G; Petrucci, P -O; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raue, M; Rayner, S M; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Ruppel, J; Ryde, F; Sahakian, V; Santangelo, A; Schlickeiser, R; Schöck, F M; Schönwald, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Shalchi, A; Sikora, M; Skilton, J L; Sol, H; Spengler, G; Stawarz, Ł; Steenkamp, R; Stegmann, C; Stinzing, F; Sushch, I; Szostek, A; Tavernet, J -P; Terrier, R; Tibolla, O; Tluczykont, M; Valerius, K; van Eldik, C; Vasileiadis, G; Venter, C; Vialle, J P; Viana, A; Vincent, P; Vivier, M; Völk, H J; Volpe, F; Vorobiov, S; Vorster, M; Wagner, S J; Ward, M; Wierzcholska, A; Zajczyk, A; Zdziarski, A A; Zech, A; Zechlin, H -S; 10.1016/j.astropartphys.2010.12.006

    2010-01-01

    The Sculptor and Carina Dwarf spheroidal galaxies were observed with the H.E.S.S. Cherenkov telescope array between January 2008 and December 2009. The data sets consist of a total of 11.8 and 14.8 hours of high quality data, respectively. No gamma-ray signal was detected at the nominal positions of these galaxies above 220 GeV and 320 GeV, respectively. Upper limits on the gamma-ray fluxes at 95% C.L. assuming two forms for the spectral energy distribution (a power law shape and one derived from dark matter annihilation) are obtained at the level of 10^-13 to 10^-12 cm^-2s^-1 in the TeV range. Constraints on the velocity weighted dark matter particle annihilation cross section for both Sculptor and Carina dwarf galaxies range from ~ 10^-21 cm^3s^-1 down to ~ 10^-22 cm^3s^-1 depending on the dark matter halo model used. Possible enhancements of the gamma-ray flux are studied: the Sommerfeld effect, which is found to exclude some dark matter particle masses, the internal Bremsstrahlung and clumps in the dark...

  14. H.E.S.S. constraints on dark matter annihilations towards the sculptor and carina dwarf galaxies

    Science.gov (United States)

    H.E.S.S. Collaboration; Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Barnacka, A.; Barres de Almeida, U.; Bazer-Bachi, A. R.; Becherini, Y.; Becker, J.; Behera, B.; Bernlöhr, K.; Bochow, A.; Boisson, C.; Bolmont, J.; Bordas, P.; Borrel, V.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Büsching, I.; Carrigan, S.; Casanova, S.; Cerruti, M.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Chounet, L.-M.; Clapson, A. C.; Coignet, G.; Conrad, J.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; Drury, L. O. C.; Dubois, F.; Dubus, G.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Espigat, P.; Fallon, L.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gallant, Y. A.; Gast, H.; Gérard, L.; Gerbig, D.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Goret, P.; Göring, D.; Hague, J. D.; Hampf, D.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hoffmann, A.; Hofmann, W.; Hofverberg, P.; Horns, D.; Jacholkowska, A.; de Jager, O. C.; Jahn, C.; Jamrozy, M.; Jung, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Keogh, D.; Kerschhaggl, M.; Khangulyan, D.; Khélifi, B.; Klochkov, D.; Kluźniak, W.; Kneiske, T.; Komin, Nu.; Kosack, K.; Kossakowski, R.; Laffon, H.; Lamanna, G.; Lennarz, D.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Masbou, J.; Maurin, D.; Maxted, N.; McComb, T. J. L.; Medina, M. C.; Méhault, J.; Moderski, R.; Moulin, E.; Naumann, C. L.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Nguyen, N.; Nicholas, B.; Niemiec, J.; Nolan, S. J.; Ohm, S.; Olive, J.-F.; de Oña Wilhelmi, E.; Opitz, B.; Ostrowski, M.; Panter, M.; Paz Arribas, M.; Pedaletti, G.; Pelletier, G.; Petrucci, P.-O.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raue, M.; Rayner, S. M.; Reimer, A.; Reimer, O.; Renaud, M.; de Los Reyes, R.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Ruppel, J.; Ryde, F.; Sahakian, V.; Santangelo, A.; Schlickeiser, R.; Schöck, F. M.; Schönwald, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Shalchi, A.; Sikora, M.; Skilton, J. L.; Sol, H.; Spengler, G.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Sushch, I.; Szostek, A.; Tavernet, J.-P.; Terrier, R.; Tibolla, O.; Tluczykont, M.; Valerius, K.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Vialle, J. P.; Viana, A.; Vincent, P.; Vivier, M.; Völk, H. J.; Volpe, F.; Vorobiov, S.; Vorster, M.; Wagner, S. J.; Ward, M.; Wierzcholska, A.; Zajczyk, A.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.; H.E.S.S. Collaboration

    2011-03-01

    The Sculptor and Carina dwarf spheroidal galaxies were observed with the H.E.S.S. Cherenkov telescope array between January 2008 and December 2009. The data sets consist of a total of 11.8 h and 14.8 h of high quality data, respectively. No gamma-ray signal was detected at the nominal positions of these galaxies above 220 GeV and 320 GeV, respectively. Upper limits on the gamma-ray fluxes at 95% CL assuming two forms for the spectral energy distribution (a power law shape and one derived from dark matter annihilation) are obtained at the level of 10-13-10-12 cm-2 s-1 in the TeV range. Constraints on the velocity weighted dark matter particle annihilation cross section for both Sculptor and Carina dwarf galaxies range from ˜ 10-21 cm3 s-1 down to ˜ 10-22 cm3 s-1 depending on the dark matter halo model used. Possible enhancements of the gamma-ray flux are studied: the Sommerfeld effect, which is found to exclude some dark matter particle masses, the internal Bremsstrahlung and clumps in the dark-matter halo distributions.

  15. Herschel far-infrared observations of the Carina Nebula complex II: The embedded young stellar and protostellar population

    CERN Document Server

    Gaczkowski, Benjamin; Ratzka, Thorsten; Roccatagliata, Veronica; Ohlendorf, Henrike; Zinnecker, Hans

    2012-01-01

    The Carina Nebula represents one of the largest and most active star forming regions known in our Galaxy with numerous very massive stars.Our recently obtained Herschel PACS & SPIRE far-infrared maps cover the full area (about 8.7 deg^2) of the Carina Nebula complex and reveal the population of deeply embedded young stellar objects, most of which are not yet visible in the mid- or near-infrared.We study the properties of the 642 objects that are independently detected as point-like sources in at least two of the five Herschel bands.For those objects that can be identified with apparently single Spitzer counterparts, we use radiative transfer models to derive information about the basic stellar and circumstellar parameters.We find that about 75% of the Herschel-detected YSOs are Class 0 protostars.The luminosities of the Herschel-detected YSOs with SED fits are restricted to values of <=5400 Lsun, their masses (estimated from the radiative transfer modeling) range from about 1 Msun to 10 Msun.Taking the...

  16. VLT-UVES observations of the Balmer line variations of eta Carinae during the 2003 spectroscopic event

    CERN Document Server

    Weis, K; Bomans, D J; Davidson, K; Gull, T R; Humphreys, R M; Weis, Kerstin; Stahl, Otmar; Bomans, Dominik J.; Davidson, Kris; Gull, Theodore R.; Humphreys, Roberta M.

    2004-01-01

    We present high spectral resolution echelle observations of the Balmer line variations during the 2003.5 ``spectroscopic event'' of eta Carinae. Spectra have been recorded of both eta Carinae and the Homunculus at the FOS4 position in its SE lobe. This spot shows a reflected stellar spectrum which is less contaminated by nebular emission lines than ground-based observations of the central object itself. Our observations show that the spectroscopic event is much less pronounced at this position than when seen directly on eta Car using HST/STIS. Assuming that the reflected spectrum is indeed latitude dependent this indicates that the spectral changes during the event seen pole-on (FOS4) are different from those closer to the equator (directly on the star). In contrast to the spectrum of the star, the scattered spectrum of FOS4 always shows pronounced P Cygni absorption with little variation across the ``spectroscopic event''. After that event an additional high-velocity absorption component appears. The emissio...

  17. The Absorption Spectrum of High-Density Stellar Ejecta in the Line-of-Sight to Eta Carinae

    CERN Document Server

    Gull, T R; Bruhweiler, F C; Nielsen, K E; Verner, E; Danks, A

    2004-01-01

    Using the high dispersion NUV mode of the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST) to observe Eta Carinae, we have resolved and identified over 500 sharp, circumstellar absorption lines of iron-group singly-ionized and neutral elements with ~20 velocity components ranging from -146 km/s to -585 km/s. These lines are from transitions originating from ground and metastable levels as high as 40,000 cm-1 above ground. The absorbing material is located either in dense inhomogeneities in the stellar wind, the warm circumstellar gas immediately in the vicinity of Eta Carinae, or within the cooler foreground lobe of the Homunculus. We have used classical curve-of-growth analysis to derive atomic level populations for FeII at -146 km/s and for TiII at -513 km/s. These populations, plus photoionization and statistical equilibrium modeling, provide electron temperatures, Te, densities, n, and constraints on distances from the stellar source, r. For the -146 km/s component, we d...

  18. The N II Lines in Eta Carinae: A Further Evidence for Mass Transfer During the Nineteenth Century Great Eruption

    CERN Document Server

    Kashi, Amit

    2011-01-01

    We argue that the emission and the absorption components of he N II lines recently observed in Eta Carinae can originate in the secondary's wind acceleration zone. We base this claim in part on the presence of these lines in hot nitrogen rich stars, such as WN 8 stars, and on the expected clumpy nature of such winds. The envelope of the secondary star in Eta Carinae is expected to be nitrogen rich due to accretion of few solar masses of the primary luminous blue variable's nitrogen rich material during the nineteenth century Great Eruption. Another argument in support of N II lines origin in the acceleration zone of the secondary wind is the behavior of the emission components. The emission components of the lines show the same Doppler shift variation as that of the absorption components. The secondary's-wind origin of the N II lines is compatible with the binary orientation in which the secondary is closer to us near periastron passage.

  19. Inclusion of Horizontal Branch stars in the derivation of star formation histories of dwarf galaxies: the Carina dSph

    CERN Document Server

    Savino, Alessandro; Tolstoy, Eline

    2015-01-01

    We present a detailed analysis of the Horizontal Branch of the Carina Dwarf Spheroidal Galaxy by means of synthetic modelling techniques, taking consistently into account the star formation history and metallicity evolution as determined from main sequence and red giant branch spectroscopic observations. We found that a range of integrated red giant branch mass loss values of 0.1-0.14 M, increasing with metallicity, is able to reproduce the colour extension of the old Horizontal Branch. However, leaving the mass loss as the only free parameter is not enough to match the detailed morphology of Carina Horizontal Branch. We explored the role played by the star formation history on the discrepancies between synthetic and observed Horizontal Branches. We derived a toy bursty star formation history that reproduces the horizontal branch star counts, and also matches qualitatively the red giant and the turn off regions. This star formation history is made of a subset of age and [M/H] components of the star formation ...

  20. Discovery of a high velocity, spatially extended emission ``shell'' in front of the southeast lobe of the eta Carinae Homunculus

    Science.gov (United States)

    Currie, D. G.; Dorland, B. N.; Kaufer, A.

    2002-07-01

    We report the discovery of the eta Carinae ``Ghost Shell,'' a high-velocity, spatially extended emission feature that lies in front of the southeast lobe of the eta Carinae Homunculus. Using data obtained with ``Kueyen,'' one of the European Southern Observatory's Very Large Telescope 8.2 m telescopes and its Ultraviolet and Visible Echelle Spectrograph instrument, we have observed a structure in velocity space of width ~35 km s-1 and with Doppler velocities ranging from -675 Ghost Shell has been detected in emission for multiple allowed Balmer lines and in forbidden lines of [NII], [SII], and [ArIII]. The feature is also associated with a complex absorption structure in Ca H and K lines. We propose that the Ghost Shell lies outside the Homunculus and represents the forward shock between the fast stellar wind of the Great Eruption epoch and the older slow massive stellar wind. Based on observations collected at the European Southern Observatory at Paranal, Chile (UVES commissioning II).

  1. AGS experiments: 1993 - 1994 - 1995

    Energy Technology Data Exchange (ETDEWEB)

    Depken, J.C.

    1996-04-01

    This report contains: FY 1995 AGS Schedule as Run; FY 1996-97 AGE Schedule (working copy); AGS Beams 1995; AGS Experimental Area FY 1993 Physics Program; AGS Experimental Area FY 1994 Physics Program; AGS Experimental Area FY 1995 Physics Program; AGS Experimental Area FY 1996 Physics Program (In progress); A listing of experiments by number; Two-page summaries of each experiment begin here, also ordered by number; Listing of publications of AGS experiments begins here; and Listing of AGS experimenters begins here. This is the twelfth edition.

  2. The Strings of Eta Carina: The HST/STIS Spectra and [Ca II

    Science.gov (United States)

    Melendez, M. B.; Gull, T. R.; Bautista, M. A.; Badnell, N. R.

    2006-01-01

    Long linear, filamentary ejecta, are found to move at very high velocity external to the Homunculus, the circumstellar hourglass-shaped ejecta surrounding Eta Carinae. The origin of the strings is a puzzle. As an example, the Weigelt Blobs have N at 10X solar and C, O at 0.01X solar abundance, along with He/H significantly enhanced. This abundance pattern is evidence for extreme CNO-processing. Similarly, the Strontium Filament has Ti/Ni at 100X solar, presumably due to the lack of oxygen to form Ti-oxide precipitates onto dust grains. We have obtained 2-D spectra with the HST/STIS of the Strontium Filament and a portion of a string. These deep spectral exposures, at moderate dispersion, span much of the near red spectral region from 5000 to 9000A. We have identified twelve emission lines in these spectra with proper velocities and spatial structure of this string and obtained line ratios for [Ca II] (7293/7325A) and [Fe Ill (7157/8619A) which are useful for determining physical conditions in this nebulosity. In an attempt to use the [Ca II] ratio to determine the physical parameters, and ultimately the abundances in the strings, we have constructed a statistical equilibrium model for Ca II , including radiative and collisional rates. These results incorporate our newly calculated atomic data for levels n = 3,4,5 and 6 configurations of Ca II. The aim is to compute the [Ca II] line ratios and use them as a diagnostic of the physical parameters. Using the [Fe II] ratio we find that for Te=10,000 K, the electron density is Ne approx.10(exp 6)/cu cm. We plan to use the [Ca II] ratio to confirm this result. Then, we will extend the use of this multilevel model Ca II atom to study the physical conditions of the Strontium filament where eight lines of Ca II, both allowed and forbidden, had been identified. With the physical conditions determined, we will be able to derive reliable estimates for the gas phase abundances in the strings.

  3. Chandra X-ray observation of the young stellar cluster NGC 3293 in the Carina Nebula Complex

    Science.gov (United States)

    Preibisch, T.; Flaischlen, S.; Gaczkowski, B.; Townsley, L.; Broos, P.

    2017-09-01

    Context. NGC 3293 is a young stellar cluster at the northwestern periphery of the Carina Nebula Complex that has remained poorly explored until now. Aims: We characterize the stellar population of NGC 3293 in order to evaluate key parameters of the cluster population such as the age and the mass function, and to test claims of an abnormal IMF and a deficit of M ≤ 2.5 M⊙ stars. Methods: We performed a deep (70 ks) X-ray observation of NGC 3293 with Chandra and detected 1026 individual X-ray point sources. These X-ray data directly probe the low-mass (M ≤ 2 M⊙) stellar population by means of the strong X-ray emission of young low-mass stars. We identify counterparts for 74% of the X-ray sources in our deep near-infrared images. Results: Our data clearly show that NGC 3293 hosts a large population of ≈solar-mass stars, refuting claims of a lack of M ≤ 2.5 M⊙ stars. The analysis of the color magnitude diagram suggests an age of 8-10 Myr for the low-mass population of the cluster. There are at least 511 X-ray detected stars with color magnitude positions that are consistent with young stellar members within 7 arcmin of the cluster center. The number ratio of X-ray detected stars in the [1-2 ] M⊙ range versus the M ≥ 5 M⊙ stars (known from optical spectroscopy) is consistent with the expectation from a normal field initial mass function. Most of the early B-type stars and ≈20% of the later B-type stars are detected as X-ray sources. Conclusions: Our data shows that NGC 3293 is one of the most populous stellar clusters in the entire Carina Nebula Complex (very similar to Tr 16 and Tr 15; only Tr 14 is more populous). The cluster probably harbored several O-type stars, whose supernova explosions may have had an important impact on the early evolution of the Carina Nebula Complex. The Chandra data described in this paper have been obtained in the open time project with ObsID 16648 (PI: T. Preibisch) ivo://ADS/Sa.CXO#obs/16648.Tables 1-3 are only

  4. A MegaCam Survey of Outer Halo Satellites. VI. The Spatially Resolved Star-formation History of the Carina Dwarf Spheroidal Galaxy

    Science.gov (United States)

    Santana, Felipe A.; Muñoz, Ricardo R.; de Boer, T. J. L.; Simon, Joshua D.; Geha, Marla; Côté, Patrick; Guzmán, Andrés E.; Stetson, Peter; Djorgovski, S. G.

    2016-10-01

    We present the spatially resolved star-formation history (SFH) of the Carina dwarf spheroidal galaxy, obtained from deep, wide-field g and r imaging and a metallicity distribution from the literature. Our photometry covers ˜2 deg2, reaching up to ˜10 times the half-light radius of Carina with a completeness higher than 50% at g ˜ 24.5, more than one magnitude fainter than the oldest turnoff. This is the first time a combination of depth and coverage of this quality has been used to derive the SFH of Carina, enabling us to trace its different populations with unprecedented accuracy. We find that Carina’s SFH consists of two episodes well separated by a star-formation temporal gap. These episodes occurred at old (\\gt 10 Gyr) and intermediate (2-8 Gyr) ages. Our measurements show that the old episode comprises the majority of the population, accounting for 54 ± 5% of the stellar mass within 1.3 times the King tidal radius, while the total stellar mass derived for Carina is 1.60+/- 0.09× {10}6 {M}⊙ , and the stellar mass-to-light ratio is 1.8 ± 0.2. The SFH derived is consistent with no recent star formation, which hints that the observed blue plume is due to blue stragglers. We conclude that the SFH of Carina evolved independently of the tidal field of the Milky Way, since the frequency and duration of its star-formation events do not correlate with its orbital parameters. This result is supported by the age-metallicity relation observed in Carina and the gradients calculated indicating that outer regions are older and more metal-poor. Based on observations obtained with the MegaCam imager on the Magellan II-Clay telescope at Las Campanas Observatory in the Atacama Region, Chile. This telescope is operated by a consortium consisting of the Carnegie Institution of Washington, Harvard University, MIT, the University of Michigan, and the University of Arizona.

  5. Poblaciones estelares en una región de Carina: detección de estrellas masivas altamente enrojecidas

    Science.gov (United States)

    Molina-Lera, J. A.; Gamen, R.; Baume, G. L.; Carraro, G.; Costa, E.

    2016-08-01

    In this work, preliminary results corresponding to a region of the Galaxy close to the direction of the Carina arm are presented. The study was based on deep homogeneous photometric data ( ), obtained in the Inter-American Observatory Cerro Tololo. Data was complemented with 2MASS catalog infrared data, spectral classification of literature and own spectroscopic observations using Gemini. From our photometric analysis of the stars in the area, we could identify three stellar populations. Two of them are linked with young open clusters and the third one is characterized by a consistent set of objects with highly reddened early stars. The spectral types determined, for a sample of these stars, allowed us to confirm this hypothesis, since in all cases they were identified as massive OB type stars.

  6. He II {lambda}4686 IN {eta} CARINAE: COLLAPSE OF THE WIND-WIND COLLISION REGION DURING PERIASTRON PASSAGE

    Energy Technology Data Exchange (ETDEWEB)

    Teodoro, M.; Damineli, A. [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao 1226, Cidade Universitaria, Sao Paulo 05508-900 (Brazil); Arias, J. I. [Departamento de Fisica, Universidad de La Serena, Av. Cisternas 1200 Norte, La Serena (Chile); De Araujo, F. X.; Borges Fernandes, M.; Pereira, C. B. [Observatorio Nacional, Rua General Jose Cristino 77, Sao Cristovao, Rio de Janeiro 20921-400 (Brazil); Barba, R. H.; Gonzalez, J. F. [Instituto de Ciencias Astronomicas, de la Tierra, y del Espacio (ICATE-CONICET), Avenida Espana Sur 1512, J5402DSP San Juan (Argentina); Corcoran, M. F. [CRESST and X-ray Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Fernandez-Lajus, E.; Gamen, R. C.; Solivella, G. R. [Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, La Plata, BA, B1900FWA (Argentina); Fraga, L. [Southern Observatory for Astrophysical Research, Colina El Pino s/n, Casilla 603, La Serena (Chile); Groh, J. H. [Max-Planck-Institute fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Marshall, J. L. [Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843-4242 (United States); McGregor, P. J.; Nicholls, D. C.; Parkin, E. R. [Research School of Astronomy and Astrophysics (RSAA), Mount Stromlo Observatory, Cotter Road, Weston, ACT 2611 (Australia); Morrell, N.; Phillips, M. M., E-mail: mairan@astro.iag.usp.br [Las Campanas Observatory, Observatories of the Carnegie Institution of Washington, Casilla 601, La Serena (Chile); and others

    2012-02-10

    The periodic spectroscopic events in {eta} Carinae are now well established and occur near the periastron passage of two massive stars in a very eccentric orbit. Several mechanisms have been proposed to explain the variations of different spectral features, such as an eclipse by the wind-wind collision (WWC) boundary, a shell ejection from the primary star or accretion of its wind onto the secondary. All of them have problems explaining all the observed phenomena. To better understand the nature of the cyclic events, we performed a dense monitoring of {eta} Carinae with five Southern telescopes during the 2009 low-excitation event, resulting in a set of data of unprecedented quality and sampling. The intrinsic luminosity of the He II {lambda}4686 emission line (L {approx} 310 L{sub Sun }) just before periastron reveals the presence of a very luminous transient source of extreme UV radiation emitted in the WWC region. Clumps in the primary's wind probably explain the flare-like behavior of both the X-ray and He II {lambda}4686 light curves. After a short-lived minimum, He II {lambda}4686 emission rises again to a new maximum, when X-rays are still absent or very weak. We interpret this as a collapse of the WWC onto the 'surface' of the secondary star, switching off the hard X-ray source and diminishing the WWC shock cone. The recovery from this state is controlled by the momentum balance between the secondary's wind and the clumps in the primary's wind.

  7. New insights into the nature of the peculiar star θ Carinae

    Science.gov (United States)

    Hubrig, S.; Briquet, M.; Morel, T.; Schöller, M.; González, J. F.; De Cat, P.

    2008-09-01

    Context: θ Carinae belongs to a group of peculiar early-type stars (OBN) with enhanced nitrogen and carbon deficiency. It is also known as a binary system, but it is not clear yet whether the chemical anomalies can be explained by mass transfer between the two components. On the basis of the previously reported spectral variability of a few metal lines it may be expected that θ Car possesses a weak magnetic field. Aims: A study of the physical nature of this hot massive binary which is furthermore a well-known blue straggler lying ~2 mag above the turnoff of the young open cluster IC 2602 is important to understand the origin of its strong chemical anomalies. Methods: We acquired high resolution spectroscopic and low resolution spectropolarimetric observations to achieve the following goals: a) to improve the orbital parameters to allow a more in-depth discussion on the possibility of mass transfer in the binary system; b) to carry out a non-local thermodynamic equilibrium (NLTE) abundance analysis; and c) to search for the presence of a magnetic field. Results: The study of the radial velocities using CORALIE spectra allowed us to significantly improve the orbital parameters. A comparative NLTE abundance analysis was undertaken for θ Car and two other early B-type stars with recently detected magnetic fields, τ Sco and ξ1 CMa. The analysis revealed significantly different abundance patterns: a one-order-of-magnitude nitrogen overabundance and carbon depletion was found in θ Car, while the oxygen abundance is roughly solar. For the stars ξ1 CMa and τ Sco the carbon abundance is solar and, while an N excess is also detected, it is of much smaller amplitude (0.4-0.6 dex). Such an N overabundance is typical of the values already found for other slowly-rotating (magnetic) B-type dwarfs. For θ Car, we attribute instead the chemical peculiarities to a past episode of mass transfer between the two binary components. The results of the search for a magnetic field

  8. Heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalyst with enhanced photocatalytic activity and stability under visible light

    Science.gov (United States)

    Wang, Wan-Sheng; Du, Hong; Wang, Rui-Xia; Wen, Tao; Xu, An-Wu

    2013-03-01

    A heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalyst was prepared by a rational in situ ion exchange reaction between Ag3PO4 micro-cubes and Br- in aqueous solution followed by photoreduction. The photocatalytic activities of obtained photocatalysts were measured by the degradation of methyl orange (MO) and methylene blue (MB) under visible light irradiation (λ >= 400 nm). Compared to AgBr/Ag, Ag3PO4/AgBr heterocrystals and pure Ag3PO4 crystals, the heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalysts exhibit much higher photocatalytic activity and stability. This enhanced photocatalytic activity suggests that the synergetic effects of the heterostructured Ag3PO4/AgBr/Ag and the strong SPR of Ag NPs on the surface result in the high efficiencies of the photocatalytic activity and the improved stability. With the assistance of Ag3PO4/AgBr/Ag heterostructures, only 8 min and 12 min are taken to completely decompose MO and MB molecules under visible-light irradiation, respectively. Furthermore, the photodegradation rate does not show an obvious decrease during ten successive cycles, indicating that our heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalysts are extremely stable under visible-light irradiation.A heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalyst was prepared by a rational in situ ion exchange reaction between Ag3PO4 micro-cubes and Br- in aqueous solution followed by photoreduction. The photocatalytic activities of obtained photocatalysts were measured by the degradation of methyl orange (MO) and methylene blue (MB) under visible light irradiation (λ >= 400 nm). Compared to AgBr/Ag, Ag3PO4/AgBr heterocrystals and pure Ag3PO4 crystals, the heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalysts exhibit much higher photocatalytic activity and stability. This enhanced photocatalytic activity suggests that the synergetic effects of the heterostructured Ag3PO4/AgBr/Ag and the strong SPR of Ag NPs on the surface result in the high

  9. About AgEcon Search

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>AgEcon Search is a free,open access repository of full - text scholarly literature in agricultural and applied economics,inclu-ding working papers,conference papers,and journal articles. AgEcon Search is

  10. AGS Booster prototype magnets

    Energy Technology Data Exchange (ETDEWEB)

    Danby, G.; Jackson, J.; Lee, Y.Y.; Phillips, R.; Brodowski, J.; Jablonski, E.; Keohane, G.; McDowell, B.; Rodger, E.

    1987-03-19

    Prototype magnets have been designed and constructed for two half cells of the AGS Booster. The lattice requires 2.4m long dipoles, each curved by 10/sup 0/. The multi-use Booster injector requires several very different standard magnet cycles, capable of instantaneous interchange using computer control from dc up to 10 Hz.

  11. The VISTA Carina Nebula Survey. II. Spatial distribution of the infrared-excess-selected young stellar population

    Science.gov (United States)

    Zeidler, P.; Preibisch, T.; Ratzka, T.; Roccatagliata, V.; Petr-Gotzens, M. G.

    2016-01-01

    We performed a deep wide-field (6.76 sq. deg) near-infrared survey with the VISTA telescope that covers the entire extent of the Carina nebula complex (CNC). The point-source catalog created from these data contains around four million individual objects down to masses of 0.1 M⊙. We present a statistical study of the large-scale spatial distribution and an investigation of the clustering properties of infrared-excesses objects, which are used to trace disk-bearing young stellar objects (YSOs). A selection based on a near-infrared (J-H) versus (H-Ks) color-color diagram shows an almost uniform distribution over the entire observed area. We interpret this as a result of the very high degree of background contamination that arises from the Carina Nebula's location close to the Galactic plane. Complementing the VISTA near-infrared catalog with Spitzer IRAC mid-infrared photometry improves the situation of the background contamination considerably. We find that a (J-H) versus (Ks- [4.5]) color-color diagram is well suited to tracing the population of YSO-candidates (cYSOs) by their infrared excess. We identify 8781 sources with strong infrared excess, which we consider as cYSOs. This sample is used to investigate the spatial distribution of the cYSOs with a nearest-neighbor analysis. The surface density distribution of cYSOs agrees well with the shape of the clouds as seen in our Herschel far-infrared survey. The strong decline in the surface density of excess sources outside the area of the clouds supports the hypothesis that our excess-selected sample consists predominantly of cYSOs with a low level of background contamination. This analysis allows us to identify 14 groups of cYSOs outside the central area.Our results suggest that the total population of cYSOs in the CNC comprises about 164 000 objects, with a substantial fraction (~35%) located in the northern, still not well studied parts. Our cluster analysis suggests that roughly half of the cYSOs constitute a

  12. AGS experiments -- 1991, 1992, 1993. Tenth edition

    Energy Technology Data Exchange (ETDEWEB)

    Depken, J.C.

    1994-04-01

    This report contains: (1) FY 1993 AGS schedule as run; (2) FY 1994--95 AGS schedule; (3) AGS experiments {ge} FY 1993 (as of 30 March 1994); (4) AGS beams 1993; (5) AGS experimental area FY 1991 physics program; (6) AGS experimental area FY 1992 physics program; (7) AGS experimental area FY 1993 physics program; (8) AGS experimental area FY 1994 physics program (planned); (9) a listing of experiments by number; (10) two-page summaries of each experiment; (11) listing of publications of AGS experiments; and (12) listing of AGS experiments.

  13. AGS experiments -- 1995, 1996 and 1997

    Energy Technology Data Exchange (ETDEWEB)

    Depken, J.C.; Presti, P.L.

    1997-12-01

    This report contains (1) FY 1995 AGS schedule as run; (2) FY 1996 AGS schedule as run; (3) FY 1997 AGS schedule as run; (4) FY 1998--1999 AGS schedule (proposed); (5) AGS beams 1997; (6) AGS experimental area FY 1995 physics program; (7) AGS experimental area FY 1996 physics program; (8) AGS experimental area FY 1997 physics program; (9) AGS experimental area FY 1998--1999 physics program (proposed); (10) a listing of experiments by number; (11) two-page summaries of each experiment, in order by number; and (12) listing of publications of AGS experiments.

  14. Carina as a useful and reliable radiological landmark for detection of accidental arterial placement of central venous catheters.

    Science.gov (United States)

    Umesh, Goneppanavar; Ranjan, Shetty; Jasvinder, Kaur; Nanda, Shetty

    2010-12-01

    Central venous catheters are commonly used in the management of critically ill patients. Their insertion can be challenging in hemodynamically unstable patients and in those with altered thoracic anatomy. Although ultrasound guided insertion can reduce this problem, this facility may not be available in all locations and in all institutions. Accidental arterial puncture is one of the very serious complications that can occur during central venous catheter insertion. This is usually detected clinically by bright color and projectile/pulsatile flow of the returning blood. However, such means are known to be misleading especially in hypoxic and hemodynamically unstable patients. Other recognized measures used to identify arterial puncture would be blood gas analysis of the returning blood, use of pressure transducer to identify waveform pattern and the pressures. In this article, we propose that trachea and carina can be used as a reliable radiological landmark to identify accidental arterial placement of central venous catheters. We further conclude that this information could be useful especially when dealing with post-resuscitation victims and hemodynamically unstable critically ill patients.

  15. The Carina Nebula and Gum 31 molecular complex: I. Molecular gas distribution, column densities and dust temperatures

    CERN Document Server

    Rebolledo, David; Green, Anne; Braiding, Catherine; Molinari, Sergio; Wong, Graeme; Blackwell, Rebecca; Elia, Davide; Schisano, Eugenio

    2015-01-01

    We report high resolution observations of the $^{12}$CO$(1\\rightarrow0)$ and $^{13}$CO$(1\\rightarrow0)$ molecular lines in the Carina Nebula and the Gum 31 region obtained with the 22-m Mopra telescope as part of the The Mopra Southern Galactic Plane CO Survey. We cover 8 deg$^2$ from $l = 285^{\\circ}$ to 290$^{\\circ}$, and from $b = -1.5^{\\circ}$ to +0.5$^{\\circ}$. The molecular gas column density distributions from both tracers have a similar range of values. By fitting a grey-body function to the observed infrared spectral energy distribution from Herschel maps, we derive gas column densities and dust temperatures. The gas column density has values in the range from $6.3\\times\\ 10^{20}$ to $1.4\\times 10^{23}$ cm$^{-2}$, while the dust temperature has values in the range from 17 to 43 K. The gas column density derived from the dust emission is approximately described by a log-normal function for a limited range of column densities. A high-column density tail is clearly evident for the gas column density dis...

  16. To v∞ and beyond! The He I absorption variability across the 2014.6 periastron passage of η Carinae

    Science.gov (United States)

    Richardson, Noel D.; Madura, Thomas I.; St-Jean, Lucas; Moffat, Anthony F. J.; Gull, Theodore R.; Russell, Christopher M. P.; Damineli, Augusto; Teodoro, Mairan; Corcoran, Michael F.; Walter, Frederick M.; Clementel, Nicola; Groh, José H.; Hamaguchi, Kenji; Hillier, D. John

    2016-09-01

    We have monitored the massive binary star η Carinae with the CTIO/Small and Moderate Aperture Research Telescope System 1.5 m telescope and CHIRON spectrograph from the previous apastron passage of the system through the recent 2014.6 periastron passage. Our monitoring has resulted in a large, homogeneous data set with an unprecedented time-sampling, spectral resolving power, and signal to noise. This allowed us to investigate temporal variability previously unexplored in the system and discover a kinematic structure in the P Cygni absorption troughs of neutral helium wind lines. The features observed occurred prior to the periastron passage and are seen as we look through the trailing arm of the wind-wind collision shock cone. We show that the bulk of the variability is repeatable across the last five periastron passages, and that the absorption occurs in the inner 230 au of the system. In addition, we found an additional, high-velocity absorption component superimposed on the P Cygni absorption troughs that has been previously unobserved in these lines, but which bears resemblance to the observations of the He I λ10830 Å feature across previous cycles. Through a comparison of the current smoothed particle hydrodynamical simulations, we show that the observed variations are likely caused by instabilities in the wind-wind collision region in our line of sight, coupled with stochastic variability related to clumping in the winds.

  17. 3D radiative transfer simulations of Eta Carinae's inner colliding winds - II: Ionization structure of helium at periastron

    CERN Document Server

    Clementel, Nicola; Kruip, Chael J H; Paardekooper, Jan-Pieter

    2015-01-01

    Spectral observations of the massive colliding wind binary Eta Carinae show phase-dependent variations, in intensity and velocity, of numerous helium emission and absorption lines throughout the entire 5.54-year orbit. Approaching periastron, the 3D structure of the wind-wind interaction region (WWIR) gets highly distorted due to the eccentric ($e \\sim 0.9$) binary orbit. The secondary star ($\\eta_{\\mathrm{B}}$) at these phases is located deep within the primary's dense wind photosphere. The combination of these effects is thought to be the cause of the particularly interesting features observed in the helium lines at periastron. We perform 3D radiative transfer simulations of $\\eta$ Car's interacting winds at periastron. Using the SimpleX radiative transfer algorithm, we post-process output from 3D smoothed particle hydrodynamic simulations of the inner 150 au of the $\\eta$ Car system for two different primary star mass-loss rates ($\\dot{M}_{\\eta_{\\mathrm{A}}}$). Using previous results from simulations at ap...

  18. The VISTA Carina Nebula Survey II. Spatial distribution of the infrared-excess-selected young stellar population

    CERN Document Server

    Zeidler, Peter; Ratzka, Thorsten; Roccatagliata, Veronica; Petr-Gotzens, Monika G

    2016-01-01

    We performed a deep wide-field (6.76 deg^2) near-infrared survey with the VISTA telescope that covers the entire extent of the Carina nebula complex (CNC). The point-source catalog created from these data contains around four million individual objects down to masses of 0.1 M_sun. We present a statistical study of the large-scale spatial distribution and an investigation of the clustering properties of infrared-excesses objects, which are used to trace disk-bearing young stellar objects (YSOs). We find that a (J - H) versus (Ks - [4.5]) color-color diagram is well suited to tracing the population of YSO-candidates (cYSOs) by their infrared excess. We identify 8781 sources with strong infrared excess, which we consider as cYSOs. This sample is used to investigate the spatial distribution of the cYSOs with a nearest-neighbor analysis. The surface density distribution of cYSOs agrees well with the shape of the clouds as seen in our Herschel far-infrared survey. The strong decline in the surface density of excess...

  19. The Spectral Temperature of Optically Thick Outflows with Application to Light Echo Spectra from $\\eta$~Carinae's Giant Eruption

    CERN Document Server

    Owocki, Stanley P

    2016-01-01

    The detection by Rest et al. (2012) of light echoes from $\\eta$ Carinae has provided important new observational constraints on the nature of its 1840's era giant eruption. Spectra of the echoes suggest a relatively cool spectral temperature of about 5500K, lower than the lower limit of about 7000K suggested in the optically thick wind outflow analysis of Davidson (1987). This has lead to a debate about the viability of this steady wind model relative to alternative, explosive scenarios. Here we present an updated analysis of the wind outflow model using newer low-temperature opacity tabulations and accounting for the stronger mass loss implied by the $>$10 Msun mass now inferred for the Homunculus. A major conclusion is that, because of the sharp drop in opacity due to free electron recombination for $T<$6500K, a low temperature of about 5000K is compatible with, and indeed expected from, a wind with the extreme mass loss inferred for the eruption. Within a spherical gray model in radiative equilibrium, w...

  20. HST/WFC3 Imaging of Protostellar Jets in Carina: [Fe II] Emission Tracing Massive Jets from Intermediate Mass Protostars

    CERN Document Server

    Reiter, Megan

    2013-01-01

    We present narrowband WFC3-UVIS and -IR images of four externally irradiated protostellar jets in the Carina nebula: HH666, HH901, HH902, and HH1066. These massive jets are unusual because they are bathed in UV radiation from dozens of nearby O stars, but despite the strong incident ionizing radiation, portions of the jet remain neutral. Near-IR [Fe II] images reveal dense, neutral gas that was not seen in previous studies of H-alpha emission. We show that near-IR [Fe II] emitting gas must be self-shielded from Lyman continuum photons, regardless of its excitation mechanism (shocks, FUV radiation, or both). High densities are required for the survival of Fe+ amid the strong Lyman continuum from Tr14, raising estimates of the mass-loss rates by an order of magnitude. Higher jet mass-loss rates require higher accretion rates onto their driving protostars, implying that these jets are driven by intermediate-mass (IM; ~2-8 Msun) stars. Indeed, the IR driving sources of two of these outflows have luminosities that...

  1. Is Eta Carinae a fast rotator, and how much does the companion influence the inner wind structure?

    CERN Document Server

    Groh, Jose H; Owocki, Stanley P; Hillier, D John; Weigelt, Gerd

    2010-01-01

    We analyze interferometric measurements of the Luminous Blue Variable Eta Carinae with the goal of constraining the rotational velocity of the primary star and probing the influence of the companion. Using 2-D radiative transfer models of latitude-dependent stellar winds, we find that prolate wind models with a ratio of the rotational velocity (vrot) to the critical velocity (vcrit) of W=0.77-0.92, inclination angle of i=60-90 degrees, and position angle PA=108-142 degrees reproduce simultaneously K-band continuum visibilities from VLTI/VINCI and closure phase measurements from VLTI/AMBER. Interestingly, oblate models with W=0.73-0.90 and i=80-90 degrees produce similar fits to the interferometric data, but require PA=210-230 degrees. Therefore, both prolate and oblate models suggest that the rotation axis of the primary star is not aligned with the Homunculus polar axis. We also compute radiative transfer models of the primary star allowing for the presence of a cavity and dense wind-wind interaction region ...

  2. Absolute dimensions of eclipsing binaries. XXIV. The Be star system DW Carinae, a member of the open cluster Collinder 228

    CERN Document Server

    Southworth, J; Southworth, John

    2006-01-01

    DW Carinae is a close but detached early B-type eclipsing binary in the young open cluster Cr 228. We have measured accurate physical properties of its components (masses and radii to 1%) and used these to derive the age, metallicity and distance of Cr 228. The rotational velocities of both components of DW Car are high, so we have investigated the performance of double-Gaussian fitting, one- and two-dimensional cross-correlation and spectral disentangling for measuring radial velocities in the presence of strong line blending. Gaussian and cross-correlation analyses require substantial corrections for the effects of line blending, which are only partially successful for cross-correlation. Disentangling is to be preferred because it does not assume anything about the shapes of spectral lines, and is not significantly affected by blending. Complete Stromgren uvby light curves have been obtained and accurate radii have been measured from them using the Wilson-Devinney program, constrained by an accurate spectro...

  3. Herschel far-infrared observations of the Carina Nebula Complex. - III: Detailed cloud structure and feedback effects

    CERN Document Server

    Roccatagliata, Veronica; Ratzka, Thorsten; Gaczkowski, Benjamin

    2013-01-01

    The Carina Nebula complex (CNC) represents one of the most massive star-forming regions in our Galaxy and shows strong feedback from the high massive stars. We use our Herschel FIR observations to study the properties of the clouds over the entire area of the CNC. The good angular resolution of the Herschel maps corresponds to physical scales of 0.1 - 0.4 pc, and allows us to analyze the small-scale structures of the clouds. The full extent of the CNC was mapped with PACS and SPIRE from 70 to 500 micron. We determine temperatures and column densities at each point in this maps by modeling the observed FIR SEDs. We also derive a map showing the strength of the UV field. We investigate the relation between the cloud properties and the spatial distribution of the high-mass stars, and compute total cloud masses for different density thresholds. Our Herschel maps resolve, for the first time, the small-scale structure of the dense clouds. Several particularly interesting regions, including the prominent pillars sou...

  4. Near-infrared integral field spectroscopy of the Homunculus nebula around Eta Carinae using Gemini/CIRPASS

    CERN Document Server

    Teodoro, M; Sharp, R G; Groh, J H; Barbosa, C L

    2008-01-01

    This work presents the first integral field spectroscopy of the Homunculus nebula around Eta Carinae in the near-infrared spectral region (J band). We confirmed the presence of a hole on the polar region of each lobe, as indicated by previous near-IR long-slit spectra and mid-IR images. The holes can be described as a cylinder of height (i.e. the thickness of the lobe) and diameter of 6.5 and 6.0x10^{16} cm, respectively. We also mapped the blue-shifted component of He I 10830 seen towards the NW lobe. Contrary to previous works, we suggested that this blue-shifted component is not related to the Paddle but it is indeed in the equatorial disc. We confirmed the claim of Smith (2005) and showed that the spatial extent of the Little Homunculus matches remarkably well the radio continuum emission at 3 cm, indicating that the Little Homunculus can be regarded as a small HII region. Therefore, we used the optically-thin 1.3 mm radio flux to derive a lower limit for the number of Lyman-continuum photons of the centr...

  5. [Fe II] 1.64 um Features of Jets and Outflows from Young Stellar Objects in the Carina Nebula

    CERN Document Server

    Shinn, Jong-Ho; Lee, Jae-Joon; Lee, Ho-Gyu; Kim, Hyun-Jeong; Koo, Bon-Chul; Sung, Hwankyung; Chun, Moo Young; Lyo, A -Ran; Moon, Dae-Sik; Kyeong, Jaemann; Park, Byeong-Gon; Hur, Hyeonoh; Lee, Yong-Hyun

    2013-01-01

    We present [Fe II] 1.64 {\\mu}m imaging observations for jets and outflows from young stellar objects (YSOs) over the northern part (~ 24'x45') of the Carina Nebula, a massive star forming region. The observations were performed with IRIS2 of Anglo-Australian Telescope and the seeing was ~1.5"+-0.5". Eleven jet and outflow features are detected at eight different regions, and are named as Ionized Fe Objects (IFOs). One Herbig-Haro object candidate missed in Hubble Space Telescope H{\\alpha} observations is newly identified as HHc-16, referring our [Fe II] images. IFOs have knotty or longish shapes, and the detection rate of IFOs against previously identified YSOs is 1.4 %, which should be treated as a lower limit. Four IFOs show an anti-correlated peak intensities in [Fe II] and H{\\alpha}, where the ratio I([Fe II])/I(H{\\alpha}) is higher for longish IFOs than for knotty IFOs. We estimate the outflow mass loss rate from the [Fe II] flux, using two different methods. The jet-driving objects are identified for th...

