The Iguaraçu H5 chondrite: a fall from Paraná State,Brazil     

R. R. Brooks  M. Hoashi  E. Fernandes de Lima  M. L. dos Santos  D. E. Ryan  J. Holzbecher  J. H. Johnston  Y. Kawachi  P. P. Sipiera 《Meteoritics & planetary science》1990,25(3):231-232

Abstract— The Iguaraçu meteorite, a single stone of 1200 g, fell in Paraná State, Brazil in October 1977. It is classified as an H5 ordinary chondrite with olivine of composition Fa 18.7.  相似文献   

Semi-empirical analysis of Sloan Digital Sky Survey galaxies – II. The bimodality of the galaxy population revisited     

Abílio Mateus  Laerte Sodré Jr    Roberto Cid Fernandes  Gra&#;yna Stasi&#;ska  William Schoenell  Jean M. Gomes 《Monthly notices of the Royal Astronomical Society》2006,370(2):721-737

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Gemini/GMOS Integral Field Unit stellar kinematics of the nuclear region of six nearby active galaxies     

F. K. B. Barbosa  T. Storchi-Bergmann  R. Cid Fernandes  Cláudia Winge  H. Schmitt 《Monthly notices of the Royal Astronomical Society》2006,371(1):170-184

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POlarization Emission of Millimeter Activity at the Sun (POEMAS): New Circular Polarization Solar Telescopes at Two Millimeter Wavelength Ranges     

Adriana Valio  P. Kaufmann  C. G. Giménez de Castro  J.-P. Raulin  L. O. T. Fernandes  A. Marun 《Solar physics》2013,283(2):651-665

We present a new system of two circular polarization solar radio telescopes, POEMAS, for observations of the Sun at 45 and 90 GHz. The novel characteristic of these instruments is the capability to measure circular right- and left-hand polarizations at these high frequencies. The two frequencies were chosen so as to bridge the gap at radio frequencies between 20 and 200 GHz of solar flare spectra. The telescopes, installed at CASLEO Observatory (Argentina), observe the full disk of the Sun with a half power beam width of 1.4^°, a time resolution of 10 ms at both frequencies, a sensitivity of 2?–?4 K that corresponds to 4 and 20 solar flux unit (=10⁴ Jy), considering aperture efficiencies of 50±5 % and 75±8 % at 45 and 90 GHz, respectively. The telescope system saw first light in November 2011 and is satisfactorily operating daily since then. A few flares were observed and are presented here. The millimeter spectra of some flares are seen to rise toward higher frequencies, indicating the presence of a new spectral component distinct from the microwave one.  相似文献   

The bombardment history of the Moon as recorded by 40Ar‐39Ar chronology     

V. A. Fernandes  J. Fritz  B. P. Weiss  I. Garrick‐Bethell  D. L. Shuster 《Meteoritics & planetary science》2013,48(2):241-269

New petrography and ⁴⁰Ar‐³⁹Ar ages have been obtained for 1–3 mm sized rock fragments from Apollo 16 Station 13 soil 63503 (North Ray crater ejecta) and chips from three rocks collected by Apollo 16 and Apollo 17 missions. Selection of these samples was aimed at the old ⁴⁰Ar‐³⁹Ar ages to understand the early history of the lunar magnetic field and impact flux. Fifteen samples were studied including crustal material, polymict feldspathic fragmental breccias, and impact melts. The impact ages obtained range between approximately 3.3 and 4.3 billion years (Ga). Polymict fragmental breccia 63503,1 exhibits the lowest signs of recrystallization observed and a probable old relic age of 4.547 ± 0.027. The plateau age of 4.293 ± 0.044 Ga obtained for impact melt rock 63503,13 represents the oldest known age for such a lithology. Possibly, this age represents the minimum age for the South Pole‐Aitken (SPA) Basin. In agreement with literature data, these results show that impact ages >3.9 Ga are found in lunar rocks, especially within soil 63503. Impact exhumation of deep‐seated warm crustal material onto the lunar surface is considered to explain the common 4.2 Ga ages obtained for weakly shocked samples from soil 63503 and Apollo 17. This would directly imply that one or more basin‐forming events occurred at that time. Some rock fragments showing none to limited petrologic features indicate thermal annealing. These rocks may have lost Ar while resident within the hot‐ejecta of a large basin. Concurrent with previous studies, these results lead us to advocate for a complex impact flux in the inner solar system during the initial approximately 1.3 Ga.  相似文献   

Digital complex correlator for a C-band polarimetry survey     

Miguel Bergano  Francisco Fernandes  Luís Cupido  Domingos Barbosa  Rui Fonseca  Ivan Ferreira  Bruce Grossan  George Smoot 《Experimental Astronomy》2011,30(1):23-37

