746 research outputs found

    Signatures of rocky planet engulfment in HAT-P-4. Implications for chemical tagging studies

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    Aims. To explore the possible chemical signature of planet formation in the binary system HAT-P-4, by studying abundance vs condensation temperature Tc trends. The star HAT-P-4 hosts a planet detected by transits while its stellar companion does not have any detected planet. We also study the Lithium content, which could shed light on the problem of Li depletion in exoplanet host stars. Conclusions. The exoplanet host star HAT-P-4 is found to be ~0.1 dex more metal rich than its companion, which is one of the highest differences in metallicity observed in similar systems. This could have important implications for chemical tagging studies, disentangling groups of stars with a common origin. We rule out a possible peculiar composition for each star as lambda Boo, delta Scuti or a Blue Straggler. The star HAT-P-4 is enhanced in refractory elements relative to volatile when compared to its stellar companion. Notably, the Lithium abundance in HAT-P-4 is greater than in its companion by ~0.3 dex, which is contrary to the model that explains the Lithium depletion by the presence of planets. We propose a scenario where, at the time of planet formation, the star HAT-P-4 locked the inner refractory material in planetesimals and rocky planets, and formed the outer gas giant planet at a greater distance. The refractories were then accreted onto the star, possibly due to the migration of the giant planet. This explains the higher metallicity, the higher Lithium content, and the negative Tc trend detected. A similar scenario was recently proposed for the solar twin star HIP 68468, which is in some aspects similar to HAT-P-4. We estimate a mass of at least Mrock ~ 10 Mearth locked in refractory material in order to reproduce the observed Tc trends and metallicity.Comment: 5 pages, 6 figures, A&A Letters accepte

    Testing LSST dither strategies for Survey Uniformity and Large-Scale Structure Systematics

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    The Large Synoptic Survey Telescope (LSST) will survey the southern sky from 2022{2032 with unprecedented detail. Since the observing strategy can lead to artifacts in the data, we investigate the eects of telescope-pointing osets (called dithers) on the r-band coadded 5 depth yielded after the 10-year survey. We analyze this survey depth for several geometric patterns of dithers (e.g.,random, hexagonal lattice, spiral) with amplitude as large as the radius of the LSST eld-of-view, implemented on dierent timescales (per season, per night, per visit). Our results illustrate that per night and per visit dither assignments are more eective than per season. Also, we find that some dither geometries (e.g., hexagonal lattice) are particularly sensitive to the timescale on whichthe dithers are implemented, while others like random dithers perform well on all timescales. We then model the propagation of depth variations to articial uctuations in galaxy counts, which are a systematic for large-scale structure studies. We calculate the bias in galaxy counts caused by the observing strategy, accounting for photometric calibration uncertainties, dust extinction, and magnitude cuts; uncertainties in this bias limit our ability to account for structure induced by the observing strategy. We nd that after 10 years of the LSST survey, the best dither strategies lead to uncertainties in this bias smaller than the minimum statistical floor for a galaxy catalog as deep asr<27.5. A few of these strategies bring the uncertainties close to the statistical floor for r<25.7 after only one year of survey.Fil: Awan, Humna. Rutgers University; Estados UnidosFil: Gawiser, Eric. Rutgers University; Estados UnidosFil: Kurczynski, Peter. Rutgers University; Estados UnidosFil: Lynne Jones, R.. University of Washington; Estados UnidosFil: Zhan, Hu. Chinese Academy of Sciences; República de ChinaFil: Padilla, Nelson David. Pontificia Universidad Católica de Chile; ChileFil: Muñoz Arancibia, Alejandra M.. Pontificia Universidad Católica de Chile; ChileFil: Orsi, Alvaro. Centro de Estudios de Fisica del Cosmos de Aragon; EspañaFil: Cora, Sofia Alejandra. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica la Plata; ArgentinaFil: Yoachim, Peter. University of Washington; Estados Unido

    Multi-decadal trends in global terrestrial evapotranspiration and its components

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    Evapotranspiration (ET) is the process by which liquid water becomes water vapor and energetically this accounts for much of incoming solar radiation. If this ET did not occur temperatures would be higher, so understanding ET trends is crucial to predict future temperatures. Recent studies have reported prolonged declines in ET in recent decades, although these declines may relate to climate variability. Here, we used a well-validated diagnostic model to estimate daily ET during 1981–2012, and its three components: transpiration from vegetation (Et), direct evaporation from the soil (Es) and vaporization of intercepted rainfall from vegetation (Ei). During this period, ET over land has increased significantly (p < 0.01), caused by increases in Et and Ei, which are partially counteracted by Es decreasing. These contrasting trends are primarily driven by increases in vegetation leaf area index, dominated by greening. The overall increase in Et over land is about twofold of the decrease in Es. These opposing trends are not simulated by most Coupled Model Intercomparison Project phase 5 (CMIP5) models, and highlight the importance of realistically representing vegetation changes in earth system models for predicting future changes in the energy and water cycle