  6. Suzaku Monitoring of Hard X-ray Emission from Eta Carinae over a Single Binary Orbital Cycle

    CERN Document Server

    Hamaguchi, Kenji; Takahashi, Hiromitsu; Yuasa, Takayuki; Ishida, Manabu; Gull, Theodore R; Pittard, Julian M; Russell, Christopher M P; Madura, Thomas I

    2014-01-01

    The Suzaku X-ray observatory monitored the supermassive binary system Eta Carinae 10 times during the whole 5.5 year orbital cycle between 2005-2011. This series of observations presents the first long-term monitoring of this enigmatic system in the extremely hard X-ray band between 15-40 keV. During most of the orbit, the 15-25 keV emission varied similarly to the 2-10 keV emission, indicating an origin in the hard energy tail of the kT ~4 keV wind-wind collision (WWC) plasma. However, the 15-25 keV emission declined only by a factor of 3 around periastron when the 2-10 keV emission dropped by two orders of magnitude due probably to an eclipse of the WWC plasma. The observed minimum in the 15-25 keV emission occurred after the 2-10 keV flux had already recovered by a factor of ~3. This may mean that the WWC activity was strong, but hidden behind the thick primary stellar wind during the eclipse. The 25-40 keV flux was rather constant through the orbital cycle, at the level measured with INTEGRAL in 2004. Thi...

  7. 3D radiative transfer simulations of Eta Carinae's inner colliding winds - I. Ionization structure of helium at apastron

    CERN Document Server

    Clementel, Nicola; Kruip, Chael; Paardekooper, Jan-Pieter; Gull, Theodore R

    2014-01-01

    The highly eccentric binary system Eta Carinae shows numerous time-variable emission and absorption features. These observational signatures are the result of interactions between the complex three-dimensional (3D) wind-wind collision regions and photoionization by the luminous stars. Specifically, helium presents several interesting spectral features that provide important clues on the geometry and physical properties of the system and the individual stars. We use the SimpleX algorithm to post-process 3D smoothed particle hydrodynamics simulation output of the interacting winds in Eta Car in order to obtain the fractions of ionized helium assuming three different primary star mass-loss rates. The resultant ionization maps constrain the regions where helium is singly- and doubly-ionized. We find that reducing the primary's mass-loss rate increases the volume of He+. Lowering the primary mass-loss rate produces large variations in the volume of He+ in the pre-shock primary wind on the periastron side of the sy...

  8. High energy emission from massive stars: the precocious X-Ray recovery of Eta Carinae after January 2009 minimum

    CERN Document Server

    Pian, Elena; Chincarini, Guido; Corcoran, Michael F; Hamaguchi, Kenji; Gull, Theodore; Mazzali, Paolo A; Thoene, Christina C; Morris, David; Gehrels, Neil

    2009-01-01

    We observed the massive binary stellar system of Eta Carinae in the 0.3-10 keV energy range with the X-ray Telescope onboard the Swift satellite during the period 15 December 2008 - 11 March 2009, i.e. 1 month before to 2 months after the X-ray drop from maximum to minimum, thought to be associated with the periastron encounter of the primary star by the hot companion. Beginning a few months before eclipse, the interaction between the winds of the two stars intensifies and the X-ray flux reaches maximum. The flux drops dramatically thereafter, subsiding in about 20 days to a level that is at least a factor 10 lower than the 'high state', i.e. the X-ray emission state of the system during the largest fraction of its 5.52 yr orbit (~e-11 erg/s/cm2). Unlike in previous cycles, when the low state lasted about 2.5 months, observations with RXTE showed that the X-ray flux started its recovery to normal level about 1.5 months after the minimum. We suggest that this early recovery may be due to the fact that the comp...

  9. Constraints on decreases in Eta Carinae's mass loss from 3D hydrodynamic simulations of its binary colliding winds

    CERN Document Server

    Madura, Thomas I; Okazaki, Atsuo T; Russell, Christopher M P; Owocki, Stanley P; Groh, Jose H; Corcoran, Michael F; Hamaguchi, Kenji; Teodoro, Mairan

    2013-01-01

    Recent work suggests that the mass-loss rate of the primary star (Eta A) in the massive colliding wind binary Eta Carinae dropped by a factor of 2-3 between 1999 and 2010. We present results from large- (r=1545au) and small- (r=155au) domain, 3D smoothed particle hydrodynamic (SPH) simulations of Eta Car's colliding winds for 3 Eta A mass-loss rates (2.4, 4.8, and 8.5 x 10^-4 M_sun/yr), investigating the effects on the dynamics of the binary wind-wind collision (WWC). These simulations include orbital motion, optically thin radiative cooling, and radiative forces. We find that Eta A's mass-loss rate greatly affects the time-dependent hydrodynamics at all spatial scales investigated. The simulations also show that the post-shock wind of the companion star (Eta B) switches from the adiabatic to the radiative-cooling regime during periastron passage. The SPH simulations together with 1D radiative transfer models of Eta A's spectra reveal that a factor of 2 or more drop in Eta A's mass-loss rate should lead to su...

  10. Constraining the Absolute Orientation of Eta Carinae's Binary Orbit: A 3-D Dynamical Model for the Broad [Fe III] Emission

    CERN Document Server

    Madura, Thomas I; Owocki, Stanley P; Groh, Jose H; Okazaki, Atsuo T; Russell, Christopher M P

    2011-01-01

    We present a three-dimensional (3-D) dynamical model for the broad [Fe III] emission observed in Eta Carinae using the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS). This model is based on full 3-D Smoothed Particle Hydrodynamics (SPH) simulations of Eta Car's binary colliding winds. Radiative transfer codes are used to generate synthetic spectro-images of [Fe III] emission line structures at various observed orbital phases and STIS slit position angles (PAs). Through a parameter study that varies the orbital inclination i, the PA {\\theta} that the orbital plane projection of the line-of-sight makes with the apastron side of the semi-major axis, and the PA on the sky of the orbital axis, we are able, for the first time, to tightly constrain the absolute 3-D orientation of the binary orbit. To simultaneously reproduce the blue-shifted emission arcs observed at orbital phase 0.976, STIS slit PA = +38 degrees, and the temporal variations in emission seen at negative slit PAs, the binary ...

  11. Light Echoes from $\\eta$ Carinae's Great Eruption: Spectrophotometric Evolution and the Rapid Formation of Nitrogen-rich Molecules

    CERN Document Server

    Prieto, J L; Bianco, F B; Matheson, T; Smith, N; Walborn, N R; Hsiao, E Y; Chornock, R; Alvarez, L Paredes; Campillay, A; Contreras, C; Gonzalez, C; James, D; Knapp, G R; Kunder, A; Margheim, S; Morrell, N; Phillips, M M; Smith, R C; Welch, D L; Zenteno, A

    2014-01-01

    We present follow-up optical imaging and spectroscopy of one of the light echoes of $\\eta$ Carinae's 19th-century Great Eruption discovered by Rest et al. (2012). By obtaining images and spectra at the same light echo position between 2011 and 2014, we follow the evolution of the Great Eruption on a three-year timescale. We find remarkable changes in the photometric and spectroscopic evolution of the echo light. The $i$-band light curve shows a decline of $\\sim 0.9$ mag in $\\sim 1$ year after the peak observed in early 2011 and a flattening at later times. The spectra show a pure-absorption early G-type stellar spectrum at peak, but a few months after peak the lines of the [Ca II] triplet develop strong P-Cygni profiles and we see the appearance of [Ca II] 7291,7324 doublet in emission. These emission features and their evolution in time resemble the spectra of some Type IIn supernovae and supernova impostors. Most surprisingly, starting $\\sim 300$ days after peak brightness, the spectra show strong molecular...

  12. CCD observations of additional interstellar lines in stars associated with the Vela Remnant and Eta Carinae nebulosity

    Science.gov (United States)

    Wallerstein, George; Gilroy, Kalpana K.

    1992-01-01

    Nine stars from the Vela Remnant and seven stars in the Eta Carinae complex are examined with CCD spectrograms with high signal-to-noise ratios for data regarding the optical interstellar lines. These data are supplemented by observations of objects with known high-velocity components and substantial interstellar Ti II lines. The CCD spectrograms have signal-to-noise ratios of 100-300, a 2-pixel resolving power of 20,000, and cover features of Na I, Ti II, Ca I, CH(+), and CH in the 3200-4400-A range. The Ca I line confirms the high H density in Vela, and the Ti II lines show evidence of shock-induced grain evaporation. Weak shocks are thought to contribute to the CH(+) component, and a high H I density in some clouds is inferred from the CH line. The high H I density is supported by IUE data on Ca I and on the fine-structure carbon lines. The data point to a significant difference in spectroscopic morphology between the two groups of stars, and the need for theoretical support is underscored.

  13. Mass accretion rates from multi-band photometry in the Carina Nebula: the case of Trumpler 14

    CERN Document Server

    Beccari, G; Panagia, N; Valenti, E; Carraro, G; Romaniello, M; Zoccali, M; Weidner, C

    2014-01-01

    We present a study of the mass accretion rates of pre-Main Sequence (PMS) stars in the cluster Trumpler 14 (Tr14) in the Carina Nebula. Using optical multi-band photometry we were able to identify 356 PMS stars showing H-alpha excess emission with equivalent width EW(H-alpha)>20\\AA. We interpret this observational feature as indication that these objects are still actively accreting gas from their circumstellar medium. From a comparison of the HR diagram with PMS evolutionary models we derive ages and masses of the PMS stars. We find that most of the PMS objects are younger than 10 Myr with a median age of ~3 Myr. Surprisingly, we also find that ~20% of the mass accreting objects are older than 10 Myr. For each PMS star in Trumpler 14 we determine the mass accretion rate ($\\dot{M}_{acc}$) and discuss its dependence on mass and age. We finally combine the optical photometry with near-IR observations to build the spectral energy distribution (SED) for each PMS star in Tr14. The analysis of the SEDs suggests the...

  14. Spitzer Space Telescope observations of the Carina Nebula: The steady march of feedback-driven star formation

    CERN Document Server

    Smith, Nathan; Whitney, Barbara A; Churchwell, Ed; Babler, Brian L; Meade, Marilyn R; Bally, John; Gehrz, Robert D; Robitaille, Thomas P; Stassun, Keivan G

    2010-01-01

    We report the first results of imaging the Carina Nebula with Spitzer/IRAC, providing a catalog of point sources and YSOs based on SED fits. We discuss several aspects of the extended emission, including dust pillars that result when a clumpy molecular cloud is shredded by massive star feedback. There are few "extended green objects" (EGOs) normally taken as signposts of outflow activity, and none of the HH jets detected optically are seen as EGOs. A population of "extended red objects" tends to be found around OB stars, some with clear bow-shocks. These are dusty shocks where stellar winds collide with flows off nearby clouds. Finally, the relative distributions of O stars and subclusters of YSOs as compared to dust pillars shows that while some YSOs are located within pillars, many more stars and YSOs reside just outside pillar heads. We suggest that pillars are transient phenomena, part of a continuous outwardly propagating wave of star formation driven by massive star feedback. As pillars are destroyed, t...

  15. The Secret Lives of Cepheids: Evolution, Mass Loss, and Ultraviolet Emission of the Long-Period Classical Cepheid $l$ Carinae

    CERN Document Server

    Neilson, Hilding R; Guinan, Edward F; Bisol, Alexandra C; Butterworth, Neil

    2016-01-01

    The classical Cepheid $l$ Carinae is an essential calibrator of the Cepheid Leavitt Law as a rare long-period Galactic Cepheid. Understanding the properties of this star will also constrain the physics and evolution of massive ($M \\ge 8$ $M_\\odot$) Cepheids. The challenge, however, is precisely measuring the star's pulsation period and its rate of period change. The former is important for calibrating the Leavitt Law and the latter for stellar evolution modeling. In this work, we combine previous time-series observations spanning more than a century with new observations to remeasure the pulsation period and compute the rate of period change. We compare our new rate of period change with stellar evolution models to measure the properties of $l$ Car, but find models and observations are, at best, marginally consistent. The results imply that $l$ Car does not have significantly enhanced mass-loss rates like that measured for $\\delta$ Cephei. We find that the mass of $l$ Car is about 8 - 10 $M_\\odot$. We present...

  16. Stellar Velocities in the Carina, Fornax, Sculptor and Sextans dSph Galaxies: Data from the Magellan/MMFS Survey

    CERN Document Server

    Walker, Matthew G; Olszewski, Edward

    2008-01-01

    We present spectroscopic data for individual stars observed from 2004 March through 2008 August as part of our Michigan/MIKE Fiber System (MMFS) survey of four dwarf spheroidal (dSph) galaxies: Carina, Fornax, Sculptor and Sextans. Using MMFS at the Magellan/Clay Telescope at Las Campanas Observatory, we have acquired 8855 spectra from 7103 red giant candidates in these Galactic satellites. We list measurements of each star's line-of-sight velocity (median error +/- 2.1 km/s) and spectral line indices for iron and magnesium absorption features. We use globular cluster spectra to calibrate the indices onto standard [Fe/H] metallicity scales, but comparison of the resulting metallicities with published values suggests that the MMFS indices are best used as indicators of relative, not absolute metallicity. The empirical distributions of velocity and spectral indices also allow us to quantify the amount of contamination by foreground stars. In a companion paper we develop an algorithm that evaluates the membershi...

  17. Ag transport in CrN-Ag nanocomposite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Mulligan, C.P. [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); U.S. Army Armament Research Development and Engineering Center, Benet Laboratories, Watervliet, NY 12189 (United States); Papi, P.A. [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Gall, D., E-mail: galld@rpi.edu [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

    2012-09-01

    2-{mu}m-thick CrN-Ag composite coatings containing 22 at.% Ag were deposited on Si(001) by reactive co-sputtering at T{sub s} = 300, 400, and 500 Degree-Sign C. Subsequent vacuum annealing at T{sub a} = 425, 525, and 625 Degree-Sign C causes Ag transport to the surface. Auger electron spectroscopy and plan-view microscopy are used to quantify the Ag transport to the surface, which increases strongly with increasing {Delta}T = T{sub a} - T{sub s}. Compositional depth profiles and cross-sectional microscopy show that annealing causes a negligible Ag gradient through the composite layer, suggesting that the Ag transport is detachment-limited as opposed to diffusion-limited. Statistical analyses of Ag aggregate size-distributions within the matrix show that large aggregates ({>=} 50 nm) are unaffected by annealing, while the Ag in a large fraction of small aggregates (< 50 nm) moves to the surface, leaving behind 10-50 nm wide voids in the annealed composite. This indicates that the Ag from the smaller grains, with a higher chemical potential and thus a higher detachment rate, is transferred to the large grains on the surface which are 200-1000 nm wide. - Highlights: Black-Right-Pointing-Pointer CrN-Ag coatings were deposited at T{sub s} = 300-500 Degree-Sign C and annealed at T{sub a} = 425-625 Degree-Sign C. Black-Right-Pointing-Pointer Ag diffuses from aggregates in the coating to the surface, if T{sub a} > T{sub s}. Black-Right-Pointing-Pointer During annealing, aggregates < 50 nm become voids, those > 50 nm are unaffected. Black-Right-Pointing-Pointer The Ag transport is detachment rather than diffusion limited.

  18. Results of work in the hot cells of Laboratory Testing Materials Irradiated Areva of Carina project for the expansion of the database of mechanical characteristics of fractures in materials of RPV German irradiated; Resultados del trabajo en las celdas calientes del Laboratorio de Ensayos de Materiales Irradiados de Areva del proyecto Carina para la ampliacion de la base de datos de caracteristicas mecanicas de las fracturas en materiales de RPV alemanas irradiados

    Energy Technology Data Exchange (ETDEWEB)

    Barthelmes, J.; Schabel, H.; Hein, H.; Kein, E.; Eiselt, C.

    2013-07-01

    In the frame of the already completed research projects CARINA and its predecessor CARISMA a data base was created for pre-irradiated original RPV steels of German PWRs which allowed to examine the consequences if the Master Curve (T{sub 0}) approach instead of the RT{sub N}OT concept is applied to the RPV safety assessment. Furthermore in CARINA different irradiation conditions with respect to the accumulated neutron fluences and specific impact parameters were investigated. Besides a brief introduction of the CARINA project and an overview of the main results an overview on the requirements of the hot laboratory work in terms of specimen manufacturing and material testing is given and examples for realization are shown. (Author)

  19. Ag-Air Service

    Science.gov (United States)

    1981-01-01

    Econ, Inc.'s agricultural aerial application, "ag-air," involves more than 10,000 aircraft spreading insecticides, herbicides, fertilizer, seed and other materials over millions of acres of farmland. Difficult for an operator to estimate costs accurately and decide what to charge or which airplane can handle which assignment most efficiently. Computerized service was designed to improve business efficiency in choice of aircraft and determination of charge rates based on realistic operating cost data. Each subscriber fills out a detailed form which pertains to his needs and then receives a custom-tailored computer printout best suited to his particular business mix.

  20. Binary populations in Milky Way satellite galaxies: Constraints from multi-epoch data in the Carina, Fornax, Sculptor, and Sextans dwarf spheroidal galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Minor, Quinn E. [Department of Science, Borough of Manhattan Community College, City University of New York, New York, NY 10007 (United States); Department of Astrophysics, American Museum of Natural History, New York, NY 10024 (United States)

    2013-12-20

    We introduce a likelihood analysis of multi-epoch stellar line-of-sight velocities to constrain the binary fractions and binary period distributions of dwarf spheroidal galaxies. This method is applied to multi-epoch data from the Magellan/MMFS survey of the Carina, Fornax, Sculptor, and Sextans dSph galaxies, after applying a model for the measurement errors that accounts for binary orbital motion. We find that the Fornax, Sculptor, and Sextans dSphs are consistent with having binary populations similar to that of Milky Way field binaries to within 68% confidence limits, whereas the Carina dSph is remarkably deficient in binaries with periods less than ∼10 yr. If Carina is assumed to have a period distribution identical to that of the Milky Way field, its best-fit binary fraction is 0.14{sub −0.05}{sup +0.28}, and is constrained to be less than 0.5 at the 90% confidence level; thus it is unlikely to host a binary population identical to that of the Milky Way field. By contrast, the best-fit binary fraction of the combined sample of all four galaxies is 0.46{sub −0.09}{sup +0.13}, consistent with that of Milky Way field binaries. More generally, we infer probability distributions in binary fraction, mean orbital period, and dispersion of periods for each galaxy in the sample. Looking ahead to future surveys, we show that the allowed parameter space of binary fraction and period distribution parameters in dSphs will be narrowed significantly by a large multi-epoch survey. However, there is a degeneracy between the parameters that is unlikely to be broken unless the measurement error is of order ∼0.1 km s{sup –1} or smaller, presently attainable only by a high-resolution spectrograph.

  1. Preparation and antibacterial activities of Ag/Ag+/Ag3+ nanoparticle composites made by pomegranate (Punica granatum) rind extract

    Science.gov (United States)

    Yang, Hui; Ren, Yan-yu; Wang, Tao; Wang, Chuang

    Nano-silver and its composite materials are widely used in medicine, food and other industries due to their strong conductivity, size effect and other special performances. So far, more microbial researches have been applied, but a plant method is rarely reported. In order to open up a new way to prepare AgNP composites, pomegranate peel extract was used in this work to reduce Ag+ to prepare Ag/Ag+/Ag3+ nanoparticle composites. UV-Vis was employed to detect and track the reduction of Ag+ and the forming process of AgNPs. The composition, structure and size of the crystal were analyzed by XRD and TEM. Results showed that, under mild conditions, pomegranate peel extract reacted with dilute AgNO3 solution to produce Ag/Ag+/Ag3+ nanoparticle composites. At pH = 8 and 10 mmol/L of AgNO3 concentration, the size of the achieved composites ranged between 15 and 35 nm with spherical shapes and good crystallinity. The bactericidal experiment indicated that the prepared Ag/Ag+/Ag3+ nanoparticles had strong antibacterial activity against gram positive bacteria and gram negative bacteria. FTIR analysis revealed that biological macromolecules with groups of sbnd NH2, sbnd OH, and others were distributed on the surface of the newly synthesized Ag/Ag+/Ag3+ nanoparticles. This provided a useful clue to further study the AgNP biosynthesis mechanism.

  2. Construction of Ag/AgCl nanostructures from Ag nanoparticles as high-performance visible-light photocatalysts

    Science.gov (United States)

    Yang, Fan; Liu, Dongzhi; Wang, Tianyang; Li, Wei; Hu, Wenping; Zhou, Xueqin

    2016-11-01

    A combined strategy of in situ oxidation and assembly is developed to prepare Ag/AgCl nanospheres and nanocubes from Ag nanoparticles under room temperature. It is a new facile way to fabricate Ag/AgCl with small sizes and defined morphologies. Ag/AgCl nanospheres with an average size of 80 nm were achieved without any surfactants, while Ag/AgCl nanocubes with a mean edge length of 150 nm were obtained by introduction of N-dodecyl- N, N-dimethyl-2-ammonio-acetate. The possible formation mechanism involves the self-assembly of AgCl nanoparticles, Ostwald ripening and photoreduction of Ag+ into Ag0 by the room light. The as-prepared Ag/AgCl nanospheres and nanocubes exhibit excellent photocatalytic activity and stability toward degradation of organic pollutants under visible-light irradiation. It is demonstrated that Ag/AgCl nanocubes display enhanced photocatalytic activity in comparison with Ag/AgCl nanospheres due to the more efficient charge transfer. This work may pave an avenue to construct various functional materials via the assembly strategy using nanoparticles as versatile building blocks.

  3. About AgEcon Search

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>AgEcon Search is a free,open access repository of full-text scholarly literature in agricultural and applied economics,including working papers,conference papers,and journal articles. AgEcon Search is co-sponsored by the Department of Applied Economics and

  4. About AgEcon Search

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>AgEcon Search is a free,open access repository of full-text scholarly literature in agricultural and applied economics,including working papers,conference papers,and journal articles.AgEcon Search is co-sponsored by the Department of Applied Economics andthe University Libraries

  5. About AgEcon Search

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>AgEcon Search is a free,open access repository of full-text scholarly literature in agricultural and applied economics,including working papers,conference papers,and journal articles. AgEcon Search is cosponsored by the Department of Applied Economics and the University Libraries at University of Minnesota and the Agricultural and Applied Economics Association.

  6. About AgEcon Search

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>AgEcon Search is a free,open access repository of full-text scholarly literature in agricultural and applied economics,including working papers,conference papers,and journal articles. AgEcon Search is co-sponsored by the Department of Applied Economics and the University Libraries at University of Minnesota and the Agricultural and Applied

  7. About AgEcon Search

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>AgEcon Search is a free,open access repository of full-text scholarly literature in agricultural and applied economics,including working papers,conference papers,and journal articles.AgEcon Search is co-sponsored by the Department of Applied Economics and the University Libraries

  8. About AgEcon Search

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>AgEcon Search is a free,open access repository of full-text scholarly literature in agricultural and applied economics,including working papers,conference papers,and journal articles. AgEcon Search is co-sponsored by the Department of Applied Economics and the University Libraries at University of Minnesota and the Agricultural and Applied Economics Association. Research

  9. About AgEcon Search

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>AgEcon Search is a free,open access repository of full-text scholarly literature in agricultural and applied economics,including working papers,conference papers,and journal articles. AgEcon Search is co-sponsored by the Department of Applied E-

  10. AGS Experiments: 1989, 1990, 1991

    Energy Technology Data Exchange (ETDEWEB)

    Depken, J.C.

    1992-02-01

    This report contains: Experimental areas layout; table of beam parameters and fluxes; experiment schedule ``as run``; proposed 1992 schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS Experiments begin here; and list of AGS Experimenters begins here.

  11. AGS Experiments: 1989, 1990, 1991

    Energy Technology Data Exchange (ETDEWEB)

    Depken, J.C.

    1992-02-01

    This report contains: Experimental areas layout; table of beam parameters and fluxes; experiment schedule as run''; proposed 1992 schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS Experiments begin here; and list of AGS Experimenters begins here.

  12. About AgEcon Search

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>AgEcon Search is a free, open access repository of full-text scholarly literature in agricultural and applied economics, including working papers, conference papers, and journal articles.AgEcon Searchis co-sponsored by the Department of Applied E

  13. The spectral temperature of optically thick outflows with application to light echo spectra from η Carinae's giant eruption

    Science.gov (United States)

    Owocki, Stanley P.; Shaviv, Nir J.

    2016-10-01

    The detection by Rest et al. of light echoes from η Carinae has provided important new observational constraints on the nature of its 1840s era giant eruption. Spectra of the echoes suggest a relatively cool spectral temperature of about 5500 K, lower than the lower limit of about 7000 K suggested in the optically thick wind-outflow analysis of Davidson. This has led to a debate about the viability of this steady wind model relative to alternative, explosive scenarios. Here we present an updated analysis of the wind-outflow model using newer low-temperature opacity tabulations and accounting for the stronger mass-loss implied by the >10 M⊙ mass now inferred for the Homunculus. A major conclusion is that, because of the sharp drop in opacity due to recombination loss of free electrons for T < 6500 K, a low temperature of about 5000 K is compatible with, and indeed expected from, a wind with the extreme mass-loss inferred for the eruption. Within a spherical grey model in radiative equilibrium, we derive spectral energy distributions for various assumptions for the opacity variation of the wind, providing a basis for comparisons with observed light echo spectra. The scaling results here are also potentially relevant for other highly optically thick outflows, including those from classical novae, giant eruptions of luminous blue variables and supernovae Type IIn precursors. A broader issue therefore remains whether the complex, variable features observed from such eruptions are better understood in terms of a steady or explosive paradigm, or perhaps a balance of these idealizations.

  14. Constraining the Absolute Orientation of eta Carinae's Binary Orbit: A 3-D Dynamical Model for the Broad [Fe III] Emission

    Science.gov (United States)

    Madura, T. I.; Gull, T. R.; Owocki, S. P.; Groh, J. H.; Okazaki, A. T.; Russell, C. M. P.

    2011-01-01

    We present a three-dimensional (3-D) dynamical model for the broad [Fe III] emission observed in Eta Carinae using the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS). This model is based on full 3-D Smoothed Particle Hydrodynamics (SPH) simulations of Eta Car's binary colliding winds. Radiative transfer codes are used to generate synthetic spectro-images of [Fe III] emission line structures at various observed orbital phases and STIS slit position angles (PAs). Through a parameter study that varies the orbital inclination i, the PA(theta) that the orbital plane projection of the line-of-sight makes with the apastron side of the semi-major axis, and the PA on the sky of the orbital axis, we are able, for the first time, to tightly constrain the absolute 3-D orientation of the binary orbit. To simultaneously reproduce the blue-shifted emission arcs observed at orbital phase 0.976, STIS slit PA = +38deg, and the temporal variations in emission seen at negative slit PAs, the binary needs to have an i approx. = 130deg to 145deg, Theta approx. = -15deg to +30deg, and an orbital axis projected on the sky at a P A approx. = 302deg to 327deg east of north. This represents a system with an orbital axis that is closely aligned with the inferred polar axis of the Homunculus nebula, in 3-D. The companion star, Eta(sub B), thus orbits clockwise on the sky and is on the observer's side of the system at apastron. This orientation has important implications for theories for the formation of the Homunculus and helps lay the groundwork for orbital modeling to determine the stellar masses.

  15. Space Telescope Imaging Spectrograph Observations of High-Velocity Interstellar Absorption-Line Profiles in the Carina Nebula

    Science.gov (United States)

    Walborn, Nolan R.; Danks, Anthony C.; Vieira, Gladys; Landsman, Wayne B.

    2002-06-01

    An atlas of ultraviolet interstellar absorption-line profiles toward four stars in the Carina Nebula is presented. The observations have been made with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope, with a resolving power of 114,000. Low-ionization, high-ionization, and excited-state lines from a wide array of chemical species are included. Extensive measurements of radial velocities, velocity dispersions, and column densities of individual components in these profiles are also given. The unprecedented capabilities of STIS reveal many more velocity components than previously known; most of the high-velocity components in previous observations with the International Ultraviolet Explorer are now resolved into multiple subcomponents, and even higher velocities are seen. The great range of line strengths available permits the detection of the low-velocity components in the weakest lines, and progressively higher velocities in stronger lines (in which the low-velocity components become completely blended). The weak and high-ionization lines trace global structure in the H II region, while the strong low-ionization lines show intricate high-velocity structure that likely originates relatively near to the O stars observed. The extreme velocities found in the low-ionization lines toward these four stars are -388 and +127 km s-1, with 23-26 resolved components in each. Some components in different stars may be related, but many are different in each line of sight. A remarkably well-defined Routly-Spitzer effect is found in this region. Temporal variations toward one star observed twice have already been reported. These measurements will be used in subsequent astrophysical analyses to further constrain the origins of the phenomena. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract

  16. Multiple Absorption Components in the Post-Periastron He I P Cygni Absorption Troughs of Eta Carinae

    Science.gov (United States)

    Richardson, Noel D.; Damineli, Augusto; Gull, Ted; Moffat, Anthony; Groh, Jose; St.-Jean, Lucas; Walter, Frederick M.; Teodoro, Mairan; Madura, Tom; Corcoran, Michael; Hamaguchi, Kenji; Russell, Christopher

    2015-01-01

    We have obtained more than 100 high spectral resolution (R approx. 90,000) spectra of the massive binary star eta Carinae since 2012 in an effort to continue our orbital and long-term echelle monitoring of this extreme binary (Richardson et al. 2010, AJ, 139, 1534) with the CHIRON spectrograph on the CTIO 1.5 m telescope (Tokovinin et al. 2013, PASP, 125, 1336) in the 4550-7500A region. We increased our monitoring efforts and observation frequency as the periastron event of 2014 has approached, and resumed observations in October. We note that since mid-October, we have observed unusual multiple absorption components in the P Cygni troughs of the He I lines (4714, 5876, 6678, and 7065; 4921 and 5015 are blended with Fe II). In particular, we note that these components extend to -700 km/s, well beyond the terminal wind speed of the primary. These absorptions are likely related to clumps and turbulence in the wind-wind collision region and bow shock, as suggested by the high-velocity absorption observed by Groh et al. (2010, A&A, 519, 9) in the He I 10830A transition and our pre-periastron observations (Richardson et al. 2014, ATel #6336). In these cases, we suspect that we look along an arm of the shock cone and that we see a fast absorption change from the other collision region shortly after periastron. Further, high spectral resolution data are highly encouraged, especially for resolving powers greater than 50,000. These observations were obtained with the CTIO 1.5 m telescope, operated by the SMARTS Consortium, and were obtained through both SMARTS and NOAO programs 2012A-0216, 2012B-0194, and 2013b-0328. We thank Emily MacPherson (Yale) for her efforts in scheduling the observations that we have and will obtain in the coming weeks and months.

  17. EPIDAUROS Biotechnologie AG.

    Science.gov (United States)

    Arnold, Hans-Peter; Kluge, Peter; Mauch, Simon

    2005-07-01

    EPIDAUROS Biotechnologie AG is a leading provider of pharmacogenetic consulting, genotyping and research services to the international pharmaceutical and biotechnology industries, contract research organizations and healthcare providers. The company's mission is to improve safety, efficacy and predictability in drug development and drug therapy. EPIDAUROS determines its customers' needs in the field of pharmacogenetics using an in-depth consultancy process. The development and conduct of genotyping assays for drug-metabolizing enzymes, drug transporters and drug targets (for example, receptors)--all performed under stringent quality standards--are a major activity at EPIDAUROS. The company offers its research services to academic and industrial partners for the development of innovative diagnostic solutions by using its intellectual property.

  18. Plasmonic Ag2MoO4/AgBr/Ag composite: Excellent photocatalytic performance and possible photocatalytic mechanism

    Science.gov (United States)

    Wang, Zhongliao; Zhang, Jinfeng; Lv, Jiali; Dai, Kai; Liang, Changhao

    2017-02-01

    Plasmonic Ag2MoO4/AgBr/Ag composite is fabricated by in-situ ion exchange and reduction methods at room temperature. The samples are characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance (DRS), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscope (SEM) and photoluminescence (PL) measurements. The results show that butterfly-like Ag2MoO4 nanosheets served as the precursor, and Ag2MoO4/AgBr/Ag is formed in phase transformation with MoO42- displaced by Br-. The ternary Ag2MoO4/AgBr/Ag composite photocatalysts show greatly enhanced photocatalytic activity in photodegrading methylene blue (MB) under visible light irradiation compared with AgBr and Ag2MoO4. The pseudo-first-order rate constant kapp of Ag2MoO4/AgBr/Ag is 0.602 min-1, which is 11.6 and 18.3 times as high as that of AgBr and Ag2MoO4, respectively. Meanwhile, the efficiency of degradation still kept 90% after ten times cyclic experiments. Eventually, possible photocatalytic mechanism was proposed.

  19. The Carina Project VII: Towards the breaking of the age-metallicity degeneracy of red giant branch stars using the c_UBI index

    CERN Document Server

    Monelli, M; Fabrizio, M; Bono, G; Stetson, P B; Walker, A R; Cassisi, S; Gallart, C; Nonino, M; Aparicio, A; Buonanno, R; Dall'Ora, M; Ferraro, I; Iannicola, G; Pulone, L; Thévenin, F

    2014-01-01

    We present an analysis of photometric and spectroscopic data of the Carina dSph galaxy, testing a new approach similar to that used to disentangle multiple populations in Galactic globular clusters (GCs). We show that a proper colour combination is able to separate a significant fraction of the red giant branch (RGB) of the two main Carina populations (the old one, \\sim 12 Gyr, and the intermediate-age one, 4-8 Gyr). In particular, the c_UBI=(U-B)-(B-I) pseudo-colour allows us to follow the RGB of both populations along a relevant portion of the RGB. We find that the oldest stars have more negative c_UBI pseudo-colour than intermediate-age ones. We correlate the pseudo-colour of RGB stars with their chemical properties, finding a significant trend between the iron content and the c_UBI. Stars belonging to the old population are systematically more metal poor ([Fe/H]=-2.32\\pm0.08 dex) than the intermediate-age ones ([Fe/H]=-1.82\\pm0.03 dex). This gives solid evidence on the chemical evolution history of this g...

  20. Spectroscopy of {sup 96}Ag.

    Energy Technology Data Exchange (ETDEWEB)

    Boutachkov, P.; Gorska, M.; Grawe, H.; Pietri, S.; Pardo, C.D.; Farinon, F.; Kojouharov, I.; Kurz, N.; Nociforo, C.; Prochazka, A.; Prokopowicz, W.; Caceres, L.; Engert, T.; Gerl, J.; Goel, N.; Schaffner, H.; Weick, H.; Wollersheim, H.J.; Merchant, E. [GSI (Germany); Braun, N.; Blazhev, A.; Bettermann, L.; Finke, F.; Geibel, K.; Ilie, G.; Iwasaki, H.; Reiter, P.; Scholl, C.; Warr, N. [Univ. Koeln (Germany); Brock, T.; Nara Singh, B.S.; Wadsworth, R. [Univ. York (United Kingdom); Liu, Z.; Gottardo, A.; Woods, P. [Univ. Edinburgh (United Kingdom); Faestermann, T.; Eppinger, K.; Hinke, C.; Kruecken, R. [TU Munich (Germany); Grebosz, J. [Inst. Fizyki, Krakow (Poland); Podolyak, Zs.; Steer, S.; Regan, P. [Univ. Surrey (United Kingdom); Hoischen, R. [GSI (Germany); Lund Univ. (Sweden); Nyberg, J.; Soederstroem, P.A. [Uppsala Univ. (Sweden); Pfuetzner, M. [Warsaw Univ. (Poland); Rinta-Antila, S. [Univ. Liverpool (United Kingdom); Rudolph, D. [Lund Univ. (Sweden); Atac, A. [Ankara Univ. (Turkey)

    2010-07-01

    A measurement with the RISING setup at the GSI-FRS facility has been performed to study isomer and {beta} decays in N{proportional_to}Z Cd, Ag and Pd isotopes. This study provides information on the shell evolution around the N=Z=50 shell closure. In particular, three new isomeric states were observed in {sup 96}Ag, extending the level scheme to high-spin spherical structures, including core-excited states. A comparison to shell-model calculations ascertains the {sup 100}Sn shell gap from this data. The new {sup 96}Ag results are presented.

  1. Bioceres: AG Biotechnology from Argentina

    Directory of Open Access Journals (Sweden)

    Roberto Feeney

    2016-04-01

    Full Text Available In this case we present a business decision-making situation in which the CEO of an Argentine Ag Biotech company, Bioceres, has to decide the best way to commercialize a new drought-tolerant transgenic technology. The company was founded by twenty three farmers, who shared a common dream that Argentina could become a benchmark in the development of Ag biotechnology. The case has strategic and financial implications, as well as decision-making situation involving a joint venture with an American biotechnology company. It also introduces to discussion the business models of Ag biotechnology companies in developing countries.

  2. Luminescent molecular Ag-S nanocluster [Ag(62)S(13)(SBu(t))(32)](BF(4))(4).

    Science.gov (United States)

    Li, Gen; Lei, Zhen; Wang, Quan-Ming

    2010-12-22

    The first observation of luminescence from a structurally well-defined Ag(2)S molecular nanocluster is reported. Reaction of AgSBu(t)/AgBF(4) with N(2)H(4) in methanol affords the tetracationic cluster [Ag(62)S(13)(SBu(t))(32)](BF(4))(4), which has a core-shell configuration. The 14 silver(I) centers of the [Ag(14)S(13)] core are in a face-centered cubic arrangement with each edge bridged by a S(2-) ligand; the core is further connected to the [Ag(48)(SBu(t))(32)] shell via both Ag-S bonds and Ag···Ag interactions. This novel cluster displays intense red emission in both the solid state and solution at room temperature.

  3. Dissolved inorganic carbon, alkalinity, pH, temperature, salinity, and other variables collected from profile observations using CTD, discrete bottles, and other instruments from October 7, 1977 to March 11, 2006, as synthesized in the CARbon dioxide IN the Atlantic Ocean (CARINA) Database (NODC Accession 0113899)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The CARINA (CARbon dioxide IN the Atlantic Ocean) data synthesis project is an international collaborative effort of the EU IP CARBOOCEAN, and US partners. It has...

  4. Incorporated Organic Modified Ag Nanoparticles in Ormocer

    Institute of Scientific and Technical Information of China (English)

    Haiping XIA; Jianli ZHANG; Jinhao WANG; Qiuhua NIE

    2004-01-01

    Ag nanoparticles coated trisodium citrate were incorporated in ormocer by sol-gel method. The doping concentration of Ag in ormocer is about 1.0% in weight. The HRTFM demonstrated that the particles disperse in ormocer, and the size of Ag nanoparticles is 5~10 nm. The absorption band of Ag nanoparticle at 410 nm was observed.

  5. Spin dynamics simulations at AGS

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H.; MacKay, W.W.; Meot, F.; Roser, T.

    2010-05-23

    To preserve proton polarization through acceleration, it is important to have a correct model of the process. It has been known that with the insertion of the two helical partial Siberian snakes in the Alternating Gradient Synchrotron (AGS), the MAD model of AGS can not deal with a field map with offset orbit. The stepwise ray-tracing code Zgoubi provides a tool to represent the real electromagnetic fields in the modeling of the optics and spin dynamics for the AGS. Numerical experiments of resonance crossing, including spin dynamics in presence of the snakes and Q-jump, have been performed in AGS lattice models, using Zgoubi. This contribution reports on various results so obtained.

  6. Constraints on Decreases in Eta Carinae's Mass-loss from 3D Hydrodynamic Simulations of Its Binary Colliding Winds

    Science.gov (United States)

    Madura, T. I.; Gull, T. R.; Okazaki, A. T.; Russell, C. M. P.; Owocki, S. P.; Groh, J. H.; Corcoran, M. F.; Hamaguchi, K.; Teodoro, M.

    2013-01-01

    Recent work suggests that the mass-loss rate of the primary star Eta-A in the massive colliding wind binary Eta Carinae dropped by a factor of 2-3 between 1999 and 2010. We present result from large- (+/- 1545 au) and small- (+/- 155 au) domain, 3D smoothed particle hydrodynamics (SPH) simulations of Eta Car's colliding winds for three Eta-A mass-loss rates ( (dot-M(sub Eta-A) = 2.4, 4.8 and 8.5 × 10(exp -4) M(solar)/ yr), investigating the effects on the dynamics of the binary wind-wind collision (WWC). These simulations include orbital motion, optically thin radiative cooling and radiative forces. We find that dot-M Eta-A greatly affects the time-dependent hydrodynamics at all spatial scales investigated. The simulations also show that the post-shock wind of the companion star Eta-B switches from the adiabatic to the radiative-cooling regime during periastron passage (Phi approx.= 0.985-1.02). This switchover starts later and ends earlier the lower the value of dot-M Eta-A and is caused by the encroachment of the wind of Eta-A into the acceleration zone of Eta-B's wind, plus radiative inhibition of Eta-B's wind by Eta-A. The SPH simulations together with 1D radiative transfer models of Eta-A's spectra reveal that a factor of 2 or more drop in dot-M EtaA should lead to substantial changes in numerous multiwavelength observables. Recent observations are not fully consistent with the model predictions, indicating that any drop in dot- M Eta-A was likely by a factor of approx. decrease in dot-M Eta-A may be responsible, but changes in the wind/stellar parameter of Eta-B, while less likely, cannot yet be fully ruled out. We suggest observations during Eta-Car's next periastron in 2014 to further test for decreases in dot-M Eta-A. If dot-M Eta-A is declining and continues to do so, the 2014 X-ray minimum should be even shorter than that of 2009.

  7. Detection of High Velocity Absorption Components in the He I Lines of Eta Carinae near the Time of Periastron

    Science.gov (United States)

    Richardson, Noel D.; St-Jean, Lucas; Gull, Theodore R.; Madura, Thomas; Hillier, D. John; Teodoro, Mairan; Moffat, Anthony; Corcoran, Michael; Damineli, Augusto

    2014-01-01

    We have obtained a total of 58 high spectral resolution (R90,000) spectra of the massive binary star eta Carinae since 2012 in an effort to continue our orbital and long-term echelle monitoring of this extreme binary (Richardson et al. 2010, AJ, 139, 1534) with the CHIRON spectrograph on the CTIO 1.5 m telescope (Tokovinin et al. 2013, PASP, 125, 1336) in the 45507500A region. We have increased our monitoring efforts and observation frequency as the periastron event of 2014 has approached. We note that there were multiple epochs this year where we observe unusual absorption components in the P Cygni troughs of the He I triplet lines. In particular, we note high velocity absorption components related to the following epochs for the following lines: He I 4713: HJD 2456754- 2456795 (velocity -450 to -560 kms) He I 5876: HJD 2456791- 2456819 (velocity -690 to -800 kms) He I 7065: HJD 2456791- 2456810 (velocity -665 to -730 kms) Figures: Note that red indicates a high-velocity component noted above. He I 4713: http:www.astro.umontreal.carichardson4713.png He I 5876: http:www.astro.umontreal.carichardson5876.png He I 7065: http:www.astro.umontreal.carichardson7065.png These absorptions are likely related to the wind-wind collision region and bow shock, as suggested by the high-velocity absorption observed by Groh et al. (2010, AA, 519, 9) in the He I 10830 Atransition. In these cases, we suspect that we look along an arm of the shock cone and that we will see a fast absorption change from the other collision region shortly after periastron. We suspect that this is related to the multiple-components of the He II 4686 line that was noted by Walter (ATel6334), and is confirmed in our data. Further, high spectral resolution data are highly encouraged,especially for resolving powers greater than 50,000.These observations were obtained with the CTIO 1.5 m telescope, operated by the SMARTS Consortium, and were obtained through both SMARTS and NOAO programs 2012A-0216,2012B-0194

  8. About AgEcon Search

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>AgEcon Search is a free,open access repository of full-text scholarly literature in agricultural and applied economics,including working papers,conference papers,and journal articles.AgEcon Search is co-sponsored by the Department of Applied Economics and the University Libraries at University of Minnesota and the Agricultural and Applied Economics Association.Research in Agricultural

  9. About AgEcon Search

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>AgEcon Search is a free,open access repository of full-text scholarly literature in agricultural and applied economics,including working papers,conference papers,and journal articles. AgEcon Search is co-sponsored by the Department of Applied Economics and the University Libraries at University of Minnesota and the Agricultural and Applied Economics Association. Research in Agricultural

  10. File list: His.Dig.50.AllAg.AGS [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Dig.50.AllAg.AGS hg19 Histone Digestive tract AGS SRX482979,SRX482980,SRX482982...,SRX482978,SRX482983,SRX482985,SRX482981,SRX482984 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/His.Dig.50.AllAg.AGS.bed ...

  11. File list: Oth.Dig.20.AllAg.AGS [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Dig.20.AllAg.AGS hg19 TFs and others Digestive tract AGS SRX367641,SRX371981,SR...X367642,SRX367640 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.Dig.20.AllAg.AGS.bed ...