The international Galactic Emission Mapping project aims to map and characterize the polarization field of the Milky Way. In Portugal it will map the sky polarized emission of the Northern Hemisphere in C-band and provide templates for map calibration and foreground control of microwave space data to be provided by ESA Planck Surveyor mission and later missions. The receiver system is equipped with a novel receiver with a full digital back-end using a low-cost Field Programmable Gate Array without compromising its performance relation. This new digital backend comprises a base-band complex cross-correlator outputting the four Stokes parameters of the incoming polarized radiation. In this document we describe the design and implementation of the complex correlator using the FPGA and the dedicated digitizers at each receiver arm, detailing the method applied at the several algorithm stages. This correlator is suitable for large sky area polarization continuum surveys.  相似文献   

Mass spectrometric analysis in planetary science: Investigation of the surface and the atmosphere     

P. Wurz  D. Abplanalp  M. Tulej  M. Iakovleva  V. A. Fernandes  A. Chumikov  G. G. Managadze 《Solar System Research》2012,46(6):408-422

Knowing the chemical, elemental, and isotopic composition of planetary objects allows the study of their origin and evolution within the context of our Solar System. Landed probes are critical to such an investigation. Instruments on a landed platform can answer a different set of scientific questions than can instruments in orbit or on Earth. Composition studies for elemental, isotopic, and chemical analysis are best performed with dedicated mass spectrometer systems. Mass spectrometers have been part of the early lunar missions, and have been successfully employed to investigate the atmospheres of Mars, Venus, Jupiter, Saturn, Titan, and in comet missions. Improved mass spectrometer systems are foreseen for many planetary missions currently in planning or implementation.  相似文献   

The Chandrayaan-1 X-ray Spectrometer: First results     

S.Z. Weider  B.J. Kellett  B.M. Swinyard  I.A. Crawford  K.H. Joy  M. Grande  C.J. Howe  J. Huovelin  S. Narendranath  L. Alha  M. Anand  P.S. Athiray  N. Bhandari  J.A. Carter  A.C. Cook  L.C. d'Uston  V.A. Fernandes  O. Gasnault  M. Wieczorek 《Planetary and Space Science》2012,60(1):217-228

We present X-ray fluorescence observations of the lunar surface, made by the Chandrayaan-1 X-ray Spectrometer during two solar flare events early in the mission (12th December 2008 and 10th January 2009). Modelling of the X-ray spectra with an abundance algorithm allows quantitative estimates of the MgO/SiO₂ and Al₂O₃/SiO₂ ratios to be made for the two regions, which are in mainly basaltic areas of the lunar nearside. One of these ground tracks includes the Apollo 14 landing site on the Fra Mauro Formation. Within the 1σ errors provided, the results are inside the range of basaltic samples from the Apollo and Luna collections. The Apollo 14 soil composition is in agreement with the results from the January flare at the 1σ uncertainty level. Discrepancies are observed between our results and compositions derived for the same areas by the Lunar Prospector gamma-ray spectrometer; some possible reasons for this are discussed.  相似文献   

Geochemistry of the Neoproterozoic (800–767 Ma) Cerro Bori orthogneisses, Dom Feliciano Belt in Uruguay: tectonic evolution of an ancient continental arc     

C. Lenz  C. C. Porcher  L. A. D. Fernandes  H. Masquelin  E. Koester  R. V. Conceição 《Mineralogy and Petrology》2013,107(5):785-806

The Cerro Bori orthogneisses, crystallized between ca. 800 and 767 Ma, are composed of a sequence of mafic gneisses, with dioritic-gabbroic and dioritic composition tectonically interleaved with a sequence of tonalitic and granodioritic gneisses. These rocks intruded the Chafalote paragneisses (metapelites, semipelites, carbonate and mafic rocks) and they were metamorphosed of high P-T conditions at ca. 676–654 Ma. This paper presents the first major and trace geochemical signatures, as well as Sm and Pb isotopic composition for the Cerro Bori orthogneisses, which allow distinguishing three different groups of rocks. Type I rocks are mafic gneisses with tholeiitic affinity, whereas the Type II rocks are tonalitic and granodioritic gneisses with calc-alkaline affinity. The third type is composed of biotite-rich mafic gneisses with potassic and ultrapotassic affinities. All the three types of rocks have negative ?_ND values (between ?2.12 and ?6.67) and old T_DM ages (between 1.2 and 2.0 Ga), indicating that the process of crustal assimilation/contamination was an important process, together with fractional crystallization. An continental arc tectonic setting is suggested to this association of rocks between 800 and 767 Ma. This subduction suggests the existence of an ocean between Rio de La Plata and adjacent cratons during the break up of the Rodinia supercontinent.  相似文献   

Electrochemical Treatment of Olive Processing Wastewater Using a Boron‐Doped Diamond Anode          下载免费PDF全文

José Barbosa  Annabel Fernandes  Lurdes Ciríaco  Ana Lopes  Maria José Pacheco 《洁净——土壤、空气、水》2016,44(9):1242-1249

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