Photometric Studies of O-type Hot Subdwarfs     

C. Rodríguez López  A. Ulla  R. Garrido  M. Manteiga  P. Thejll 《Astrophysics and Space Science》2004,291(3-4):431-434

We present a photometric study of eight sdOs and one sdOB on which simultaneous photometry in four Strömgren filters was performed. Our study seeks to detect the possible pulsators among the candidates.  相似文献   

GHASP: A 3-D Survey of Spiral and Irregular Galaxies at Hα     

P. Amram  C. Adami  C. Balkowski  S. Blais-Ouellette  A. Boselli  J. Boulesteix  C. Carignan  V. Cayatte  L. Chemin  J.L. Gach  O. Garrido  O. Hernandez  M. Marcelin  L. Michel-Dansac  H. Plana  D. Russeil  B. Vollmer  H. Wozniak 《Astrophysics and Space Science》2002,281(1-2):393-396

  相似文献   

FIRST radio counterpart candidates to ULXs: a catalogue     

D. Pérez-Ramírez  J. R. Sánchez-Sutil  A. Muñoz-Arjonilla  J. Martí  J. L. Garrido  P. Luque-Escamilla 《Astrophysics and Space Science》2007,309(1-4):147-150

Ultraluminous X-ray sources (ULXs) are the most luminous discrete X-ray sources (excluding AGNs) in the local Universe with observed luminosities above, and in many cases in excess of, 10³⁹ erg?s^?1. Their physical nature is still uncertain, and many models have been proposed to explain their unusual luminosities. Some of them favour the possible nature of these objects as extragalactic microquasars with strong beaming effects. Others, instead, rely on accretion onto intermediate-mass black holes. In any case, both interpretations offer perspectives for possible gamma-ray detections by future space missions. In order to help to constrain at present the ULX physical nature, we provide here an account of our search for radio counterparts to ULXs located in nearby galaxies, based on a systematic cross-identification of the most recent, available and extensive ULX catalogues and radio archival data. Although we ended up with 70 positional coincidences, most of them were located within the nuclear regions of these galaxies, and thus, they do not represent true ULXs. However, among these sources we identify 11 remarkable cases not previously reported of ULX and radio emission coincidence. Future follow up of these promising cases with a multi-wavelength approach could be useful to improve our understanding of the ULX phenomenon.  相似文献   

Time-dependent convection seismic study of five γ Doradus stars     

M.-A. Dupret  A. Grigahcène  R. Garrido  J. De Ridder  R. Scuflaire  M. Gabriel 《Monthly notices of the Royal Astronomical Society》2005,360(3):1143-1152

We apply for the first time the time-dependent convection (TDC) treatment of Gabriel and Grigahcène et al. to the photometric mode identification in γ Doradus (γ Dor) stars. We consider the influence of this treatment on the theoretical amplitude ratios and phase differences. Comparison with the observed amplitudes and phases of the stars γ Dor, 9 Aurigae, HD 207223 = HR 8330, HD 12901 and 48501 is presented and enables us to identify the degree ℓ of the pulsation modes for four of them. We also determine the mode stability for different models of these stars. We show that our TDC models agree better with observations than with frozen convection models. Finally, we compare the results obtained with different values of the mixing-length parameter α.  相似文献   

δ Sct-type pulsations in eclipsing binary systems: RZ Cas     

E. Rodríguez  J. M. García  D. E. Mkrtichian  V. Costa  S.-L. Kim  M. J. López-González  E. Hintz  A. V. Kusakin  A. Y. Gamarova  J. W. Lee  J.-H. Youn  E. B. Janiashvili  R. Garrido  A. Moya  Y. W. Kang 《Monthly notices of the Royal Astronomical Society》2004,347(4):1317-1326

  相似文献   

Succession of macrofauna on macroalgal wrack of an exposed sandy beach: effects of patch size and site     