  12. File list: Oth.Dig.10.AllAg.AGS [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Dig.10.AllAg.AGS hg19 TFs and others Digestive tract AGS SRX367641,SRX367642,SR...X371981,SRX367640 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.Dig.10.AllAg.AGS.bed ...

  13. File list: ALL.Dig.05.AllAg.AGS [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Dig.05.AllAg.AGS hg19 All antigens Digestive tract AGS SRX367641,SRX367642,SRX3...X482983 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/ALL.Dig.05.AllAg.AGS.bed ...

  14. File list: His.Dig.05.AllAg.AGS [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Dig.05.AllAg.AGS hg19 Histone Digestive tract AGS SRX482980,SRX482979,SRX482981...,SRX482978,SRX482984,SRX482982,SRX482985,SRX482983 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/His.Dig.05.AllAg.AGS.bed ...

  15. File list: ALL.Dig.10.AllAg.AGS [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Dig.10.AllAg.AGS hg19 All antigens Digestive tract AGS SRX367641,SRX367642,SRX3...X482983 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/ALL.Dig.10.AllAg.AGS.bed ...

  16. File list: His.Dig.20.AllAg.AGS [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Dig.20.AllAg.AGS hg19 Histone Digestive tract AGS SRX482980,SRX482979,SRX482981...,SRX482978,SRX482982,SRX482983,SRX482985,SRX482984 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/His.Dig.20.AllAg.AGS.bed ...

  17. File list: Oth.Dig.05.AllAg.AGS [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Dig.05.AllAg.AGS hg19 TFs and others Digestive tract AGS SRX367641,SRX367642,SR...X371981,SRX367640 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.Dig.05.AllAg.AGS.bed ...

  18. File list: Oth.Dig.50.AllAg.AGS [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Dig.50.AllAg.AGS hg19 TFs and others Digestive tract AGS SRX367641,SRX371981,SR...X367642,SRX367640 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.Dig.50.AllAg.AGS.bed ...

  19. File list: ALL.Dig.50.AllAg.AGS [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Dig.50.AllAg.AGS hg19 All antigens Digestive tract AGS SRX367641,SRX371982,SRX3...X367640 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/ALL.Dig.50.AllAg.AGS.bed ...

  20. File list: ALL.Dig.20.AllAg.AGS [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Dig.20.AllAg.AGS hg19 All antigens Digestive tract AGS SRX367641,SRX371982,SRX3...X367640 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/ALL.Dig.20.AllAg.AGS.bed ...

  1. File list: His.Dig.10.AllAg.AGS [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Dig.10.AllAg.AGS hg19 Histone Digestive tract AGS SRX482979,SRX482980,SRX482981...,SRX482984,SRX482978,SRX482982,SRX482985,SRX482983 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/His.Dig.10.AllAg.AGS.bed ...

  2. The Carina spiral feature: Strömgren-β photometry approach. II. Distances and space distribution of the O and B stars

    Science.gov (United States)

    Kaltcheva, N.; Scorcio, M.

    2010-05-01

    Aims: In recent years a significant development has become evident in the study of the stellar structure of the Galactic disk. This is especially true for the 3rd Galactic quadrant, where the stellar population was extensively investigated beyond 10 kpc, revealing details about the warped geometry of the thin and thick disks and outer arm. The 4th Galactic quadrant offers even better opportunity to follow the distribution of the young stellar populace to a large distance, since the line of sight is parallel to the largest single segment of a spiral arm seen from our position in the Galaxy: the Carina spiral feature. This paper further contributes to the study of the structure of the Galactic disk in the direction of Carina field utilizing homogeneous photometric distances of a sample of about 600 bright early-type stars seen in this direction up to 6 kpc. Methods: The derived stellar distances are based on uvbyβ photometry. All O and B type stars with uvbyβ data presently available are included in the study. Results: The photometry-derived parameters allow us to study the structure and characteristics of this segment of the Carina arm. We find that the stellar distribution is consistent with a location of the apparent edge of the arm at l = 287°. Toward the edge of the arm the warp of the Galactic plane can be traced up to 6 kpc where it reaches negative 200 pc. The field toward the edge seems to be much more complex than harboring just one OB association, and it is likely that some of the apparent concentrations in this field represent parts of long segments of the edge. In the 284° longitude range an interarm space about 1 kpc wide is found beyond 850 pc from the Sun. The giant molecular clouds and open clusters do not follow the edge of the arm as defined by the OB stars and indicate a possible presence of an age gradient in a direction perpendicular to the formal Galactic plane. Table 4 is only available in electronic form at the CDS via anonymous ftp to

  3. AG-3340 (Agouron Pharmaceuticals Inc).

    Science.gov (United States)

    Griffioen, A W

    2000-03-01

    Agouron Pharmaceuticals is developing AG-3340 (prinomastat), the lead compound in a series of structurally related metalloproteinase inhibitors, for the potential treatment of cancer and age-related macular degeneration. AG-3340, an oral, non-peptide inhibitor of gelatinase types A and B (MMP-2 and -9), MT1-MP (MMP-14) and collagenase III [234058], was selected following demonstration of activity in a variety of in vivo preclinical models upon oral dosing. In May 1999, phase III trials for lung and prostate cancers of AG-3340 in front-line combination with chemotherapy was begun in the US and Canada [286380,326640]. The tested dose for these trials is 5 to 15 mg bid. Following demonstration of the enhanced efficacy of chemotherapy when supplemented with AG-3340 in preclinical tumor models, pilot combination studies and double-blinded, placebo-controlled phase III trials in 700 patients are in progress for the treatment of non-small cell lung cancer or advanced hormone-refractory prostate cancer [302584,327014]. In August 1999, Agouron initiated a second, confirmatory phase III trial of AG-3340 in combination with chemotherapy in patients with advanced non-small cell lung cancer [337253]. Pharmacokinetic studies have been conducted in healthy male volunteers and single agent dose-escalation studies in patients demonstrated toxicities (grade 1 or 2; joint related) were not doselimiting [302238]. At the 10th European Organization for Research and Treatment of Cancer (EORTC) meeting in Amsterdam (June 1998), Agouron released encouraging results from two phase I studies and one preclinical study of AG-3340 [289688]. In a further 15- patient, phase I study of AG-3340 with paclitaxel and carboplatin, the combination was safe and well tolerated [326268]. AG-3340 has demonstrated significant antimetastatic and antitumor activity in animal models, as well as oral bioavailability and a favorable pharmacokinetic profile. Daily doses of 50 mg/kg completely halted growth of

  4. Asymmetric interfaces in Fe/Ag and Ag/Fe bilayers prepared by molecular beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Tunyogi, A. [KFKI Research Institute for Particle and Nuclear Physics, P.O. Box 49, H-1525 Budapest (Hungary)]. E-mail: tunyogi@rmki.kfki.hu; Paszti, F. [KFKI Research Institute for Particle and Nuclear Physics, P.O. Box 49, H-1525 Budapest (Hungary); Osvath, Z. [MTA Research Institute for Technical Physics and Materials Science, P.O. Box 49, H-1525 Budapest (Hungary); Tancziko, F. [KFKI Research Institute for Particle and Nuclear Physics, P.O. Box 49, H-1525 Budapest (Hungary); Major, M. [KFKI Research Institute for Particle and Nuclear Physics, P.O. Box 49, H-1525 Budapest (Hungary); Szilagyi, E. [KFKI Research Institute for Particle and Nuclear Physics, P.O. Box 49, H-1525 Budapest (Hungary)

    2006-08-15

    Single layers of Fe and Ag, as well as Fe/Ag (iron deposited first) and Ag/Fe bilayers were prepared by molecular beam evaporation onto Si. The samples were investigated with backscattering spectrometry (BS) and atomic force microscopy (AFM). BS spectra of Fe/Ag and Ag/Fe indicate a significant difference at the interface. In the case of Fe/Ag the Ag peak has a long tail at the interface, while for Ag/Fe the interface is abrupt. The tail in the Fe/Ag spectrum is too large to be caused by double or plural scattering. According to AFM, the effect of surface roughness is also negligible. In spite of the fact that Fe and Ag are completely immiscible in equilibrium, this tail, however, suggests that some Ag is located in the Fe layer. After annealing, both samples show mixing between the two layers; this is much larger again for Fe/Ag.

  5. Facile synthesis, structure, and properties of Ag2S/Ag heteronanostructure

    Science.gov (United States)

    Sadovnikov, S. I.; Gusev, A. I.

    2016-09-01

    Ag2S/Ag heteronanostructure has been produced by a simple one-stage chemical deposition from aqueous solutions of silver nitrate, sodium sulfide, and sodium citrate with the use of monochromatic light irradiation. For simultaneous synthesis of Ag2S and Ag nanoparticles, deposition has been performed from reaction mixtures with reduced sodium sulfide concentration. The size of Ag2S and Ag nanoparticles is 45-50 and 15-20 nm, respectively. It is established that in the contact layer between silver sulfide and silver, nonconducting α-Ag2S acanthite transforms into superionic β-Ag2S argentite under the action of external electric field. The scheme of the operation of a resistive switch based on an Ag2S/Ag heteronanostructure is proposed. The UV-Vis optical absorption spectra of colloidal solutions of Ag2S/Ag heteronanostructures have been studied.

  6. Ruhrgas AG. Business report 2000; Ruhrgas AG. Geschaeftsbericht 2000

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    A detailed account of the situation of the international gas market provides the basis of the status report of Ruhrgas AG and the group of affiliated companies. Emphasis is placed on gas procurement aspects, sales volumes, the construction and operation of natural gas distribution systems, and on development, utilization and application aspects. The activities and situation of major Ruhrgas AG holding companies are described, and the annual financial statements are documented. (orig.) [German] Ausgehend von einer eingehenden Beschreibung des internationalen Gasmarktes wird ein Lagebericht des Konzerns sowie der Ruhrgas AG gegeben. Dabei wird insbesondere auf Fragen der Gasbeschaffung, des Gasabsatzes, des Baus und Betriebs von Erdgasverteilungsnetzen, sowie der Entwicklung und der Anwendungstechnik eingegangen. Ferner wird ueber den Geschaeftsverlauf wesentlicher Ruhrgas-Beteiligungsgesellschaften berichtet. Abschliessend wird der Jahresabschluss dokumentiert. (orig.)

  7. The peculiar isolated neutron star in the Carina Nebula - Deep XMM-Newton and ESO-VLT observations of 2XMM J104608.7-594306

    CERN Document Server

    Pires, Adriana Mancini; Turolla, Roberto; Schwope, Axel; Pilia, Maura; Treves, Aldo; Popov, Sergei B; Janot-Pacheco, Eduardo

    2012-01-01

    While fewer in number relative to the dominant rotation-powered radio pulsar population, peculiar classes of isolated neutron stars (INSs) -- which include magnetars, the ROSAT-discovered "Magnificent Seven" (M7), rotating radio transients (RRATs) and central compact objects in supernova remnants (CCOs) -- represent a key element to understand the neutron star phenomenology. We report here on the results of an observational campaign aiming at studying the properties of the source 2XMM J104608.7-594306. Its evolutionary state is investigated by means of deep dedicated observations obtained with XMM-Newton, the ESO Very Large Telescope as well as on publicly available gamma-ray data from the Fermi and AGILE missions. The observations confirm previous expectations and further reveal a unique object. The source, likely within the Carina Nebula, shows a soft spectrum with absorption features and no magnetospheric emission. The optical counterpart is fainter than V=27 and no gamma-ray emission is significantly dete...

  8. The Carina project. VII. Toward the breaking of the age-metallicity degeneracy of red giant branch stars using the C {sub U,} {sub B,} {sub I} index

    Energy Technology Data Exchange (ETDEWEB)

    Monelli, M.; Milone, A. P.; Gallart, C.; Aparicio, A. [Instituto de Astrofísica de Canarias, Calle Via Lactea s/n, E-38205 La Laguna, Tenerife (Spain); Fabrizio, M.; Cassisi, S.; Buonanno, R. [Istituto Nazionale di Astrofisica-Osservatorio Astronomico Collurania, Via M. Maggini, I-64100 Teramo (Italy); Bono, G. [Dipartimento di Fisica, Universitá di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Rome (Italy); Stetson, P. B. [Dominion Astrophysical Observatory, NRC-Herzberg, 5071 West Saanich Road, Victoria, BC, V9E 2E7 (Canada); Walker, A. R. [Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena (Chile); Nonino, M. [Istituto Nazionale di Astrofisica-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, I-40131 Trieste (Italy); Dall' Ora, M. [INAF—Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Napoli (Italy); Ferraro, I.; Iannicola, G.; Pulone, L. [Istituto Nazionale di Astrofisica-Osservatorio Astronomico di Roma, Via Frascati 33, Monte Porzio Catone, I-00044 Rome (Italy); Thévenin, F., E-mail: monelli@iac.es [Université de Nice Sophia-antipolis, CNRS, Observatoire de la Côte d' Azur, Laboratoire Lagrange, BP 4229, F-06304 Nice (France)

    2014-12-01

    We present an analysis of photometric and spectroscopic data of the Carina dSph galaxy, testing a new approach similar to that used to disentangle multiple populations in Galactic globular clusters (GCs). We show that a proper color combination is able to separate a significant fraction of the red giant branch (RGB) of the two main Carina populations (the old one, ∼12 Gyr, and the intermediate-age one, 4-8 Gyr). In particular, the c {sub U,} {sub B,} {sub I} = (U – B) – (B – I) pseudo-color allows us to follow the RGB of both populations along a relevant portion of the RGB. We find that the oldest stars have a more negative c {sub U,} {sub B,} {sub I} pseudo-color than intermediate-age ones. We correlate the pseudo-color of RGB stars with their chemical properties, finding a significant trend between the iron content and the c {sub U,} {sub B,} {sub I}. Stars belonging to the old population are systematically more metal-poor ([Fe/H] =–2.32 ± 0.08 dex) than the intermediate-age ones ([Fe/H] =–1.82 ± 0.03 dex). This gives solid evidence of the chemical evolution history of this galaxy, and we have a new diagnostic that can allow us to break the age-metallicity degeneracy of H-burning advanced evolutionary phases. We compared the distribution of stars in the c {sub U,} {sub B,} {sub I} plane with theoretical isochrones, finding that no satisfactory agreement can be reached with models developed in a theoretical framework based on standard heavy element distributions. Finally, we discuss possible systematic differences when compared with multiple populations in GCs.

  9. Optical spectroscopy of X-Mega targets in the Carina nebula - VII. On the multiplicity of Tr16-112, HD93343 and HD93250

    Science.gov (United States)

    Rauw, G.; Nazé, Y.; Fernández Lajús, E.; Lanotte, A. A.; Solivella, G. R.; Sana, H.; Gosset, E.

    2009-09-01

    We present the results of a spectroscopic monitoring campaign devoted to three O-type stars in the Carina nebula. We derive the full SB2 orbital solution of the binary system Tr16-112, an exceptional dissymmetrical system consisting of an O5.5-6V((f+?p)) primary and a B2V-III secondary. We also report on low-amplitude brightness variations in Tr16-112 that are likely due to the ellipsoidal shape of the O5.5-6 primary revolving in an eccentric orbit around the system's centre of mass. We detect for the first time a clear SB2 binary signature in the spectrum of HD93343 (O8 + O8), although our data are not sufficient to establish an orbital solution. This system also displays low-amplitude photometric modulations. On the other hand, no indication of multiplicity is found in the optical spectra of HD93250. Finally, we discuss the general properties of multiple massive stars in the Carina OB1 association. Based on observations collected at the European Southern Observatory (La Silla, Chile), at Complejo Astronómico El Leoncito (Argentina), at the Cerro Tololo Inter-American Observatory (CTIO) and with XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA). E-mail: rauw@astro.ulg.ac.be ‡ Research Associate FRS/FNRS (Belgium). § Postdoctoral Researcher FRS/FNRS (Belgium). ¶ Senior Research Associate FRS/FNRS (Belgium).

  10. Compare the photocatalytic properties of nanocomposites with tandem n (AgBr)-n (Ag2CO3) and p (AgCl)-n (Ag2CO3) heterojunctions

    Science.gov (United States)

    Asadollahi, A.; Sohrabnezhad, Sh.; Ansari, R.

    2017-07-01

    In this work, Ag2CO3 nanoparticles (NPs) (as a n-type semiconductor) incorporated in mordenite zeolite (MOR) by a facile precipitation method. Silver halides, AgCl (as a p-type semiconductor) and AgBr (as a n-type semiconductor), with different weight percentage (20%, 40% and 50%) were coupled into Ag2CO3-MOR nanocomposite (NC) and producing a series of novel AgCl/Ag2CO3 (p-n heterojunction)-MOR and AgBr/Ag2CO3 (n-n heterojunction)-MOR NCs. The effects of silver halides on the Ag2CO3-MOR catalyst for the photocatalytic degradation of methyl blue (MB) under visible light irradiation have been investigated. The structure, composition and optical properties of NCs were investigated by UV-Visible diffuse reflectance spectroscopy (UV-Vis DRS), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM). The prepared AgX/Ag2CO3-MOR NCs with the optimal content of AgX (50 wt%) indicated higher photocatalytic activity than that of the Ag2CO3-MOR and Ag2CO3. The cycle experiments on the heterojuctions NCs indicated that photocatalytic stability of AgBr/Ag2CO3-MOR NC was more than AgCl/Ag2CO3-MOR NC in all cycles. On the basis of the experimental results, a possible mechanism for the enhanced photocatalytic activity and photoinduced stability of silver compounds was proposed.

  11. Functional Ag porous films prepared by electrospinning

    Science.gov (United States)

    Dong, Guoping; Xiao, Xiudi; Liu, Xiaofeng; Qian, Bin; Liao, Yang; Wang, Chen; Chen, Danping; Qiu, Jianrong

    2009-06-01

    Face-centered cubic Ag porous films have been prepared directly from the heat treatment of AgNO 3-doped poly(vinyl alcohol) (PVA) electrospun nanofibers. Using Rhodamine B (RB) as the probing molecule, the surface-enhanced Raman scattering (SERS) effect of Ag porous films was demonstrated. The antibacterial activity of Ag porous films was also studied in this work. The propagation and biological activity of yeast cells were effectively inhibited by Ag porous films. These functional Ag porous films were expected to be applied in many fields, such as catalysis, diagnostics, sensors and antibacterial, etc.

  12. Effect of Ag Templates on the Formation of Au-Ag Hollow/Core-Shell Nanostructures.

    Science.gov (United States)

    Tsai, Chi-Hang; Chen, Shih-Yun; Song, Jenn-Ming; Haruta, Mitsutaka; Kurata, Hiroki

    2015-12-01

    Au-Ag alloy nanostructures with various shapes were synthesized using a successive reduction method in this study. By means of galvanic replacement, twined Ag nanoparticles (NPs) and single-crystalline Ag nanowires (NWs) were adopted as templates, respectively, and alloyed with the same amount of Au(+) ions. High angle annular dark field-scanning TEM (HAADF-STEM) images observed from different rotation angles confirm that Ag NPs turned into AuAg alloy rings with an Au/Ag ratio of 1. The shifts of surface plasmon resonance and chemical composition reveal the evolution of the alloy ring formation. On the other hand, single-crystalline Ag NWs became Ag@AuAg core-shell wires instead of hollow nanostructure through a process of galvanic replacement. It is proposed that in addition to the ratio of Ag templates and Au ion additives, the twin boundaries of the Ag templates were the dominating factor causing hollow alloy nanostructures.

  13. About AgEcon Search

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>AgEcon Search is a free,open access repository of full-text scholarly literature in agricultural and applied economics,inclu-ding working papers,conference papers,and journal articles. AgEcon Search is co-sponsored by the Department of Applied Eco-nomics and the University Libraries at University of Minnesota and the Agricultural and Applied Economics Association. Research in Agricultural and Applied Economics collects,indexes,and electronically distributes full text copies of scholarly research in the

  14. About AgEcon Search

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>AgEcon Search is a free,open access repository of full-text scholarly literature in agricultural and applied economics,including working papers,conference papers,and journal articles.AgEcon Search is co-sponsored by the Department of Applied Economics and the University Libraries at University of Minnesota and the Agricultural and Applied Economics Association.Research in Agricultural and Applied Economics collects,indexes,and electronically distributes full text copies of scholarly research in the broadly defined field of agricultural economics including sub disciplines such as agribusiness,food supply,natural resource economics,environmental eco-

  15. About AgEcon Search

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>AgEcon Search is a free,open access repository of full-text scholarly literature in agricultural and applied economics,inclu-ding working papers,conference papers,and journal articles. AgEcon Search is co-sponsored by the Department of Applied Eco-nomics and the University Libraries at University of Minnesota and the Agricultural and Applied Economics Association. Researchin Agricultural and Applied Economics collects,indexes,and electronically distributes full text copies of scholarly research in the

  16. Synthesis, morphological control, and antibacterial properties of hollow/solid Ag2S/Ag heterodimers

    KAUST Repository

    Pang, Maolin

    2010-08-11

    Ag2S and Ag are important functional materials that have received considerable research interest in recent years. In this work, we develop a solution-based synthetic method to combine these two materials into hollow/solid Ag2S/Ag heterodimers at room temperature. Starting from monodisperse Cu2O solid spheres, CuS hollow spheres can be converted from Cu2O through a modified Kirkendall process, and the obtained CuS can then be used as a solid precursor for preparation of the Ag2S/Ag heterodimers through ion exchange and photo-assisted reduction. We have found that formation of the Ag2S/Ag heterodimers is instantaneous, and the size of Ag nanocrystals on the hollow spheres of Ag2S can be controlled by changing the concentration and power of reducing agents in the synthesis. The growth of Ag nanoparticles on hollow spheres of Ag2S in the dimers is along the [111] direction of the silver crystal; the light absorption properties have also been investigated. Furthermore, coupling or tripling of Ag2S/Ag heterodimers into dumbbell-like trimers ((Ag 2S)2/Ag, linear) and triangular tetramers ((Ag 2S)3/Ag, coplanar) can also be attained at 60°C by adding the bidentate ligand ethylenediamine as a cross-linking agent. To test the applicability of this highly asymmetric dipolar composite, photocatalytic inactivation of Escherichia coli K-12 in the presence of the as-prepared Ag 2S/Ag heterodimers has been carried out under UV irradiation. The added Ag2S/Ag heterodimers show good chemical stability under prolonged UV irradiation, and no appreciable solid dissolution is found. Possible mechanisms regarding the enhanced antibacterial activity have also been addressed. © 2010 American Chemical Society.

  17. A straightforward and effective strategy for controllable synthesis of Ag/Ag{sub 2}S and Ag/CdS heterojunction nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Xuandi [Southern Medical University, State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Nanfang Hospital (China); Feng, Xiumei; Hu, Jianqiang, E-mail: jqhusc@scut.edu.cn [South China University of Technology, Key Lab of Fuel Cell Technology of Guangdong Province, Department of Chemistry, College of Chemistry and Chemical Engineering (China); Tan, Lishan [Southern Medical University, State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Nanfang Hospital (China); Liu, Jianyu, E-mail: jyliu@scut.edu.cn; Chen, Yuyu; Deng, Xiulong [South China University of Technology, Key Lab of Fuel Cell Technology of Guangdong Province, Department of Chemistry, College of Chemistry and Chemical Engineering (China); Li, Aiqing, E-mail: liaiqing@smu.edu.cn [Southern Medical University, State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Nanfang Hospital (China)

    2015-02-15

    Ag/Ag{sub 2}S heterojunction nanowires (HJNWs) have been successfully fabricated through one-pot solution-phase method, which were transferred into Ag/CdS HJNWs by cation exchange. The synthesis involved a template-less, non-seed, and one-pot solution-phase process to high-quality Ag/Ag{sub 2}S HJNWs. The sizes, positions, and spacing distances between the Ag{sub 2}S or CdS NPs of the growing Ag{sub 2}S and CdS NPs in the Ag/Ag{sub 2}S and Ag/CdS HJNWs could be finely tailored by reaction temperatures and PVP concentrations. By varying reaction temperature, the sizes and positions (tip or surface) of the growing Ag{sub 2}S and CdS NPs in the Ag/Ag{sub 2}S and Ag/CdS HJNWs could be effectively controlled while PVP concentration could tailor the sizes and spacing distances between the Ag{sub 2}S or CdS NPs of the growing Ag{sub 2}S and CdS NPs in the Ag/Ag{sub 2}S and Ag/CdS HJNWs. We also proposed a primary experimental model to illustrate the growth mechanism of the Ag/Ag{sub 2}S and Ag/CdS HJNWs.

  18. AGS experiments, 1988, 1989, 1990

    Energy Technology Data Exchange (ETDEWEB)

    Depken, J.C.

    1991-04-01

    This report contains: experimental areas layout; table of beam parameters and fluxes; experiment schedule as run''; experiment long range schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS experiments; and list of experimenters.

  19. AGS 20th anniversary celebration

    Energy Technology Data Exchange (ETDEWEB)

    Baggett, N.V. (ed.)

    1980-05-22

    On May 22, 1980, a symposium was held at Brookhaven to celebrate the 20th birthday of the AGS, to recall its beginnings, and to review major discoveries that have been made with its beams. The talks at the symposium are recorded in this volume.

  20. AGS experiments: 1985, 1986, 1987

    Energy Technology Data Exchange (ETDEWEB)

    Depken, J.C.

    1987-01-01

    This report contains: Experimental areas layout, table of beam parameters and fluxes, experiment schedule ''as run,'' experiment long range schedule, a listing of experiments by number, two-page summaries of each experiment, also ordered by number, and publications of AGS experiments, 1982-1987.

  1. AGS experiments: 1990, 1991, 1992. Ninth edition

    Energy Technology Data Exchange (ETDEWEB)

    Depken, J.C.

    1993-04-01

    This report contains a description of the following: AGS Experimental Area - High Energy Physics FY 1993 and Heavy Ion Physics FY 1993; Table of Beam Parameters and Fluxes; Experiment Schedule ``as run``; Proposed 1993 Schedule; A listing of experiments by number; Two-page summaries of each experiment begin here, also ordered by number; Publications of AGS Experiments; and List of AGS Experimenters.

  2. Loading effect of Ag/AgO on the photocatalytic performance of ZnO rods

    Science.gov (United States)

    Samsuddin, Aida Fitri; Aziz, Siti Nor Qurratu Aini Abd; Pung, Swee-Yong

    2017-01-01

    The photocatalytic performance of ZnO rods in degradation of Rhodamine B dye under UV light was improved by 7.3% via deposition of Ag/AgO using 1.0 × 10-3 g mL-1 of silver nitrate solution. However, its photodegradation efficiency decreased with the increase in silver nitrate concentration which was used to prepare the Ag/AgO-ZnO rods. This result suggests that the loading of Ag/AgO on the surface of ZnO rods affected the photocatalytic performance differently. The scavenger study indicates that the main reactive species responsible for the degradation of Rhodamine B dye by Ag-/AgO-deposited ZnO rods were holes, followed by superoxide anion free radicals, hydroxyl free radicals and electrons. Based on these findings, a refined photodegradation mechanism of Rhodamine B by Ag/AgO-ZnO rods is proposed.

  3. In situ solid-state fabrication of hybrid AgCl/AgI/AgIO3 with improved UV-to-visible photocatalytic performance.

    Science.gov (United States)

    Xie, Jing; Cao, Yali; Jia, Dianzeng; Li, Yizhao; Wang, Kun; Xu, Hui

    2017-09-28

    The AgCl/AgI/AgIO3 composites were synthesized through a one-pot room-temperature in situ solid-state approach with the feature of convenient and eco-friendly. The as-prepared composites exhibit superior photocatalytic performance than pure AgIO3 for the degradation of methyl orange (MO) under both UV and visible light irradiation. The photodegradation rate toward MO of the AgCl/AgI/AgIO3 photocatalyst can reach 100% after 12 min irradiation under UV light, or 85.4% after 50 min irradiation under visible light, being significantly higher than AgCl, AgI, AgIO3 and AgI/AgIO3. In addition, the AgCl/AgI/AgIO3 photocatalyst possesses strong photooxidation ability for the degradation of rhodamine B (RhB), methylene blue (MB), phenol, bisphenol A (BPA) and tetracycline hydrochloride under visible light irradiation. The reactive species capture experiments confirmed that the h(+) and •O(2-) play an essential role during the photocatalytic process under UV light or visible light irradiation. The enhanced effect may be beneficial from the enhanced light adsorption in full spectrum and increased separation efficiency of photogenerated hole-electron pairs, which can be ascribed to the synergistic effect among AgCl, AgI and AgIO3 nanoplates in AgCl/AgI/AgIO3 composites.

  4. Comparative study of antimicrobial activity of AgBr and Ag nanoparticles (NPs).

    Science.gov (United States)

    Suchomel, Petr; Kvitek, Libor; Panacek, Ales; Prucek, Robert; Hrbac, Jan; Vecerova, Renata; Zboril, Radek

    2015-01-01

    The diverse mechanism of antimicrobial activity of Ag and AgBr nanoparticles against gram-positive and gram-negative bacteria and also against several strains of candida was explored in this study. The AgBr nanoparticles (NPs) were prepared by simple precipitation of silver nitrate by potassium bromide in the presence of stabilizing polymers. The used polymers (PEG, PVP, PVA, and HEC) influence significantly the size of the prepared AgBr NPs dependently on the mode of interaction of polymer with Ag+ ions. Small NPs (diameter of about 60-70 nm) were formed in the presence of the polymer with low interaction as are PEG and HEC, the polymers which interact with Ag+ strongly produce nearly two times bigger NPs (120-130 nm). The prepared AgBr NPs were transformed to Ag NPs by the reduction using NaBH4. The sizes of the produced Ag NPs followed the same trends--the smallest NPs were produced in the presence of PEG and HEC polymers. Prepared AgBr and Ag NPs dispersions were tested for their biological activity. The obtained results of antimicrobial activity of AgBr and Ag NPs are discussed in terms of possible mechanism of the action of these NPs against tested microbial strains. The AgBr NPs are more effective against gram-negative bacteria and tested yeast strains while Ag NPs show the best antibacterial action against gram-positive bacteria strains.

  5. Direct electrospinning of Ag/polyvinylpyrrolidone nanocables

    DEFF Research Database (Denmark)

    Chen, Menglin; Havelund, Rasmus; Li, Qiang

    2011-01-01

    Core-sheath silver nanowire/polyvinylpyrrolidone (AgNW/PVP) nanocables have been fabricated via an efficient single-spinneret electrospinning method. The core-sheath structure is revealed by combining several characterization methods. A possible formation mechanism of the AgNW/PVP nanocable...... involving a strong stretching during the electrospinning process is proposed. Further, electrical measurements were performed on AgNW/PVP nanocables as well as bare AgNWs, which indicated the nanocables became insulating due to the isolation of highly conductive AgNWs by insulating PVP sheath. Therefore...

  6. Thermochemical properties of silver tellurides including empressite (AgTe) and phase diagrams for Ag-Te and Ag-Te-O

    Science.gov (United States)

    Voronin, Mikhail V.; Osadchii, Evgeniy G.; Brichkina, Ekaterina A.

    2017-04-01

    This study compiles original experimental and literature data on the thermodynamic properties (ΔfG°, S°, ΔfH°) of silver tellurides (α-Ag2Te, β-Ag2Te, Ag1.9Te, Ag5Te3, AgTe) obtained by the method of solid-state galvanic cell with the RbAg4I5 and AgI solid electrolytes. The thermodynamic data for empressite (AgTe, pure fraction from Empress Josephine Mine, Colorado USA) have been obtained for the first time by the electrochemical experiment with the virtual reaction Ag + Te = AgTe. The Ag-Te phase diagrams in the T - x and logfTe2 (gas) - 1/T coordinates have been refined, and the ternary Ag-Te-O diagrams with Ag-Te-TeO2 (paratellurite) composition range have been calculated.

  7. Polymorphism of LiAg

    Science.gov (United States)

    Pavlyuk, V. V.; Dmytriv, G. S.; Tarasiuk, I. I.; Chumak, I. V.; Pauly, H.; Ehrenberg, H.

    2010-02-01

    A phase transition from the cubic CsCl-type structure (Pm-3m space group) into a tetragonal UPb-type structure (I4 1/amd) is observed for the LiAg binary compound at ambient conditions. The crystal structure of the tetragonal modification of the LiAg binary compound was solved by direct methods in SHELXS on the base of structure factors which were extracted from a powder diffraction pattern and refined by SHELXL and the Rietveld method ( a = 3.9605(1), c = 8.2825(2) Å, Bragg R-factor = 4.81, Rf-factor = 4.87). Elevated temperatures and/or a small Li-excess versus the equimolar composition favour the cubic structure whereas ambient and lower temperatures and/or a small Li-deficiency stabilize the tetragonal structure. This reconstructive transition is reversible but proceeds slowly.

  8. Synthesis of highly efficient Ag@AgCl plasmonic photocatalysts with various structures.

    Science.gov (United States)

    Wang, Peng; Huang, Baibiao; Lou, Zaizhu; Zhang, Xiaoyang; Qin, Xiaoyan; Dai, Ying; Zheng, Zhaoke; Wang, Xiaoning

    2010-01-11

    By means of a simple ion-exchange process (using different precursors) and a light-induced chemical reduction reaction, highly efficient Ag@AgCl plasmonic photocatalysts with various self-assembled structures-including microrods, irregular balls, and hollow spheres-have been fabricated. All the obtained Ag@AgCl catalysts were characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and UV-visible diffuse reflectance spectroscopy. The effect of the different morphologies on the properties of the photocatalysts was studied. The average content of elemental Ag in Ag@AgCl was found to be about 3.2 mol %. All the catalysts show strong absorption in the visible-light region. The obtained Ag@AgCl samples exhibit enhanced photocatalytic activity for the degradation of organic contaminants under visible-light irradiation. The stability of the plasmonic photocatalysts was also investigated in detail.

  9. Realization of Ag-S codoped p-type ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tian Ning, E-mail: xtn9886@zju.edu.cn [Department of Science, Zhijiang College of Zhejiang University of Technology, Hangzhou, Zhejiang 310024 (China); Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Li, Xiang; Lu, Zhong [Department of Science, Zhijiang College of Zhejiang University of Technology, Hangzhou, Zhejiang 310024 (China); Chen, Yong Yue [Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Sui, Cheng Hua [Department of Science, Zhijiang College of Zhejiang University of Technology, Hangzhou, Zhejiang 310024 (China); Wu, Hui Zhen [Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China)

    2014-10-15

    Highlights: • Ag-S codoped p-type ZnO thin films have been fabricated. • The films exhibit low resistivity and high Hall mobility and hole concentration. • A ZnO:(Ag, S)/i-ZnO/ZnO:Al homojunction has been fabricated and shows rectifying behaviors. - Abstract: Ag-S codoped ZnO films have been grown on quartz substrates by e-beam evaporation at low temperature (100 °C). The effects of Ag{sub 2}S content on the structural and electrical properties of the films were investigated. The results showed that 2 wt% Ag{sub 2}S doped films exhibited p-type conduction, with a resistivity of 0.0347 Ω cm, a Hall mobility of 9.53 cm{sup 2} V{sup −1} s{sup −1}, and a hole concentration of 1.89 × 10{sup 19} cm{sup −3} at room temperature. The X-ray photoelectron spectroscopy measurements showed that Ag and S have been incorporated into the films. To further confirm the p-type conduction of Ag-S codoped ZnO films, a ZnO:(Ag, S)/i-ZnO/ZnO:Al homojunction was fabricated and rectifying behaviors of which was measured. High electrical performance and low growth temperature indicate that Ag{sub 2}S is a promising dopant to fabricate p-type Ag-S codoped ZnO films.

  10. Flower-like Ag/AgCl microcrystals: Synthesis and photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Daupor, Hasan; Wongnawa, Sumpun, E-mail: sumpun.w@psu.ac.th

    2015-06-01

    Silver/silver chloride (Ag/AgCl) composites with a novel flower-like morphology were prepared via a hot precipitation assisted by the vinyl acetate monomer (VAM) route. An aqueous solution of AlCl{sub 3} was mixed with the vinyl acetate monomer and acetic acid before adding a AgNO{sub 3} solution at a temperature of 100 °C. The octapod shaped flower-like Ag/AgCl particles (or “flower-like Ag/AgCl” hereinafter) has eight petals each of which was about 7–11 μm in length. The flower-like octapods were formed by preferential overgrowth along the <111> directions of the cubic seeds. Detailed studies of the growth process at different AlCl{sub 3} concentrations revealed that the concave cube developed into a Rubik's cube where eight corners grew further into the flower-like structures. The VAM and acetic acid concentration strongly affected the growth of the Ag/AgCl to the flower-like structure and their optimum concentrations were determined. The morphologies of these particles were carefully examined by scanning electron microscopy (SEM). The crystal structures and orientation relationship were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–visible diffused reflectance spectroscopy (DRS). The flower-like Ag/AgCl microcrystals were tested for their photocatalytic degradation of orange G dye (OG) catalyzed by visible light. From comparative test runs, the flower-like Ag/AgCl exhibited better photocatalytic activity than simple and commercial Ag/AgCl particles. - Highlights: • Interesting transformation of microcrystals Ag/AgCl from concave cube via Rubik's cube to flower-like shape. • The first to use VAM as morphology control reagent. • High photocatalytic activity under visible light irradiation.

  11. Capacitive deionization of seawater effected by nano Ag and Ag@C on graphene.

    Science.gov (United States)

    Cai, P-F; Su, C-J; Chang, W-T; Chang, F-C; Peng, C-Y; Sun, I-W; Wei, Y-L; Jou, C-J; Wang, H Paul

    2014-08-30

    Drinking water shortage has become worse in recent decades. A new capacitive deionization (CDI) method for increasing water supplies through the effective desalination of seawater has been developed. Silver as nano Ag and Ag@C which was prepared by carbonization of the Ag(+)-β-cyclodextrin complex at 573 K for 30 min can add the antimicrobial function into the CDI process. The Ag@C and Ag nanoparticles dispersed on reduced graphene oxide (Ag@C/rGO and nano Ag/rGO) were used as the CDI electrodes. The nano Ag/rGO and Ag@C/rGO electrodes can reduce the charging resistant, and enhance the electrosorption capability. Better CDI efficiencies with the nano Ag/rGO and Ag@C/rGO electrodes can therefore be obtained. When reversed the voltage, the electrodes can be recovered up to 90% within 5 min. This work presents the feasibility for the nano Ag and Ag@C on rGO electrodes applied in CDI process to produce drinking water from seawater or saline water.

  12. Constraining the Properties of the Eta Carinae System via 3-D SPH Models of Space-Based Observations: The Absolute Orientation of the Binary Orbit

    Science.gov (United States)

    Madura, Thomas I.; Gull, Theodore R.; Owocki, Stanley P.; Okazaki, Atsuo T.; Russell, Christopher M. P.

    2011-01-01

    The extremely massive (> 90 Stellar Mass) and luminous (= 5 x 10(exp 6) Stellar Luminosity) star Eta Carinae, with its spectacular bipolar "Homunculus" nebula, comprises one of the most remarkable and intensely observed stellar systems in the Galaxy. However, many of its underlying physical parameters remain unknown. Multiwavelength variations observed to occur every 5.54 years are interpreted as being due to the collision of a massive wind from the primary star with the fast, less dense wind of a hot companion star in a highly elliptical (e approx. 0.9) orbit. Using three-dimensional (3-D) Smoothed Particle Hydrodynamics (SPH) simulations of the binary wind-wind collision, together with radiative transfer codes, we compute synthetic spectral images of [Fe III] emission line structures and compare them to existing Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) observations. We are thus able, for the first time, to tightly constrain the absolute orientation of the binary orbit on the sky. An orbit with an inclination of approx. 40deg, an argument of periapsis omega approx. 255deg, and a projected orbital axis with a position angle of approx. 312deg east of north provides the best fit to the observations, implying that the orbital axis is closely aligned in 3-D space with the Homunculus symmetry axis, and that the companion star orbits clockwise on the sky relative to the primary.

  13. 3D Radiative Transfer in Eta Carinae: Application of the SimpleX Algorithm to 3D SPH Simulations of Binary Colliding Winds

    Science.gov (United States)

    Clementel, N.; Madura, T. I.; Kruip, C. J. H.; Icke, V.; Gull, T. R.

    2014-01-01

    Eta Carinae is an ideal astrophysical laboratory for studying massive binary interactions and evolution, and stellar wind-wind collisions. Recent three-dimensional (3D) simulations set the stage for understanding the highly complex 3D flows in Eta Car. Observations of different broad high- and low-ionization forbidden emission lines provide an excellent tool to constrain the orientation of the system, the primary's mass-loss rate, and the ionizing flux of the hot secondary. In this work we present the first steps towards generating synthetic observations to compare with available and future HST/STIS data. We present initial results from full 3D radiative transfer simulations of the interacting winds in Eta Car. We use the SimpleX algorithm to post-process the output from 3D SPH simulations and obtain the ionization fractions of hydrogen and helium assuming three different mass-loss rates for the primary star. The resultant ionization maps of both species constrain the regions where the observed forbidden emission lines can form. Including collisional ionization is necessary to achieve a better description of the ionization states, especially in the areas shielded from the secondary's radiation. We find that reducing the primary's mass-loss rate increases the volume of ionized gas, creating larger areas where the forbidden emission lines can form. We conclude that post processing 3D SPH data with SimpleX is a viable tool to create ionization maps for Eta Car.

  14. 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...

  15. To $v_\\infty$ and beyond! The He I absorption variability across the 2014.6 periastron passage of $\\eta$ Carinae

    CERN Document Server

    Richardson, Noel D; St-Jean, Lucas; Moffat, Anthony F J; Gull, Theodore R; Russell, Christopher M P; Damineli, Augusto; Teodoro, Mairan; Corcoran, Michael F; Walter, Frederick M; Clementel, Nicola; Groh, José H; Hamaguchi, Kenji; Hillier, D John

    2016-01-01

    We have monitored the massive binary star $\\eta$ Carinae with the CTIO/SMARTS 1.5~m telescope and CHIRON spectrograph from the previous apastron passage of the system through the recent 2014.6 periastron passage. Our monitoring has resulted in a large, homogeneous data set with an unprecedented time-sampling, spectral resolving power, and signal-to-noise. This allowed us to investigate temporal variability previously unexplored in the system and discover a kinematic structure in the P Cygni absorption troughs of neutral helium wind lines. The features observed occurred prior to the periastron passage and are seen as we look through the trailing arm of the wind-wind collision shock cone. We show that the bulk of the variability is repeatable across the last five periastron passages, and that the absorption occurs in the inner 230 AU of the system. In addition, we found an additional, high-velocity absorption component super-imposed on the P Cygni absorption troughs that has been previously un-observed in these...

  16. Chandra X-ray Grating Spectrometry of Eta Carinae near X-ray Minimum: I. Variability of the Sulfur and Silicon Emission Lines

    CERN Document Server

    Henley, D B; Pittard, J M; Stevens, I R; Hamaguchi, K; Gull, T R

    2008-01-01

    We report on variations in important X-ray emission lines in a series of Chandra grating spectra of the supermassive colliding wind binary star Eta Carinae, including key phases around the X-ray minimum/periastron passage in 2003.5. The X-rays arise from the collision of the slow, dense wind of Eta Car with the fast, low-density wind of an otherwise hidden companion star. The X-ray emission lines provide the only direct measure of the flow dynamics of the companion's wind along the wind-wind collision zone. We concentrate here on the silicon and sulfur lines, which are the strongest and best resolved lines in the X-ray spectra. Most of the line profiles can be adequately fit with symmetric Gaussians with little significant skewness. Both the silicon and sulfur lines show significant velocity shifts and correlated increases in line widths through the observations. The R = forbidden-to-intercombination ratio from the Si XIII and S XV triplets is near or above the low-density limit in all observations, suggestin...

  17. Detection of high-velocity material from the wind-wind collision zone of Eta Carinae across the 2009.0 periastron passage

    CERN Document Server

    Groh, Jose H; Damineli, Augusto; Gull, Theodore R; Madura, Thomas I; Hillier, D J; Teodoro, Mairan; Driebe, Thomas; Weigelt, Gerd; Hartman, Henrik; Kerber, Florian; Okazaki, Atsuo T; Owocki, Stan P; Millour, Florentin; Murakawa, Koji; Kraus, Stefan; Hofmann, Karl-Heinz; Schertl, Dieter

    2010-01-01

    We report near-IR spectroscopic observations of the Eta Carinae massive binary system during 2008-2009 using VLT/CRIRES. We detect a strong, broad absorption wing in He I 10833 extending up to -1900 km/s across the 2009.0 spectroscopic event. Archival HST/STIS ultraviolet and optical data shows a similar high-velocity absorption (up to -2100 km/s) in the UV resonance lines of Si IV 1394, 1403 across the 2003.5 event. UV lines from low-ionization species, such as Si II 1527, 1533 and C II 1334, 1335, show absorption up to -1200 km/s, indicating that the absorption with v from -1200 to -2100 km/s originates in a region markedly faster and more ionized than the nominal wind of the primary star. Observations obtained at the OPD/LNA during the last 4 spectroscopic cycles (1989-2009) also display high-velocity absorption in He I 10833 during periastron. Based on the OPD/LNA dataset, we determine that material with v 1.049. Therefore, we constrain the duration of the high-velocity absorption to be 95 to 206 days (o...