    The ALMA Frontier Fields Survey - IV. Lensing-corrected 1.1 mm number counts in Abell 2744, MACSJ0416.1-2403 and MACSJ1149.5+2223

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    [abridged] Characterizing the number counts of faint, dusty star-forming galaxies is currently a challenge even for deep, high-resolution observations in the FIR-to-mm regime. They are predicted to account for approximately half of the total extragalactic background light at those wavelengths. Searching for dusty star-forming galaxies behind massive galaxy clusters benefits from strong lensing, enhancing their measured emission while increasing spatial resolution. Derived number counts depend, however, on mass reconstruction models that properly constrain these clusters. We estimate the 1.1 mm number counts along the line of sight of three galaxy clusters, i.e. Abell 2744, MACSJ0416.1-2403 and MACSJ1149.5+2223, which are part of the ALMA Frontier Fields Survey. We perform detailed simulations to correct these counts for lensing effects. We use several publicly available lensing models for the galaxy clusters to derive the intrinsic flux densities of our sources. We perform Monte Carlo simulations of the number counts for a detailed treatment of the uncertainties in the magnifications and adopted source redshifts. We find an overall agreement among the number counts derived for the different lens models, despite their systematic variations regarding source magnifications and effective areas. Our number counts span ~2.5 dex in demagnified flux density, from several mJy down to tens of uJy. Our number counts are consistent with recent estimates from deep ALMA observations at a 3σ\sigma level. Below \approx 0.1 mJy, however, our cumulative counts are lower by \approx 1 dex, suggesting a flattening in the number counts. In our deepest ALMA mosaic, we estimate number counts for intrinsic flux densities \approx 4 times fainter than the rms level. This highlights the potential of probing the sub-10 uJy population in larger samples of galaxy cluster fields with deeper ALMA observations.Comment: 19 pages, 14 figures, 3 tables. Accepted for publication in A&

    Musical preferences and technologies: Contemporary material and symbolic distinctions criticised

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    Today how individuals interact with various cultural items is not perfectly consistent with theoretical frameworks of influential scholars on cultural consumption, such as Bourdieu (1984), Gans (1999), and Peterson and Simkus (1992). One such variation is in the ever increasing variety of technological modes to acquire and listen to music (Pinch and Bijsterveld, 2004). However, as a consequence of digital divides (van Dijk, 2006), technological items may not be distributed equally among social groups. At present, the value of status-making through a preference for different genres of music extends itself to different forms of consumption and ways of experiencing music. We are yet to fully understand the power these practices have on generating status. This article is therefore motivated by the need to integrate within quantitative frameworks of taste and cultural consumption, an analysis of individuals’ technological engagement. These two dimensions, integrated as components of musical practices, enhance our understanding of cultural boundaries across different social groups.The objective is to bridge a gap detected in the literature, addressing the following questions: Are technological modes to listen to music related to musical tastes

    Diabetes y su impacto en el territorio periodontal

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    ResumenDiabetes y enfermedad periodontal corresponden probablemente al mejor ejemplo de cómo una enfermedad sistémica puede tener un efecto en el territorio periodontal. Si bien esta asociación ha sido extensamente estudiada, muchas de las asociaciones propuestas presentan contradicciones. En la presente revisión de la literatura se analizan los siguientes tópicos relevantes para la práctica clínica en periodoncia e implantología: i) Identificación de enfermedad periodontal severa y su capacidad para diagnosticar casos de diabetes; ii) Efectos de la diabetes sobre la enfermedad periodontal; iii) Efectos de la diabetes sobre la reparación periodontal y periimplantaria; iv) Efecto del tratamiento periodontal sobre el control metabólico de la diabetes.AbstractDiabetes and periodontal disease correspond to conditions that probably exemplify how a systemic disease may have a strong impact in the periodontium. Although this association has been studied for several years, many of these studies still show contradictory results. The present review analyses the following questions relevant for the clinician in the fields of periodontology: i) Value of the diagnosis of severe periodontitis and its capacity to identify previously un-diagnosed cases of diabetes; ii) Effects of diabetes on periodontal disease; iii) Effects of diabetes on periodontal and periimplant tissue repair and regeneration and; iv) Effect of periodontal therapy on the metabolic control of diabetes

    Sinistral shear during Middle Jurassic emplacement of the Matancilla Plutonic Complex in northern Chile (25.4◦ S) as evidence of oblique plate convergence during the early Andean orogeny