Olabarria C  Lastra M  Garrido J 《Marine environmental research》2007,63(1):19-40

In this study, we used experimental manipulation of algal wrack to test hypotheses about influences on macrofaunal assemblages inhabiting the upper shore level of different sites along an exposed sandy beach. First, we hypothesized that decomposition of algal wrack depends on wrack patch size and site. With respect to macrofauna, we tested the hypotheses that (1) abundance of colonising individuals and species vary with wrack patch size, (2) succession (i.e. sequence of colonisation and species replacement) depends on time, and (3) as a result, macrofaunal assemblages associated with wrack patches vary with the patch size and time. We also predicted that responses could be different across sites because of their slightly different environmental conditions. The decomposition of wrack patches was similar in all sites and was dependent on wrack patch size. It was strongly influenced by time-specific environmental and/or biological factors. The pattern of colonisation, i.e. total number of species and individuals, varied among wrack patch sizes. Small patches had fewer species and individuals than medium and large patches. Nevertheless, pattern of colonisation varied among species, across sites and through time. Colonisation of wrack patches was rapid (i.e. within 3 days) for most species. There was some evidence to support the hypothesis that macrofaunal assemblages change in response to patch size and time.  相似文献   

Migration and accumulation of ultra-depleted subduction-related melts in the Massif du Sud ophiolite (New Caledonia)   总被引：1，自引：0，他引：1  

Claudio Marchesi  Carlos J. Garrido  Marguerite Godard  France Belley  Eric Ferr 《Chemical Geology》2009,266(3-4):180-195

The Massif du Sud is a large ophiolitic complex that crops out in the southern region of New Caledonia (SW Pacific). It is dominated by harzburgite tectonite that locally shows a transitional gradation to massive dunite up section. Clinopyroxene, orthopyroxene and plagioclase progressively appear in dunite up to the transition to layered wehrlite and orthopyroxene–gabbro. The dunite–wehrlite and wehrlite–gabbro contacts are parallel and the latter defines the paleo-Moho.Highly depleted modal, mineral and bulk rock compositions indicate that harzburgites are residues after high degrees (20–30%) of partial melting mainly in the spinel-stability field. Their relative enrichment in HFSE, LREE and MREE is due to re-equilibration of melting residues with percolating melts. Dunite formed in the Moho transition zone by reaction between residual mantle harzburgite and olivine-saturated melts that led to pyroxene dissolution and olivine precipitation. Rare clinopyroxene and plagioclase crystallized in interstitial melt pores of dunite from primitive, low-TiO₂, ultra-depleted liquids with a geochemical signature transitional between those of island arc tholeiites and boninites.Ascending batches of relatively high-SiO₂, ultra-depleted melts migrated through the Moho transition zone and generated wehrlite by olivine dissolution and crystallization of clinopyroxene, orthopyroxene and plagioclase in variable amounts. These liquids were more evolved and were produced by higher degrees of melting or from a more depleted source compared with melts that locally crystallized clinopyroxene in dunite. Ultra-depleted magmas, non-cogenetic with those that formed the Moho transition zone, ascended to the lower crust and generated gabbroic cumulates with subduction-related affinity. Thus, the ultramafic and mafic rocks in the Moho transition zone and lower crust of the Massif du Sud ophiolite are not products of fractional crystallization from a single magma-type but are the result of migration and accumulation of different melts in a multi-stage evolution.The record of high partial melting in the mantle section, and migration and accumulation of ultra-depleted subduction-related melts in the Moho transition zone and lower crust support that the Massif du Sud ophiolite is a portion of forearc lithosphere generated in an extensional regime during the early phases of the subduction zone evolution. Our results show the existence of different types of ultra-depleted melt compositions arriving at the Moho transition zone and lower crust of an infant intraoceanic paleo-arc. Ultra-depleted melts may thus be a significant component of the melt budget generated in oceanic spreading forearcs prior to aggregation and mixing of a large range of melt compositions in the crust.  相似文献   

An experimental investigation of antigorite dehydration in natural silica-enriched serpentinite   总被引：1，自引：0，他引：1  

José Alberto Padrón-Navarta  Jörg Hermann  Carlos J. Garrido  Vicente López Sánchez-Vizcaíno  María Teresa Gómez-Pugnaire 《Contributions to Mineralogy and Petrology》2010,159(1):25-42