  18. 3D Radiative Transfer in $\\eta$ Carinae: Application of the SimpleX Algorithm to 3D SPH Simulations of Binary Colliding Winds

    CERN Document Server

    Clementel, N; Kruip, C J H; Icke, V; Gull, T R

    2014-01-01

    Eta Carinae is an ideal astrophysical laboratory for studying massive binary interactions and evolution, and stellar wind-wind collisions. Recent three-dimensional (3D) simulations set the stage for understanding the highly complex 3D flows in $\\eta$ Car. Observations of different broad high- and low-ionization forbidden emission lines provide an excellent tool to constrain the orientation of the system, the primary's mass-loss rate, and the ionizing flux of the hot secondary. In this work we present the first steps towards generating synthetic observations to compare with available and future HST/STIS data. We present initial results from full 3D radiative transfer simulations of the interacting winds in $\\eta$ Car. We use the SimpleX algorithm to post-process the output from 3D SPH simulations and obtain the ionization fractions of hydrogen and helium assuming three different mass-loss rates for the primary star. The resultant ionization maps of both species constrain the regions where the observed forbidde...

  19. Ag nanoprisms with Ag₂S attachment.

    KAUST Repository

    Xiong, Shenglin

    2013-01-01

    Triangular Ag nanoprisms are a type of most-studied noble-metal nanostructures over the past decade owing to their special structural architecture and outstanding optical and catalytic properties for a wide range of applications. Nevertheless, in contrast to active research for the synthesis of phase-pure Ag nanoprisms, no asymmetric heterodimers containing Ag prisms have been developed so far, probably due to lack of suitable synthetic methods. Herein, we devise a simple ion-exchange method to synthesize Ag2S/Ag heterodimers at room temperature, through which Ag nanoprisms with controllable size and thickness can be fabricated. Formation chemistry and optical properties of the heterodimers have been investigated. These semiconductor/metal heterodimers have exhibited remarkable bactericidal activity to E. coli cells under visible light illumination.

  20. Facile synthesis of S-Ag nanocomposites and Ag2S short nanorods by the interaction of sulfur with AgNO3 in PEG400

    Science.gov (United States)

    Zhang, Yan-Li; Xie, Xin-Yuan; Liang, Ming; Xie, Shu-Ming; Chen, Jie-Mei; Zheng, Wen-Jie

    2016-06-01

    A facile, eco-friendly and inexpensive method to prepare Ag2S short nanorods and S-Ag nanocomposites using sublimed sulfur, AgNO3, PVP and PEG400 was studied. According to x-ray diffraction and scanning electron microscopy of the Ag2S, the products are highly crystalline and pure Ag2S nanorods with diameters of 70-160 nm and lengths of 200-360 nm. X-ray diffraction of the S-Ag nanocomposites shows that we obtained cubic Ag and S nanoparticles. Transmission electron microscopy shows that the molar ratio of PVP to Ag+ plays an important role in controlling the size and morphology of the S-Ag nanocomposites. When the molar ratio of PVP to Ag+ was 10:1, smaller sizes, better dispersibility and narrower distribution of S-Ag nanocomposites with diameters of 10-40 nm were obtained. The formation mechanism of the S-Ag nanocomposites was studied by designing a series of experiments using ultraviolet-visible measurement, and it was found that S nanoparticles are produced first and act as seed crystals; then Ag+ becomes Ag nanocrystals on the surfaces of the S nanoparticles by the reduction of PVP. PEG400 acts as a catalyzer, accelerating the reaction rate, and protects the S-Ag nanocomposites from reacting to produce Ag2S. The antimicrobial experiments show that the S-Ag nanocomposites have greater antimicrobial activity on Staphylococcus aureus, Aspergillus niger and blue mold than Ag nanoparticles.

  1. A Study of Surfactant-Induced Growth of Ag on Ag (111)

    Institute of Scientific and Technical Information of China (English)

    WU Li-Li; HU Juan-Mei; WU Feng-Min

    2008-01-01

    A new growth model is introduced to describe surfactant-induced growth of Ag on Ag (111) with realistic physical parameters. In this model, the A-S exchange mechanism is considered for the first time. Using the Monte Carlo simulations, the influence of exchange mechanism, surface temperature T, the exchange barrier Eex, and the coverage of surfactant θM on the growth mode and morphology during multilayer film growth of Ag/Ag (111) are studied in detail. Both the referenced value of surfactant coverage and the method to obtain perfect layer-by-layer film in surfactant-induced Ag/Ag (111) system are provided. Our simulation results are consistent with many experimental observations for surfactant-induced growth of Ag on Ag (111).

  2. Transformation from Ag@Ag3PO4 to Ag@Ag2SO4 hybrid at room temperature: preparation and its visible light photocatalytic activity

    Science.gov (United States)

    Wei, Ting; Gao, Shanmin; Wang, Qingyao; Xu, Hui; Wang, Zeyan; Huang, Baibiao; Dai, Ying

    2017-02-01

    In the present study, Ag/Ag2SO4 hybrid photocatalysts were obtained via a facile redox-precipitation reaction approach by using Ag@Ag3PO4 nanocomposite as the precursor and KMnO4 as the oxidant. Multiple techniques, such as X-ray diffraction pattern (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS) and Brunauer-Emmett-Teller (BET), photocurrent and electrochemical impedance spectroscopy (EIS), were applied to investigate the structures, morphologies, optical, and electronic properties of as-prepared samples. The photocatalytic activities were evaluated by photodegradation of organic rhodamine B (RhB) and methyl orange (MO) under visible light irradiation. It was found that pure Ag2SO4 can partially transform into metallic Ag during the photocatalytic degradation of organic pollutants, but the Ag/Ag2SO4 hybrids can maintain its structure stability and show enhanced visible light photocatalytic activity because of the surface plasma resonance effect of the metallic Ag.

  3. Multiple Partial Siberian Snakes in the AGS

    Science.gov (United States)

    Takano, J.; Ahrens, L. A.; Bai, M.; Brown, K.; Courant, E. D.; Gardner, C. J.; Glenn, J. W.; Hattori, T.; Huang, H.; Lin, F.; Luccio, A. U.; MacKay, W. W.; Okamura, M.; Roser, T.; Tepikian, S.; Tsoupas, N.; Yip, K.; Zelenski, A.; Zeno, K.

    2007-06-01

    Polarized protons are accelerated up to 24.3 GeV in the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL). To accelerate the beam with preserving the polarization, two different types of helical dipole partial Siberian snake have been installed to the AGS. One is a superconducting magnet (Cold Snake, CSNK), and the other is a normal conducting one (Warm Snake, WSNK). With these snake magnets, the polarization at the AGS extraction achieved 65%. However, the AGS has spin mismatches at the injection and extraction. This description shows calculated results to have better spin matching with using two or three snakes.

  4. Highly efficient visible light plasmonic photocatalyst Ag@Ag(Br,I).

    Science.gov (United States)

    Wang, Peng; Huang, Baibiao; Zhang, Qianqian; Zhang, Xiaoyang; Qin, Xiaoyan; Dai, Ying; Zhan, Jie; Yu, Jiaoxian; Liu, Haixia; Lou, Zaizhu

    2010-09-03

    The new plasmonic photocatalyst Ag@Ag(Br,I) was synthesized by the ion-exchange process between the silver bromide and potassium iodide, then by reducing some Ag(+) ions in the surface region of Ag(Br,I) particles to Ag(0) species. Ag nanoparticles are formed from Ag(Br,I) by the light-induced chemical reduction reaction. The Ag@Ag(Br,I) particles have irregular shapes with their sizes varying from 83 nm to 1 mum. The as-grown plasmonic photocatalyst shows strong absorption in the visible light region because of the plasmon resonance of Ag nanoparticles. The ability of this compound to reduce Cr(VI) under visible light was compared with those of other reference photocatalyst. The plasmonic photocatalyst is shown to be highly efficient under visible light. The stability of the photocatalyst was examined by X-ray diffraction and X-ray photoelectron spectroscopy. The XRD pattern and XPS spectra prove the stability of the plasmonic photocatalyst Ag@Ag(Br,I).

  5. Preparation of Ag/C catalysts for the O{sub 2} electrode by the Ag(I) SCRM

    Energy Technology Data Exchange (ETDEWEB)

    Han Jiajun, E-mail: hanjj20032000@yahoo.com.cn [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Li Ning; Liu Deli [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)

    2009-06-15

    Ag/C catalysts with different Ag particle-size distribution were prepared by Ag(I) single crystal reduction method (Ag(I) SCRM) and physically characterized. Their electrochemical performances were investigated by using Ag/C as O{sub 2} reduction catalysts in alkaline electrolyte. The results showed that the electrocatalytic activity of Ag/C catalysts prepared by the Ag(I) SCRM was significantly enhanced compared with that of Ag/C catalysts prepared by Ag{sub 2}O reduction method (Ag{sub 2}O RM) under the same content of Ag. The cyclic voltammetry indicate that the larger Ag particles are favourable to the four-electron reduction of O{sub 2}, the finer Ag particles are favourable to the two-electron reduction of O{sub 2}; the overpotential of four-electron reduction is higher, the overpotential of two-electron reduction is lower.

  6. Kinetics of Ag-rich precipitates formation in Cu-Al-Ag alloys

    Energy Technology Data Exchange (ETDEWEB)

    Adorno, A.T.; Guerreiro, M.R.; Silva, R.A.G

    2004-06-15

    The kinetics of Ag-rich precipitates formation in the Cu-2 wt.% Al alloy with additions of 2, 4, 6, 8, 10 and 12 wt.% Ag was studied using microhardness changes with temperature and time, differential scanning calorimetry (DSC), differential thermal analysis (DTA), scanning electron microscopy (SEM), optical microscopy (OM), energy dispersive X-ray analysis (EDX) and X-ray diffractometry (XRD). The results indicated that an increase in the Ag content decreases the activation energy for Ag-rich precipitates formation, and that it is possible to estimate the values of the diffusion and nucleation activation energies for the Ag precipitates.

  7. The AGS synchrotron with four helical magnets

    Energy Technology Data Exchange (ETDEWEB)

    Tsoupas N.; Huang, H.; Roser, T.; MacKay, W.W.; Trbojevic, D.

    2012-05-20

    The idea of using two partial helical magnets was applied successfully to the AGS synchrotron to preserve the proton beam polarization. In this paper we explore in details the idea of using four helical magnets placed symmetrically in the AGS ring. The placement of four helical magnets in the AGS ring provides many advantages over the present setup of the AGS which uses two partial helical magnets. First, the symmetric placement of the four helical magnets allows for a better control of the AGS optics with reduced values of the beta functions especially near beam injection, second, the vertical spin direction during beam injection and extraction is closer to vertical, and third, it provides for a larger 'spin tune gap', which allows the vertical and horizontal tunes to be placed, and prevent the horizontal and vertical intrinsic spin resonances of the AGS to occur during the acceleration cycle. Although the same spin gap can be obtained with a single or two partial helices, the required high field strength of a single helix makes its use impractical, and that of the double helix rather difficult. In this paper we will provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and compare these results with the present setup of the AGS that uses two partial helical magnets.

  8. Visible light driven photocatalysis and antibacterial activity of AgVO{sub 3} and Ag/AgVO{sub 3} nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Anamika [Department of Life Sciences, University of Mumbai, Santacruz (E), Mumbai 400 098 (India); Dutta, Dimple P., E-mail: dimpled@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Ballal, A. [Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Fulekar, M.H. [School of Environment and Sustainable Development, Central University of Gujarat, Gandhinagar 382 030, Gujarat (India)

    2014-03-01

    Graphical abstract: - Highlights: • Ag/AgVO{sub 3} and pure AgVO{sub 3} nanowires synthesized by sonochemical process. • Characterization done using XRD, SEM, TEM, EDX and BET analysis. • Visible light degradation of RhB by Ag/AgVO{sub 3} within 45 min. • Antibacterial activity of Ag/AgVO{sub 3} demonstrated. - Abstract: Ag/AgVO{sub 3} nanowires and AgVO{sub 3} nanorods were synthesized in aqueous media via a facile sonochemical route. The as-synthesized products were characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy together with an energy dispersion X-ray spectrum analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The results revealed that inert atmosphere promotes the formation of Ag/AgVO{sub 3} nanowires. The photocatalytic studies revealed that the Ag/AgVO{sub 3} nanowires exhibited complete photocatalytic degradation of Rhodamine B within 45 min under visible light irradiation. The antibacterial activity of Ag/AgVO{sub 3} nanowires was tested against Escherechia coli and Bacillus subtilis. The minimum growth inhibitory concentration value was found to be 50 and 10 folds lower than for the antibiotic ciprofloxacin for E. coli and B. subtilis, respectively. The antibacterial properties of the β-AgVO{sub 3} nanorods prove that in case of the Ag dispersed Ag/AgVO{sub 3} nanowires, the enhanced antibacterial action is also due to contribution from the AgVO{sub 3} support.

  9. Ligand and counterion control of Ag(I) architectures: assembly of a {Ag8} ring cluster mediated by hydrophobic and Ag...Ag interactions.

    Science.gov (United States)

    Fielden, John; Long, De-liang; Slawin, Alexandra M Z; Kögerler, Paul; Cronin, Leroy

    2007-10-29

    A strategy combining ligand design and counterion variation has been used to investigate the assembly of silver(I) complexes. As a result, dinuclear, octanuclear, and polymeric silver(I) species have been synthesized by complexation of the rigid aliphatic amino ligands cis-3,5-diamino-trans-hydroxycyclohexane (DAHC), cis-3,5-diamino-trans-methoxycyclohexane (DAMC), and cis-3,5-diamino-trans-tert-butyldimethylsilylanyloxycyclohexane (DATC) with silver(I) triflate, nitrate, and perchlorate. The compositions of these aggregates, established by X-ray crystallography and elemental analysis, are [{Ag(DAHC)}2](CF3SO3)2 (1), [{Ag(DAMC)}2](CF3SO3)2 (2), [{Ag(DAMC)}2](NO3)2 (3), [{Ag(DATC)}6{Ag(DAHC)}2](NO3)8 (4), and [{Ag(DATC}n](NO3)n (5), where the DAHC present in 4 is formed by in situ hydrolysis of the acid labile silyl ether group. The type of aggregate formed depends both upon the noncoordinating O-substituent of the ligand and the (also noncoordinating) counterion, with the normal preference of the ligand topology for forming Ag2L2 structures being broken by introduction of the bulky, lipophilic O-tert-butyldimethylsilyl (TBDMS) group. Of particular note is the octanuclear silver ring structure 4, which is isolated only when both the O-TBDMS group and the nitrate counteranion are present and is formed from four Ag2L2 dimers connected by Ag...Ag and hydrogen-bonding interactions. Diffusion rate measurement of this {Ag8} complex by 1H NMR (DOSY) indicates dissociation in CD3OD and CD3CN, showing that this supramolecular ring structure is formed upon crystallization, and establishing a qualitative limit to the strength of Ag...Ag interactions in solution. When solutions of the {Ag8} cluster in methanol are kept for several days though, a new UV-vis absorption is observed at around 430 nm, consistent with the formation of silver nanoparticles.

  10. Growth of Ag nanocrystals on multiwalled carbon nanotubes and Ag-carbon nanotube interaction

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The experimental investigations on the interaction between Ag-nanocrystal particles (Ag-NCPs) and carbon nanotubes (CNTs) in Ag-nanocrystal particles/carbon nanotubes (Ag-NCPs/CNTs) hybrid structures were reported. The growth of Ag-NCPs on multiwalled carbon nanotubes (MWCNTs) was carried out by thermal evaporation deposition. High-resolution transmission electron microscopy and X-ray diffraction analyses revealed that Ag-NCPs had the crystal lattice feature of face-centered cube (fcc). The growth of Ag-NCPs on MWCNTs induced the cross-section deformation of MWCNT. The experimental results also showed that the synthesized Ag-NCPs/CNTs hybrid structure appeared as quasi-one dimensional nanowires containing the Ag-NCP/CNT hetero-junction. There was local cross-section deformation on MWCNTs at the interface of hetero-junction. These results involve the important topic about fundamental and practical studies for structure of MNCPs on CNTs and also find clues to further research of Ag nanocrystal growing on MWCNTs and related Ag-CNT interaction.

  11. Label-Free Detection of Ag+ Based on Gold Nanoparticles and Ag+-Specific DNA.

    Science.gov (United States)

    Pu, Wendan; Zhao, Zhao; Wu, Liping; Liu, Yue; Zhao, Huawen

    2015-08-01

    A sensitive label-free method was presented for the determination of silver ion (Ag+) in this paper. Cytosine-rich DNA (C-DNA) was used as Ag+ specific DNA. Without Ag+ in the solution, fluorescence of fluorescein (FAM) is quenched by C-DNA stabilized gold nanoparticles (AuNPs) in high salt environment. When Ag+ is present in the solution, however, Ag+-mediated cytosine-Ag+-cytosine (C-Ag+-C) base pairs induced the C-DNA folding into a hairpin structure, which can not stabilize AuNPs in high salt environment, thus causing AuNPs aggregation. After centrifugation to remove the aggregated AuNPs, the quenching ability of the supernatant for FAM is decreased and the fluorescence intensity of solution increases with increasing the Ag+ concentration. Due to the highly specific interaction of the C-DNA towards Ag+ and the strong fluorescent quenching ability of AuNPs for FAM, the method has high selectivity and sensitivity for Ag+. Under the optimal conditions, the fluorescence intensity at 515 nm increased linearly with the concentration of Ag+ ranging from 15 nM to 700 nM, and the detection limit was determined as 6 nM based on 3 σ/slope. This method is simple, sensitive, and may be applied to other detection systems by selecting the appropriate DNA sequences.

  12. Strain distributions of confined Au/Ag and Ag/Au nanoparticles

    Institute of Scientific and Technical Information of China (English)

    黄红华; 章英; 刘晓山; 骆兴芳; 袁彩雷; 叶双莉

    2015-01-01

    The strain distributions of Au/Ag and Ag/Au nanoparticles confined in the Al2O3 matrix with different core sizes are investigated by using the finite element method, respectively. The simulation results clearly indicate that the compressive strains exerted on the Au/Ag and Ag/Au nanoparticles can be induced by the Al2O3 matrix. Moreover, it can be found that the strain gradient existing in a Au/Ag nanoparticle is much larger than that in a Ag/Au nanoparticle, which could be due to the larger Young’s modulus of Au than that of Ag. With the core size increasing, the strain gradient existing in the Au/Ag nanoparticle becomes larger, while the strain gradient existing in the Ag/Au nanoparticle keeps constant. These different strain distributions may have significant infl uences on the structures and morphologies of the Au/Ag and Ag/Au nanoparticles, leading to the different physical properties for potential applications.

  13. Photocatalytic oxidation removal of Hg0 using ternary Ag/AgI-Ag2CO3 hybrids in wet scrubbing process under fluorescent light

    Science.gov (United States)

    Zhang, Anchao; Zhang, Lixiang; Chen, Xiaozhuan; Zhu, Qifeng; Liu, Zhichao; Xiang, Jun

    2017-01-01

    A series of ternary Ag/AgI-Ag2CO3 photocatalysts synthesized using a facile coprecipitation method were employed to investigate their performances of Hg0 removal in a wet scrubbing reactor. The hybrids were characterized by N2 adsorption-desorption, XRD, SEM-EDS, HRTEM, XPS, DRS and ESR. The photocatalytic activities of Hg0 removal were evaluated under fluorescent light. The results showed that AgI content, fluorescent light irradiation, reaction temperature all showed significant influences on Hg0 removal. NO exhibited significant effect on Hg0 removal in comparison to SO2. Among these ternary Ag/AgI-Ag2CO3 hybrids, Ag/AgI(0.1)-Ag2CO3 showed the highest Hg0 removal efficiency, which could be ascribed to the effective separation of photogenerated electron-hole pairs between AgI and Ag2CO3 and the surface plasmon resonance (SPR) effect in the visible region by metallic silver nanoparticles (Ag0 NPs). The trapping studies of reactive radicals showed that the superoxide radicals (rad O2-) may play a key role in Hg0 removal under fluorescent light. According to the experimental and characterization results, a possible photocatalytic oxidation mechanism for enhanced Hg0 removal over Ag/AgI(0.1)-Ag2CO3 hybrid under fluorescent light was proposed.

  14. Au, Ag and Au:Ag colloidal nanoparticles synthesized by pulsed laser ablation as SERS substrates

    Directory of Open Access Journals (Sweden)

    M. Vinod

    2014-12-01

    Full Text Available Chemically pure colloidal suspensions of gold and silver nanoparticles were synthesized using pulsed laser ablation. The dependence of laser fluence on the surface plasmon characteristics of the nanoparticles was investigated. Au:Ag colloidal suspensions were prepared by mixing highly monodisperse Au and Ag nanocolloids. The plasmon band of these mixtures was found to be highly sensitive to Au:Ag concentration ratio and wavelength of the laser beam used in the ablation process. The Au:Ag mixture consists of almost spherical shaped nanostructures with a tendency to join with adjacent ones. The surface enhanced Raman scattering activity of the Au, Ag and Au:Ag colloidal suspensions was tested using crystal violet as probe molecules. Enhancement in Raman signal obtained with Au:Ag substrates was found to be promising and strongly depends on its plasmon characteristics.

  15. Au, Ag and Au:Ag colloidal nanoparticles synthesized by pulsed laser ablation as SERS substrates

    Institute of Scientific and Technical Information of China (English)

    M. Vinod; K.G.Gopchandran

    2014-01-01

    Chemically pure colloidal suspensions of gold and silver nanoparticles were synthesized using pulsed laser ablation. The dependence of laser fluence on the surface plasmon characteristics of the nanoparticles was investigated. Au:Ag colloidal suspensions were prepared by mixing highly monodisperse Au and Ag nanocolloids. The plasmon band of these mixtures was found to be highly sensitive to Au:Ag concentration ratio and wavelength of the laser beam used in the ablation process. The Au:Ag mixture consists of almost spherical shaped nanostructures with a tendency to join with adjacent ones. The surface enhanced Raman scattering activity of the Au, Ag and Au:Ag colloidal suspensions was tested using crystal violet as probe molecules. Enhancement in Raman signal obtained with Au:Ag substrates was found to be promising and strongly depends on its plasmon characteristics.

  16. Identification of Ag-acceptor related photoluminescence in $^{111}\\!$Ag doped CdTe

    CERN Document Server

    Hamann, J; Deicher, M; Filz, T; Ostheimer, V; Schmitz, C; Wolf, H; Wichert, T

    1998-01-01

    Bridgman-grown, nominally undoped CdTe crystals were doped with Ag by implanting radioactive $^{111}\\!$Ag. Photoluminescence spectra of the crystals show a donor-acceptor pair (DAP) line at 1.491 eV. The decrease of the intensity of this line with a half life of T$_{1/2}$=(7.2$\\pm$0.4) d is in good agreement with the half life of the $\\beta\\!^{-}$-decay of $^{111}\\!$Ag to $^{111}\\!$Cd of 7.45 d. This decrease is not caused by the aging behavior of Ag which was reported in the literature. The data show that the involved acceptor defect contains exactly one Ag atom and confirm the earlier assignment of the acceptor to the AgCd defect. Based on the DAP line at 1.491 eV, the spectra did not reveal a contamination of the CdTe crystals by stable Ag.

  17. Effects of soil and dietary exposures to Ag nanoparticles and AgNO₃ in the terrestrial isopod Porcellionides pruinosus.

    Science.gov (United States)

    Tourinho, Paula S; van Gestel, Cornelis A M; Jurkschat, Kerstin; Soares, Amadeu M V M; Loureiro, Susana

    2015-10-01

    The effects of Ag-NPs and AgNO3 on the isopod Porcellionides pruinosus were determined upon soil and dietary exposures. Isopods avoided Ag in soil, with EC50 values of ∼16.0 and 14.0 mg Ag/kg for Ag-NPs and AgNO3, respectively. Feeding inhibition tests in soil showed EC50s for effects on consumption ratio of 127 and 56.7 mg Ag/kg, respectively. Although similar EC50s for effects on biomass were observed for nanoparticulate and ionic Ag (114 and 120 mg Ag/kg dry soil, respectively), at higher concentrations greater biomass loss was found for AgNO3. Upon dietary exposure, AgNO3 was more toxic, with EC50 for effects on biomass change being >1500 and 233 mg Ag/kg for Ag-NPs and AgNO3, respectively. The difference in toxicity between Ag-NPs and AgNO3 could not be explained from Ag body concentrations. This suggests that the relation between toxicity and bioavailability of Ag-NPs differs from that of ionic Ag in soils.

  18. Discovery of VHE emission towards the Carina arm region with the H.E.S.S. telescope array: HESS J1018-589

    Science.gov (United States)

    H. E. S. S. Collaboration; Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Balzer, A.; Barnacka, A.; Becherini, Y.; Becker, J.; Bernlöh, K.; Birsin, E.; Biteau, J.; Bochow, A.; Boisson, C.; Bolmont, J.; Bordas, P.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Büsching, I.; Carrigan, S.; Casanova, S.; Cerruti, M.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Cologna, G.; Conrad, J.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; Drury, L. O'C.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Espigat, P.; Fallon, L.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gallant, Y. A.; Gast, H.; Gérard, L.; Gerbig, D.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Göring, D.; Häffner, S.; Hague, J. D.; Hahn, J.; Hampf, D.; Harris, J.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hofverberg, P.; Holler, M.; Horns, D.; Jacholkowska, A.; de Jager, O. C.; Jahn, C.; Jamrozy, M.; Jung, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Keogh, D.; Khélifi, B.; Klochkov, D.; Klużniak, D.; Kneiske, T.; Komin, Nu.; Kosack, K.; Kossakowski, R.; Krayzel, F.; Laffon, H.; Lamanna, G.; Lenain, J.-P.; Lennarz, D.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Masbou, J.; Maxted, N.; Mayer, M.; McComb, T. J. L.; Medina, M. C.; Méhault, J.; Moderski, R.; Mohamed, M.; Moulin, E.; Naumann, C. L.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Nguyen, N.; Nicholas, B.; Niemiec, J.; Nolan, S. J.; Ohm, S.; de Oña Wilhelmi, E.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Paz Arribas, M.; Pekeur, N. W.; Pelletier, G.; Perez, J.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raue, M.; Rayner, S. M.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Sanchez, D. A.; Santangelo, A.; Schlickeiser, R.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Sheidaei, F.; Skilton, J. L.; Sol, H.; Spengler, G.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Szostek, A.; Tavernet, J.-P.; Terrier, R.; Tluczykont, M.; Valerius, K.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Viana, A.; Vincent, P.; Völk, H. J.; Volpe, F.; Vorobiov, S.; Vorster, M.; Wagner, S. J.; Ward, M.; White, R.; Wierzcholska, A.; Zacharias, M.; Zajczyk, A.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.

    2012-05-01

    The Carina arm region, containing the supernova remnant SNR G284.3-1.8, the high-energy (HE; E > 100 MeV) binary 1FGL J1018.6-5856 and the energetic pulsar PSR J1016-5857 and its nebula, has been observed with the H.E.S.S. telescope array. The observational coverage of the region in very-high-energy (VHE; E > 0.1 TeV) γ-rays benefits from deep exposure (40 h) of the neighboring open cluster Westerlund 2. The observations have revealed a new extended region of VHE γ-ray emission. The new VHE source HESS J1018-589 shows a bright, point-like emission region positionally coincident with SNR G284.3-1.8 and 1FGL J1018.6-5856 and a diffuse extension towards the direction of PSR J1016-5857. A soft (Γ = 2.7 ± 0.5stat)photon index, with a differential flux at 1 TeV of N0 = (4.2 ± 1.1) × 10-13 TeV-1 cm-2 s-1 is found for the point-like source, whereas the total emission region including the diffuse emission region is well fit by a power-law function with spectral index Γ = 2.9 ± 0.4stat and differential flux at 1 TeV of N0 = (6.8 ± 1.6) × 10-13 TeV-1 cm-2 s-1. This H.E.S.S. detection motivated follow-up X-ray observations with the XMM-Newton satellite to investigate the origin of the VHE emission. The analysis of the XMM-Newton data resulted in the discovery of a bright, non-thermal point-like source (XMMU J101855.4-58564) with a photon index of Γ = 1.65 ± 0.08 in the center of SNR G284.3-1.8, and a thermal, extended emission region coincident with its bright northern filament. The characteristics of this thermal emission are used to estimate the plasma density in the region as n ≈ 0.5 cm-3 (2.9 kpc/d)2. The position of XMMU J101855.4-58564 is compatible with the position reported by the Fermi-LAT collaboration for the binary system 1FGL J1018.6-5856 and the variable Swift XRT source identified with it. The new X-ray data are used alongside archival multi-wavelength data to investigate the relationship between the VHE γ-ray emission from HESS J1018-589 and the

  19. An efficient photocatalyst for degradation of various organic dyes: Ag@Ag{sub 2}MoO{sub 4}–AgBr composite

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Yu-Yang; Lu, Yi; Liu, Jin-Ku, E-mail: jkliu@ecust.edu.cn

    2016-04-15

    Highlights: • Ag@Ag{sub 2}MoO{sub 4}–AgBr composite is synthesized by in-situ exchange and photo depositio nmethod. • Compared with pure Ag{sub 2}MoO{sub 4} crystal, the photocatalytic activity of Ag@Ag{sub 2}MoO{sub 4}–AgBr composite was increased by 348.4%. • Silver particles act as electron trap to enhance electron–hole separation. • This composite has the promising application to degrade organic wastewater. - Abstract: The Ag{sub 2}MoO{sub 4}-AgBr composite was prepared by a facile in-situ anion-exchange method, then the Ag nanoparticles were coated on this composite through photodeposition route to form a novel Ag@Ag{sub 2}MoO{sub 4}–AgBr composite. The in-situ Br{sup −} replacement in a crystal lattice node position of Ag{sub 2}MoO{sub 4} crystal allows for overcoming the resistance of electron transition effectively. Meanwhile silver nano-particles on the surface of Ag@Ag{sub 2}MoO{sub 4}–AgBr composite could act as electron traps to intensify the photogeneration electron-hole separation and the subsequent transfer of the trapped electron to the adsorbed O{sub 2} as an electron acceptor. As an efficient visible light catalyst, the Ag@Ag{sub 2}MoO{sub 4}–AgBr composite exhibited superior photocatalytic activity for the degradation of various organic dyes. The experimental results demonstrated superior photocatalytic rate of Ag@Ag{sub 2}MoO{sub 4}–AgBr composite compared to pure AgBr and Ag{sub 2}MoO{sub 4} crystals (37.6% and 348.4% enhancement respectively). The Ag@Ag{sub 2}MoO{sub 4}–AgBr composite cloud degraded Rhodamin B, bromophenol blue, and amino black 10b completed in 7 min.

  20. LIGHT ECHOES FROM η CARINAE'S GREAT ERUPTION: SPECTROPHOTOMETRIC EVOLUTION AND THE RAPID FORMATION OF NITROGEN-RICH MOLECULES

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, J. L.; Knapp, G. R. [Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544 (United States); Rest, A.; Walborn, N. R. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bianco, F. B. [Department of Physics, New York University, New York, NY 10012 (United States); Matheson, T. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Smith, N. [Steward Observatory, University of Arizona, Tucson, Arizona 85721 (United States); Hsiao, E. Y.; Campillay, A.; Contreras, C.; González, C.; Morrell, N.; Phillips, M. M. [Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile); Chornock, R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Paredes Álvarez, L.; James, D.; Smith, R. C. [Cerro Tololo Inter-American Observatory, Casilla 603, La Serena (Chile); Kunder, A. [Leibniz-Institut für Astrophysik Potsdam, an der Sternwarte 16, D-14482, Potsdam (Germany); Margheim, S. [Gemini Observatory, Southern Operations Center, Casilla 603, La Serena (Chile); Welch, D. L. [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); and others

    2014-05-20

    We present follow-up optical imaging and spectroscopy of one of the light echoes of η Carinae's nineteenth century Great Eruption discovered by Rest et al. By obtaining images and spectra at the same light echo position between 2011 and 2014, we follow the evolution of the Great Eruption on a 3 yr timescale. We find remarkable changes in the photometric and spectroscopic evolution of the echo light. The i-band light curve shows a decline of ∼0.9 mag in ∼1 yr after the peak observed in early 2011 and a flattening at later times. The spectra show a pure-absorption early G-type stellar spectrum at peak, but a few months after peak the lines of the Ca II triplet develop strong P-Cygni profiles and we see the appearance of [Ca II] 7291, 7324 doublet in emission. These emission features and their evolution in time resemble those observed in the spectra of some Type IIn supernovae and supernova impostors. Most surprisingly, starting ∼300 days after peak brightness, the spectra show strong molecular transitions of CN at ≳ 6800 Å. The appearance of these CN features can be explained if the ejecta are strongly nitrogen enhanced, as is observed in modern spectroscopic studies of the bipolar Homunculus nebula. Given the spectroscopic evolution of the light echo, velocities of the main features, and detection of strong CN, we are likely seeing ejecta that contributes directly to the Homunculus nebula.

  1. Preparation and Characterization of γ-AgI in Superionic Composite Glasses (AgIx(AgPO31-x

    Directory of Open Access Journals (Sweden)

    S. Suminta

    2007-07-01

    Full Text Available The γ-AgI phase was stabilized at room temperature in the composites glasses (AgIx(AgPO31-x with x = 0.6 and 0.7 via rapid quenching of their molten mixture. The measurement of the crystal structure has been carried out using an X-ray Difractometer at the Physics Departement of Ibaraki University, Japan. The micro strain and crystal size are derived from Hall’s equation. The X-ray diffraction pattern shows some Bragg peaks that correspond to the crystalline γ-AgI. By increasing the concentration of AgI, the peak width becomes more narrow and the position shifts to the higher angle. This indicates that the crystalline size and microstrain are increasing. The increase of micro strain (η, and particle size (D will increase the ionic mobility, thus increasing the ionic conductivity. It is concluded that solidification process on melt AgI into glass matrix AgPO3 not only decreases the micro strain and the particle size, but it also increases the ionic conductivity.

  2. Formation of AgGaS2 nano-pyramids from Ag2S nanospheres through intermediate Ag2S-AgGaS2 heterostructures and AgGaS2 sensitized Mn2+ emission

    Science.gov (United States)

    Huang, Feng; Zhou, Jiangcong; Xu, Ju; Wang, Yuansheng

    2014-01-01

    A one-pot solution synthesis of monodisperse AgGaS2 nanocrystals with uniform pyramid-like shape is realized for the first time, in which an interesting phase and shape evolution from monodisperse Ag2S nanospheres to pure AgGaS2 nano-pyramids through an intermediate stage of Ag2S-AgGaS2 heterostructures, is revealed. Evidently, upon introducing Mn2+ ions into the reaction system, they are incorporated into AgGaS2 nano-pyramids which act as efficient sensitization matrixes for the red emission of Mn2+ d-d transition under blue excitation. Benefiting from their non-toxicity and facile fabrication, Mn:AgGaS2 nanocrystals may find potential applications in some fields such as blue chip excited LEDs and bio-labeling.A one-pot solution synthesis of monodisperse AgGaS2 nanocrystals with uniform pyramid-like shape is realized for the first time, in which an interesting phase and shape evolution from monodisperse Ag2S nanospheres to pure AgGaS2 nano-pyramids through an intermediate stage of Ag2S-AgGaS2 heterostructures, is revealed. Evidently, upon introducing Mn2+ ions into the reaction system, they are incorporated into AgGaS2 nano-pyramids which act as efficient sensitization matrixes for the red emission of Mn2+ d-d transition under blue excitation. Benefiting from their non-toxicity and facile fabrication, Mn:AgGaS2 nanocrystals may find potential applications in some fields such as blue chip excited LEDs and bio-labeling. Electronic supplementary information (ESI) available: Fig. S1-S2. See DOI: 10.1039/c3nr04765b

  3. Spectroscopic Study on Eu3+ Doped Borate Glasses Containing Ag Nanoparticles and Ag Aggregates.

    Science.gov (United States)

    Fu, Shaobo; Zheng, Hui; Zhang, Jinsu; Li, Xiangping; Sun, Jiashi; Hua, Ruinian; Dong, Bin; Xia, Haiping; Chen, Baojiu

    2015-01-01

    Transparent Eu(3+)-doped borate glasses containing Ag nanoparticles and Ag aggregates with composition (40 - x) CaO-59.5B2O3-0.5Eu2O3-xAgNO3 were prepared by a simple one-step melt-quenching technique. The X-ray diffraction (XRD) patterns of the glasses reveal amorphous structural properties and no diffraction peaks belonging to metal Ag particles. Ag particles and Ag aggregates were observed from the absorption spectra. Effective energy transfers from the Ag aggregates to the Eu3+ ions were observed in the excitation spectra from monitoring the intrinsic emission of Eu3+x .5D0 --> 7F2. The glasses with higher Ag content can be effectively excited by light in a wide wavelength region, indicating that these glasses have potential application in the solid state lighting driven by semiconductor light emitting diodes (LEDs). The emission spectra of the samples with higher Ag contents exhibit plenteous spectral components covering the full visible region from violet to red, thus indicating that these glass materials possess an excellent and tunable color rendering index. The color coordinates for all the glass samples were calculated by using the intensity-corrected emission spectra and the standard data issued by the CIE (Commission International de l' Eclairage) in 1931. It was found that the color coordinates for most samples with higher Ag contents fall into the white region in the color space.

  4. Study of antibacterial activity of Ag and Ag2CO3 nanoparticles stabilized over montmorillonite.

    Science.gov (United States)

    Sohrabnezhad, Sh; Pourahmad, A; Mehdipour Moghaddam, M J; Sadeghi, A

    2015-02-05

    Silver carbonate and silver nanoparticles (NPs) over of stabilizer montmorillonite (MMT) have been synthesized in aqueous and polyol solvent, respectively. Dispersions of silver nanoparticles have been prepared by the reduction of silver nitrate over of MMT in presence and absence of Na2CO3 compound in ethylene glycol. It was observed that montmorillonite was capable of stabilizing formed Ag nanoparticles through the reduction of Ag(+) ions in ethylene glycol. Na2CO3 was used as carbonate source in synthesis of Ag2CO3 NPs in water solvent and also for controlling of Ag nanoparticles size in ethylene glycol medium. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and ultraviolet-visible diffuse reflectance spectroscopy (DRS). The TEM images showed that Ag NPs size in presence Na2CO3 salts was smaller than without that. The results indicated intercalation of Ag and Ag2CO3 nanoparticles into the montmorillonite clay layers. The diffuse reflectance spectra exhibited a strong surface plasmon resonance (SPR) adsorption peak in the visible region, resulting from Ag nanoparticles. The antibacterial testing results showed that the Ag2CO3-MMT nanocomposite exhibited an antibacterial activity higher than Ag-MMT sample against Escherichia coli.

  5. The AGS with four helical magnets

    Energy Technology Data Exchange (ETDEWEB)

    Tsoupas, N.; Huang, H.; MacKay, W.W.; Roser, T.; Trbojevic, D.

    2010-02-25

    The idea of using multiple partial helical magnets was applied successfully to the AGS synchrotron, to preserve the proton beam polarization. In this paper we explore in details the idea of using four helical magnets placed symmetrically in the AGS ring. This modification provides many advantages over the present setup of the AGS that uses two partial helical magnets. First, it provides a larger 'spin tune gap' for the placement of the vertical betatron tune of the AGS during acceleration, second, the vertical spin direction during the beam injection and extraction is closer to vertical, third, the symmetric placement of the snakes allows for a better control of the AGS optics, and for reduced values of the beta and eta functions, especially near injection, fourth, the optical properties of the helical magnets also favor the placement of the horizontal betatron tune in the 'spin tune gap', thus eliminating the horizontal spin resonances. In this paper we provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and we compare these results with the present setup of the AGS that uses two partial helical magnets.

  6. Ag nanoparticle/polymer composite barcode nanorods

    Institute of Scientific and Technical Information of China (English)

    Hongxu Chen[1; Tieqiang Wang[2; Huaizhong Shen[1; Wendong Liu[1; Shuli Wang[1; Kun Liu[1; Junhu Zhang[1; Bai Yang[1

    2015-01-01

    We demonstrate a facile method combining colloidal lithography, selective ion-exchange, and the in situ reduction of Ag ions (Ag+) for the fabrication of multi-segmented barcode nanorods. First, polymer multilayer films were prepared by spin-coating alternating thin films of polystyrene and polyacrylic acid (PAA), and then multi-segmented polymer nanorods were fabricated via reactive ion etching with colloidal masks. Second, Ag nanoparticles (Ag NPs) were incorporated into the PAA segments by an ion exchange and the in situ reduction of the Ag~. The selective incorporation of the Ag NPs permitted the modification of the specific bars of the nanorods. Lastly, the Ag NP/polymer composite nanorods were released from the substrate to form suspensions for further coding applications. By increasing the number of segments and changing the length of each segment in the nanorods, the coding capacity of nanorods was improved. More importantly, this method can easily realize the density tuning of Ag NPs in different segments of a single nanorod by varying the composition of the PAA segments. We believe that numerous other coded materials can also be obtained, which introduces new approaches for fabricating barcoded nanomaterials.

  7. A FLYING WIRE SYSTEM IN THE AGS.

    Energy Technology Data Exchange (ETDEWEB)

    HUANG,H.; BUXTON,W.; MAHLER,G.; MARUSIC,A.; ROSER,T.; SMITH,G.; SYPHERS,M.; WILLIAMS,N.; WITKOVER,R.

    1999-03-29

    As the AGS prepares to serve as the injector for RHIC, monitoring and control of the beam transverse emittance become a major and important topic. Before the installation of the flying wire system, the emittance was measured with ionization profile monitors in the AGS, which require correction for space charge effects. It is desirable to have a second means of measuring profile that is less depend on intensity. A flying wire system has been installed in the AGS recently to perform this task. This paper discusses the hardware and software setup and the capabilities of the system.

  8. Theoretical Investigation on the Adsorption of Ag+ and Hydrated Ag+ Cations on Clean Si(111)Surface

    Institute of Scientific and Technical Information of China (English)

    SHENG Yong-Li; LI Meng-Hua; WANG Zhi-Guo; LIU Yong-Jun

    2008-01-01

    In this paper,the adsorption of Ag+ and hydrated Ag+ cations on clean Si(111)surface were investigated by using cluster(Gaussian 03)and periodic(DMol3)ab initio calculations.Si(111)surface was described with cluster models(Si14H17 and Si22H21)and a four-silicon layer slab with periodic boundary conditions.The effect of basis set superposition error(BSSE)was taken into account by applying the counterpoise correction.The calculated results indicated that the binding energies between hydrated Ag+ cations and clean Si(111)surface are large,suggesting a strong interaction between hydrated Ag+ cations and the semiconductor surface.With the increase of number,water molecules form hydrogen bond network with one another and only one water molecule binds directly to the Ag+ cation.The Ag+ cation in aqueous solution will safely attach to the clean Si(111)surface.

  9. Optical properties of AgI/Ag infrared hollow fiber in the visible wavelength region.

    Science.gov (United States)

    Sui, Ke-Rong; Shi, Yi-Wei; Tang, Xiao-Li; Zhu, Xiao-Song; Iwai, Katsumasa; Miyagi, Mitsunobu

    2008-02-15

    We report on AgI/Ag infrared hollow fiber with low-loss in visible region. Improved methods of silver plating and iodination were proposed to fabricate the hollow fiber. The surface roughness of the silver layer and the silver iodide layer was reduced by the pretreatment with an SnCl2 solution and low iodination temperature. Losses for the Er:YAG and green laser light were 0.4 and 7dB/m. The loss property of green laser beam was low to deliver a pilot beam for the invisible infrared laser light. Owing to the smooth and uniform AgI film, the loss spectrum of the hollow fiber showed clear interference peaks in the visible region. An empirical formula for AgI material dispersion was derived, which is of special importance for the design of high-performance AgI/Ag hollow fiber.