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    component of oblique subduction into an intra-arc shear zone. We document a shear zone at latitude 25.4◦ S near Taltal, Chile that was associated with intrusion of the Matancilla Plutonic Complex at ~169 Ma to evaluate intra-arc deformation and possible tectonic plate configurations during this time period. Polyphase folding of Paleozoic metasedimentary rocks is overprinted by mylonitic fabrics that are most extensive in a zone up to 1.4 km wide in the thermal aureole of the granodioritic Matancilla pluton, where contact metamorphic andalusite porphyroblasts are synkinematic with fabric development. Mylonite in metasedimentary rocks is overprinted by a ~130 Ma granodiorite (zircon U–Pb) and by ~133 Ma postkinematic monazite (U–Pb). Within the Jurassic Matancilla granodiorite, pervasive ductile shear occurs along the intrusive contact while centimeter-scale discrete high-strain zones throughout the pluton are associated with focused hydrothermal alteration and reaction weakening. Mylonitic foliation in the metasedimentary rocks and within the pluton strikes N- to NE and dips steeply, while stretching lineations are subhorizontal on average. Kinematic indicators record dominantly sinistral shear, though some dextral or symmetric indicators and S \u3e L fabrics suggest a component of coaxial strain and flattening. Sinistral strike-slip kinematics in the Matancilla shear zone may indicate that Middle Jurassic convergence had sinistral obliquity that was locally partitioned into the contemporaneous magmatic arc. Sinistral-oblique convergence would require the Phoenix- Farallon spreading center to be north of ~25◦ S in the Middle Jurassic, providing a constraint to plate reconstructions during the early Andean orogeny

    VALES: IV. Exploring the transition of star formation efficiencies between normal and starburst galaxies using APEX/SEPIA Band-5 and ALMA at low redshift

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    In this work we present new APEX/SEPIA Band-5 observations targeting the CO (J=2-1J=2\text{-}1) emission line of 24 Herschel-detected galaxies at z=0.10.2z=0.1-0.2. Combining this sample {with} our recent new Valpara\'iso ALMA Line Emission Survey (VALES), we investigate the star formation efficiencies (SFEs = SFR/MH2M_{\rm H_{2}}) of galaxies at low redshift. We find the SFE of our sample bridges the gap between normal star-forming galaxies and Ultra-Luminous Infrared Galaxies (ULIRGs), which are thought to be triggered by different star formation modes. Considering the SFE\rm SFE' as the SFR and the LCOL'_{\rm CO} ratio, our data show a continuous and smooth increment as a function of infrared luminosity (or star formation rate) with a scatter about 0.5 dex, instead of a steep jump with a bimodal behaviour. This result is due to the use of a sample with a much larger range of sSFR/sSFRms_{\rm ms} using LIRGs, with luminosities covering the range between normal and ULIRGs. We conclude that the main parameters controlling the scatter of the SFE in star-forming galaxies are the systematic uncertainty of the αCO\alpha_{\rm CO} conversion factor, the gas fraction and physical size.Comment: 9pages, 7 figures, 1 table, accepted for publication in MNRA

    Mineralogical and thermal characterization of borate minerals from Rio Grande deposit, Uyuni (Bolivia)

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    Large volumes of borate resources exist in Bolivia, with the most important being the Rio Grande deposit, located close to the Salar of Uyuni. Here, borates occur in beds and lenses of variable thickness. A mineralogical and thermal characterization of borates from the Rio Grande was made using XRD, FTIR, SEM and DTA TG. The deposit is mainly composed of B2O3, CaO and Na2O, with minor contents of MgO and K2O. Some outcrops are constituted by pure ulexite aggregates (NaCaB5 O6(OH)6 5H2O) of fibrous morphology; in other cases, gypsum, calcite and halite also are present. The thermal decomposition of ulexite begins at 70 C and proceeds up to *550 C; this decomposition is attributed to dehydration and dehydroxylation processes in three steps: at 115, 150 300 and 300 550 C. The last mass loss of 1 5 % at 800 C is due to the removal of Cl2 from the decomposition of halite. DTA shows two endothermic events related to the removal of water; in the first, NaCaB5O6(OH)6 5H2O evolved from NaCaB5O6(OH)6 3H2O, at 108 116 C; in the second, NaCaB5O6(OH)6 is formed at 180 185 C and NaCaB5O9 (amorphous) is formed at 300 550 C. The exothermic peak (658 720 C) is related to the crystallization of NaCaB5O9. A small endothermic peak appears due to the halite melting. Later, another endothermic event (821 877 C) appears, which is related to the decomposition of NaCaB5O9 into a crystalline phase of CaB2O4 and amorphous NaB3O5. The XRD pattern evidences that, at 1050 C, CaB2O4 still remains in the crystalline state
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