Piston cylinder experiments were performed to constrain the pressure and temperature conditions for two high-pressure antigorite dehydration reactions found in silica-enriched serpentinites from Cerro del Almirez (Nevado–Filábride Complex, Betic Cordillera, southern Spain). At 630–660°C and pressures greater than 1.6 GPa, antigorite first reacts with talc to form orthopyroxene ± chlorite + fluid. We show that orthopyroxene + antigorite is restricted to high-pressure metamorphism of silica-enriched serpentinite. This uncommon assemblage is helpful in constraining metamorphic conditions in cold subduction environments, where antigorite serpentinites have no diagnostic assemblages over a large pressure and temperature range. The second dehydration reaction leads to the breakdown of antigorite to olivine + orthopyroxene + chlorite + fluid. The maximum stability of antigorite is found at 680°C at 1.9 GPa, which also corresponds to the maximum pressure limit for tremolite coexisting with olivine + orthopyroxene. The high aluminium (3.70 wt% Al₂O₃) and chromium contents (0.59 wt% Cr₂O₃) of antigorite in the investigated starting material is responsible for the expansion of the serpentinite stability to 60–70°C higher temperatures at 1.8 GPa than the antigorite stability calculated in the Al-free system. The antigorite from our study has the highest Al–Cr contents among all experimental studies and therefore likely constraints the maximum stability of antigorite in natural systems. Comparison of experimental results with olivine–orthopyroxene–chlorite–tremolite assemblages outcropping in Cerro del Almirez indicates that peak metamorphic conditions were 680–710°C and 1.6–1.9 GPa.  相似文献   

Petrogenesis of highly depleted peridotites and gabbroic rocks from the Mayarí-Baracoa Ophiolitic Belt (eastern Cuba)   总被引：1，自引：0，他引：1  

Claudio Marchesi  Carlos J. Garrido  Marguerite Godard  Joaquín A. Proenza  Fernando Gervilla  Jesús Blanco-Moreno 《Contributions to Mineralogy and Petrology》2006,151(6):717-736

The Moa-Baracoa and Mayarí-Cristal massifs (eastern Cuba) are two ophiolitic complexes mainly constituted by harzburgite tectonites and minor dunites, cut by gabbroic dykes. The Moa-Baracoa massif exhibits a well developed Moho transition zone and an incomplete crustal section made up of layered gabbros and tectonically emplaced pillow basalts. A plutonic crustal section is absent in the Mayarí-Cristal massif and mantle tectonites are in tectonic contact with arc-related volcanic rocks. Mantle peridotites are very refractory in terms of modal composition, whole rock major element and HREE contents implying that Moa-Baracoa and Mayarí-Cristal harzburgites are residues after high degrees (20–30%) of partial melting. The relative enrichment of Th, Nb, Ta and LREE in peridotites is due to re-equilibration of melting residues with percolating melts. Peridotites lost on average 6 wt% of relative MgO by intense seafloor weathering. REE contents and Mg# of melts in equilibrium with cumulate gabbros from the Moho transition zone and crustal section of the Moa-Baracoa massif coincide with those of the spatially-related pillow basalts. On the other hand, no geochemical relation has been inferred between melt in equilibrium with Mayarí-Cristal segregate and the spatially-related arc volcanics. Our results indicate that the Mayarí-Baracoa Ophiolitic Belt formed at an original back-arc spreading centre. The Moa-Baracoa massif represents a portion of MORB-like lithosphere located nearby a back-arc mid-ocean spreading ridge, and the Mayarí-Cristal massif represents a piece of transitional (MORB to IAT) mantle located closer to the paleo-volcanic arc than Moa-Baracoa.  相似文献   

Effects of industrial by-product amendments on As,Cd and Tl retention/release in an element-spiked acidic soil     

Javier Aguilar-Carrillo  Laura Barrios  Fernando Garrido  María Teresa García-González 《Applied Geochemistry》2007

To asses the efficiency of two by-products (phosphogypsum (PG) and sugar foam (SF), rich in gypsum and calcium carbonate, respectively) in the immobilization of three toxic elements (As, Cd and Tl) in an acidic soil, batch-scale sorption and desorption experiments were conducted after 18 months of in situ amendment application. The Langmuir isotherms applied for sorption studies showed that the estimated maximum sorption capacity of the elements was highest in the SF-treated samples. The amount of element retained and the percentage of extraction after TCLP tests indicated that those samples amended with sugar foam (SF and PG + SF) had the potential to immobilize As, Cd and Tl in an acidic soil with low sorptive capacity. In addition to sorption and desorption experiments, scanning electron microscopy in back-scattered electron mode (SEM-BSE) showed the formation of Al-hydroxy polymers which provides the soil with additional sorption capacity. The three target elements were associated with the Al-hydroxy polymers, probably through direct coordination or the formation of ternary complexes. By means of statistical analysis it has been found that sorption processes of As, Cd and Tl in this soil mainly depend on the treatment, whereas desorption is an element-dependent process.  相似文献