  10. Ag-rich precipitates formation in the Cu–11%Al–10%Mn–3%Ag alloy

    Energy Technology Data Exchange (ETDEWEB)

    Silva, R.A.G., E-mail: galdino.ricardo@gmail.com [Departamento de Ciências Exatas e da Terra, UNIFESP, 09972-270 Diadema, SP (Brazil); Paganotti, A.; Jabase, L. [Departamento de Ciências Exatas e da Terra, UNIFESP, 09972-270 Diadema, SP (Brazil); Adorno, A.T.; Carvalho, T.M.; Santos, C.M.A. [Departamento de Físico-Química, Instituto de Química, UNESP, 14801-970 Araraquara, SP (Brazil)

    2014-12-05

    Highlights: • Cu-rich nanoprecipitates are formed in the presence of Ag. • Bainite precipitation is shifted to higher temperatures in the Cu–11%Al–10%Mn–3%Ag alloy. • The eutectoid α phase and bainite α{sub 1} phase compete by the Cu atoms during precipitation process. - Abstract: The formation of Ag-rich precipitates in the Cu–11%Al–10%Mn–3%Ag alloy initially quenched from 1123 K was analyzed. The results showed that nanoprecipitates of a Cu-rich phase are produced at about 523 K. In higher temperatures these nanoparticles grow and the relative fraction of Ag dissolved in it is increased, thus forming the Ag-rich phase.

  11. Comparative toxicity study of Ag, Au, and Ag-Au bimetallic nanoparticles on Daphnia magna.

    Science.gov (United States)

    Li, Ting; Albee, Brian; Alemayehu, Matti; Diaz, Rocio; Ingham, Leigha; Kamal, Shawn; Rodriguez, Maritza; Bishnoi, Sandra Whaley

    2010-09-01

    A comparative assessment of the 48-h acute toxicity of aqueous nanoparticles synthesized using the same methodology, including Au, Ag, and Ag-Au bimetallic nanoparticles, was conducted to determine their ecological effect in freshwater environments through the use of Daphnia magna, using their mortality as a toxicological endpoint. D. magna are one of the standard organisms used for ecotoxicity studies due to their sensitivity to chemical toxicants. Particle suspensions used in toxicity testing were well-characterized through a combination of absorbance measurements, atomic force or electron microscopy, flame atomic absorption spectrometry, and dynamic light scattering to determine composition, aggregation state, and particle size. The toxicity of all nanoparticles tested was found to be dose and composition dependent. The concentration of Au nanoparticles that killed 50% of the test organisms (LC(50)) ranged from 65-75 mg/L. In addition, three different sized Ag nanoparticles (diameters = 36, 52, and 66 nm) were studied to analyze the toxicological effects of particle size on D. magna; however, it was found that toxicity was not a function of size and ranged from 3-4 μg/L for all three sets of Ag nanoparticles tested. This was possibly due to the large degree of aggregation when these nanoparticles were suspended in standard synthetic freshwater. Moreover, the LC(50) values for Ag-Au bimetallic nanoparticles were found to be between that of Ag and Au but much closer to that of Ag. The bimetallic particles containing 80% Ag and 20% Au were found to have a significantly lower toxicity to Daphnia (LC(50) of 15 μg/L) compared to Ag nanoparticles, while the toxicity of the nanoparticles containing 20% Ag and 80% Au was greater than expected at 12 μg/L. The comparison results confirm that Ag nanoparticles were much more toxic than Au nanoparticles, and that the introduction of gold into silver nanoparticles may lower their environmental impact by lowering the amount

  12. AgSat Areas of Interest

    Data.gov (United States)

    Farm Service Agency, Department of Agriculture — The AgSat Areas of Interest map contains area polygons where satellite imagery will be collected for the Farm Service Agency (FSA) to provide imagery coverage for...

  13. AgSat Imagery Collection Footprints

    Data.gov (United States)

    Farm Service Agency, Department of Agriculture — The AgSat Imagery Collection Footprints map shows the imagery footprints which have been collected under the USDA satellite blanket purchase agreement. Click on a...

  14. Temperature stability of AgCu nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sopoušek, Jiří, E-mail: sopousek@mail.muni.cz; Zobač, Ondřej; Vykoukal, Vít [Masaryk University, Department of Chemistry, Faculty of Science (Czech Republic); Buršík, Jiří; Roupcová, Pavla [Institute of Physics of Materials ASCR (Czech Republic); Brož, Pavel; Pinkas, Jiří [Masaryk University, Department of Chemistry, Faculty of Science (Czech Republic); Vřešťál, Jan [Masaryk University, Central European Institute of Technology, CEITEC (Czech Republic)

    2015-12-15

    The colloidal solutions of the Ag–Cu nanoparticles (NPs, 10–32 nm) were prepared by solvothermal reactions. The samples of dried AgCu NPs and the resulting microstructures after heat treatment in air were investigated by various methods including electron microscopy (TEM, SEM) and high-temperature X-ray powder diffraction (HTXRD). The AgCu randomly mixed, Cu-rich, and Ag-rich face centred cubic crystal lattices were detected during the experiments. The temperature induced sintering was observed experimentally by HTXRD at 250 °C. The phase transformations at high temperatures were monitored by differential scanning calorimetry. The formation of the Ag-rich grains during heating in air and evolution of copper oxide microstructure were detected.Graphical abstract.

  15. Redetermination of AgPO(3).

    Science.gov (United States)

    Terebilenko, Katherina V; Zatovsky, Igor V; Ogorodnyk, Ivan V; Baumer, Vyacheslav N; Slobodyanik, Nikolay S

    2011-02-09

    Single crystals of silver(I) polyphosphate(V), AgPO(3), were prepared via a phospho-ric acid melt method using a solution of Ag(3)PO(4) in H(3)PO(4). In comparison with the previous study based on single-crystal Weissenberg photographs [Jost (1961 ▶). Acta Cryst. 14, 779-784], the results were mainly confirmed, but with much higher precision and with all displacement parameters refined anisotropically. The structure is built up from two types of distorted edge- and corner-sharing [AgO(5)] polyhedra, giving rise to multidirectional ribbons, and from two types of PO(4) tetra-hedra linked into meandering chains (PO(3))(n) spreading parallel to the b axis with a repeat unit of four tetra-hedra. The calculated bond-valence sum value of one of the two Ag(I) ions indicates a significant strain of the structure.

  16. Redetermination of AgPO3

    Science.gov (United States)

    Terebilenko, Katherina V.; Zatovsky, Igor V.; Ogorodnyk, Ivan V.; Baumer, Vyacheslav N.; Slobodyanik, Nikolay S.

    2011-01-01

    Single crystals of silver(I) polyphosphate(V), AgPO3, were prepared via a phospho­ric acid melt method using a solution of Ag3PO4 in H3PO4. In comparison with the previous study based on single-crystal Weissenberg photographs [Jost (1961 ▶). Acta Cryst. 14, 779–784], the results were mainly confirmed, but with much higher precision and with all displacement parameters refined anisotropically. The structure is built up from two types of distorted edge- and corner-sharing [AgO5] polyhedra, giving rise to multidirectional ribbons, and from two types of PO4 tetra­hedra linked into meandering chains (PO3)n spreading parallel to the b axis with a repeat unit of four tetra­hedra. The calculated bond-valence sum value of one of the two AgI ions indicates a significant strain of the structure. PMID:21522230

  17. VLTI-AMBER velocity-resolved aperture-synthesis imaging of Eta Carinae with a spectral resolution of 12000. Studies of the primary star wind and innermost wind-wind collision

    CERN Document Server

    Weigelt, G; Schertl, D; Clementel, N; Corcoran, M F; Damineli, A; de Wit, W -J; Grellmann, R; Groh, J; Guieu, S; Gull, T; Heininger, M; Hillier, D J; Hummel, C A; Kraus, S; Madura, T; Mehner, A; Mérand, A; Millour, F; Moffat, A F J; Ohnaka, K; Patru, F; Petrov, R G; Rengaswamy, S; Richardson, N D; Rivinius, T; Schöller, M; Teodoro, M; Wittkowski, M

    2016-01-01

    Context. The mass loss from massive stars is not understood well. Eta Car is a unique object for studying the massive stellar wind during the LBV phase. It is also an eccentric binary with a period of 5.54 yr. The nature of both stars is uncertain, although we know from X-ray studies that there is a wind-wind collision whose properties change with orbital phase. Methods. Observations of Eta Car were carried out with the ESO VLTI and the AMBER instrument between approximately five and seven months before the August 2014 periastron passage. Velocity-resolved aperture-synthesis images were reconstructed from the spectrally dispersed interferograms. Interferometric studies can provide information on the binary orbit, the primary wind, and the wind collision. Results. We present velocity-resolved aperture-synthesis images reconstructed in more than 100 different spectral channels distributed across the Br Gamma 2.166 micrometer emission line. The intensity distribution of the images strongly depends on wavelength....

  18. HBsAg, HBcAg, and combined HBsAg/HBcAg-based therapeutic vaccines in treating chronic hepatitis B virus infection

    Institute of Scientific and Technical Information of China (English)

    Sheikh Mohammad Fazle Akbar; Mamun Al-Mahtab

    2013-01-01

    BACKGROUND: As  the  host  immunity  is  diminished  in patients with chronic hepatitis B (CHB), different approaches have  been  used  to  up-regulate  their  immune  responses  to produce therapeutic effects. But, cytokines, growth factors and polyclonal  immune  modulators  could  not  exhibit  sufficient therapeutic  effects  in  these  patients.  Immune  therapy  with HBV-related antigens (vaccine therapy) has been used in CHB patients. But there is a paucity of information about the design of HBV antigen-based immune therapy in these patients. DATA  SOURCE: Preclinical  and  clinical  studies  on  immune therapy with HBsAg-based vaccine, HBcAg and combination of HBsAg/HBcAg-based vaccines have been discussed. RESULTS: HBsAg-based  prophylactic  vaccine  was  used  as an  immune  therapeutic  agent  in  CHB  patients;  however, monotherapy  with  HBsAg-based  immune  therapy  could not  lead  to  sustained  control  of  HBV  replication  and/or  liver damages.  HBsAg-based  vaccine  was  used  as  a  combination therapy  with  cytokines,  growth  factors,  and  antiviral  drugs. HBsAg-based  vaccine  was  also  used  for  cell-based  therapy. However,  satisfactory  therapeutic  effects  of  HBsAg-based vaccine could not be documented in CHB patients. In the mean time, evidences have supported that HBcAg-specific immunity is  endowed  with  antiviral  and  liver  protecting  capacities  in CHB  patients.  Recent  data  concentrate  on  the  clinical  use  of combined HBsAg- and HBcAg-based vaccines in CHB patients. CONCLUSION: Antigen-based  immune  therapy

  19. Monolayer solid of N-2/Ag(111)

    DEFF Research Database (Denmark)

    Bruch, L.W.; Hansen, Flemming Yssing

    1998-01-01

    An incommensurate monolayer solid of N-2/Ag(111) is modeled using extensive molecular-dynamics simulations. The conditions treated range from the low-temperature orientationally ordered solid to the melting of the solid. The properties are evaluated as a function of spreading pressure. Comparison...... is made to recent experimental data for N-2/Ag(111) and to results for N-2 adsorbed on graphite. Cu(110), and MgO(001). [S0163-1829(98)02715-5]....

  20. Epigallocatechin-3-gallate-capped Ag nanoparticles: preparation and characterization.

    Science.gov (United States)

    Hussain, Shokit; Khan, Zaheer

    2014-07-01

    We used an aqueous leaf extract of Camellia sinensis to synthesize Ag nanoparticles (AgNPs). A layer of ca. 6 nm around a group of the AgNPs in which the inner layer is bound to the AgNPs surface via the hydroxyl groups of catechin has been observed. TEM analysis of AgNPs showed the formation of truncated triangular nanoplates and/or nanodisks and spherical with some irregular-shaped polydispersed nanoparticles in absence and presence of shape-directing cetyltrimethylammonium bromide. The polyphenolic groups of epigallocatechin-3-gallate (EGCG) are responsible for the rapid reduction of Ag(+) ions into metallic Ag(0). The free -OH groups are able to stabilize AgNPs by the interaction between the surface Ag atoms of AgNPs and oxygen atoms of EGCG molecules.

  1. Acceleration of polarized protons in the AGS

    Energy Technology Data Exchange (ETDEWEB)

    Tsoupas, N.; Ahrens, L.; Bai, M.; Brown, K.; Courant, E.; Glenn, J.W.; Huang, H.; Luccio, A.; MacKay, W.W.; Roser, T.; Schoefer, V.; Zeno, K.

    2010-02-25

    The high energy (s{sup 1/2} = 500 GeV) polarized proton beam experiments performed in RHIC, require high polarization of the proton beam. With the AGS used as the pre-injector to RHIC, one of the main tasks is to preserve the polarization of the proton beam, during the beam acceleration in the AGS. The polarization preservation is accomplished by the two partial helical magnets [1,2,3,4,5,6,7] which have been installed in AGS, and help overcome the imperfection and the intrinsic spin resonances which occur during the acceleration of protons. This elimination of the intrinsic resonances is accomplished by placing the vertical tune Q{sub y} at a value close to 8.98, within the spin-tune stop-band created by the snake. At this near integer tune the perturbations caused by the partial helical magnets is large resulting in large beta and dispersion waves. To mitigate the adverse effect of the partial helices on the optics of the AGS, we have introduced compensation quads[2] in the AGS. In this paper we present the beam optics of the AGS which ameliorates this effect of the partial helices.

  2. Antibacterial Ag/a-C nanocomposite coatings: The influence of nano-galvanic a-C and Ag couples on Ag ionization rates

    Energy Technology Data Exchange (ETDEWEB)

    Manninen, N.K., E-mail: nora.sousa@dem.uc.pt [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); GRF-CFUM, Physics Department, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); Calderon, S. [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); GRF-CFUM, Physics Department, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); Carvalho, I. [GRF-CFUM, Physics Department, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); CEB—Centre of Biological Engineering, LIBRO-Laboratório de Investigação em Biofilmes Rosário Oliveira, University of Minho, 4710-057 Braga (Portugal); Henriques, M. [CEB—Centre of Biological Engineering, LIBRO-Laboratório de Investigação em Biofilmes Rosário Oliveira, University of Minho, 4710-057 Braga (Portugal); Cavaleiro, A. [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); Carvalho, S. [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); GRF-CFUM, Physics Department, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal)

    2016-07-30

    Highlights: • Amorphous carbon (a-C), Ag/a-C and Ag coatings were deposited by magnetron sputtering. • a-C/Ag coating shows antibacterial activity against S. epidermidis. • The formation of nano-galvanic couples in a-C/Ag enhances the Ag{sup +} ionization rate. • The Ag{sup +} ionization occurs along with Ag nanoparticles agglomeration in 0.9% NaCl. - Abstract: Biofilm formation has been pointed as a major concern in different industrial applications, namely on biomedical implants and surgical instruments, which has prompted the development of new strategies for production of efficient antimicrobial surfaces. In this work, nano-galvanic couples were created to enhance the antibacterial properties of silver, by embedding it into amorphous carbon (a-C) matrix. The developed Ag/a-C nanocomposite coatings, deposited by magnetron sputtering, revealed an outstanding antibacterial activity against Staphylococcus epidermidis, promoting a total reduction in biofilm formation with no bacteria counts in all dilution. The open circuit potential (OCP) tests in 0.9% NaCl confirmed that a-C shows a positive OCP value, in contrast to Ag coating, thus enhancing the ionization of biocidal Ag{sup +} due to the nano-galvanic couple activation. This result was confirmed by the inductively coupled plasma-optical emission spectroscopy (ICP-OES), which revealed a higher Ag ionization rate in the nanocomposite coating in comparison with the Ag coating. The surface of Ag/a-C and Ag coatings immersed in 0.9% NaCl were monitored by scanning electron microscopy (SEM) over a period of 24 h, being found that the Ag ionization determined by ICP-OES was accompanied by an Ag nanoparticles coalescence and agglomeration in Ag/a-C coating.

  3. An Ab Initio Study of the Low-Lying Doublet States of AgO and AgS

    Science.gov (United States)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.

    1990-01-01

    Spectroscopic constants (D(sub o), r(sub e), mu(sub e), T(sub e)) are determined for the doublet states of AgO and AgS below approx. = 30000/cm. Large valence basis sets are employed in conjunction with relativistic effective core potentials (RECPs). Electron correlation is included using the modified coupled-pair functional (MCPF) and multireference configuration interaction (MRCI) methods. The A(sup 2)Sigma(sup +) - X(sup 2)Pi band system is found to occur in the near infrared (approx. = 9000/cm) and to be relatively weak with a radiative lifetime of 900 microns for A(sup 2)Sigma(sup +) (upsilon = 0). The weakly bound C(sup 2)Pi state (our notation), the upper state of the blue system, is found to require high levels of theoretical treatment to determine a quantitatively accurate potential. The red system is assigned as a transition from the C(sup 2)Pi state to the previously unobserved A(sup 2)Sigma(sup +) state. Several additional transitions are identified that should be detectable experimentally. A more limited study is performed for the vertical excitation spectrum of AgS. In addition, a detailed all-electron study of the X(sup 2)Pi and A(sup 2)Sigma(sup +) states of AgO is carried out using large atomic natural orbital (ANO) basis sets. Our best calculated D(sub o) value for AgO is significantly less than the experimental value, which suggests that there may be some systematic error in the experimental determination.

  4. Facile synthesis of ternary Ag/AgBr-Ag{sub 2}CO{sub 3} hybrids with enhanced photocatalytic removal of elemental mercury driven by visible light

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Anchao, E-mail: anchaozhang@126.com [School of Mechanical and Power Engineering, Henan Polytechnic University, Jiaozuo, 454000 (China); Zhang, Lixiang; Lu, Hao; Chen, Guoyan; Liu, Zhichao [School of Mechanical and Power Engineering, Henan Polytechnic University, Jiaozuo, 454000 (China); Xiang, Jun; Sun, Lushi [State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, 430074 (China)

    2016-08-15

    Graphical abstract: Schematic illustration for the charge transfer in the Ag/AgBr(0.7)-Ag{sub 2}CO{sub 3} system. - Highlights: • A novel technique on Hg{sup 0} removal using visible-light-driven Ag/AgBr-Ag{sub 2}CO{sub 3} hybrids was proposed. • Ag/AgBr-Ag{sub 2}CO{sub 3} hybrids were synthesized by a simple modified co-precipitation method. • Hg{sup 0} was mainly removed by the photogenerated holes (h{sup +}). • The possible reaction mechanism for superior Hg{sup 0} removal was proposed. - Abstract: A novel technique for photocatalytic removal of elemental mercury (Hg{sup 0}) using visible-light-driven Ag/AgBr-Ag{sub 2}CO{sub 3} hybrids was proposed. The ternary Ag/AgBr-Ag{sub 2}CO{sub 3} hybrids were synthesized by a simple modified co-precipitation method and characterized by N{sub 2} adsorption-desorption, scanning electron microscope (SEM), X-ray diffraction (XRD), UV–vis diffused reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) techniques. The effects of AgBr content, fluorescent lamp (FSL) irradiation, solution temperature, SO{sub 2} and NO on Hg{sup 0} removal were investigated in detail. Furthermore, a possible reaction mechanism for higher Hg{sup 0} removal was proposed, and the simultaneous removal of Hg{sup 0}, SO{sub 2} and NO was studied. The results showed that a high efficiency of Hg{sup 0} removal was obtained by using Ag/AgBr-Ag{sub 2}CO{sub 3} hybrids under fluorescent lamp irradiation. The AgBr content, FSL irradiation, solution temperature, and SO{sub 2} all exhibited significant effects on Hg{sup 0} removal, while NO had slight effect on Hg{sup 0} removal. The addition of Ca(OH){sub 2} demonstrated a little impact on Hg{sup 0} removal and could significantly improve the SO{sub 2}-resistance performance of Ag/AgBr(0.7)-Ag{sub 2}CO{sub 3} hybrid. The characterization results exhibited that hydroxyl radical (·OH), superoxide radical (·O{sub 2}{sup −}), hole (h{sup +}), and Br

  5. High Visible Photoelectrochemical Activity of Ag Nanoparticle-Sandwiched CdS/Ag/ZnO Nanorods.

    Science.gov (United States)

    Yang, Xu; Li, Hui; Zhang, Wu; Sun, Mingxuan; Li, Lequn; Xu, Ning; Wu, Jiada; Sun, Jian

    2017-01-11

    We report on the sensitizing of CdS-coated ZnO (CdS/ZnO) nanorods (NRs) by Ag nanoparticles (NPs) embedded between the CdS coating and the ZnO nanorod and the improved optical and photoelectrochemical properties of the Ag NP-sandwiched nanostructure CdS/Ag/ZnO NRs. The CdS/Ag/ZnO NRs were fabricated by growing Ag NPs on hydrothermally grown ZnO NRs and subsequently depositing CdS coatings followed by subsequent N2 annealing. The structure of the fabricated CdS/Ag/ZnO NRs was characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman backscattering, revealing that the ZnO NRs and the CdS coatings are both structured with hexagonal wurtzite and the Ag NPs contact well with ZnO and CdS. Optical properties were evaluated by measuring optical absorption and photoluminescence, showing that the Ag NPs behave well as sensitizers for optical property improvement and the CdS/Ag/ZnO NRs exhibit better photoresponse in a wide spectral region than CdS/ZnO because of plasmon-enhanced absorption due to the embedment of Ag NPs. The Ag NPs also serve as electron relays from CdS to ZnO, facilitating electron transfer from the CdS coatings to the ZnO NRs. The excellent photoresponse and efficient electron transfer make the CdS/Ag/ZnO NRs highly photoelectrochemically active. The CdS/Ag/ZnO NRs fabricated on indium-tin oxide present much better photoelectrochemical performance as photoanodes working in the visible region than CdS/ZnO NRs without Ag NPs. Under visible illumination, a maximum optical-to-chemical conversion efficiency of 3.13% is obtained for CdS/Ag/ZnO NR photoanodes against 1.35% for CdS/ZnO NR photoanodes.

  6. Synthesis, structure, and magnetic properties of EuAgCd and YbAgCd

    Energy Technology Data Exchange (ETDEWEB)

    Fickenscher, T.; Kotzyba, G.; Hoffmann, R.D.; Poettgen, R. [Ludwig-Maximilians-Univ. Muenchen (Germany). Dept. Chemie

    2001-07-01

    New intermetallic compounds EuAgCd and YbAgCd were synthesized in quantitative yield by reaction of the elements in sealed tantalum tubes in a high-frequency furnace. Both compounds were investigated by X-ray diffraction on powders and single crystals: KHg{sub 2} type, Imma, a = 490.41(8), b = 771.0(1), c = 834.4(2) pm, wR2 = 0.0624, 255 F{sup 2} values, 12 variables for EuAgCd, and MgZn{sub 2} type, P6{sub 3}/mmc, a = 584.66(5), c = 946.83(9) pm, wR2 = 0.0502, 187 F{sup 2} values, 11 variables for YbAgCd. Owing to the very small difference in scattering power, no long range ordering of the silver and cadmium atoms is evident from the X-ray data, although Ag-Cd ordering is expected. The silver and cadmium atoms randomly occupy the mercury and zinc positions of the KHg{sub 2} and MgZn{sub 2} type structures, respectively. In EuAgCd the [AgCd] substructure consists of strongly puckered, orthorhombically distorted Ag{sub 3}Cd{sub 3} hexagons, while a three-dimensional network of face- and corner-sharing tetrahedra is observed in YbAgCd. The rare earth atoms fill the space between the Ag{sub 3}Cd{sub 3} hexagons (EuAgCd) or within the three-dimensional tetrahedral network (YbAgCd). Magnetic susceptibility measurements indicate Pauli paramagnetism for YbAgCd and Curie-Weiss behavior above 60 K for EuAgCd with an experimental magnetic moment of 7.82(3) {mu}{sub B}/Eu indicating divalent ytterbium and europium. Ferromagnetic ordering at T{sub C} = 28.0(5) K is observed for EuAgCd. At 2 K and 5 T the saturation magnetization is 5.85(5) {mu}{sub B}/Eu. (orig.)

  7. Electron and Phonon Dynamics in Hexagonal Pd Nanosheets and Ag/Pd/Ag Sandwich Nanoplates.

    Science.gov (United States)

    Wang, Li; Sagaguchi, Takuya; Okuhata, Tomoki; Tsuboi, Motohiro; Tamai, Naoto

    2017-02-28

    Pd and its hybrid nanostructures have attracted considerable attention over the past decade, with both catalytic and plasmonic properties. The electron and phonon properties directly govern conversion efficiencies in applications such as energy collectors and photocatalysts. We report the dynamic processes of electron-phonon coupling and coherent acoustic phonon vibration in hexagonal Pd nanosheets and Ag/Pd/Ag sandwich nanoplates using transient absorption spectroscopy. The electron-phonon coupling constant of Pd nanosheets, GPd-nanosheet (8.7 × 10(17) W/(m(3)·K)) is larger than that of the bulk GPd (5.0 × 10(17) W/(m(3)·K)). The effective coupling constant Geff of Ag/Pd/Ag nanoplates decreases with increasing Ag shell thickness, finally approaching the bulk GAg. The variation of Geff is explained in terms of reduced density of states near Fermi level of Pd nanosheets with 1.8 nm ultrathin thickness. Coherent acoustic phonon vibration in Pd nanosheets is assigned to a fundamental breathing mode, similar to the vibration of benzene. The period increases with increasing Ag shell thickness. For Ag/Pd/Ag nanoplates with 20 nm thick Ag shells, the vibrational mode is ascribed to a quasi-extensional mode. The results show that the modes of the coherent acoustic phonon vibration transform with the geometric variation of Pd nanosheets and Ag/Pd/Ag nanoplates. Our results represent an understanding of quantum-confinement related electron dynamics and bulk-like phonon kinetics in the ultrathin Pd nanosheets and their hybrid nanostructures.

  8. Ag-Ag2S/reduced graphene oxide hybrids used as long-wave UV radiation emitting nanocomposites

    Science.gov (United States)

    Li, Wenyao; Xu, Ruoyu; Ling, Min; He, Guanjie

    2017-10-01

    We report a facile thermal decomposition approach to synthesize Ag-Ag2S/reduced graphene oxide (Ag-Ag2S/rGO), the Ag-Ag2S nanoparticles uniformly dispersed on reduced graphene oxide with diameters of 10-20 nm. The photoluminescence spectra of Ag-Ag2S/rGO showed two obvious emission peaks at 327 and 339 nm with the excitation wavelength at 287 nm. Compared with Ag-Ag2S heterostructured clusters with two peaks at 407 and 430 nm, it showed a big blue shift and higher intensity, which makes it a novel candidate for long-wave UV radiation emitting nanocomposite.

  9. HBcrAg Identifies Patients Failing to Achieve HBeAg Seroconversion Treated with Pegylated Interferon Alfa-2b

    Directory of Open Access Journals (Sweden)

    Hui Ma

    2016-01-01

    Conclusions: Effective antiviral treatment can decrease HBcrAg levels in the serum. The NPVs of HBcrAg for predicting HBeAg seroconversion at 24-week follow-up was 100%, but the PPVs were not satisfactory (all <31%. The serum HBcrAg levels of the patients with HBeAg seroconversion at the end of the 24-week follow-up steadily declined or even became undetectable during the LTFU.

  10. Ultra-Fast Synthesis for Ag2Se and CuAgSe Thermoelectric Materials

    Science.gov (United States)

    DUAN, H. Z.; LI, Y. L.; ZHAO, K. P.; QIU, P. F.; SHI, X.; CHEN, L. D.

    2016-10-01

    Ag2Se and CuAgSe have been recently reported as promising thermoelectric materials at room temperature. The traditional melting-annealing-sintering processes are used to grow Ag2Se and CuAgSe materials with the disadvantages of high costs of energy and time. In this work, phase-pure polycrystalline Ag2Se and CuAgSe compounds were synthesized from raw elemental powders directly by manual mixing followed by spark plasma sintering (MM-SPS) in a few minutes. The influence of SPS heating rate on the phase composition, microstructure, and thermoelectric properties, including Seebeck coefficient, electrical conductivity, and thermal conductivity, were investigated. The zTs of 0.8 at 390 K and 0.6 at 450 K are obtained for Ag2Se and CuAgSe, respectively, which is comparable with the values in the materials prepared by the traditional method. Furthermore, this ultrafast sample synthesis can significantly save material synthesis time and thus has the obvious advantage for large-scale production.

  11. Beet Juice-Induced Green Fabrication of Plasmonic AgCl/Ag Nanoparticles

    Science.gov (United States)

    A simple, green, and fast approach (complete within 5 min) was explored for the fabrication of hybrid AgCl/Ag plasmonic nanoparticles under microwave (MW) irradiation. In this method, beet juice served as a reducing reagent, which is an abundant sugar-rich agricultural produce. I...

  12. Observation of a Ag protrusion on a Ag2S island using a scanning tunneling microscope

    Directory of Open Access Journals (Sweden)

    Takeo Ohno

    2015-01-01

    Full Text Available A silver sulfide (Ag2S island as an ionic conductor in resistive switching memories was formed and a protrusion of silver from the Ag2S formed by an electrochemical reaction was observed using a scanning tunneling microscope.

  13. Calibration of qualitative HBsAg assay results for quantitative HBsAg monitoring.

    Science.gov (United States)

    Gunning, Hans; Adachi, Dena; Tang, Julian W

    2014-10-01

    Evidence is accumulating that quantitative hepatitis B surface antigen monitoring may be useful in managing patients with chronic HBV infection on certain treatment regimens. Based on these results with the Abbott Architect qualitative and quantitative HBsAg assays, it seems feasible to convert qualitative to quantitative HBsAg values for this purpose. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Properties of Ag/AgCl electrodes fabricated with IC-compatible technologies

    NARCIS (Netherlands)

    Bousse, L.J.; Bergveld, P.; Geeraedts, H.J.M.

    1986-01-01

    The purpose of this work is to fabricate and characterize Ag/AgCl electrodes made on a silicon chip at the wafer level with integrated circuit-compatible fabrication techniques. Such electrodes are useful as reference electrodes in several kinds of chemical sensors. Two types of electrode were inves

  15. Beet Juice-Induced Green Fabrication of Plasmonic AgCl/Ag Nanoparticles

    Science.gov (United States)

    A simple, green, and fast approach (complete within 5 min) was explored for the fabrication of hybrid AgCl/Ag plasmonic nanoparticles under microwave (MW) irradiation. In this method, beet juice served as a reducing reagent, which is an abundant sugar-rich agricultural produce. I...

  16. Abnormal growth of Ag3Sn intermetallic compounds in Sn-Ag lead-free solder

    Institute of Scientific and Technical Information of China (English)

    SHEN Jun; LIU Yongchang; GAO Houxiu

    2006-01-01

    The abnormal growth of Ag3Sn intermetallic compounds in eutectic Sn-3.5% Ag solder was investigated through high-temperature aging treatment. Microstructural evolutions of this solder before and after the aging treatment were observed by optical microscopy and scanning electron microscopy. Precise differential thermal analysis was made to study the changes in enthalpies of the solder under different conditions. The results reveal that the water-cooled solder is in metastable thermodynamic state due to the high free energy of Ag3Sn nanoparticles, which sporadically distribute in the matrix as second-phase. The second-phase Ag3Sn nanoparticles aggregate rapidly and grow to form bulk intermetallic compounds due to the migration of grain boundary between primary Sn-rich phase and the Ag3Sn nanoparticles during high temperature aging treatment.

  17. Observation of nonvolatile resistive memory switching characteristics in Ag/graphene-oxide/Ag devices.

    Science.gov (United States)

    Venugopal, Gunasekaran; Kim, Sang-Jae

    2012-11-01

    In this paper, we report highly stable and bipolar resistive switching effects of Ag/Graphene oxide thinfilm/Ag devices. The graphene-oxide (GO) thinfilms were prepared on Ag/SiO2/Si substrates by spin-coating technique. The Ag/GO/Ag devices showed a steady and bipolar resistive switching characteristic. The resistance switching from low resistance state (LRS) and high resistance state (HRS) with the resistance ratio of HRS to LRS of about 10 which was attained at a voltage bias of 0.1 V. Based on the filamentary conduction model, the dominant conduction mechanism of switching effect was well explained. Our results show GO can be a promising candidate for future development of nonvolatile memory devices.

  18. First-principles study of surface plasmons on Ag(111) and H/Ag(111)

    DEFF Research Database (Denmark)

    Yan, Jun; Jacobsen, Karsten Wedel; Thygesen, Kristian Sommer

    2011-01-01

    Linear-response time-dependent density functional theory is used to investigate the relation between molecular bonding and surface plasmons for the model system H/Ag(111). We employ an orbital-dependent exchange-correlation functional to obtain a correct description of the Ag 3d band, which...... is crucial to avoid overscreening the plasmon by the s-d interband transitions. For the clean surface, this approach reproduces the experimental plasmon energies and dispersion to within 0.15 eV. Adsorption of hydrogen shifts and damps the Ag(111) surface plasmon and induces a new peak in the loss function...... at 0.6 eV below the Ag(111) plasmon peak. This feature originates from interband transitions between states located on the hydrogen atoms and states on the Ag surface atoms....

  19. Noble-metal Ag nanoparticle chains: annealing Ag/Bi superlattice nanowires in vacuum

    Science.gov (United States)

    Xu, Shao Hui; Fei, Guang Tao; You, Qiao; Gao, Xu Dong; Huo, Peng Cheng; De Zhang, Li

    2016-09-01

    One-dimensional noble-metal Ag nanoparticle chains have been prepared by electrodepositing Ag/Bi superlattice nanowires in a porous anodic alumina oxide (AAO) template and following an annealing process in vacuum. It is found that Bi, as a sacrificial metal, can be removed completely after annealing at 450 °C with a vacuum degree of 10-5 Torr. The regulation of particle size, shape and interparticle spacing of Ag NP chains has been realized by adjusting the segment length of the Ag/Bi superlattice nanowires and the annealing condition. With an extension of the annealing time, it is observed that Ag particles display the transform trend from ellipsoid to sphere. Our findings could inspire further investigation on the design and fabrication of metal nanoparticle chains.

  20. Effects of Ag nanomaterials (NM300K) and Ag salt (AgNO3) can be discriminated in a full life cycle long term test with Enchytraeus crypticus

    DEFF Research Database (Denmark)

    Bicho, Rita C; Ribeiro, Tânia; Rodrigues, Natália P;

    2016-01-01

    . Results showed that effects were higher compared to the standard reproduction test, which is shorter and does not cover the FLC. Both Ag forms caused a reduction on hatching success, juvenile and adult survival and reproduction with similar ECx. Differences between AgNO3 and Ag NM300K could...

  1. Ag on Si(111) from basic science to application

    Energy Technology Data Exchange (ETDEWEB)

    Belianinov, Aleksey [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    In our work we revisit Ag and Au adsorbates on Si(111)-7x7, as well as experiment with a ternary system of Pentacene, Ag and Si(111). Of particular interest to us is the Si(111)-(√3x√3)R30°}–Ag (Ag-Si-√3 hereafter). In this thesis I systematically explore effects of Ag deposition on the Ag-Si-√3 at different temperatures, film thicknesses and deposition fluxes. The generated insight of the Ag system on the Si(111) is then applied to generate novel methods of nanostructuring and nanowire growth. I then extend our expertise to the Au system on the Ag-Si(111) to gain insight into Au-Si eutectic silicide formation. Finally we explore behavior and growth modes of an organic molecule on the Ag-Si interface.

  2. Synthesis, characterization and antimycobacterial activity of Ag(I)-aspartame, Ag(I)-saccharin and Ag(I)-cyclamate complexes.

    Science.gov (United States)

    Cavicchioli, Maurício; Leite, Clarice Q F; Sato, Daisy N; Massabni, Antonio C

    2007-10-01

    The present work describes the synthesis and antimycobacterial activity of three Ag(I)-complexes with the sweeteners aspartame, saccharin, and cyclamate as ligands, with the aim of finding new candidate substances for fighting tuberculosis and other mycobacterial infections. The minimal inhibitory concentration of these three complexes was investigated in order to determine their in-vitro antimycobacterial activity against Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium malmoense, and Mycobacterium kansasii. The MIC values were determined using the Microplate Alamar Blue Assay. The best MIC values found for the complexes were 9.75 microM for Ag(I)-aspartame against M. kansasii and 15.7 microM for Ag(I)-cyclamate against M. tuberculosis.

  3. Bipolar Ag-Zn battery

    Science.gov (United States)

    Giltner, L. John

    1994-02-01

    The silver-zinc (AgZn) battery system has been unique in its ability to safely satisfy high power demand applications with low mass and volume. However, a new generation of defense, aerospace, and commercial applications will impose even higher power demands. These new power demands can be satisfied by the development of a bipolar battery design. In this configuration the power consuming, interelectrode current conductors are eliminated while the current is then conducted via the large cross-section electrode substrate. Negative and positive active materials are applied to opposite sides of a solid silver foil substrate. In addition to reducing the weight and volume required for a specified power level, the output voltage performance is also improved as follows. Reduced weight through: elimination of the plastic cell container; elimination of plate leads and intercell connector; and elimination of internal plate current collector. Increased voltage through: elimination of resistance of current collector; elimination of resistance of plate lead; and elimination of resistance of intercell connector. EPI worked previously on development of a secondary bipolar silver zinc battery. This development demonstrated the electrical capability of the system and manufacturing techniques. One difficulty with this development was mechanical problems with the seals. However, recent improvements in plastics and adhesives should eliminate the major problem of maintaining a seal around the periphery of the bipolar module. The seal problem is not as significant for a primary battery application or for a requirement for only a few discharge cycles. A second difficulty encountered was with activation (introducing electrolyte into the cell) and with venting gas from the cell without loss of electrolyte. During previous work, the following projections for energy density were made from test data for a high power system which demonstrated in excess of 50 discharge/charge cycles. Projected

  4. Comparative Study on Performance of Engineering Ag/AgC1 Reference Electrode%工程用Ag/AgCl参比电极性能对比研究

    Institute of Scientific and Technical Information of China (English)

    尹鹏飞; 马长江; 许立坤

    2011-01-01

    使用热浸涂法和粉压法制备了工程用Ag/AgCl参比电极.电化学性能测试表明热浸涂法和粉压法制备的Ag/AgCl参比电极的电位稳定性都比较好,但热浸涂法制备的Ag/AgCl参比电极的耐极化性能优于粉压法制备的Ag/AgCl参比电极.热浸涂法和粉压法制备的Ag/AgCl参比电极的温度系数都比较小,温度响应特性较好.海水流速对热浸涂法和粉压法制备的Ag/AgCl参比电极的电位有明显影响,参比电极封装外壳可改善电极在流动海水中的电位稳定性能.%Ag/AgCl reference electrodes for engineering were prepared with powder press and thermal dip-coating method. The electrochemical test result showed that the potential stability of them were both good; the Ag/AgCl reference electrode prepared with thermal dip-coating method has smaller polarization resistance than the one prepared with powder press method; the temperature coefficient of Ag/AgCl reference electrodes prepared with thermal dip-coating and powder press method are both small. It showed that the relative flow velocity of seawater has obvious effect on the electrode potential; encapsulation of reference electrodes can- improve their potential stability in flowing seawater.

  5. Ag/lamellar hosts composites: a route to morphology-controllable synthesis of Ag nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Luiz P. da; Quites, Fernando J.; Sigoli, Fernando A.; Mazali, Italo O., E-mail: mazali@iqm.unicamp.br; Pastore, Heloise O., E-mail: gpmmm@iqm.unicamp.br [University of Campinas (UNICAMP), Institute of Chemistry (Brazil)

    2013-08-15

    An easy and novel routine are reported for the preparation of metallic silver nanoparticles (AgNPs) with controlled morphology, using Na{sup +}-magadiite swelled with hexadecyltrimethylammonium bromide (CTA{sup +}-magadiite) and a layered aluminophosphate with kanemite-type structure modified with n-dodecylammonium and n-butylammonium (but,dod-AlPO-kan) as hosts. For the preparation of the metallic AgNPs (Ag{sup 0}) in the interlamellar space, the CTA{sup +}-magadiite and but,dod-AlPO-kan hosts were dispersed in N,N-dimethylformamide (DMF) solution with different AgNO{sub 3} concentrations. DMF acts as reducing agent of Ag{sup +} ions leading to nanoparticles with disk-like morphology of magadiite silicate; these were characterized by TEM and UV-Vis spectroscopy. On the other hand, the AgNPs are intercalated in but,dod-AlPO-kan showing spherical-like morphology. The UV-Vis spectra of the nanocomposites based on Ag{sup 0} and magadiite silicate show bands at 565 nm that can be attributed to Ag{sup 0} nanodisks. The Ag-but,dod-AlPO-kan-based nanocomposites present a band at 422 nm attributed to the surface plasmon resonance of Ag{sup 0} nanospheres. The results of transmission electron microscopy agree very well with XRD and UV-Vis analysis, indicating the formation of AgNPs with different morphologies using the two kinds of lamellar materials. The magadiite host has an important role in the synthesis of Ag nanodisks, because it controls the growth of nanoparticles inside the interlayer region with disk-like morphology due the high interlayer interactions of the silicate, leading to the growth of nanoparticles in only two directions (xy plane). On the other hand, when but,dod-AlPO-kan is used a sphere-like morphology is preferred due the best accommodation of AgNPs between the layers of aluminophosphate host.

  6. Facile synthesis of AgCl/polydopamine/Ag nanoparticles with in-situ laser improving Raman scattering effect

    Science.gov (United States)

    Zhang, Yan; Zhang, Wenqi; Wang, Lin; Wang, Feng; Yang, Haifeng

    2017-01-01

    We reported a simple and fast method to prepare a composite material of polydopamine (PDA) adlayer covered cubic AgCl core, which was inlaid with Ag nanoparticles (NPs), shortly named as AgCl/PDA/AgNPs. The resultant AgCl/PDA/AgNPs could be employed as surface-enhanced Raman scattering (SERS) substrate for in-situ detection and the SERS activity could be further greatly improved due to the production of more AgNPs upon laser irradiation. With 4-mercaptopyridine (4-Mpy) as the probe molecule, the enhancement factor could reach 107. Additionally, such SERS substrate shows good reproducibility with relative standard deviation of 7.32% and long term stability (after storage for 100 days under ambient condition, SERS intensity decay is less than 25%). In-situ elevating SERS activity of AgCl/PDA/AgNPs induced by laser may be beneficial to sensitive analysis in practical fields.

  7. Enhanced Raman scattering of graphene on Ag nanoislands

    Institute of Scientific and Technical Information of China (English)

    HU Wei; HUANG ZhiYi; ZHOU YingHui; CAI WeiWei; KANG JunYong

    2014-01-01

    The effect of Ag nanoislands on the Raman of graphene was investigated in this work.Compared with that on the bare silicon wafer,Raman enhancement was observed in the graphene film that covered on Ag/Si surface with nanoscale Ag islands,which would be induced by the localized plasmon resonance in Ag nanostructures.The interaction between the graphene sheet and Ag/Si substrate was further studied.The peak shift and line shape of Raman spectroscopy indicated a nonuniform strain distribution in the Ag/Si supported graphene film.

  8. Comp ositionally Graded Microstructure for Ag-Fe Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Chandan Srivastava∗; K. V. L. Sushma

    2012-01-01

    Ag-Fe nanoparticles with a highly Ag rich average composition were synthesized by the sono-chemical route. Silver-iron system exhibits a wide miscibility gap in the bulk materials. Interestingly, a graded compositional profile along the nanoparticle radius was observed. Regions at and near the surface of the nanoparticle contained both Ag and Fe atoms. The composition got relatively deficient Fe towards the center of the particle with particle core made up of pure Ag. Alloying of Ag and Fe is confirmed by the absence of diffraction signal corresponding to pure Fe phase and presence of a paramagnetic phase in nanoparticles containing a diamagnetic (Ag) and ferromagnetic (Fe) elements.

  9. Template synthesis of Ag/AgCl microrods and their efficient visible light-driven photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hua; Xiao, Liang; Huang, Jianhua, E-mail: jhhuang@zstu.edu.cn

    2014-09-15

    Highlights: • Preparation ofAg/AgCl microrods by reaction of Ag{sub 2}WO{sub 4} microrods with NaCl solution. • Generation of metallic Ag is induced by the ambient light in the synthesis process. • Ag/AgCl shows excellent visible light-driven photodegradation of organic dyes. - Abstract: Ag/AgCl microrods, aggregated by nanoparticles with a diameter ranging from 100 nm to 2 μm, were prepared by an ion-exchange reaction at 80 °C between Ag{sub 2}WO{sub 4} template and NaCl solution. The existence of metallic Ag species was confirmed by XRD, DRS and XPS measurements. Ag/AgCl microrods showed excellent photocatalytic activity for the degradation of rhodamine B and methylene blue under visible light irradiation. The degradation rate constants of rhodamine B and methylene blue are 0.176 and 0.114 min{sup −1}, respectively. The cycling photodegradation experiments suggest that Ag/AgCl microds could be employed as stable plasmonic photocatalysts for the degradation of organic dyes under visible light irradiation.

  10. BiPO4 photocatalyst employing synergistic action of Ag/Ag3PO4 nanostructure and graphene nanosheets

    Science.gov (United States)

    Mohaghegh, N.; Rahimi, E.

    2016-06-01

    Graphene-supported BiPO4/Ag/Ag3PO4 photocatalyst has been fabricated by simple hydrothermal and impregnation reaction. In BiPO4/Ag/Ag3PO4 based on Reduced Graphene Oxide (RGO), this network renders numerous pathways for rapid mass transport, strong adsorption and multireflection of incident light; meanwhile, the interface between BiPO4/Ag/Ag3PO4 and RGO increases the active sites and electron transfer rate. BiPO4/Ag/Ag3PO4 based on RGO noticeably exhibited high photocatalytic activity than that of BiPO4/Ag/Ag3PO4 and P25 under visible light irradiation for cationic dye (Rhodamine B), anionic dye (methyl orange) and 4-chlorophenol (4-CP) as a neutral pollutant, which are usually difficult to be degraded over the other catalysts. This enhanced photocatalytic activity of Graphene-supported BiPO4/Ag/Ag3PO4 for all pollutants could be mainly ascribed to the reinforced charge transfer from BiPO4/Ag/Ag3PO4 to RGO, which suppresses the recombination of electron/hole pairs. Besides that, this photocatalyst can be used repetitively with a high photocatalytic activity and no apparent loss of activity occurs. The results reveal that the RGO nanosheets work as a photocatalyst promoter during the photocatalytic reaction, leading to an improved photocatalytic activity.

  11. Determination of isothermal section of Ag-Ti-Zr ternary system at 1 023 K

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The isothermal section of Ag-Ti-Zr ternary system at 1023 K was determined by diffusion triple and electron probe microanalysis. The results indicate that four binary intermetallic phases of AgTi, AgTi2, AgZr and AgZr2 are found in Ag-Ti-Zr ternary system at 1 023 K. AgZr2 and AgTi2 form a continuous solid solution, namely Ag(Ti,Zr)2. Four three-phase regions: AgTi+AgZr + Ag, AgTi +AgZr + Ag (Ti, Zr)2, α-Zr +β3(Ti, Zr)+ Ag (Ti, Zr)2 and α-Ti +β(Ti, Zr)+ Ag (Ti, Zr)2 exist in the isothermal section. No ternary compound is observed.

  12. Effect of cysteine and humic acids on bioavailability of Ag from Ag nanoparticles to a freshwater snail

    Science.gov (United States)

    Luoma, Samuel N.; Tasha Stoiber,; Croteau, Marie-Noele; Isabelle Romer,; Ruth Merrifeild,; Lead, Jamie

    2016-01-01

    Metal-based engineered nanoparticles (NPs) will undergo transformations that will affect their bioavailability, toxicity and ecological risk when released to the environment, including interactions with dissolved organic material. The purpose of this paper is to determine how interactions with two different types of organic material affect the bioavailability of silver nanoparticles (AgNPs). Silver uptake rates by the pond snail Lymnaea stagnalis were determined after exposure to 25 nmol l-1 of Ag as PVP AgNPs, PEG AgNPs or AgNO3, in the presence of either Suwannee River humic acid or cysteine, a high-affinity thiol-rich organic ligand. Total uptake rate of Ag from the two NPs was either increased or not strongly affected in the presence of 1 – 10 mg 1-1 humic acid. Humic substances contain relatively few strong ligands for Ag explaining their limited effects on Ag uptake rate. In contrast, Ag uptake rate was substantially reduced by cysteine. Three components of uptake from the AgNPs were quantified in the presence of cysteine using a biodynamic modeling approach: uptake of dissolved Ag released by the AgNPs, uptake of a polymer or large (>3kD) Ag-cysteine complex and uptake of the nanoparticle itself. Addition of 1:1 Ag:cysteine reduced concentrations of dissolved Ag, which contributed to, but did not fully explain the reductions in uptake. A bioavailable Ag-cysteine complex (> 3kD) appeared to be the dominant avenue of uptake from both PVP AgNPs and PEG AgNPs in the presence of cysteine. Quantifying the different avenues of uptake sets the stage for studies to assess toxicity unique to NPs.

  13. Mussel-inspired green synthesis of polydopamine-Ag-AgCl composites with efficient visible-light-driven photocatalytic activity.

    Science.gov (United States)

    Cai, Aijun; Wang, Xiuping; Guo, Aiying; Chang, Yongfang

    2016-09-01

    Polydopamine-Ag-AgCl composites (PDA-Ag-AgCl) were synthesized using a mussel-inspired method at room temperature, where PDA acts as a reducing agent to obtain the noble Ag nanoparticles from a precursor. The morphologies and structures of the as-prepared PDA-Ag-AgCl were characterized by several techniques including field emission scanning electron microscopy (FESEM), transmission electron microscopy (SEM), Raman spectra, and X-Ray photoelectron spectrum (XPS). The morphological observation depicts formation of nanoparticles with various micrometer size diameters and surface XPS analysis shows presence of various elements including Ag, N, Cl, and O. The enhanced absorbance of the PDA-Ag-AgCl particles in the visible light region is confirmed through UV-Vis diffuse reflectance spectra (DRS), and the charge transfer is demonstrated by photoluminescence (PL) and photocurrent response. The synthesized PDA-Ag-AgCl composites could be used as visible-light-driven photocatalysts for the degradation of Rhodamine B. The elevated photocatalytic activity is ascribed to the effective charge transfer from plasmon-excited Ag to AgCl that can improve the efficiency of the charge separation during the photocatalytic reaction. Furthermore, differences in the photocatalytic performance among the different PDA-Ag-AgCl composites are noticed that could be attributed to the Brunauer-Emmett-Teller (BET) specific surface area, which benefits to capture the visible light efficiently. The PDA-Ag-AgCl exhibits excellent stability without a significant loss in activity after 5cycles. The proposed method is low-cost and environmentally friendly, hence a promising new way to fabricate plasmon photocatalysts. Copyright © 2016. Published by Elsevier B.V.

  14. 异常核型者的Ag-NOR和Ag-AA分析%Analysis of Ag-NOR-Ag-AA for patients with chromosome anomalies

    Institute of Scientific and Technical Information of China (English)

    彭惠民; 唐吟宇; 郭玉萍; 张静

    2000-01-01

    为了解异常核型者的rRNA基因活性及近端着丝粒染色体联合频率的变化规律,用硝酸银染色法对14例染色体罗伯逊易位携带者,26例klinefelter综合征患者,16例Turner综合征患者及30名正常对照,进行银染核仁组织者区(Ag-NOR)和银染近端着丝粒染色体联合(Ag-AA)频率的研究.发现Kinefelter综合征和Turner综合征患者的Ag-NOR/细胞(6.93、6.49)及Ag-AA细胞(1.02、1.05)均显著高于对照(5.30、0.60).罗伯逊易位携带者Ag+NOR/细胞(5.10)与对照无显著性差异,Ag-AA/细胞(1.21)显著高于对照.提示罗伯逊易位丢失的rRNA基因可由其他近端着丝粒染色体上的rRNA基因增加转录活性来补偿,近端着丝粒染色体联合频率的增加可能与染色体不分离或易位的形成有关.

  15. Optical absorption spectra of Ag-11 isomers

    DEFF Research Database (Denmark)

    Martinez, Jose Ignacio; Fernandez, E. M.

    2009-01-01

    The optical absorption spectra of the three most; stable structural isomers of the Ag-11 cluster were calculated using the time-dependent, density functional theory within the Casida formalism. The slightly different, spectra, of the isomers may permit the identification of the ground-stale confi......The optical absorption spectra of the three most; stable structural isomers of the Ag-11 cluster were calculated using the time-dependent, density functional theory within the Casida formalism. The slightly different, spectra, of the isomers may permit the identification of the ground...

  16. Isomorphism and solid solutions among Ag- and Au-selenides

    Energy Technology Data Exchange (ETDEWEB)

    Palyanova, Galina A.; Seryotkin, Yurii V. [Sobolev Institute of Geology and Mineralogy, Novosibirsk (Russian Federation); Novosibirsk State University (Russian Federation); Kokh, Konstantin A., E-mail: k.a.kokh@gmail.com [Sobolev Institute of Geology and Mineralogy, Novosibirsk (Russian Federation); Novosibirsk State University (Russian Federation); Tomsk State University (Russian Federation); Bakakin, Vladimir V. [Nikolaev Institute of Inorganic Chemistry, Novosibirsk (Russian Federation)

    2016-09-15

    Au-Ag selenides were synthesized by heating stoichiometric mixtures of elementary substances of initial compositions Ag{sub 2−x}Au{sub x}Se with a step of x=0.25 (0≤x≤2) to 1050 °C and annealing at 500 °C. Scanning electron microscopy, optical microscopy, electron microprobe analysis and X-ray powder diffraction methods have been applied to study synthesized samples. Results of studies of synthesized products revealed the existence of three solid solutions with limited isomorphism Ag↔Au: naumannite Ag{sub 2}Se – Ag{sub 1.94}Au{sub 0.06}Se, fischesserite Ag{sub 3}AuSe{sub 2} - Ag{sub 3.2}Au{sub 0.8}Se{sub 2} and gold selenide AuSe - Au{sub 0.94}Ag{sub 0.06}Se. Solid solutions and AgAuSe phases were added to the phase diagram of Ag-Au-Se system. Crystal-chemical interpretation of Ag-Au isomorphism in selenides was made on the basis of structural features of fischesserite, naumannite, and AuSe. - Highlights: • Au-Ag selenides were synthesized. • Limited Ag-Au isomorphism in the selenides is affected by structural features. • Some new phases were introduced to the phase diagram Ag-Au-Se.

  17. Luminescent Property of a Supramolecular Silver(I)-Thiolate Complex Based on Secondary Ag-S Interactions and Hydrogen Bonds

    Institute of Scientific and Technical Information of China (English)

    SU,Wei-Pinga(苏伟平); SU,Wei-Ping; HONG,Mao-Chun(洪茂椿); HONG,Mao-Chun; CAO,Rong (曹荣); CAO,Rong; WENG,Jia-Bao(翁家宝); WENG,Jia-Bao; ZHOU,Zhong-Yuan(周忠远); ZHOU,Zhong-Yuan; CHAN,S.C.Albert(陈新滋); CHAN,S.C.Albert

    2001-01-01

    The supramolecular silver(I)-thiolate complex [Ag(μ2-SC4N2I4)2(SCN)]n has been prepared from the reaction of AgSCN and p iyrimidine-2-thiol in DMF. X-ray diffraction analysis shows that the supramolecular structure exhibits onedimemional chain through the secondary Ag-S interactions and the chains are further linked by strong hydrogen bonds to form a three dimensional network. The luminescenee effect from the silver-centered state of SAg LMCT in solid state is different from that in solution due to the secondary Ag-S interactions.

  18. Effect of Ag in structural, electrical and magnetic properties of Ag-sheated Bi-2223 wires

    Directory of Open Access Journals (Sweden)

    D Sohrabi

    2009-08-01

    Full Text Available  In this study, the superconducting properties of Bi-2223/Ag wires, made by the PIT method have been studied. Powder samples were prepared using conventional solid state reaction method. After calcination, samples with different Ag percent (0, 5, 10, 15, 20, and 25 prepared and sintered at 830 °C. It was shown that Ag addition has not only affected the formation of the desired Bi-2223 phase and the microstructure of these wires, but also influenced on the critical current density (JC and critical temperature.

  19. Hierarchical Ag mesostructures for single particle SERS substrate

    Science.gov (United States)

    Xu, Minwei; Zhang, Yin

    2017-01-01

    Hierarchical Ag mesostructures with highly rough surface morphology have been synthesized at room temperature through a simple seed-mediated approach. Electron microscopy characterizations indicate that the obtained Ag mesostructures exhibit a textured surface morphology with the flower-like architecture. Moreover, the particle size can be tailored easily in the range of 250-500 nm. For the growth process of the hierarchical Ag mesostructures, it is believed that the self-assembly mechanism is more reasonable rather than the epitaxial overgrowth of Ag seed. The oriented attachment of nanoparticles is revealed during the formation of Ag mesostructures. Single particle surface enhanced Raman spectra (sp-SERS) of crystal violet adsorbed on the hierarchical Ag mesostructures were measured. Results reveal that the hierarchical Ag mesostructures can be highly sensitive sp-SERS substrates with good reproducibility. The average enhancement factors for individual Ag mesostructures are estimated to be about 106.

  20. Effect of Ag shapes and surface compositions on the photocatalytic performance of Ag/ZnO nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Jia [Hubei Collaborative Innovation Center for High-efficiency Utilization of Solar Energy, Hubei University of Technology, Wuhan (China); School of Mechanical Engineering, Hubei University of Technology, Wuhan (China); Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan (China); Wang, Huihu, E-mail: wanghuihu@mail.hbut.edu.cn [Hubei Collaborative Innovation Center for High-efficiency Utilization of Solar Energy, Hubei University of Technology, Wuhan (China); School of Mechanical Engineering, Hubei University of Technology, Wuhan (China); Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan (China); Dong, Shijie [School of Mechanical Engineering, Hubei University of Technology, Wuhan (China); Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan (China); Wang, Fanqiang; Dong, Yifan [School of Mechanical Engineering, Hubei University of Technology, Wuhan (China)

    2014-12-25

    Highlights: • Ag/ZnO nanorods were synthesized via photoreduction and hydrothermal methods. • Ag presents nanosheet and nanoparticle shapes in different synthesis methods. • SPR effect and Ag{sup +} is observed only for Ag/ZnO prepared by hydrothermal method. • Ag nanosheets modified ZnO shows the high activity under UV–Vis. irradiation. • Only Ag nanoparticles modified ZnO nanorods has the visible-light-driven activity. - Abstract: Photoreduction and hydrothermal methods were used respectively to prepare Ag surface modified ZnO nanorods in this paper. The surface microstructure and photocatalytic performance of Ag/ZnO nanorods for methyl orange degradation were evaluated in detail. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS) and UV–Vis. diffuse reflectance spectroscopy (DRS) were used for microstructure analysis of as-prepared Ag/ZnO nanorods. FESEM images showed that Ag presented nanosheets in Ag/ZnO sample (AZP) prepared by photoreduction method, while it exhibited nanoparticles in the sample (AZH) using hydrothermal method. DRS studies clearly displayed surface plasmon resonance (SPR) effect of Ag in AZH samples. Furthermore, there was a red shift on absorption edge for AZH samples compared with bare ZnO and AZP samples. The XPS results revealed that Ag{sup +} ions existed on the surface of AZH samples. In contrast to AZH sample, AZP sample demonstrated the higher photocatalytic activity under UV–Vis. light illumination. However, it was interesting that AZH samples exhibited the visible-light-driven photocatalytic activity, which may be due to the cooperation role of the existence of Ag{sup +} ions and SPR effect of Ag nanoparticles. All these results illustrated that the shapes and surface compositions of Ag may be important factors that influence the photocatalytic performance of Ag/ZnO nanorods. The surface microstructure related photocatalytic mechanism was finally

  1. Removal of I by adsorption with AgX (Ag-impregnated X Zeolite) from high-radioactive seawater waste

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eil Hee; Lee, Keun Young; Kim, Kwang Wook; Kim, Hyung Ju; Kim, Ik Soo; Chung, Dong Yong; Moon, Jei Kwon; Choi, Jong Won [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-09-15

    This study aimed to the adsorption-removal of high- radioactive iodide (I) contained in the initially generated high-radioactive seawater waste (HSW), with the use of AgX (Ag-impregnated X zeolite). Adsorption of I by AgX (hereafter denoted as AgX-I adsorption) was increased by increasing the Ag-impregnated concentration in AgX, and its concentration was suitable at about 30 wt%. Because of AgCl precipitation by chloride ions contained in seawater waste, the leaching yields of Ag from AgX (Ag-impregnated concentration : about 30-35 wt%) was less than those in distilled water (< 1 mg/L). AgX-I adsorption was above 99% in the initial iodide concentration (Ci) of 0.01-10 mg/L at m/V (ratio of weight of adsorbent to solution volume)=2.5 g/L. This shows that efficient removal of I is possible. AgX-I adsorption was found to be more effective in distilled water than in seawater waste, and the influence of solution temperature was insignificant. Ag-I adsorption was better described by a Freundlich isotherm rather than a Langmuir isotherm. AgX-I adsorption kinetics can be expressed by a pseudo-second order rate equation. The adsorption rate constants (k2) decreased by increasing Ci, and conversely increased by increasing the ratio of m/V and the solution temperature. This time, the activation energy of AgX-I adsorption was about 6.3 kJ/mol. This suggests that AgX-I adsorption is dominated by physical adsorption with weaker bonds. The evaluation of thermodynamic parameters (a negative Gibbs free energy and a positive Enthalpy) indicates that AgX-I adsorption is a spontaneous reaction (forward reaction), and an endothermic reaction indicating that higher temperatures are favored.

  2. Bifunctional AgCl/Ag composites for SERS monitoring and low temperature visible light photocatalysis degradation of pollutant

    Science.gov (United States)

    Dong, Lihong; Zhu, Junyi; Xia, Guangqing

    2014-12-01

    With the assistance of Polyvinylpyrrolidone (PVP), AgCl/Ag composites were fabricated in N, N-Dimethylformamide (DMF) solvent via a photoactivated route. The size of AgCl particles was in the range of 500 nm to 1 μm and the Ag particle's diameter was about 10-20 nm. Different from those core-shell structures reported before, the Ag nanoparticles were dispersed uniformly both on the surface and in the body of AgCl particles. The generation of such kind of composites was resulted from the reducing ability of DMF and light irradiation during the formation of AgCl particles. The as-obtained AgCl/Ag composites presented great activity for both surface-enhanced Raman scattering (SERS) detection and visible light photocatalytic degradation of organic dyes. Additionally, the AgCl/Ag composites could maintain high photocatalytic activity even though the ambient temperature was as low as 15 °C and recycle photocatalysis experiments indicated that the photocatalyst exhibited higher stability. Such kind of AgCl/Ag composites holds great potential for environmental monitoring devices and pollutant treatments.

  3. Preparation and Characterization of Highly Efficient and Stable Visible-Light-Responsive Photocatalyst AgBr/Ag3PO4

    Directory of Open Access Journals (Sweden)

    Zhang Jinfeng

    2013-01-01

    Full Text Available AgBr/Ag3PO4 photocatalyst was synthesized using a facile coprecipitation method. The photocatalyst was characterized by X-ray powder diffraction (XRD, UV-Vis diffuse reflectance spectroscopy (DRS, scanning electron microscopy (SEM, Brunauer-Emmett-Teller (BET surface areas, and photoluminescence (PL technique. The activity of the photocatalyst was evaluated by the degradation of methyl orange (MO and rhodamine B (RhB. The results showed that the prepared AgBr/Ag3PO4 exhibited excellent performance and much higher photocatalytic activity than the single one under visible-light irradiation. The optimum mole ratio of Br/P in AgBr/Ag3PO4 samples is 0.3. The prepared AgBr/Ag3PO4 photocatalyst was transformed to Ag/AgBr/Ag3PO4 system with excellent property and good stability in the photocatalytic process. The possible mechanisms of the enhanced photocatalytic activity for the AgBr/Ag3PO4 were also discussed in detail.

  4. A multi-wire beam profile monitor in the AGS

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H.; Buxton, W.; Castillo, V.; Glenn, J.W. [and others

    1997-07-01

    A multi-wire beam profile monitor which can be used to directly monitor and control the optical matching between the Booster and AGS rings has been installed and tested in the AGS. Placement of a multi-wire monitor directly in the AGS provides profile measurements taken upon injection and the first two or more revolutions of the beam. The data from such measurements can be used to determine the optical properties of the beam transport line leading into the AGS.

  5. Study of structural modification of PVA by incorporating Ag nanoparticles

    DEFF Research Database (Denmark)

    Saini, I.; Sharma, A.; Rozra, J.

    2016-01-01

    Nanocomposites of PVA with Ag nanoparticles dispersed in it were synthesized using solution casting method. The morphology and size distribution of Ag nanoparticles embedded in PVA matrix were obtained by transmission electron microscopy (TEM) and Field emission scanning electron microscopy (FE......-SEM). Raman spectroscopy was used to examine structural changes taking place inside polyvinyl alcohol (PVA) matrix due to incorporation of Ag nanoparticle. Raman analysis indicates that Ag nanoparticles interact with PVA through H-bonding. © 2016 Author(s)....

  6. Surface-enhanced Raman scattering from AgNP-graphene-AgNP sandwiched nanostructures.

    Science.gov (United States)

    Wu, Jian; Xu, Yijun; Xu, Pengyu; Pan, Zhenghui; Chen, Sheng; Shen, Qishen; Zhan, Li; Zhang, Yuegang; Ni, Weihai

    2015-11-07

    We developed a facile approach toward hybrid AgNP-graphene-AgNP sandwiched structures using self-organized monolayered AgNPs from wet chemical synthesis for the optimized enhancement of the Raman response of monolayer graphene. We demonstrate that the Raman scattering of graphene can be enhanced 530 fold in the hybrid structure. The Raman enhancement is sensitively dependent on the hybrid structure, incident angle, and excitation wavelength. A systematic simulation is performed, which well explains the enhancement mechanism. Our study indicates that the enhancement resulted from the plasmonic coupling between the AgNPs on the opposite sides of graphene. Our approach towards ideal substrates offers great potential to produce a "hot surface" for enhancing the Raman response of two-dimensional materials.

  7. Evidence for enhancement of critical current by intergrain Ag in YBaCuO-Ag ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Dwir, B.; Affronte, M.; Pavuna, D.

    1989-07-24

    We report the evidence for enhancement of critical current density /ital J//sub /ital c// by /similar to/50%, which occurs when /similar to/10 wt. % Ag is added to Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7/minus//delta// ceramics. The maximal /ital J//sub /ital c// (/similar to/700 A/cm/sup 2/ at /ital T/=77 K) appears simultaneously with maximum YBaCuO compactness in the samples. The silver fills the intergranular space (holes) without Cu substitution, and the critical temperature /ital T//sub /ital c// is not reduced from the bulk value (/similar to/91 K). Normal-state resistivity of Ag-YBaCuO samples is decreased by an order of magnitude, and samples exhibit improved contact resistance and resistance to water. While the critical density is improved by adding /similar to/10 wt. % Ag, it decreases at higher Ag concentrations.

  8. AGS experiments -- 1996, 1997, 1998, 1999. Fifteenth edition

    Energy Technology Data Exchange (ETDEWEB)

    Lo Presti, P.

    1999-03-01

    This report is a compilation of two-page summaries for AGS experiments for FY 1996, FY 1997, FY 1998, FY 1999. The bulk of the experiments are for high energy physics and nuclear physics programs. Also included are the run schedules for the AGS for each of those years and a listing of publications of AGS experiments for 1982--1999.

  9. Thermal stability of substitutional ag in CdTe

    NARCIS (Netherlands)

    Jahn, SG; Hofsass, H; Restle, M; Ronning, C; Quintel, H; BharuthRam, K; Wahl, U

    1996-01-01

    The thermal stability of substitutional Ag in CdTe was deduced from lattice location measurements at different temperatures. Substitutional Ag probe atoms were generated via transmutation doping from radioactive Cd isotopes. The lattice sites of Ag isotopes were determined by measuring the channelin

  10. [Prognostic value of AgNORs in breast cancer].

    Science.gov (United States)

    Aubele, M; Auer, G; Jütting, U

    1994-03-01

    Silver stained AgNORs were investigated by means of a semiautomatic image analysis system. Paraffin sections from 137 invasive ductal carcinomas of the breast were available with clinical and histological data, several DNA distribution parameters, and follow-up data of about 10 years (45 to 165 months). By means of the Chi 2-test the correlation of AgNOR features with the other variables was investigated. A significant correlation was found between AgNORs and the histological grading, and between AgNORs and most of the DNA parameters. Tumor size (pT) and pTNM-stage showed significant correlation with one of the AgNOR parameters: standard deviation (SD) of average AgNOR area and of AgNOR number, respectively. No correlation was found between AgNORs and the axillary nodal status (pN). The prognostic significance of AgNORs was estimated by using Cox regression analysis. In a multivariate approach offering all parameters available one AgNOR feature (coefficient of variation of relative AgNOR area) ranked at the third position beyond the SD of DNA distribution and the pTNM-staging. Considering the distant-recurrence free interval of patients instead of the survival time the same AgNOR feature showed an independent prognostic value.

  11. Analysis of the complexation reaction between Ag+ and ethylene

    NARCIS (Netherlands)

    Nymeijer, Kitty; Visser, Tymen; Brilman, Wim; Wessling, Matthias

    2004-01-01

    In the present work the reversible, bimolecular (1,1) reaction between ethylene and Ag+ in concentrated AgNO3(aq) solutions is analyzed. Due to interactions between the positively charged Ag+ ions and the negatively charged NO3- ions, the silver nitrate is not completely dissociated and the actual f

  12. Thermal stability of substitutional ag in CdTe

    NARCIS (Netherlands)

    Jahn, SG; Hofsass, H; Restle, M; Ronning, C; Quintel, H; BharuthRam, K; Wahl, U

    1996-01-01

    The thermal stability of substitutional Ag in CdTe was deduced from lattice location measurements at different temperatures. Substitutional Ag probe atoms were generated via transmutation doping from radioactive Cd isotopes. The lattice sites of Ag isotopes were determined by measuring the channelin

  13. Effect of Ag+ and PO43- ratios on the microstructure and photocatalytic activity of Ag3PO4

    Science.gov (United States)

    Qin, Jiaqian; Zhang, Xinyu; Yang, Chengwu; Song, Aijun; Zhang, Bing; Rajendran, Saravanan; Ma, Mingzhen; Liu, Riping

    2016-09-01

    In this work, the catalyst silver phosphate (Ag3PO4) with different initial ratios of Ag+ and PO43- in aqueous solution was synthesized by a simple precipitation method from AgNO3 and NH4H2PO4 which were used as the precursor. After that, the prepared samples were characterized by different techniques such as field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (UV-DRS) and decomposition evolution of rhodamine B (RhB) solution. The results indicate that the initial ratios of Ag+/PO43- in aqueous solution can modify the morphology and also it can significantly affect the photocatalytic performance. During photocatalytic process, the rich Ag+ ion Ag3PO4 can form the surface plasmon resonance (SPR) of Ag nanoparticles, which inhibit the reduction of Ag3PO4 resulting in higher photocatalytic activity and stability.

  14. Antibacterial Ag/a-C nanocomposite coatings: The influence of nano-galvanic a-C and Ag couples on Ag ionization rates

    Science.gov (United States)

    Manninen, N. K.; Calderon, S.; Carvalho, I.; Henriques, M.; Cavaleiro, A.; Carvalho, S.

    2016-07-01

    Biofilm formation has been pointed as a major concern in different industrial applications, namely on biomedical implants and surgical instruments, which has prompted the development of new strategies for production of efficient antimicrobial surfaces. In this work, nano-galvanic couples were created to enhance the antibacterial properties of silver, by embedding it into amorphous carbon (a-C) matrix. The developed Ag/a-C nanocomposite coatings, deposited by magnetron sputtering, revealed an outstanding antibacterial activity against Staphylococcus epidermidis, promoting a total reduction in biofilm formation with no bacteria counts in all dilution. The open circuit potential (OCP) tests in 0.9% NaCl confirmed that a-C shows a positive OCP value, in contrast to Ag coating, thus enhancing the ionization of biocidal Ag+ due to the nano-galvanic couple activation. This result was confirmed by the inductively coupled plasma-optical emission spectroscopy (ICP-OES), which revealed a higher Ag ionization rate in the nanocomposite coating in comparison with the Ag coating. The surface of Ag/a-C and Ag coatings immersed in 0.9% NaCl were monitored by scanning electron microscopy (SEM) over a period of 24 h, being found that the Ag ionization determined by ICP-OES was accompanied by an Ag nanoparticles coalescence and agglomeration in Ag/a-C coating.

  15. Electron beam induced evolution in Au, Ag, and interfaced heterogeneous Au/Ag nanoparticles.

    Science.gov (United States)

    Liu, Yuzi; Sun, Yugang

    2015-08-28

    A sintering process of nanoparticles made of Ag, Au, and interfaced Ag/Au heterodimers was investigated by in situ transmission electron microscopy at room temperature. Such a process is driven by the illumination of a high-energy electron beam accelerated at 200 kV that promotes atom diffusion in the nanoparticles that are in physical contact. Upon electron illumination, adjacent Au nanoparticles gradually merge together to form a larger particle along with the reduction of the surface area despite the fact that orientated attachment is not observed. According to the detailed analysis of the size change of the particles and the contact area, it was found that the nanoparticle fusion process is significantly different from the well-established thermal diffusion mechanism. In addition to the similar fusion process of Au nanoparticles, Ag nanoparticles undergo apparent sublimation induced by knock on damage because the transferred energy from the electron beam to nanoparticles is higher than the surface binding energy of Ag atoms when the electron scattering angle is larger than 112°. The particles with a smaller size diffuse faster. Surface diffusion dominates at the beginning of the fusion process followed by slower lattice diffusion. Electron beam illumination can transform the interfaced Au/Ag dimers to Au@Ag core-shell particles followed by a slow removal of the Ag shells. This process under normal electron beam illumination is a lot faster than the thermally driven process. Both diffusion and sublimation of Ag atoms are dependent on the intensity of the electron beam, i.e., a higher beam intensity is favorable to accelerate both the processes.

  16. Surface-enhanced Raman scattering from AgNP-graphene-AgNP sandwiched nanostructures

    Science.gov (United States)

    Wu, Jian; Xu, Yijun; Xu, Pengyu; Pan, Zhenghui; Chen, Sheng; Shen, Qishen; Zhan, Li; Zhang, Yuegang; Ni, Weihai

    2015-10-01

    We developed a facile approach toward hybrid AgNP-graphene-AgNP sandwiched structures using self-organized monolayered AgNPs from wet chemical synthesis for the optimized enhancement of the Raman response of monolayer graphene. We demonstrate that the Raman scattering of graphene can be enhanced 530 fold in the hybrid structure. The Raman enhancement is sensitively dependent on the hybrid structure, incident angle, and excitation wavelength. A systematic simulation is performed, which well explains the enhancement mechanism. Our study indicates that the enhancement resulted from the plasmonic coupling between the AgNPs on the opposite sides of graphene. Our approach towards ideal substrates offers great potential to produce a ``hot surface'' for enhancing the Raman response of two-dimensional materials.We developed a facile approach toward hybrid AgNP-graphene-AgNP sandwiched structures using self-organized monolayered AgNPs from wet chemical synthesis for the optimized enhancement of the Raman response of monolayer graphene. We demonstrate that the Raman scattering of graphene can be enhanced 530 fold in the hybrid structure. The Raman enhancement is sensitively dependent on the hybrid structure, incident angle, and excitation wavelength. A systematic simulation is performed, which well explains the enhancement mechanism. Our study indicates that the enhancement resulted from the plasmonic coupling between the AgNPs on the opposite sides of graphene. Our approach towards ideal substrates offers great potential to produce a ``hot surface'' for enhancing the Raman response of two-dimensional materials. Electronic supplementary information (ESI) available: Additional SEM images, electric field enhancement profiles, Raman scattering spectra, and structure-dependent peak ratios. See DOI: 10.1039/c5nr04500b

  17. High-Reliability Low-Ag-Content Sn-Ag-Cu Solder Joints for Electronics Applications

    Science.gov (United States)

    Shnawah, Dhafer Abdulameer; Said, Suhana Binti Mohd; Sabri, Mohd Faizul Mohd; Badruddin, Irfan Anjum; Che, Fa Xing

    2012-09-01

    Sn-Ag-Cu (SAC) alloy is currently recognized as the standard lead-free solder alloy for packaging of interconnects in the electronics industry, and high- Ag-content SAC alloys are the most popular choice. However, this choice has been encumbered by the fragility of the solder joints that has been observed in drop testing as well as the high cost of the Ag itself. Therefore, low-Ag-content SAC alloy was considered as a solution for both issues. However, this approach may compromise the thermal-cycling performance of the solders. Therefore, to enhance the thermal-cycling reliability of low-Ag-content SAC alloys without sacrificing their drop-impact performance, alloying elements such as Mn, Ce, Ti, Bi, In, Sb, Ni, Zn, Al, Fe, and Co were selected as additions to these alloys. However, research reports related to these modified SAC alloys are limited. To address this paucity, the present study reviews the effect of these minor alloying elements on the solder joint reliability of low-Ag-content SAC alloys in terms of thermal cycling and drop impact. Addition of Mn, Ce, Bi, and Ni to low-Ag-content SAC solder effectively improves the thermal-cycling reliability of joints without sacrificing the drop-impact performance. Taking into consideration the improvement in the bulk alloy microstructure and mechanical properties, wetting properties, and growth suppression of the interface intermetallic compound (IMC) layers, addition of Ti, In, Sb, Zn, Al, Fe, and Co to low-Ag-content SAC solder has the potential to improve the thermal-cycling reliability of joints without sacrificing the drop-impact performance. Consequently, further investigations of both thermal-cycling and drop reliability of these modified solder joints must be carried out in future work.

  18. A comparative study about electronic structures at rubrene/Ag and Ag/rubrene interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Sumona, E-mail: sumona.net.09@gmail.com; Mukherjee, M. [Saha Institute of Nuclear Physics, 1/AF, Bidhan Nagar, Kolkata 700064 (India)

    2015-10-15

    The contact between the electrode and the organic semiconductor is one of the most crucial factors in determining the organic device performance. The development and production technology of different organic devices require the understanding of different types of metal/organic semiconducting thin film interfaces. Comparisons about the electronic structures at Rubrene/Ag and Ag/Rubrene interfaces have been studied using photoemission spectroscopy. The Ag on rubrene interfaces is found to show more interesting and complex natures than its counterpart. The vacuum level (VL) was shifted about 0.51 eV from push back effect for deposition of 5 Å rubrene onto Ag film whereas the electronic features of silver was only suppressed and no energy shift was resulted. While the deposition of 5 Å Ag onto rubrene film leads to the diffusion of the Ag atoms, as a cluster with quantum size effect, inside the film. Angle dependent XPS measurement indicates that diffused metal clusters were present at entire probed depth of the film. Moreover these clusters dope the uppermost surface of the rubrene film which consequences a shift of the electronic states of thick organic film towards higher binding energy. The VL was found to shift about 0.31 eV toward higher binding energy whereas the shift was around 0.21 eV for the electronic states of rubrene layer.

  19. Ag induced electromagnetic interference shielding of Ag-graphite/PVDF flexible nanocomposites thinfilms

    Energy Technology Data Exchange (ETDEWEB)

    Kumaran, R.; Alagar, M. [Polymer Composite Laboratory, Department of Chemical Engineering, Anna University, Chennai 600 025 (India); Dinesh Kumar, S.; Subramanian, V. [Microwave Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Dinakaran, K., E-mail: kdinakaran.tvu@gmail.com [Department of Chemistry, Thiruvalluvar University, Serkkadu, Vellore 632115 (India)

    2015-09-14

    We report Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/poly-vinylidene difluoride (PVDF). PVDF nanocomposite thin-films were synthesized by intercalating Ag in Graphite (GIC) followed by dispersing GIC in PVDF. The X-ray diffraction analysis and the high-resolution transmission electron microscope clearly dictate the microstructure of silver nanoparticles in graphite intercalated composite of PVDF matrix. The conductivity values of nanocomposites are increased upto 2.5 times when compared to neat PVDF having a value of 2.70 S/cm at 1 MHz. The presence of Ag broadly enhanced the dielectric constant and lowers the dielectric loss of PVDF matrix proportional to Ag content. The EMI shielding effectiveness of the composites is 29.1 dB at 12.4 GHz for the sample having 5 wt. % Ag and 10 wt. % graphite in PVDF.

  20. A comparative study about electronic structures at rubrene/Ag and Ag/rubrene interfaces

    Directory of Open Access Journals (Sweden)

    Sumona Sinha

    2015-10-01

    Full Text Available The contact between the electrode and the organic semiconductor is one of the most crucial factors in determining the organic device performance. The development and production technology of different organic devices require the understanding of different types of metal/organic semiconducting thin film interfaces. Comparisons about the electronic structures at Rubrene/Ag and Ag/Rubrene interfaces have been studied using photoemission spectroscopy. The Ag on rubrene interfaces is found to show more interesting and complex natures than its counterpart. The vacuum level (VL was shifted about 0.51 eV from push back effect for deposition of 5 Å rubrene onto Ag film whereas the electronic features of silver was only suppressed and no energy shift was resulted. While the deposition of 5 Å Ag onto rubrene film leads to the diffusion of the Ag atoms, as a cluster with quantum size effect, inside the film. Angle dependent XPS measurement indicates that diffused metal clusters were present at entire probed depth of the film. Moreover these clusters dope the uppermost surface of the rubrene film which consequences a shift of the electronic states of thick organic film towards higher binding energy. The VL was found to shift about 0.31 eV toward higher binding energy whereas the shift was around 0.21 eV for the electronic states of rubrene layer.

  1. Biochemical Synthesis of Ag/AgCl Nanoparticles for Visible-Light-Driven Photocatalytic Removal of Colored Dyes

    OpenAIRE

    Xiyun Zhao; Jie Zhang; Binsong Wang; Amir Zada; Muhammad Humayun

    2015-01-01

    Photocatalytic removal of organic pollution such as waste colored dyes was a promising technique for environment technique. However, effective photocatalysts were needed to enhance the photocatalytic efficiency. Ag/AgCl was regarded as high performance catalyst for photocatalytic degradation. Ag/AgCl nanoparticles were biochemically prepared with metabolin of living fungi which was used as reductant and characterized by X-Ray diffraction (XRD), UV-visible spectroscopy and transmission electro...

  2. Ag/AgCl Loaded Bi2WO6 Composite: A Plasmonic Z-Scheme Visible Light-Responsive Photocatalyst

    Directory of Open Access Journals (Sweden)

    Xiangchao Meng

    2016-01-01

    Full Text Available Hierarchical flower-like Bi2WO6 was successfully synthesized by facile hydrothermal method at low pH. And Ag/AgCl was loaded by photoreduction on its surface. As-prepared photocatalysts were characterized by various techniques. Bi2WO6 was successfully synthesized at a size of 2-3 μm. Depositing Ag/AgCl did not destroy the crystal structure, and both Ag+ and metallic Ag0 were found. The band gap of the composite was 2.57 eV, which indicates that visible light could be the activating irradiation. In the photocatalytic activity test, the composite with 10 wt% Ag/AgCl boasted the highest removal efficiency (almost 100% in 45 min. The significant enhancement can be attributed to the surface plasmon resonance (SPR effect and the establishment of heterostructures between Ag/AgCl and Bi2WO6. A possible mechanism of photocatalytic oxidation in the presence of Ag/AgCl-Bi2WO6 was proposed. This work sheds light on the potential applications of plasmonic metals in photocatalysis to enhance their activities.

  3. A dry method to synthesize dendritic Ag2Se nanostructures utilizing CdSe quantum dots and Ag thin films

    Science.gov (United States)

    Hu, Lian; Zhang, Bingpo; Xu, Tianning; Li, Ruifeng; Wu, Huizhen

    2015-01-01

    Dendritic Ag2Se nanostructures are synthesized in a dry environment by UV irradiating the hybrids composed of CdSe quantum dots (QDs) and silver (Ag). UV irradiation on CdSe QDs induces a photooxidation effect on the QD surface and leads to the formation of SeO2 components. Then SeO2 reacts with the Ag atoms in either Ag film or QD layer to produce the Ag2Se. The growth mechanism of Ag2Se dendrites on solid Ag films is explored and explained by a diffusion limited aggregation model in which the QD layer provides enough freedom for Ag2Se motion. Since the oxidation of the CdSe QDs is the critical step for the Ag2Se dendrites formation this dry chemical interaction between QDs and Ag film can be applied in the study of the QD surface chemical properties. With this dry synthesis method, the Ag2Se dendrites can also be facilely formed at the designed area on Ag substrates.

  4. Hexagonally arranged arrays of urchin-like Ag hemispheres decorated with Ag nanoparticles for surface-enhanced Raman scattering substrates

    Institute of Scientific and Technical Information of China (English)

    Haibin Tang[1; Guowen Meng[1,2; Zhongbo Li[1; Chuhong Zhu[1; Zhulin Huang[1; Zhaoming Wang[1; Fadi Li[1

    2015-01-01

    The surface topography of noble metal particles is a significant factor in tailoring surface-enhanced Raman scattering (SERS) properties. Here, we present a simple fabrication route to hexagonally arranged arrays of surface-roughened urchin- like Ag hemispheres (Ag-HSs) decorated with Ag nanoparticles (Ag-NPs) for highly active and reproducible SERS substrates. The urchin-like Ag-HS arrays are achieved by sputtering Ag onto the top surface of a highly ordered porous anodic aluminum oxide (AAO) template to form ordered arrays of smooth Ag-HSs and then by electrodepositing Ag-NPs onto the surface of each Ag-HS. Owing to the ordered arrangement of the Ag-HSs and the improved surface roughness, the urchin-like hierarchical Ag-HS arrays can provide sufficient and uniform "hot spots" for reproducible and highly active SERS effects. Using the urchin-like Ag-HS arrays as SERS substrates, 10-7 M dibutyl phthalate (a member of plasticizers family) and 1.5 × 10-5 M PCB-77 (one congener of polychlorinated biphenyl, a notorious class of pollutants) are identified, showing promising potential for these substrates in the rapid recognition of organic pollutants.

  5. Detection of HBsAg, HBcAg, and HBV DNA in ovarian tissues from patients with HBV infection

    Institute of Scientific and Technical Information of China (English)

    Li-Zhang Chen; Xue-Gong Fan; Jian-Ming Gao

    2005-01-01

    AIM: To investigate the presence of HBsAg, HBcAg, and HBV DNA in ovarian tissues from patients with HBV infection.METHODS: HBsAg and HBcAg were examined in ovarian biopsy tissues from 26 patients with HBV infection by immunocytochemistry, and HBV DNA was detected in ovarian tissues by PCR.RESULTS: HBsAg and HBcAg were present with the same positive rate of 34.6% (9/26). The total positive rate was 46.2% (12/26). HBsAg and HBcAg were positive in 6 (23.1%) of the 26 patients. Brown positive particles were diffusely distributed in ovarian cells. The positive rate of HBV DNA was 58.3% (7/12).CONCLUSION: HBsAg, HBcAg, and HBV DNA can be detected in ovarian tissues from patients with HBV infection. The presence of HBsAg and HBcAg in ovarian tissues does not correlate with the HBV markers in serum.

  6. New insight into daylight photocatalysis of AgBr@Ag: synergistic effect between semiconductor photocatalysis and plasmonic photocatalysis.

    Science.gov (United States)

    Jiang, Jing; Li, Hao; Zhang, Lizhi

    2012-05-14

    Noble metal nanoparticles (NPs) are often used as electron scavengers in conventional semiconductor photocatalysis to suppress electron-hole (e(-)-h(+) ) recombination and promote interfacial charge transfer, and thus enhance photocatalytic activity of semiconductors. In this contribution, it is demonstrated that noble metal NPs such as Ag NPs function as visible-light harvesting and electron-generating centers during the daylight photocatalysis of AgBr@Ag. Novel Ag plasmonic photocatalysis could cooperate with the conventional AgBr semiconductor photocatalysis to enhance the overall daylight activity of AgBr@Ag greatly because of an interesting synergistic effect. After a systematic investigation of the daylight photocatalysis mechanism of AgBr@Ag, the synergistic effect was attributed to surface plasmon resonance induced local electric field enhancement on Ag, which can accelerate the generation of e(-)-h(+) pairs in AgBr, so that more electrons are produced in the conduction band of AgBr under daylight irradiation. This study provides new insight into the photocatalytic mechanism of noble metal/semiconductor systems as well as the design and fabrication of novel plasmonic photocatalysts.

  7. Biochemical Synthesis of Ag/AgCl Nanoparticles for Visible-Light-Driven Photocatalytic Removal of Colored Dyes

    Directory of Open Access Journals (Sweden)

    Xiyun Zhao

    2015-04-01

    Full Text Available Photocatalytic removal of organic pollution such as waste colored dyes was a promising technique for environment technique. However, effective photocatalysts were needed to enhance the photocatalytic efficiency. Ag/AgCl was regarded as high performance catalyst for photocatalytic degradation. Ag/AgCl nanoparticles were biochemically prepared with metabolin of living fungi which was used as reductant and characterized by X-Ray diffraction (XRD, UV-visible spectroscopy and transmission electron microscopy (TEM. The Ag/AgCl nanoparticle composites showed spherical aggregation shape with an average size of about 3–5 nm which is well inside the quantum regime. The UV-visible study showed that Ag/AgCl nanoparticles had strong visible light absorption and exhibited excellent visible-light-driven photocatalytic performance. Photocatalytic results indicated that the obtained Ag/AgCl nanoparticles were suitable for photocatalytic removal of RhB dye under visible light irradiation. The excellent photocatalytic activities could be attributed to the quantum size nanoparticles and the Plasmon resonance of Ag/AgCl composites.

  8. The strange diffusivity of Ag atoms in CdTe

    CERN Document Server

    Wolf, H; Ostheimer, V; Schachtrup, A R; Stolwijk, N A; Wichert, T

    2001-01-01

    The diffusion of Ag atoms in CdTe was investigated using the radiotracer $^{111}\\!$Ag, which was introduced by implantation with an energy of 60 or 80 keV. The measured diffusion profiles are explained by assuming the existence of a repulsive interaction between Ag and residual Cu atoms causing a drift of the Ag atoms towards the centre of the crystal, which supposes the diffusion in a concentration gradient. This effect vanishes if the Ag concentration is increased and becomes more pronounced if the crystals are simultaneously co- doped with Cu. (11 refs).

  9. Thickness-dependent spontaneous dewetting morphology of ultrathin Ag films.

    Science.gov (United States)

    Krishna, H; Sachan, R; Strader, J; Favazza, C; Khenner, M; Kalyanaraman, R

    2010-04-16

    We show here that the morphological pathway of spontaneous dewetting of ultrathin Ag films on SiO2 under nanosecond laser melting is dependent on film thickness. For films with thickness h of 2 nm intermolecular forces, we have estimated the morphological transition thickness for the intermolecular forces for Ag on SiO2. The theory predictions agree well with observations for Ag. These results show that it is possible to form a variety of complex Ag nanomorphologies in a consistent manner, which could be useful in optical applications of Ag surfaces, such as in surface enhanced Raman sensing.

  10. AKTIVITAS ANTIBAKTERI KAIN KASA TERLAPISI TiO¬2/Ag AMORF, Ag, DAN KITOSAN/Ag TERHADAP BAKTERI GRAM NEGATIF DAN POSITIF (The Antibacterial Activity of Gauze Coated by Tio¬2/Ag Amorphous, Ag, and Chitosan/Ag Against Gram Negative and Positive Bacteria)

    OpenAIRE

    Purnawan, Candra; Martini, Tri; Rawiningtyas, Sotya; Zidny, Zidny Z.S.R.A.

    2014-01-01

    ABSTRAKPelapisan kain kasa dengan komposit TiO2/Ag amorf, kitosan/Ag, dan Ag telah dilakukan menggunakan metode dip coating dengan variasi urutan pelapisan. Komposit TiO2/Ag amorf disintesis dengan metode sol gel dalam pelarut etanol. Hasil sintesis dikarakterisasi menggunakan FTIR dan XRD. Kain kasa hasil pelapisan dikarakterisasi menggunakan XRD dan dilakukan uji antibakteri menggunakan metode optical density pada λ 600nm terhadap aktivitas bakteri Eschericia coli dan Stapylococcus aureus. ...

  11. Microstructure evolution during 300 °C storage of sintered Ag nanoparticles on Ag and Au substrates

    Energy Technology Data Exchange (ETDEWEB)

    Paknejad, S.A. [King’s College London, Physics Department, Strand, London WC2R 2LS (United Kingdom); Dumas, G. [Eltek Semiconductors Ltd, Nelson Road Industrial Estate, Dartmouth, Devon TQ6 9LA (United Kingdom); West, G. [Loughborough University, Materials Department, Loughborough LE11 3TU (United Kingdom); Lewis, G. [Eltek Semiconductors Ltd, Nelson Road Industrial Estate, Dartmouth, Devon TQ6 9LA (United Kingdom); Mannan, S.H., E-mail: samjid.mannan@kcl.ac.uk [King’s College London, Physics Department, Strand, London WC2R 2LS (United Kingdom)

    2014-12-25

    Highlights: • Shear strength of pressure-free sintered Ag found to increase during ageing at 300 °C on Ag substrate. • Rapid collapse of void number density after 24 h ageing in the sintered Ag layer. • Higher porosity at edge of joint compared to the middle. • Shear strength of pressure-free sintered Ag decreases during ageing at 300 °C due to high porosity layer growth. • Void free layer and high porosity layer growth explained in terms of atomic diffusion and grain boundary migration. - Abstract: A silver nanoparticle based die attach material was used in a pressure free process to bond 2.5 mm square Ag plated Si die to Ag and Au plated substrates. The assemblies were stored at 300 °C for up to 500 h and the morphology of the sintered Ag and the shear strength were monitored as a function of time. On Ag substrate it was found that die shear strength increased and that the Ag grains grew in size and porosity decreased over time. There was also a clear difference in morphology between sintered Ag at the die edge and centre. On Au substrate, it was observed that the initially high die shear strength decreased with storage time and that voids migrated away from the Ag/Au interface and into the Ag joint. This has led to the formation of a void free layer at the interface followed by a high porosity region, which weakened the joint. The microstructure reveals a high density of grain and twin boundaries which facilitate the Ag and Au atomic diffusion responsible. The grain structure of the plated Au led to diffusion of Au into the Ag via high-angle tilt grain boundaries, and grain boundary migration further dispersed the Au into the Ag layer.

  12. Biotic and abiotic interactions in aquatic microcosms determine fate and toxicity of Ag nanoparticles: part 2-toxicity and Ag speciation.

    Science.gov (United States)

    Bone, Audrey J; Colman, Benjamin P; Gondikas, Andreas P; Newton, Kim M; Harrold, Katherine H; Cory, Rose M; Unrine, Jason M; Klaine, Stephen J; Matson, Cole W; Di Giulio, Richard T

    2012-07-03

    To study the effects of complex environmental media on silver nanoparticle (AgNP) toxicity, AgNPs were added to microcosms with freshwater sediments and two species of aquatic plants (Potamogeton diversifolius and Egeria densa), followed by toxicity testing with microcosm surface water. Microcosms were designed with four environmental matrices in order to determine the contribution of each environmental compartment to changes in toxicity: water only (W), water + sediment (WS), water + plants (WP), and water + plants + sediment (WPS). Silver treatments included AgNPs with two different coatings, gum arabic (GA-AgNPs) or polyvinylpyrollidone (PVP-AgNPs), as well as AgNO(3). Water samples taken from the microcosms at 24 h postdosing were used in acute toxicity tests with two standard model organisms, early life stage zebrafish (Danio rerio) and Daphnia magna. Speciation of Ag in these samples was analyzed using Ag L3-edge X-ray absorption near edge spectroscopy (XANES). Silver speciation patterns for the nanoparticle treatments varied significantly by coating type. While PVP-AgNPs were quite stable and resisted transformation across all matrices (>92.4% Ag(0)), GA-AgNP speciation patterns suggest significantly higher transformation rates, especially in treatments with plants (Ag(0) in WP and WPS, respectively) and moderately increased transformation with sediments (Ag(0)). Additionally, the presence of plants in the microcosms (with and without sediments) reduced both the concentration of Ag in the water column and toxicity for all Ag treatments. Reductions in toxicity may have been related to decreased water column concentrations as well as changes in the surface chemistry of the particles induced by organic substances released from the plants.

  13. An Efficient Ag+ Ionophore Based on Thiacalix[4]arene

    Institute of Scientific and Technical Information of China (English)

    LI Xiong; GONG Shu-Ling; YANG Wei-Ping; CHEN Yuan-Yin

    2008-01-01

    A novel Ag+ ionophore, p-tert-butyi-tetrakis(hydrazinocarbonylmethoxy)thiacalix[4]arene in 1,3-alternate conformation (thiacalix[4]arene tetrahydrazide, 1) was synthesized. Its binding properties towards alkali and transition metal cations were studied by noncompetitive liquid-liquid extraction of alkali metal (Li+, Na+, K+ and Cs+)and transition metal (Co2+, Ni2+, Cu2+, Zn2+, Ag+) picrates. It was found that the thiacalix[4]arene tetrahydrazide exhibited high extractability towards Ag+, lower percent extraction towards Cu2+, and little or no extraction ability towards the others. The selectivity towards Ag+ was further evaluated by competitive Ag+ extraction experiments in the mixture of the above-mentioned nine cations, the concentration of which was monitored with ICP-OES. 1HNMR titration experiments and ESI-MS proved the stoichiometry of 1 to Ag+ was 1 : 1, and the 'N-Ag+' interaction with the assistance of thiacalixarene skeleton was primarily involved in the complexation.

  14. Effects of Ag addition on FePt L10 ordering transition: A direct observation of ordering transition and Ag segregation in FePtAg alloy films

    Science.gov (United States)

    Wang, Lei; Gao, Tenghua; Yu, Youxing

    2015-12-01

    FePt and (FePt)91.2Ag8.8 alloy films were deposited by magnetron sputtering. The average coercivity of (FePt)91.2Ag8.8 films reaches 8.51 × 105 A/m, which is 0.63 × 105 A/m higher than that of the corresponding FePt films. Ag addition effectively promotes the FePt L10 ordering transition at a relatively low annealing temperature of 400 °C. The promotion mechanism was investigated by using in situ high-resolution transmission electron microscopy (HRTEM) and ex situ X-ray absorption fine structure (XAFS). The concurrence of ordering transition and Ag segregation in FePtAg alloy films was first observed by using in situ heating HRTEM. The time-resolved evolution reveals more details on the role of Ag addition in FePt low-temperature ordering. Ex situ XAFS results further confirm that Ag replaces Fe sites in the as-deposited films and segregates from FePt-Ag solid solution phase through annealing at elevated temperatures. The segregation of Ag atoms leaves vacancies in the grain. The vacancy formation is believed to accelerate the diffusion of Fe and Pt atoms, which is critical for the L10 ordering transition.

  15. Shell Thickness-Dependent Strain Distributions of Confined Au/Ag and Ag/Au Core-Shell Nanoparticles

    OpenAIRE

    Feng Liu; Honghua Huang; Ying Zhang; Ting Yu; Cailei Yuan; Shuangli Ye

    2015-01-01

    The shell thickness-dependent strain distributions of the Au/Ag and Ag/Au core-shell nanoparticles embedded in Al2O3 matrix have been investigated by finite element method (FEM) calculations, respectively. The simulation results clearly indicate that there is a substantial strain applied on both the Au/Ag and Ag/Au core-shell nanoparticles by the Al2O3 matrix. For the Au/Ag nanoparticles, it can be found that the compressive strain existing in the shell is stronger than that on the center of ...

  16. Ag3Sn plate formation in the solidification of near-ternary eutectic Sn-Ag-Cu

    Science.gov (United States)

    Kang, Sung K.; Shih, Da-Yuan; Donald, Ny.; Henderson, W.; Gosselin, Timothy; Sarkhel, Amit; Charles Goldsmith, Ny.; Puttlitz, Karl J.; Choi, Won Kyoung

    2003-06-01

    Near-ternary eutectic Sn-Ag-Cu alloys are leading lead-free candidate solders for various applications. These alloys yield three phases upon solidification: β-Sn,Ag3Sn, and Cu6Sn5. Large, plate-like, pro-eutectic Ag3Sn structures can grow rapidly within the liquid phase, potentially adversely affecting the mechanical behavior and reducing the fatigue life of solder joints. This article reports on the formation of such plates in Sn-Ag-Cu solder balls and joints and demonstrates how large Ag3Sn plate formation can be minimized.

  17. The Y-Ag-Al system

    Energy Technology Data Exchange (ETDEWEB)

    Gumenyuk, T.M.; Kuz' ma, Yu.B.; Stel' makhovych, B.M. [L' vov State Univ. (Ukraine). Dept. of Anal. Chem.

    2000-03-14

    The interaction between the components in the Y-Ag-Al system at 870 K has been studied using X-ray analysis. The phase diagram in the region up to 50 at.% of yttrium has been constructed. The limits of the solid solution regions of the binary compounds and the homogeneity ranges of the ternary ones have been determined. The crystal structures of the ternary aluminides Y{sub 3}Ag{sub 2}Al{sub 7} (Ca{sub 3}Cu{sub 2}Al--type structure, space group R anti 3m, a=0.55422(2), c=2.6259(1) nm) and YAg{sub 0.6}Al{sub 1.4} (KHg{sub 2}-type structure, space group Imma, a=0.45399(2), b=0.71551(3), c=0.78712(4) nm) have been studied for the first time. (orig.)

  18. Size-dependent transformation from Ag templates to Au-Ag nanoshells via galvanic replacement reaction in organic medium

    Energy Technology Data Exchange (ETDEWEB)

    Karvianto; Chow, G. M., E-mail: msecgm@nus.edu.sg [National University of Singapore, Department of Materials Science and Engineering (Singapore)

    2012-10-15

    The transformation from Ag templates to Au-Ag nanoshells via galvanic replacement reaction with HAuCl{sub 4} was systematically studied in an organic medium in the presence of oleylamine. Decahedral ({approx}43 nm in size) and triangular prism ({approx}53 nm in edge length) Ag templates transformed into equiaxed and triangular prismatic Au-Ag nanoshells, respectively. The first step involved structural and morphological changes from Ag templates to Au-Ag nanoshells with an interior cavity. In the second step, the growth of the shells continued through the deposition of Au. The shell thickness increased from {approx}5 to {approx}10 nm for the equiaxed Au-Ag nanoshells ({approx}39-nm interior cavity) and {approx}5 to {approx}8 nm for the triangular prismatic Au-Ag nanoshells ({approx}52-nm interior edge length). Oleylamine not only served as a surfactant but also removed AgCl precipitates and reduced HAuCl{sub 4}. For the nanoshells derived from the {approx}20-nm Ag decahedrons, further reaction in excess HAuCl{sub 4} collapsed the nanoshells into Au-rich solid fragments. However, the nanoshells derived from the {approx}43-nm Ag decahedrons, the nanoshell structure not only persisted in excess HAuCl{sub 4}, but its shell thickness also increased. The size-dependent transformation of these nanoshells is discussed.

  19. New frontiers in water purification: highly stable amphopolycarboxyglycinate-stabilized Ag-AgCl nanocomposite and its newly discovered potential

    Science.gov (United States)

    Krutyakov, Yurii A.; Zherebin, Pavel M.; Kudrinskiy, Alexey A.; Zubavichus, Yan V.; Presniakov, Mikhail Yu; Yapryntsev, Alexey D.; Karabtseva, Anastasia V.; Mikhaylov, Dmitry M.; Lisichkin, Georgii V.

    2016-09-01

    A simple synthetic procedure for high-stable dispersions of porous composite Ag/AgCl nanoparticles stabilized with amphoteric surfactant sodium tallow amphopolycarboxyglycinate has been proposed for the first time. The prepared samples were characterized by UV-vis spectroscopy, x-ray powder diffraction (XRD), x-ray photoelectron spectroscopy, small area electron diffraction (SAED), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and electron probe micro-analysis. In addition, measurements (carried out at the Kurchatov synchrotron radiation source stations) of the Ag K-edge extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge structure (XANES) spectra and XRD of the prepared nanoparticles have been performed. The obtained results suggest that small-sized Ag clusters are homogeneously distributed in the mass of the AgCl nanoparticle (~80 nm) formed during the synthesis. The Ag/AgCl dispersion demonstrates photocatalytic activity (with respect to methyl orange) and high bactericidal activity against E. coli. This activity is superior to the activity of both Ag and AgCl nanoparticles stabilized by the same surfactant. Thus, porous composite Ag/AgCl nanoparticles can be used as a multifunctional agent that is able to remove both pollutants and bacterium from water.

  20. Sequestration of Ag(I) from aqueous solution as Ag(0) nanostructures by nanoscale zero valent iron (nZVI)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yalei, E-mail: zhangyalei2003@163.com [Tongji University, State Key Laboratory of Pollution Control and Resources Reuse (China); Yan, Jing [Tongji University, Modern Agricultural Science and Engineering Institute (China); Dai, Chaomeng, E-mail: daichaomeng@163.com, E-mail: daichaomeng@tongji.edu.cn [Tongji University, College of Civil Engineering (China); Li, Yuting; Zhu, Yan [Tongji University, Modern Agricultural Science and Engineering Institute (China); Zhou, Xuefei [Tongji University, State Key Laboratory of Pollution Control and Resources Reuse (China)

    2015-11-15

    This study investigates the application of nanoparticle zero valent iron (nZVI) to sequester Ag(I) as Ag(0) nanostructures from aqueous solution. Batch experiments were performed with nZVI exposed to aqueous Ag(I) to investigate the effects of environmental parameters, including nZVI dose, temperature and pH. High temperature facilitates Ag(I) sequestration, and the rate constants are determined to be 0.02, 0.12, and 0.31 mg L/m{sup 2} at 30, 50, and 60 °C, respectively. Ag(I) sequestration was adversely affected by adding nitric acid to the solution due to significant acid washing, decreasing the available nZVI active sites. Characterization techniques including TEM, XRD, and HR-XPS revealed that nZVI is oxidized to lepidocrocite and magnetite/maghemite and confirmed the formation of nanocrystalline silver. HR-XPS analysis indicated that Ag{sub 2}O forms rapidly as an intermediate due to Ag(I) adsorption onto the FeOOH layer. The Ag(0) nanostructures that are formed are fractal, spherical, and dendritic or rod-like, respectively, in morphology by FE-TEM images at different Ag/Fe mass ratios. A general reaction model for the interaction Ag(I) with nZVI is proposed. Our results suggest that nZVI is effective for Ag(I) removal.

  1. Orientation of nickelocene on Ag(100)

    Science.gov (United States)

    Pugmire, D. L.; Woodbridge, C. M.; Langell, M. A.

    1998-08-01

    High-resolution electron-energy-loss spectroscopy has been used to study the molecular adsorption of nickelocene, Ni(C 5H 5) 2, on Ag(100). Results indicate that at up to one monolayer coverage, nickelocene adsorbs molecularly with its axis approximately perpendicular to the surface. At very high coverages, the molecular axis is not exclusively oriented along the surface normal. This is possibly due to randomization of the metallocene orientation as multilayers are formed.

  2. Results from the AGS Booster transverse damper

    Energy Technology Data Exchange (ETDEWEB)

    Russo, D.; Brennan, M.; Meth, M.; Roser, T.

    1993-01-01

    To reach the design intensity of 1.5 [times] 10[sup 13] protons per pulse in the AGS Booster, transverse coupled bunch instabilities with an estimated growth rate of 1500s[sup [minus]1] have to be dampened. A prototype transverse damper has been tested successfully using a one turn digital delay and closed orbit suppression implemented in a programmable gate array. An updated damper, which includes an algorithm to optimize damping for a changing betatron rune, will also be presented.

  3. Results from the AGS Booster transverse damper

    Energy Technology Data Exchange (ETDEWEB)

    Russo, D.; Brennan, M.; Meth, M.; Roser, T.

    1993-06-01

    To reach the design intensity of 1.5 {times} 10{sup 13} protons per pulse in the AGS Booster, transverse coupled bunch instabilities with an estimated growth rate of 1500s{sup {minus}1} have to be dampened. A prototype transverse damper has been tested successfully using a one turn digital delay and closed orbit suppression implemented in a programmable gate array. An updated damper, which includes an algorithm to optimize damping for a changing betatron rune, will also be presented.

  4. Multifunction of Ni/Ag Nanocompound Fluid

    Directory of Open Access Journals (Sweden)

    Mu-Jung Kao

    2013-01-01

    Full Text Available An arc-submerged nanoparticle synthesis system (ASNSS is proposed and developed for fabricating Ni/Ag nanocompound fluid. In the development process, the positive and negative electrodes in the system are Ni and Ag, respectively. Applied electrical energy then produces heating source by generating an adequate arc with a high temperature that can melt and vaporize the two electrodes. The nanocompound fluid that is generated by the synthesis system is analyzed by morphological analysis, Zeta potential analysis, heat conductivity analysis, magnetic characteristic analysis, and UV-Vis absorption spectra analysis. Experimental results show that increasing the concentration of added particles and the higher temperature can be helpful to the enhancement of thermal conductivity. The Ni/Ag nanofluid not only preserves the magnetic character of the nickel and the ability of silver to absorb visible light but also enhances the thermal conductivity. The absorption occurs at 406 nm wavelength (redshift from 396 nm to 406 nm, which means that, under the excitement of visible light range (400~700 nm, it can let more easy electrons jump to the conductivity zone from the valence electron zone.

  5. The Y-Ag-Ga system

    Energy Technology Data Exchange (ETDEWEB)

    Krachan, T.; Stel' makhovych, B.; Kuz' ma, Yu

    2005-01-11

    The isothermal section at 670 K of the Y-Ag-Ga system in the region of 0-33 at.% Y has been constructed using X-ray diffraction data. The existence of earlier known ternary gallides has been confirmed. Their homogeneity regions, atomic coordinates and distribution of atoms in the structures have been determined: Y{sub 3}Ag{sub 2.55}Ga{sub 8.45} (La{sub 3}Al{sub 11}-type structure, a 0.4310(1) nm, b = 1.2865(3) nm, c = 0.9552(3) nm, R{sub F} = 0.043), YAg{sub 0.22}Ga{sub 1.78} (CaIn{sub 2}-type structure, a = 0.44565(1) nm, c 0.72032(2) nm, R{sub I} = 0.081), YAg{sub 0.74}Ga{sub 1.26} (KHg{sub 2}-type structure, a 0.45302(2) nm, b = 0.70805(3) nm, c = 0.78056(3) nm, R{sub I} = 0.059). The crystal structure of the new ternary compound YAg{sub 1.1}Ga{sub 1.9} ({beta}-YbAgGa{sub 2}-type structure, Pnma, a = 0.69654(3) nm, b = 0.43391(2) nm, c = 1.02126(5) nm, R{sub I} = 0.087) has been studied for the first time.

  6. Electrochemical detection of aqueous Ag+ based on Ag+-assisted ligation reaction

    Science.gov (United States)

    Miao, Peng; Han, Kun; Wang, Bidou; Luo, Gangyin; Wang, Peng; Chen, Mingli; Tang, Yuguo

    2015-03-01

    In this work, a novel strategy to fabricate a highly sensitive and selective biosensor for the detection of Ag+ is proposed. Two DNA probes are designed and modified on a gold electrode surface by gold-sulfur chemistry and hybridization. In the presence of Ag+, cytosine-Ag+-cytosine composite forms and facilitates the ligation event on the electrode surface, which can block the release of electrochemical signals labeled on one of the two DNA probes during denaturation process. Ag+ can be sensitively detected with the detection limit of 0.1 nM, which is much lower than the toxicity level defined by U.S. Environmental Protection Agency. This biosensor can easily distinguish Ag+ from other interfering ions and the performances in real water samples are also satisfactory. Moreover, the two DNA probes are designed to contain the recognition sequences of a nicking endonuclease, and the ligated DNA can thus be cleaved at the original site. Therefore, the electrode can be regenerated, which allows the biosensor to be reused for additional tests.

  7. Identification of Ag and Cd photoluminescence in $^{111}$Ag-doped GaN

    CERN Document Server

    Stötzler, A; Deicher, M

    1999-01-01

    In order to unambiguously identify the chemical nature of Cd and Ag related optical transitions in GaN, epitaxial GaN layers were implanted with the radioactive isotope $^{111}$Ag which decays into stable $^{111}$Cd. This chemical transmutation was monitored by photoluminescence (PL) spectroscopy. Being an element specific property, the half-life of this decay was used to establish the chemical assignment of the optical transitions to a specific defect. We found that the Ag related transitions consist of a series of four single lines (1.610, 1.600, 1.594, and 1.573 eV), each accompanied by two phonon replicas separated by 63 meV. Cd produces two PL bands centered at 2.7 and 3.2 eV. Additional Cd-related single transitions at 3.341, 3.328, and 3.249 eV have been observed. Exponential fits to the PL intensities yield half-lives of $t_{1/2}^{Ag}$= (7.61$\\pm$0.27) d and $t_{1/2}^{Cd}$=(7.60$\\pm$0.27) d, respectively, in good agreement with the half-life of $^{111}$Ag of 7.45 d. (13 refs).

  8. Mechanical and electrical properties of In-Bi solder at Bi2212 superconductor interface with annealed Ag spray layers and Ag precoating layers

    Institute of Scientific and Technical Information of China (English)

    Seung-Yong SHIN; Ji-Hyun LEE; Hai-Woong PARK

    2009-01-01

    The electrical properties of solder contact layers between Cu-Ni shunt metal and tube type Bi2212 superconductor that is applied in superconducting fault current limiter were studied. The contact properties of the solders are improved not only by Ag precoating layers, but also by the pre-sprayed Ag layer and subsequent Ag precoating layers. The annealed Ag sprayed layers onto Bi2212 superconductor prior to Ag electroplating work as protecting layers for the superconductor from plating solutions. The contact angle of the electroplated Ag layer is 42.91- and decreases to 15.25- and 5.88- with Ag sprayed layer and additional Ag electroplated layers. The Ag sprayed layer with suitable annealing prior to Ag electroplating improves contact strength of the Ag electroplated layer by about 12% due to denser microstructure of the Ag electroplated layers.

  9. Effect of Ag nanostructures and annealing process on the localized surface plasmon resonance properties of Ag-based AZO films

    Science.gov (United States)

    Jin, Jing; Hui, Chaoxian; Liu, Can; Shi, Weimin

    2017-08-01

    Ag nanoparticles were obtained in Ag/AZO and AZO/Ag/AZO films by magnetron sputtering method at room temperature with different deposition time. The morphology of Ag nanoparticles is strongly affected by the particle size, shape and distribution as well as annealing temperatures, which determine the optical response of films. The high quality of AZO film with better crystallinity can enhance the optical transmittance and a good coverage by AZO as top layer on Ag nanoparticles can also enhance the surface plasmon resonance (SPR) absorption of Ag in long wavelengths. The mechanisms involved in shifts and broadening of SPR peaks have been explained detailedly. The effect of annealing process on SPR of Ag and photoelectric properties of AZO/Ag/AZO films can be also discussed. It is shown that the SPR peak of 664 nm only appears in AZO/Ag (5 s)/AZO film and no SPR peaks are found in annealed AZO/Ag/AZO films. The AZO/Ag (20 s)/AZO film annealed at 300 °C shows a great figure of merit (F_{{TC}}) of 4.8 × 10-2 Ω-1 because of high visible optical average transmittance of 85% and low sheet resistance (R_{{S}}) of 4.1 Ω/sq. The overall results reveal that annealing process can improve the electrical property of film and may not be able to promote the SPR of Ag nanoparticles, especially when AZO top layer is added. The introduction of Ag nanoparticles in AZO/Ag/AZO films should be very effective for improving the SPR or photoelectric properties of films depending on deposition conditions and annealing process.

  10. Mechanisms of Toxicity of Ag Nanoparticles in Comparison to Bulk and Ionic Ag on Mussel Hemocytes and Gill Cells.

    Science.gov (United States)

    Katsumiti, Alberto; Gilliland, Douglas; Arostegui, Inmaculada; Cajaraville, Miren P

    2015-01-01

    Silver nanoparticles (Ag NPs) are increasingly used in many products and are expected to end up in the aquatic environment. Mussels have been proposed as marine model species to evaluate NP toxicity in vitro. The objective of this work was to assess the mechanisms of toxicity of Ag NPs on mussel hemocytes and gill cells, in comparison to ionic and bulk Ag. Firstly, cytotoxicity of commercial and maltose stabilized Ag NPs was screened in parallel with the ionic and bulk forms at a wide range of concentrations in isolated mussel cells using cell viability assays. Toxicity of maltose alone was also tested. LC50 values were calculated and the most toxic Ag NPs tested were selected for a second step where sublethal concentrations of each Ag form were tested using a wide array of mechanistic tests in both cell types. Maltose-stabilized Ag NPs showed size-dependent cytotoxicity, smaller (20 nm) NPs being more toxic than larger (40 and 100 nm) NPs. Maltose alone provoked minor effects on cell viability. Ionic Ag was the most cytotoxic Ag form tested whereas bulk Ag showed similar cytotoxicity to the commercial Ag NPs. Main mechanisms of action of Ag NPs involved oxidative stress and genotoxicity in the two cell types, activation of lysosomal AcP activity, disruption of actin cytoskeleton and stimulation of phagocytosis in hemocytes and increase of MXR transport activity and inhibition of Na-K-ATPase in gill cells. Similar effects were observed after exposure to ionic and bulk Ag in the two cell types, although generally effects were more marked for the ionic form. In conclusion, results suggest that most observed responses were due at least in part to dissolved Ag.

  11. Clinical analysis of 48 cases of primary tumors of the trachea and carina%原发性气管、隆突肿瘤外科治疗48例临床分析

    Institute of Scientific and Technical Information of China (English)

    艾波; 付向宁; 廖永德; 严华; 孙威; 张霓; 徐沁孜

    2011-01-01

    Objective To accumulate experience of surgical treatment of primary tracheal or earinal tumors. Methods There were 48 patients with tumor of trachea or carina underwent surgical treatment analyzed from 2001 to 2010, resection and reconstruction of trachea in 35 patients, carinal resection and reconstruction in 12 patients, and trachea wedge resection in 1 patient. Cardiopulmonary bypass was required in 5 patients for nearly complete obstruction of the trachea. Results none patients died perioperatively. 41 cases (85. 4% ) were clinical cured. Follow-up was complete up to June 2010 or to the date of death. 5 cases ( 10. 4% ) were died, 43 cases (89. 6% ) survived, with 9 cases ( 18. 8% ) over 5 years. The assisted time last from 28 to 46 min in the 5 cases which required cardiopulmonary bypass, with average time 36 min, and good anesthesia was gain. Conclusion Surgical treatrnent of primary tumor of trachea and carina shows exact effect, proper operation method should be chosen, the operation can be safer by reasonable assist of cardiopulmonary bypass.%目的 总结原发性气管、隆突肿瘤外科治疗经验.方法 回顾分析我科2001~2010年手术治疗48例气管、隆突肿瘤的临床资料,气管环形切除+对端吻合35例,气管+隆突切除重建12例,气管楔形切除1例;5例术中辅助体外循环.结果 无围手术期死亡,临床治愈41例(85.4%);术后随访7个月~7年,死亡5例(10.4%),生存至今43例(89.6%),其中生存5年及以上者9例(18.8%);5例术中辅助体外循环28~46 min,平均36 min,麻醉满意.结论 气管、隆突肿瘤外科手术疗效确切,合理选择手术方式,适当应用体外循环技术可提高手术安全性.

  12. Heterojunction double dumb-bell Ag2Te-Te-Ag2Te nanowires

    Science.gov (United States)

    Som, Anirban; Pradeep, T.

    2012-07-01

    Growth of isolated axial heterojunction nanowires by a solution phase growth process is reported. The dumb-bell shaped nanowires contain two silver telluride sections at the extremes joined by a tellurium section. Reaction of silver nitrate with tellurium NWs in aqueous solution at a molar ratio of 1 : 1 leads to the formation of amorphous partially silver reacted Te NWs. Low temperature (75 °C) solution phase annealing of these silver deficient NWs results in phase segregation producing crystalline Ag2Te and Te phases with clear phase boundaries along the wire axis. Structural characterization of these dumb-bell shaped NWs was performed with different microscopic and spectroscopic tools. Solution phase silver concentration over the course of annealing indicated leaching of silver into the solution during the formation of biphasic NWs. Similar Ag : Te ratios were observed in both partially silver reacted Te NWs and phase segregated Ag2Te-Te-Ag2Te NWs and this was attributed to redeposition of leached silver on the amorphous NW tips which eventually resulted in complete phase segregation. Successful integration of different chemical components in single NWs is expected to open up new application possibilities as physical and chemical properties of the heterostructure can be exploited.Growth of isolated axial heterojunction nanowires by a solution phase growth process is reported. The dumb-bell shaped nanowires contain two silver telluride sections at the extremes joined by a tellurium section. Reaction of silver nitrate with tellurium NWs in aqueous solution at a molar ratio of 1 : 1 leads to the formation of amorphous partially silver reacted Te NWs. Low temperature (75 °C) solution phase annealing of these silver deficient NWs results in phase segregation producing crystalline Ag2Te and Te phases with clear phase boundaries along the wire axis. Structural characterization of these dumb-bell shaped NWs was performed with different microscopic and spectroscopic

  13. Photoconductive properties of organic-inorganic Ag/p-CuPc/n-GaAs/Ag cell

    Institute of Scientific and Technical Information of China (English)

    Khasan Sanginovich Karimov; Muhammad Tariq Saeed; Fazal Ahmad Khalid; Zioda Mirzoevna Karieva

    2011-01-01

    A thin film of copper phthalocyanine (CuPc),a p-type semiconductor,was deposited by thermal evaporation in vacuum on an n-type gallium arsenide (GaAs) single-crystal semiconductor substrate.Then semitransparent Ag thin film was deposited onto the CuPc film also by thermal evaporation to fabricate the Ag/pCuPc/n-GaAs/Ag cell.Photoconduction of the cell was measured in photoresistive and photodiode modes of operation.It was observed that with an increase in illumination,the photoresistance decreased in reverse bias while it increased in forward bias.The photocurrent was increased in reverse bias operation.In forward bias operation with an increase in illumination,the photocurrent showed a different behavior depending on the voltage applied.

  14. SPIN TRANSPORT FROM AGS TO RHIC WTIH TWO PARTIAL SNAKES IN AGS.

    Energy Technology Data Exchange (ETDEWEB)

    MACKAY, W.W.; LUCCIO, A.U.; TSOUPAS, N.; TAKANO, J.

    2006-06-23

    The stable spin direction in the RHIC rings is vertical. With one or two partial helical Siberian snakes in the AGS, the stable spin direction at extraction is not vertical. Interleaved vertical and horizontal bends in the transport line between AGS and the RHIC rings also tend to tip the spin away from the vertical. In order to maximize polarization in RHIC, we examined several options to improve the matching of the stable spin direction during beam transfer from the AGS to each of the RHIC rings. While the matching is not perfect, the most economical method appears to be a lowering of the injection energy by one unit of G{gamma} from 46.5 to 45.5.

  15. AKTIVITAS ANTIBAKTERI KAIN KASA TERLAPISI TiO¬2/Ag AMORF, Ag, DAN KITOSAN/Ag TERHADAP BAKTERI GRAM NEGATIF DAN POSITIF (The Antibacterial Activity of Gauze Coated by Tio¬2/Ag Amorphous, Ag, and Chitosan/Ag Against Gram Negative and Positive Bacteria

    Directory of Open Access Journals (Sweden)

    Candra Purnawan

    2014-05-01

    Full Text Available ABSTRAK Pelapisan kain kasa dengan komposit TiO2/Ag amorf, kitosan/Ag, dan Ag telah dilakukan menggunakan metode dip coating dengan variasi urutan pelapisan. Komposit TiO2/Ag amorf disintesis dengan metode sol gel dalam pelarut etanol. Hasil sintesis dikarakterisasi menggunakan FTIR dan XRD. Kain kasa hasil pelapisan dikarakterisasi menggunakan XRD dan dilakukan uji antibakteri menggunakan metode optical density pada λ 600nm terhadap aktivitas bakteri Eschericia coli dan Stapylococcus aureus. Kain kasa dengan urutan pelapisan kitosan/Ag, komposit TiO2/Ag amorf, dan Ag memiliki daya antibakteri optimum. Daya antibakteri kain kasa terhadap E. coli sebesar 98, 66% setelah jam ke-24. Daya antibakteri tersebut lebih besar dibandingkan dengan daya antibakteri terhadap S. aureus yaitu 71,47% setelah jam ke-24.   ABSTRACT TiO2/Ag amorphous composite has been synthesized by sol gel method in ethanol. This composite  was characterized using FTIR and XRD. TiO2/Ag amorphous composite, chitosan/ Ag, and Ag coated in gauze using dip coating method with plating sequence variation. Coated gauze was characterized using XRD and antibacterial test was conducted by optical density at λ 600 nm against Escherichia coli and Staphylococcus aureus. The results showed that coated gauze with the sequence was chitosan/Ag, TiO2/Ag amorphous composite, and Ag was optimum antibacterial power. The inhibition against Escherichia coli was greater than Staphylococcus aureus. The inhibition against Escherichia coli was 98.66% for 24 hours and against Staphylococcus aureus was 71.47% for 24 hours.

  16. Chronically Implanted, Nafion-Coated Ag/AgCl Reference Electrodes for Neurochemical Applications.

    Science.gov (United States)

    Hashemi, Parastoo; Walsh, Paul L; Guillot, Thomas S; Gras-Najjar, Julie; Takmakov, Pavel; Crews, Fulton T; Wightman, R Mark

    2011-11-16

    Fast-scan cyclic voltammetry (FSCV) at carbon fiber microelectrodes can be used to measure behaviorally correlated dopamine changes in the extracellular fluid of the brain of freely moving rats. These experiments employ a chronically implanted Ag/AgCl reference electrode. When dopamine measurements are taken 4 days after implantation, there is often a potential shift, typically greater than +0.2 V, in the anodic and cathodic peaks in the cyclic voltammogram for dopamine. In this work, we optimized a method to coat sintered Ag/AgCl reference electrodes with the perfluorinated polymer, Nafion, to prevent this shift. We find that we can stabilize reference electrodes for up to 28 days. Immunohistochemistry of the tissue around the implant site shows extensive glial encapsulation around both bare and Nafion-coated devices. However, the lesion around bare electrodes has a rough texture implying that these cells are strongly adsorbed onto the bare reference electrode, while the lesion around a Nafion-coated electrode shows that cells are more intact implying that they adsorb less strongly. EDS and SEM analysis of the surface of the electrodes confirms this by visualizing a heavy build up of plaques, organic in nature, only on bare electrodes. Impedance spectroscopy indicates no difference between the impedance of bare and Nafion-coated Ag/AgCl electrodes, indicating that glial encapsulation does not lead to an increase in uncompensated resistance between the working and reference electrodes. The electrochemical shift therefore must be due to the unique chemical microenvironment around the reference electrode that alters the chloride equilibrium, a process that the Nafion coating prevents.

  17. Enhanced Visible Light Photocatalytic Degradation of Organic Pollutants over Flower-Like Bi2O2CO3 Dotted with Ag@AgBr

    Directory of Open Access Journals (Sweden)

    Shuanglong Lin

    2016-10-01

    Full Text Available A facile and feasible oil-in-water self-assembly approach was developed to synthesize flower-like Ag@AgBr/Bi2O2CO3 micro-composites. The photocatalytic activities of the samples were evaluated through methylene blue degradation under visible light irradiation. Compared to Bi2O2CO3, flower-like Ag@AgBr/Bi2O2CO3 micro-composites show enhanced photocatalytic activities. In addition, results indicate that both the physicochemical properties and associated photocatalytic activities of Ag@AgBr/Bi2O2CO3 composites are shown to be dependent on the loading quantity of Ag@AgBr. The highest photocatalytic performance was achieved at 7 wt % Ag@AgBr, degrading 95.18% methylene blue (MB after 20 min of irradiation, which is over 1.52 and 3.56 times more efficient than that of pure Ag@AgBr and pure Bi2O2CO3, respectively. Bisphenol A (BPA was also degraded to further demonstrate the degradation ability of Ag@AgBr/Bi2O2CO3. A photocatalytic mechanism for the degradation of organic compounds over Ag@AgBr/Bi2O2CO3 was proposed. Results from this study illustrate an entirely new approach to fabricate semiconductor composites containing Ag@AgX/bismuth (X = a halogen.

  18. Effect of Nanoscale Ag Film Thickness on the Electrical and Optical Properties of Transparent IZTO/Ag/IZTO Multilayer Films Deposited on Glass Substrates.

    Science.gov (United States)

    Oh, Dohyun; Lee, Nam Hyun; Cho, Woon-Jo; Kim, Tae Whan

    2015-07-01

    The effect of nanoscale Ag film thickness on the electrical and optical properties in transparent conducting oxide films consisting of an IZTO/Ag/IZTO multilayer were investigated. The homoge- neous morphologies of the Ag films sandwiched between the IZTO films affected the optical and electrical properties of the IZTO/Ag/IZTO multilayer films. The transmittance and resistivity of the IZTO/Ag/IZTO multilayer films decreased with increasing Ag film thickness. The resistivities of the IZTO/Ag/IZTO multilayer films grown on glass substrates were decreased by using an Ag thin inter- layer in comparison with that of the IZTO single layer.

  19. Electrical and optical investigations in Te–Ge–Ag and Te–Ge–AgI chalcogenide glasses

    Energy Technology Data Exchange (ETDEWEB)

    Cui, S. [Glass and Ceramic Laboratory, Institute of Chemical Sciences of Rennes, UMR-CNRS 6226, University of Rennes 1, 35042 Rennes cedex (France); Department of Materials Science and Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027 (China); Le Coq, D., E-mail: david.lecoq@univ-rennes1.fr [Glass and Ceramic Laboratory, Institute of Chemical Sciences of Rennes, UMR-CNRS 6226, University of Rennes 1, 35042 Rennes cedex (France); Boussard-Plédel, C.; Bureau, B. [Glass and Ceramic Laboratory, Institute of Chemical Sciences of Rennes, UMR-CNRS 6226, University of Rennes 1, 35042 Rennes cedex (France)

    2015-08-05

    Highlights: • Evolution of the electrical conductivities in Ag and AgI-GeTe{sub 4} glasses. • We demonstrate a change of a conductivity type (electronic vs ionic) in AgI–GeTe{sub 4} glasses. • A structural model for Ag and AgI–GeTe{sub 4} glasses is proposed. • The role of Ag in the structure of the Ag and AgI–GeTe{sub 4} glasses is described. - Abstract: (GeTe{sub 4}){sub 100−x}Ag{sub x} and (GeTe{sub 4}){sub 100−x}(AgI){sub x} glasses were prepared by a melting-quenching method. The glass electrical conductivity was investigated by both electrochemical impedance spectroscopy at different temperatures from 283 K to 333 K and four-probe method at room temperature (293 K). Meanwhile, as a major factor determining the electrical conductivity of a solid, optical band gap was also studied. By comparing the electrical conductivity values and glass optical band gap evolution, it was found that (GeTe{sub 4}){sub 100−x}Ag{sub x} glasses are mainly electronic conductive. On the other hand, the electrical conductivities of (GeTe{sub 4}){sub 100−x}(AgI){sub x} glasses firstly show a monotonic decrease by increasing AgI up to 15 mol.%, and then an increase when the AgI content is higher than 15 mol.%. The activation energy E{sub a} and the pre-exponential factor σ{sub 0} show apparent turning point when AgI content is 15 mol.%, signifying a conductivity mechanism change. In this paper, correlations between the conductivity and hypothetical structures in (GeTe{sub 4}){sub 100−x}Ag{sub x} and (GeTe{sub 4}){sub 100−x}(AgI){sub x} glasses are done and the importance of the Ag role is underlined.

  20. Spreadability of Ag Layer on Oxides and High Performance of AZO/Ag/AZO Sandwiched Transparent Conductive Film

    Directory of Open Access Journals (Sweden)

    Yuchao Niu

    2017-01-01

    Full Text Available Single layers of indium tin oxide (ITO, aluminum-doped zinc oxide (AZO, and Ag, bilayers of ITO/Ag and AZO/Ag, and sandwiched layers of ITO/Ag/ITO (IAI and AZO/Ag/AZO (ZAZ were fabricated on ordinary glass substrates using magnetron sputtering. The surface morphologies of single layers and bilayers were measured. The sheet resistance and transmittance of the sandwiched layers were investigated. The results showed that the spreadability of the Ag on the AZO was significantly better than that on the ITO or bare glass substrate. The spreadability of Ag on underlayers influences obviously the performance of transparent conductive oxide/Ag/transparent conductive oxides (TCO/Ag/TCO or TAT. The sheet resistance and transmittance of the ZAZ sandwiched layer with the matching of 35 nm AZO (35 nm/Ag (9 nm/AZO (35 nm fabricated in this paper were low to 3.84 Ω/sq and up to 85.55% at 550 nm, respectively. Its maximum Haacke figure of merit was 0.05469 Ω−1, higher than that of IAI multilayer.

  1. Preparation of mesoporous Ag/AgBr/TiO2 nanocomposites with comb-type polymer as template

    Directory of Open Access Journals (Sweden)

    Li XU

    Full Text Available The mesoporous TiO2 nanocomposites were fabricated in a water bath at lower temperatures using the sol-gel method with a comb-type polymer as template and tetrabutyl titanate as Ti source. The Ag/AgBr/TiO2 nanocomposites with higher specific surface areas were obtained by the introduction of Ag/AgBr on the surface of the mesoporous TiO2 using a deposition-precipitation method. The as-prepared nanocomposites were characterized by X-ray diffraction (XRD, N2 sorption analysis, transmission electron microscope (TEM and UV-vis diffuse reflectance spectroscopy (UV-vis DRS. The results showed that both the as-prepared TiO2 and Ag/AgBr/TiO2 exhibited mesoporous structure. The introduction of Ag/AgBr not only decreased the specific surface area of the mesoporous TiO2 from 346 m2/g to 253 m2/g, but also significantly increased its visible light photocatalytic activity. The degradation rate of methyl orange under visible light irradiation over Ag/AgBr/TiO2 was 145 and 60 times of those over the commercial TiO2 P25 and the mesoporous TiO2, respectively.

  2. Synthesis of biocompatible AuAgS/Ag{sub 2}S nanoclusters and their applications in photocatalysis and mercury detection

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Qian; Chen, Shenna; Zhang, Lingyang; Huang, Haowen, E-mail: hhwn09@163.com; Liu, Fengping [Hunan University of Science and Technology, Key Laboratory of Theoretical Organic Chemistry and Function Molecule, Ministry of Education, Hunan Provincial University Key Laboratory of QSAR/QSPR, School of Chemistry and Chemical Engineering (China); Liu, Xuanyong, E-mail: xyliu@mail.sic.ac.cn [Chinese Academy of Sciences, State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics (China)

    2014-12-15

    In this paper, a facile approach for preparation of AuAgS/Ag{sub 2}S nanoclusters was developed. The unique AuAgS/Ag{sub 2}S nanoclusters capped with biomolecules exhibit interesting excellent optical and catalytic properties. The fluorescent AuAgS/Ag{sub 2}S nanoclusters show tunable luminescence depending on the nanocluster size. The apoptosis assay demonstrated that the AuAgS/Ag{sub 2}S nanoclusters showed low cytotoxicity and good biocompatibility. Therefore, the nanoclusters can be used not only as a probe for labeling cells but also for their photocatalytic activity for photodegradation of organic dye. Moreover, a highly selective and sensitive assay for detection of mercury including Hg{sup 2+} and undissociated mercury complexes was developed based on the quenching fluorescent AuAgS/Ag{sub 2}S nanoclusters, which provides a promising approach for determining various forms of Hg in the mercury-based compounds in environment. These unique nanoclusters may have potential applications in biological labeling, sensing mercury, and photodegradation of various organic pollutants in waste water.Graphical Abstract.

  3. Synthesis of biocompatible AuAgS/Ag2S nanoclusters and their applications in photocatalysis and mercury detection

    Science.gov (United States)

    Zhao, Qian; Chen, Shenna; Zhang, Lingyang; Huang, Haowen; Liu, Fengping; Liu, Xuanyong

    2014-12-01

    In this paper, a facile approach for preparation of AuAgS/Ag2S nanoclusters was developed. The unique AuAgS/Ag2S nanoclusters capped with biomolecules exhibit interesting excellent optical and catalytic properties. The fluorescent AuAgS/Ag2S nanoclusters show tunable luminescence depending on the nanocluster size. The apoptosis assay demonstrated that the AuAgS/Ag2S nanoclusters showed low cytotoxicity and good biocompatibility. Therefore, the nanoclusters can be used not only as a probe for labeling cells but also for their photocatalytic activity for photodegradation of organic dye. Moreover, a highly selective and sensitive assay for detection of mercury including Hg2+ and undissociated mercury complexes was developed based on the quenching fluorescent AuAgS/Ag2S nanoclusters, which provides a promising approach for determining various forms of Hg in the mercury-based compounds in environment. These unique nanoclusters may have potential applications in biological labeling, sensing mercury, and photodegradation of various organic pollutants in waste water.

  4. Dissociation energies of Ag-RG (RG = Ar, Kr, Xe) and AgO molecules from velocity map imaging studies.

    Science.gov (United States)

    Cooper, Graham A; Kartouzian, Aras; Gentleman, Alexander S; Iskra, Andreas; van Wijk, Robert; Mackenzie, Stuart R

    2015-09-28

    The near ultraviolet photodissociation dynamics of silver atom-rare gas dimers have been studied by velocity map imaging. Ag-RG (RG = Ar, Kr, Xe) species generated by laser ablation are excited in the region of the C ((2)Σ(+))←X ((2)Σ(+)) continuum leading to direct, near-threshold dissociation generating Ag* ((2)P3/2) + RG ((1)S0) products. Images recorded at excitation wavelengths throughout the C ((2)Σ(+))←X ((2)Σ(+)) continuum, coupled with known atomic energy levels, permit determination of the ground X ((2)Σ(+)) state dissociation energies of 85.9 ± 23.4 cm(-1) (Ag-Ar), 149.3 ± 22.4 cm(-1) (Ag-Kr), and 256.3 ± 16.0 cm(-1) (Ag-Xe). Three additional photolysis processes, each yielding Ag atom photoproducts, are observed in the same spectral region. Two of these are markedly enhanced in intensity upon seeding the molecular beam with nitrous oxide, and are assigned to photodissociation of AgO at the two-photon level. These features yield an improved ground state dissociation energy for AgO of 15 965 ± 81 cm(-1), which is in good agreement with high level calculations. The third process results in Ag atom fragments whose kinetic energy shows anomalously weak photon energy dependence and is assigned tentatively to dissociative ionization of the silver dimer Ag2.

  5. Highly efficient degradation of thidiazuron with Ag/AgCl- activated carbon composites under LED light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yisi [College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128 (China); Hubei Key Laboratory for Processing and Application of Catalytic Materials, Huanggang Normal University, Huanggang 438000 (China); College of Chemical Engineering, Huanggang Normal University, Huanggang 438000 (China); Zhang, Yan [Hubei Key Laboratory for Processing and Application of Catalytic Materials, Huanggang Normal University, Huanggang 438000 (China); College of Chemical Engineering, Huanggang Normal University, Huanggang 438000 (China); Dong, Mingguang; Yan, Ting; Zhang, Maosheng [College of Chemical Engineering, Huanggang Normal University, Huanggang 438000 (China); Zeng, Qingru, E-mail: 40083763@qq.com [College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128 (China)

    2017-08-05

    Highlights: • Photocatalytic degradation of thidiazuron was performed in a neutral water matrix. • This was carried out in the presence of Ag/AgCl-activated carbon composites and LED light. • The pH effect and the dominant active species were explored. • Degradation products and pathways in water were studied for the first time. - Abstract: Thidiazuron (TDZ; 1-phenyl-3-(1,2,3-thiadiazol-5-yl)urea) is one of the most widely used defoliant and easy to dissolve in surface water. Risk associated with the pesticide is not clearly defined, so it is important to remove/degrade TDZ with an efficient and environment friendly technology. Here, we investigated the use of Ag/AgCl-activated carbon (Ag/AgCl–AC) composites in photocatalytic degradation of TDZ under LED light. By the synergic effect of Ag/AgCl and AC, the optimum Ag/carbon weight ratio of 2:1 exhibited superior visible-light photocatalytic activity, the highest removal efficiency was close to 91% in pH 7 matrix. Different types of Ag/AgCl–AC composites were tested, all showed much faster photodegradation kinetics than bare Ag/AgCl in 210 min. The degradation products as identified by HPLC–MS revealed that the hydroxylation by hydroxyl radicals and that of oxidation by superoxide radicals as well as holes were the two main pathways for TDZ degradation. Results revealed that the adsorption concentrated TDZ molecules and the photocatalytically generated radicals rapidly degradated TDZ, the two contributions functioned together for removal of the pollutant from water.

  6. Ag surface diffusion and out-of-bulk segregation in CrN-Ag nano-composite coatings.

    Science.gov (United States)

    Incerti, L; Rota, A; Ballestrazzi, A; Gualtieri, E; Valeri, S

    2011-10-01

    CrN-Ag nanocomposite coatings are deposited on Si(100) wafers and 20MnCr5 steel disks in a mixed Ar+N2 atmosphere by reactive magnetron sputtering. Structure, composition and morphology were investigated by Scanning Electron Microscopy (SEM), Auger Electron Spectroscopy (AES), X-ray Photoemission Spectroscopy (XPS), X-ray Diffraction (XRD) and Focused Ion Beam (FIB) cross sectional analysis. The as deposited film matrix is mainly composed by CrN phase (78%), but a relevant part (28%) is composed by Cr2N. Ag agglomerates in the CrN matrix forming elongated grains 200-400 nm wide and 50-100 nm high, which extends on the top of CrN columns. At the surface Ag aggregates into two different structures: large tetrahedral crystalline clusters, with typical dimension ranging from 200 to 500 nm, and smaller Ag nanoparticles with diameter of 15-25 nm. The annealing in N2 atmosphere up to 500 degrees C does not affect size and distribution of the Ag grains in the sub-surface region, while it induces a size increase of the bigger Ag clusters on the surface, mainly related to Ag surface diffusion and clusters coalescence. Annealing at higher temperature leads to an evident Ag out-of-bulk segregation, generating Ag depleted voids in the near-surface region, and further increasing of the Ag clusters size at the surface. Tribological tests on as deposited CrN-Ag film reveal a coefficient of friction against a steel ball reduced with respect to CrN film, probably related to the presence of Ag which acts as solid lubricant, but the coating is removed after a very short sliding distance. The poor mechanical properties of the realized Ag-based coatings are confirmed by lower hardness and Young modulus values with respect to pure CrN.

  7. Study of Ag sup + /PAA (polyacrylic acid) and Ag sup 0 /PAA aqueous system at equilibrium. Etude des systemes aqueux Ag sup + /APA (acide polyacrylique) et Ag sup 0 /APA a l'equilibre

    Energy Technology Data Exchange (ETDEWEB)

    Keghouche, N.; Mostafavi, M.; Delcourt, M.O. (Paris-11 Univ., 91 - Orsay (FR))

    1991-06-01

    When submitted to gamma radiation the system Ag{sup +}-PAA-water leads to clusters Ag{sup 0}{sub n}/PAA (3 < n < 8) the UV spectrum of which at {lambda} < 380 nm is accompanied by a visible band depending on the PAA ligand ({lambda} > 420 nm) interacting with the clusters. Potentiometric measurements carried out on Ag{sup +} solutions in the presence of PAA at various pH show that the deprotonated form (polyacrylate anion) is strongly bonded to Ag{sup +}, on the opposite of the protonated form of PAA. One of the oligomer clusters can be stabilized for more than one year. Studying it by infra-red spectrometry reveals important modifications in the vibration bands of the COO{sup -} group circa 1400 and 1600 cm{sup -1} according to the bonding of PAA with Ag{sup +} or Ag{sup 0}.

  8. Double dumbbell shaped AgNi alloy by pulsed electrodeposition

    Science.gov (United States)

    Dhanapal, K.; Vasumathi, M.; Santhi, Kalavathy; Narayanan, V.; Stephen, A.

    2014-01-01

    Silver-Nickel is the well-known thermally immiscible system that makes them quite complex for the formation of alloy. This kind of alloy can be attained from electrodeposition method. In the present work, AgNi alloy was synthesized by pulsed electrodeposition in a single bath two electrode system with the use of anodic alumina membrane. The prepared AgNi alloy and pure Ag were characterized with X-ray Diffraction (XRD) for structural confirmation, Scanning Electron Microscopy (SEM) for morphological, and magnetic properties by Vibrating Sample Magnetometer, respectively. The X-ray Diffraction study shows the formation of cubic structure for pure Ag. SEM analysis reveals the double dumbbell morphology for AgNi alloy and spherically agglomeration for pure silver. Hysteresis behaviour from VSM measurement indicates that the AgNi alloy have good ferro-magnetic properties.

  9. Transport of silver nanoparticles (AgNPs) in soil.

    Science.gov (United States)

    Sagee, Omer; Dror, Ishai; Berkowitz, Brian

    2012-07-01

    The effect of soil properties on the transport of silver nanoparticles (AgNPs) was studied in a set of laboratory column experiments, using different combinations of size fractions of a Mediterranean sandy clay soil. The AgNPs with average size of ~30nm yielded a stable suspension in water with zeta potential of -39mV. Early breakthrough of AgNPs in soil was observed in column transport experiments. AgNPs were found to have high mobility in soil with outlet relative concentrations ranging from 30% to 70%, depending on experimental conditions. AgNP mobility through the column decreased when the fraction of smaller soil aggregates was larger. The early breakthrough pattern was not observed for AgNPs in pure quartz columns nor for bromide tracer in soil columns, suggesting that early breakthrough is related to the nature of AgNP transport in natural soils. Micro-CT and image analysis used to investigate structural features of the soil, suggest that soil aggregate size strongly affects AgNP transport in natural soil. The retention of AgNPs in the soil column was reduced when humic acid was added to the leaching solution, while a lower flow rate (Darcy velocity of 0.17cm/min versus 0.66cm/min) resulted in higher retention of AgNPs in the soil. When soil residual chloride was exchanged by nitrate prior to column experiments, significantly improved mobility of AgNPs was observed in the soil column. These findings point to the importance of AgNP-soil chemical interactions as a retention mechanism, and demonstrate the need to employ natural soils rather than glass beads or quartz in representative experimental investigations.

  10. The Multiplication Group of an AG-group

    OpenAIRE

    Shah, Muhammad; Ali, Asif; Ahmad, Imtiaz; Sorge, Volker

    2014-01-01

    We investigate the multiplication group of a special class of quasigroup called AG-group. We prove some interesting results such as: the multiplication group of an AG-group of order n is non-abelian group of order 2n and its left section is an abelian group of order n. The inner mapping group of an AG-group of any order is a cyclic group of order 2.

  11. Rare and forbidden kaon decays at the AGS

    Energy Technology Data Exchange (ETDEWEB)

    Kettell, S.

    1997-12-09

    An overview of the Rare Kaon Decay program at the AGS is presented, with particular emphasis on the three major experiments currently running and analyzing data. A brief overview of earlier kaon decay experiments and of the AGs performance improvements is also provided. This review concludes with a discussion of proposed and developing experiments planned to run in the year 2000 and beyond (AGS-2000).

  12. KOEKSISTENSI HBsAg DAN ANTI-HBs DI MAKASSAR

    OpenAIRE

    uleng, -

    2015-01-01

    - Infeksi virus hipatitis B (VHB) merupakan penyakit endemik dengan insidensi tinggi di indonesia dan merupakan persoalan kesehatan global. Virus hepatitis B adalah suatu virus DNA yang berlapis ganda (double shelled) yang terdiri dari bagian luar yang dikenal sebagai hepatitis B surface antigen (HbsAG) dan bagian dalam atau hepatitis core antigen (HbcAg). Keberadaan HbsAg dalam serum merupakan tanda infeksi VHB. pembersihan VHB ditandai dengan didapatkannya anti-HBs dalam serum. Anti...

  13. Ag/AgCl纳米枝状结构的制备及其光催化性能研究%Synthesis of dendritic Ag/AgCl nanostructures and their photocatalytic properties

    Institute of Scientific and Technical Information of China (English)

    李高英; 刘颖; 母建林; 任卫安; 刘鹏; 文晓刚

    2012-01-01

    In this article, a novel surfactant-free method to synthesize Ag/AgCl dendrite nanostructures. In this method, we used DESs as solvent, sodium citrate as reducing agent, chloroauric acid as seed, silver nitrate as silver source respectively. The products were characterized by SEM, XRD, EDS and their photocatalytic property was measured. It was found that the perfect nanodendrites could be obtained at 160℃ after 24h reaction. The formation of final dendrite nanostructures can be explained by a trans-formation process from AgCl to Ag. Companying the increasing reaction time, the decrease of AgCl and increase of Ag could be found. Due to the presense of AgCl, the products have good photocatalytic performance.%采用离子液体法,以离子液体(DESs)为溶剂,柠檬酸三钠为还原剂,氯金酸为晶种,硝酸银为银源,制备了Ag/AgCl纳米枝状结构。利用SEM、XRD、EDS对样品的形貌、成分、结构进行了表征分析,并测试了样品的光催化性能。结果表明,当反应温度为160℃,反应时间为24h时,可获得完整的Ag/AgCl纳米枝状结构;枝状结构的形成是基于AgCl在还原剂作用下不断向Ag转换过程的结果;产物具有较好的光催化效果,并且随着反应时间的延长,产物的光催化性能减弱。

  14. AgPi: Agents on Raspberry Pi

    Directory of Open Access Journals (Sweden)

    Tushar Semwal

    2016-10-01

    Full Text Available The Raspberry Pi and its variants have brought with them an aura of change in the world of embedded systems. With their impressive computation and communication capabilities and low footprint, these devices have thrown open the possibility of realizing a network of things in a very cost-effective manner. While such networks offer good solutions to prominent issues, they are indeed a long way from being smart or intelligent. Most of the currently available implementations of such a network of devices involve a centralized cloud-based server that contributes to making the necessary intelligent decisions, leaving these devices fairly underutilized. Though this paradigm provides for an easy and rapid solution, they have limited scalability, are less robust and at times prove to be expensive. In this paper, we introduce the concept of Agents on Raspberry Pi (AgPi as a cyber solution to enhance the smartness and flexibility of such embedded networks of physical devices in a decentralized manner. The use of a Multi-Agent System (MAS running on Raspberry Pis aids agents, both static and mobile, to govern the various activities within the network. Agents can act autonomously or on behalf of a human user and can collaborate, learn, adapt and act, thus contributing to embedded intelligence. This paper describes how Tartarus, a multi-agent platform, embedded on Raspberry Pis that constitute a network, can bring the best out of the system. To reveal the versatility of the concept of AgPi, an application for a Location-Aware and Tracking Service (LATS is presented. The results obtained from a comparison of data transfer cost between the conventional cloud-based approach with AgPi have also been included.

  15. METAL MEDIA FILTERS, AG-1 SECTION FI

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, D.

    2012-05-23

    One application of metal media filters is in various nuclear air cleaning processes including applications for protecting workers, the public and the environment from hazardous and radioactive particles. To support this application the development of the ASME AG-1 FI Standard on Metal Media has been under way for more than ten years. Development of the proposed section has required resolving several difficult issues associated with operating conditions (media velocity, pressure drop, etc.), qualification testing, and quality acceptance testing. Performance characteristics of metal media are dramatically different than the glass fiber media with respect to parameters like differential pressures, operating temperatures, media strength, etc. These differences make existing data for a glass fiber media inadequate for qualifying a metal media filter for AG-1. In the past much work has been conducted on metal media filters at facilities such as Lawrence Livermore National Laboratory (LLNL) and Savannah River National Laboratory (SRNL) to qualify the media as High Efficiency Particulate Air (HEPA) Filters. Particle retention testing has been conducted at Oak Ridge Filter Test Facility and at Air Techniques International (ATI) to prove that the metal media meets or exceeds the 99.97% particle retention required for a HEPA Filter. Even with his testing, data was lacking to complete an AG-1 FI Standard on metal media. With funding secured by Mississippi State University (MSU) from National Nuclear Security Administration (NNSA), a research test stand is being designed and fabricated at MSU's Institute for Clean Energy Technology (ICET) Facility to obtain qualification data on metal media. This in turn will support required data needed for the FI Standard. The paper will discuss in detail how the test stand at MSU will obtain the necessary data to complete the FI Standard.

  16. AG Pegasi - now a classical symbiotic star in outburst?

    Science.gov (United States)

    Tomov, T. V.; Stoyanov, K. A.; Zamanov, R. K.

    2016-11-01

    Optical spectroscopy study of the recent AG Pegasi (AG Peg) outburst observed during the second half of 2015 is presented. Considerable variations of the intensity and the shape of the spectral features as well as the changes of the hot component parameters, caused by the outburst, are discussed and certain similarities between the outburst of AG Peg and the outburst of a classical symbiotic stars are shown. It seems that after the end of the symbiotic nova phase, AG Peg became a member of the classical symbiotic stars group.

  17. Research on the Preparation,Property and Application of the Coated Wire Ag-Ag2S Ion Selective Electrode%涂丝Ag-Ag2S电极的制备、性能与应用研究

    Institute of Scientific and Technical Information of China (English)

    董红霞; 杜宝中; 姚秉华; 薛力

    2004-01-01

    介绍了涂丝Ag-Ag2S电极的响应机理及其制备方法,并测试了其电化学性能.结果表明,涂丝Ag-Ag2S电极与商品固膜硫离子选择电极具有同等的灵敏度、准确度和精密度,而且其制备方法简便,再生性好,造价低廉.

  18. Safe and Effective Ag Nanoparticles Immobilized Antimicrobial NanoNonwovens

    DEFF Research Database (Denmark)

    Song, Jie; Chen, Menglin; Regina, Viduthalai R.

    2012-01-01

    and possibility of introduction of secondary pollution. Here, we present a novel strategy to produce a safe and effective antimicrobial nanononwoven material by immobilizing AgNPs on a rigid polymer nanofibrous matrix through simple co-electrospinning of pre-prepaired AgNPs and polystyrene (PS). Distribution...... of the AgNPs on the surface of PS fibers was achieved by tuning fiber diameters during electrospinning. Atomic force microscopy (AFM) analysis revealed that the AgNPs distributed at the fiber surface were still covered by a layer of polymer, which inhibited their antimicrobial activity. UV/ozone treatment...

  19. Zwitterionic phosphorylcholine-protected water-soluble Ag nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The water-soluble Ag nanoparticles capped with novel zwitterionic thioalkylated phosphorylcholine were synthesized.The Ag nanoparticles showed remarkable stability in saline media with salt concen-trations as high as 2.0 mol/L and plasma using UV-vis absorption spectroscopy.Similarly,compared with tiopronin and citrate-protected Ag nanoparticles,the zwitterionic phosphorylcholine Ag nanopar-ticles did not precipitate out of solution when charged polyelectrolytes or biopolymers were added.The zwitterionic phosphorylcholine might be a better ligand for stabilizing metal nanoparticles.

  20. Electrochemical behavior of cast Ti-Ag alloys.

    Science.gov (United States)

    Takahashi, Masatoshi; Kikuchi, Masafumi; Takadai, Yukyo; Okabe, Toru; Okuno, Osamu

    2006-09-01

    Anodic polarization tests were performed in 0.9% NaCl and 1% lactic acid solutions to characterize the relationship between the corrosion behavior and the microstructures of cast Ti-Ag (5-40% Ag) alloys. The anodic polarization curves for the Ti-Ag alloys up to 17.5% Ag were similar to those for pure titanium in both solutions. On the other hand, an abrupt increase in the current density was observed for the alloys with more than 20% Ag in the NaCl solution and with more than 27.5% Ag in the lactic acid solution. The microstructures of the corroded alloy surfaces indicated the deterioration of precipitated intermetallic compounds along the grain boundaries. The Ti-Ag alloys up to 17.5% Ag had excellent corrosion resistance similar to that of pure titanium. The alloys with 20-25% Ag may be also used as dental alloys, since they passivated again immediately after preferential dissolution in the NaCl solution.

  1. Molecular dynamics study of nanojoining between axially positioned Ag nanowires

    Science.gov (United States)

    Cui, Jianlei; Theogene, Barayavuga; Wang, Xuewen; Mei, Xuesong; Wang, Wenjun; Wang, Kedian

    2016-08-01

    The miniaturization of electronics devices into nanometer scale is indispensable for next-generation semiconductor technology. Ag nanowires (Ag NWs) are considered to be the promising candidates for future electronic circuit owing to the excellent electrical and thermal properties. The nanojoining of axially positioned Ag NWs was performed by molecular dynamics simulation. Through the detailed atomic evolution during the nanojoining, the results indicate that the temperature and the distance between Ag NWs in axial direction have a great impact on nanojoining effect. When the nanojoining temperature is relatively high, the atoms are disordered and the atomic queues become to distort with strong thermodynamic properties and weak effect of metal bonds. At the relatively low temperature, the Ag NWs can be well connected with good junction quality and their own morphology, which is similar to the cold welding without fusion, while the distance between Ag NWs should be controlled for interaction and diffusion of interfacial atoms at nanowires head. When the Ag NWs are placed on Si and SiO2 substrate, because the atomic species and lattice structure of substrate material can differently affect the motions of Ag atoms through the interactive force between the atoms, the nanojoining quality of Ag NWs on Si substrate is better than that on the SiO2 substrate. So, for getting effective and reliable nanojoining without nanosolders and other materials, the temperature, distance and substrate surface should be reasonably controlled and selected, providing helpful theoretical guidance for experiment and application of nanojoining.

  2. RHIC FY15 pp Run RHIC and AGS polarization analysis

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H. [Brookhaven National Lab. (BNL), Upton, NY (United States); Adams, P. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-02-20

    The polarization information is important for the spin physics program in Relativistic Heavy Ion Collider (RHIC). There are discrepancies between AGS and RHIC polarization measurements. First, the face value of AGS polarization is higher than RHIC ones in general. Second, the measured polarization profile (described by the profile ratio R) is stronger in AGS than in RHIC. This note analyzes the polarization data from FY15 pp run period. The results show that the differences between AGS and RHIC polarization measurements are reasonable, but the R value difference is puzzling. The difference between blue and yellow ring is worth of spin simulation to explain.

  3. Critical current and electronic properties of YBCO-Ag compounds

    Energy Technology Data Exchange (ETDEWEB)

    Dwir, B.; Affronte, M.; Pavuna, D. (Physics Dept., Swiss Federal Inst. of Tech., Lausanne (Switzerland))

    1989-12-01

    We have found that in YBCO-Ag ceramic compounds Ag fills the intergranular space (''holes'') without affecting Tc. Normal-state resistivity is decreased by {approx equal} x 100 when adding up to 50 wt% Ag. Percolation analysis shows that the critical indices t,s are in agreement with 3D theoretical values, but p{sub c} is higher than expected. The critical current density J{sub c} is enhanced by up to 50% in the samples containing {approx equal} 10 wt% Ag, this enhancement corresponds to a maximum YBCO compactness in the samples. (orig.).

  4. Phytotoxicity of Ag nanoparticles prepared by biogenic and chemical methods

    Science.gov (United States)

    Choudhury, Rupasree; Majumder, Manna; Roy, Dijendra Nath; Basumallick, Srijita; Misra, Tarun Kumar

    2016-06-01

    Silver nanoparticles (Ag NPs) are now widely used as antibacterial and antifungal materials in different consumer products. We report here the preparation of Ag NPs by neem leaves extract ( Azadirachta) reduction and trisodium citrate-sodium borohydride reduction methods, and study of their phytotoxicity. The nanoparticles were characterized by UV-Vis spectroscopy, FTIR, and atomic force microscopy (AFM) techniques. Both neem-coated and citrate-coated Ag NPs exhibit surface plasmon around 400 nm, and their average sizes measured by AFM are about 100 and 20 nm, respectively. Antibacterial and antifungal activities of these nanomaterials have been studied by simple pea seed germination and disk diffusion methods. It has been observed from the growth of root and shoot, citrate-coated Ag NPs significantly affect seedling growth, but neem-coated Ag NPs exhibit somehow mild toxicity toward germination process due to the nutrient supplements from neem. On the other hand, antifungal activity of neem-coated Ag NPs has been found much higher than that of citrate-coated Ag NPs due to the combined effects of antifungal activity of neem and Ag NPs. Present research primarily indicates a possible application of neem-coated Ag NPs as a potential fungicide.

  5. Strongly visible-light responsive plasmonic shaped AgX:Ag (X = Cl, Br) nanoparticles for reduction of CO2 to methanol.

    Science.gov (United States)

    An, Changhua; Wang, Jizhuang; Jiang, Wen; Zhang, Meiyu; Ming, Xijuan; Wang, Shutao; Zhang, Qinhui

    2012-09-21

    Plasmonic shaped AgX:Ag (X = Cl, Br) nanoparticles have been synthesized by a facile and versatile glycerol-mediated solution route. The as-prepared AgX:Ag nanoparticles exhibit regular shapes, i.e., cube-tetrapod-like AgCl:Ag nanoparticles and AgBr:Ag nanoplates. Compared with the pristine AgX, AgX:Ag nanocomposites display stronger absorption in the visible region due to the surface plasmon resonance of silver nanoparticles. The calculation of bandgaps and band positions indicates the as-achieved AgX:Ag nanoparticles can be used as a class of potential photocatalyst for the reduction of CO(2). For example, reduction of CO(2) under visible light irradiation with the assistance of the anisotropic AgX:Ag nanoparticles yields as much as 100 μmol methanol in the products. Furthermore, the AgX:Ag nanoparticles can maintain its structure and activity after 3 runs of reactions. Therefore, the present route opens an avenue to acquire plasmonic photocatalysts for conversion of CO(2) into useful organic compounds.

  6. Modelling of the AGS using Zgoubi - Status

    Energy Technology Data Exchange (ETDEWEB)

    Meot F.; Ahrens, L.; Dutheil, Y.; Glenn, J.; Huang, H.; Roser, T.; Schoefer, V.; Tsoupas, N.

    2012-05-20

    This paper summarizes the progress achieved so far, and discusses various outcomes, regarding the development of a model of the Alternating Gradient Synchrotron at the RHIC collider. The model, based on stepwise ray-tracing methods, includes beam and polarization dynamics. This is an on-going work, and a follow-on of code developments and particle and spin dynamics simulations that have been subject to earlier publications at IPAC and PAC [1, 2, 3]. A companion paper [4] gives additional informations, regarding the use of the measured magnetic field maps of the AGS main magnets.

  7. Magnetic phase diagram of Ho-Ag

    Energy Technology Data Exchange (ETDEWEB)

    Paul-Boncour, V [Chimie Metallurgique des Terres Rares, ICMPE, CNRS, 2 rue H Dunant, 94320 Thiais (France); Hoser, A; Stuesser, N [Hahn-Meitner Institut, Glienicker Strasse 100, 14109, Berlin (Germany); Hense, K; Gratz, E [Institute for Experimental Physics, Technical University Vienna, Wiedner Hauptstrasse 8-10, A-1040 (Austria); Rotter, M [Institut fuer Physikalische Chemie, Universitaet Wien, Waehringerstrasse 42, 1090 Wien (Austria)], E-mail: paulbon@glvt-cnrs.fr

    2008-03-12

    The magnetic phase diagram of Ho-Ag has been established using magnetoresistance, magnetostriction and neutron diffraction experiments versus applied field and temperature. Three different magnetic phases were observed: an incommensurate antiferromagnetic phase (IC) below T{sub N} = 33 K, a commensurate antiferromagnetic phase (C) above 5 T and below T{sub 1} (5-8 K) and a ferromagnetic component above 3 T. The IC phase undergoes spin reorientations around 5 T (IC') and 13 T (IC'')

  8. Three proton hole structure in 106Ag

    Science.gov (United States)

    Das, B.; Rather, N.; Chattopadhyay, S.; Rajbanshi, S.; Goswami, A.; Datta, P.; Roy, S.; Palit, R.; Pal, S.; Saha, S.; Sethi, J.; Biswas, S.; Singh, P.; Jain, H. C.

    2016-06-01

    The negative parity non-yrast band of 106Ag has been studied to investigate the falling trend in magnetic dipole transition rates. In this context, the level lifetimes of the excited levels of this band have been measured using the Doppler shift attenuation method. The comparison of the experimental Routhian and the transition rates with the numerical results of the shears mechanism with the principal axis cranking calculation indicates that this band is generated due to the shears mechanism involving the three proton hole configuration.

  9. 11th AG STAB/DGLR Symposium

    CERN Document Server

    Heinemann, Hans-Joachim; Hilbig, Reinhard

    1999-01-01

    This volume contains the papers of the 11th Symposium of the AG STAB (German Aerospace Aerodynamics Association). In this association those scientists and engineers from universities, research-establishments and industry are involved, who are doing research and project work in numerical and experimental fluid mechanics and aerodynamics for aerospace and other applications. Many of the contributions are giving results from the "Luftfahrtforschungsprogramm der Bundesregierung (German Aeronautical Research Programme). Some of the papers report on work sponsored by the Deutsche Forschungsgemeinschaft, DFG, which also was presented at the symposium. The volume gives a broad overview over the ongoing work in this field in Germany.

  10. Development of carbon dots modified fluorescent molecular imprinted Polymer@Ag/AgCl nanoparticle for hepatocellular carcinoma marker

    Science.gov (United States)

    Karfa, Paramita; Madhuri, Rashmi; Sharma, Prashant K.

    2017-05-01

    In this work, a sensitive and selective fluorescent molecularly imprinted polymer (MIP) was developed for detection of hepatocellular carcinoma (HCC) biomarker i.e. alpha feto protein (AFP) using Ag/AgCl as platform. Here, the carbon dots and Ag/AgCl nanoparticles were functionalized with vinyl groups and used as functional monomer for synthesis of AFP-imprinted polymer. The imprinted polymer shows a linear range of 3.96 ng mL-1 to 80.0 ng mL-1 with detection limit of 0.42 ng mL-1.The adsorption property of the MIP@Ag/AgCl was studied and shows the high affinity binding towards their target analyte without any cross-reactivity and false-positive or false-negative results.

  11. High Activity of Hexagonal Ag/Pt Nanoshell Catalyst for Oxygen Electroreduction

    Directory of Open Access Journals (Sweden)

    Lee Chien-Liang

    2008-01-01

    Full Text Available Abstract Hexagonal Ag/Pt nanoshells were prepared by using a hexagonal Ag nanoplate as the displacement template and by introducing Pt ions. The prepared Ag/Pt nanoshells played the role of an electrocatalyst in an oxygen reduction process. Compared to spherical Pt and Ag/Pt nanoparticles, the hexagonal Ag/Pt nanoshells showed higher activity for oxygen electroreduction.

  12. Mechanical Properties of (Bi,Pb)-2223 Multifilament Tapes with Ag-Alloy Sheath

    Institute of Scientific and Technical Information of China (English)

    LIANG Ting; QU Ti-Ming; LI Pei; HAN Zheng-He

    2006-01-01

    @@ Ag-Mg-V alloy is prepared and investigated to develop a new sheath alloy used for BSCCO tapes. Bi-2223 Ag/AgMgV and Bi-2223 AgMgV/AgMgV tapes are studied with the help of stress-strain measurement, optical microstructure and critical current Ic.

  13. Partial phase diagram of Pd-Ag-Ru-Gd quaternary system

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    On the basis of the Ag-Pd-Gd, Ag-Ru-Gd and Pd-Ru-Gd ternary systems, the partial phase diagram of Pd-Ag-Ru-Gd(Gd<25% atom fraction) quaternary system has been studied by means of X-ray diffraction analysis, differential thermal analysis, electron probe microanalysis and optical microscopy.The 700℃ isothermal sections of the Ag-Pd-5Ru-Gd, Ag-Pd-20Ru-Gd and Ag-Pd-50Ru-Gd (Gd≤25%atom fraction) phase diagrams were determined respectively. And the 700℃ isothermal section of the PdAg-Ru-Gd (Gd≤25% atom fraction) quaternary system phase diagram was finally irferred. The section consists of four single-phase regions: solid solution Pd(Ag), (Ru), Pd3Gd and Ag51 Gd14; five two-phase regions: Pd(Ag) + (Ru), Pd(Ag) + Ag51 Gd14 , (Ru) + Ag51 Gd14 , Pd(Ag) + Pd3Gd and (Ru) +Pd3Gd; three three-phase regions: Pd(Ag) + Pd3Gd+ (Ru), Pd(Ag) + Ag51Gd14 + (Ru) and (Ru) +Ag51Gd14 + Pd3Gd; one four-phase region Pd(Ag) + (Ru) + Ag51Gd14 + Pd3Gd. No new quaternary intermetallic phase is found.

  14. Nano Ag@AgBr surface-sensitized Bi{sub 2}WO{sub 6} photocatalyst: oil-in-water synthesis and enhanced photocatalytic degradation

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shuanglong; Liu, Li; Hu, Jinshan; Liang, Yinghua, E-mail: liangyh@heuu.edu.cn; Cui, Wenquan, E-mail: wkcui@163.com

    2015-01-01

    Graphical abstract: - Highlights: • The plasmatic Ag@AgBr surface-sensitized Bi{sub 2}WO{sub 6} composite photocatalysts. • Ag@AgBr greatly increased visible-light absorption for Bi{sub 2}WO{sub 6}. • The plasmonic photocatalysts exhibited enhanced activity for the degradation of MB, phenol and salicylic acid. - Abstract: Nano Ag@AgBr decorated on the surface of flower-like Bi{sub 2}WO{sub 6} (hereafter designated Ag@AgBr/Bi{sub 2}WO{sub 6}) were prepared via a facile oil-in-water self-assembly method. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy (DRS), etc. The characterization results indicated that nano Ag@AgBr was observed to be evenly dispersed on the surface of Bi{sub 2}WO{sub 6}, and was approximately 20 nm in size. Ag@AgBr/Bi{sub 2}WO{sub 6} composites exhibited excellent UV–vis absorption, due to quantum dimension effect of Ag@AgBr, the surface plasmonic resonance (SPR) of Ag nanoparticles and the special flower-like structure of Bi{sub 2}WO{sub 6}. The photoelectrochemical measurement verified that the suitable band potential of Ag@AgBr and Bi{sub 2}WO{sub 6} and the existence of metal Ag resulted in the high efficiency in charge separation of the composite. The photocatalytic activities of the Ag@AgBr/Bi{sub 2}WO{sub 6} samples were examined under visible-light irradiation for the degradation of methylene blue (MB). The composite presented excellent photocatalytic activity due to the synergetic effect of Bi{sub 2}WO{sub 6}, AgBr, and Ag nanoparticles. The Ag@AgBr(20 wt.%)/Bi{sub 2}WO{sub 6} sample exhibited the best photocatalytic activity, degrading 95.03% MB after irradiation for 2 h, which was respectively 1.29 times and 1.28 times higher than that of Ag@AgBr and Bi{sub 2}WO{sub 6} photocatalyst. Meanwhile, phenol and salicylic acid were degraded to further prove the degradation ability of Ag@AgBr/Bi{sub 2

  15. Nano-galvanic coupling for enhanced Ag+ release in ZrCN-Ag films : Antibacterial application

    NARCIS (Netherlands)

    Calderon, S.; Ferreri, I.; Henriques, M.; De Hosson, J. T. M.; Cavaleiro, A.; Carvalho, S.

    2016-01-01

    The antibacterial properties of materials developed for medical devices with embedded silver nanoparticles are enhanced by controlling the release of silver ions. In this study, a simple experimental procedure for the augmentation of the silver ion release from ZrCN-Ag coatings is described. The sil

  16. Fabrication of antimicrobial bacterial cellulose-Ag/AgCl nanocomposite using bacteria as versatile biofactory

    Energy Technology Data Exchange (ETDEWEB)

    Liu Chuang [Tianjin University, Key Laboratory for Green Technology, School of Chemical Engineering and Technology (China); Yang Dong; Wang Yuangui [Tianjin University, Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of Ministry of Education, School of Chemical Engineering and Technology (China); Shi Jiafu; Jiang Zhongyi, E-mail: zhyjiang@tju.edu.cn [Tianjin University, Key Laboratory for Green Technology, School of Chemical Engineering and Technology (China)

    2012-08-15

    In nature, a number of nanocomposites are formed through biomineralization-relevant processes under mild conditions. In the present study, a total 'biologic' route to fabricate nanocomposite is reported. Non-pathogenic bacteria, Gluconacetobacter xylinum, was utilized as a versatile biofactory, which produced biopolymer bacterial cellulose (BC) and induced the formation of Ag/AgCl nanoparticles, yielding BC-Ag/AgCl nanocomposite. Scanning electron microscopy revealed that nanoparticles with average size of 17.4 nm were randomly embedded into the BC network; transmission electron microscopy and X-ray diffraction confirmed that the nanoparticles were mixtures of face-centered cubic silver and silver chloride nanoparticles. Moreover, the content of silver in the BC nanocomposite is around 0.05 wt%, determined by atomic absorption spectrometry and X-ray photoelectron spectroscopy analysis. The entire process of nanocomposite fabrication was conducted at ambient environment without utilizing toxic agents or producing hazardous products, which is not only environmentally friendly but also with less chances to generate harmful products to human bodies as biomedical materials. The resultant nanocomposite displayed the desirable activity in inhibiting bacterial growth of both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli microorganisms on agar plate and in liquid culture, indicating the potential of the material as antimicrobial wound dressing materials. This work demonstrated the feasibility of using microorganism to fabricate nanocomposite, especially for biomedical materials.

  17. Nano-galvanic coupling for enhanced Ag+ release in ZrCN-Ag films : Antibacterial application

    NARCIS (Netherlands)

    Calderon, S.; Ferreri, I.; Henriques, M.; De Hosson, J. T. M.; Cavaleiro, A.; Carvalho, S.

    2016-01-01

    The antibacterial properties of materials developed for medical devices with embedded silver nanoparticles are enhanced by controlling the release of silver ions. In this study, a simple experimental procedure for the augmentation of the silver ion release from ZrCN-Ag coatings is described. The

  18. Nano-galvanic coupling for enhanced Ag+ release in ZrCN-Ag films : Antibacterial application

    NARCIS (Netherlands)

    Calderon, S.; Ferreri, I.; Henriques, M.; De Hosson, J. T. M.; Cavaleiro, A.; Carvalho, S.

    2016-01-01

    The antibacterial properties of materials developed for medical devices with embedded silver nanoparticles are enhanced by controlling the release of silver ions. In this study, a simple experimental procedure for the augmentation of the silver ion release from ZrCN-Ag coatings is described. The sil

  19. Plasmon-assisted degradation of methylene blue with Ag/AgCl/montmorillonite nanocomposite under visible light

    Science.gov (United States)

    Sohrabnezhad, Sh.; Zanjanchi, M. A.; Razavi, M.

    2014-09-01

    Metal-semiconductor compounds, such as Ag/AgX (X = Cl, Br, I), enable visible light absorption and separation of photogenerated electron-hole through surface plasmon resonance (SPR) effect. However, the electron-hole generated and separated by light are vulnerable in Ag/AgX phase because of the occurrence of secondary recombined. In order to more effectively utilize the SPR photocatalytic effect, nanoparticles are located in a matrix. In this article, Ag/AgCl nanoparticles were synthesized in montmorillonite (MMT) matrix using dispersion method and light irradiation. The structure, composition and optical properties of such material were investigated by transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), X-ray diffraction (XRD) and FTIR. Powder X-ray diffraction showed intercalation of Ag/AgCl nanoparticles into the clay layers. The as-prepared plasmonic photocatalyst exhibited an enhanced and stable photoactivity for the degradation of methylene blue (MB) under visible light. The high activity was attributed to the surface plasmon resonance (SPR) exhibited by Ag nanoparticles on the surface of AgCl. The detection of reactive species by radical scavengers displays that rad O2- and rad OH- are the main reactive species for the degradation of MB under visible light irradiation. The studies showed that 20 min illumination under visible light can complete degradation of methylene blue (MB), and indicate a high stability of photocatalytic degradation. The mechanism of separation of the photo-generated electrons and holes at the Ag/AgCl-MMT nanocomposite was discussed.

  20. Plasmon-assisted degradation of methylene blue with Ag/AgCl/montmorillonite nanocomposite under visible light.

    Science.gov (United States)

    Sohrabnezhad, Sh; Zanjanchi, M A; Razavi, M

    2014-09-15

    Metal-semiconductor compounds, such as Ag/AgX (X=Cl, Br, I), enable visible light absorption and separation of photogenerated electron-hole through surface plasmon resonance (SPR) effect. However, the electron-hole generated and separated by light are vulnerable in Ag/AgX phase because of the occurrence of secondary recombined. In order to more effectively utilize the SPR photocatalytic effect, nanoparticles are located in a matrix. In this article, Ag/AgCl nanoparticles were synthesized in montmorillonite (MMT) matrix using dispersion method and light irradiation. The structure, composition and optical properties of such material were investigated by transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), X-ray diffraction (XRD) and FTIR. Powder X-ray diffraction showed intercalation of Ag/AgCl nanoparticles into the clay layers. The as-prepared plasmonic photocatalyst exhibited an enhanced and stable photoactivity for the degradation of methylene blue (MB) under visible light. The high activity was attributed to the surface plasmon resonance (SPR) exhibited by Ag nanoparticles on the surface of AgCl. The detection of reactive species by radical scavengers displays that O2- and OH- are the main reactive species for the degradation of MB under visible light irradiation. The studies showed that 20 min illumination under visible light can complete degradation of methylene blue (MB), and indicate a high stability of photocatalytic degradation. The mechanism of separation of the photo-generated electrons and holes at the Ag/AgCl-MMT nanocomposite was discussed.