Properties and occurrence rates of KeplerKepler exoplanet candidates as a function of host star metallicity from the DR25 catalog

Correlations between the occurrence rate of exoplanets and their host star properties provide important clues about the planet formation processes. We studied the dependence of the observed properties of exoplanets (radius, mass, and orbital period) as a function of their host star metallicity. We analyzed the planetary radii and orbital periods of over 2800 $Kepler$ candidates from the latest $Kepler$ data release DR25 (Q1-Q17) with revised planetary radii based on $Gaia$~DR2 as a function of host star metallicity (from the Q1-Q17 (DR25) stellar and planet catalog). With a much larger sample and improved radius measurements, we are able to reconfirm previous results in the literature. We show that the average metallicity of the host star increases as the radius of the planet increases. We demonstrate this by first calculating the average host star metallicity for different radius bins and then supplementing these results by calculating the occurrence rate as a function of planetary radius and host star metallicity. We find a similar trend between host star metallicity and planet mass: the average host star metallicity increases with increasing planet mass. This trend, however, reverses for masses $> 4.0\, M_\mathrm{J}$: host star metallicity drops with increasing planetary mass. We further examined the correlation between the host star metallicity and the orbital period of the planet. We find that for planets with orbital periods less than 10 days, the average metallicity of the host star is higher than that for planets with periods greater than 10 days.Comment: 14 pages, 13 Figures, Accepted for publication in The Astronomical Journa

Emission from Water Vapor and Absorption from Other Gases at 5-7.5 Microns in Spitzer-IRS Spectra of Protoplanetary Disks

We present spectra of 13 T Tauri stars in the Taurus-Auriga star-forming region showing emission in Spitzer Space Telescope Infrared Spectrograph (IRS) 5-7.5 micron spectra from water vapor and absorption from other gases in these stars' protoplanetary disks. Seven stars' spectra show an emission feature at 6.6 microns due to the nu_2 = 1-0 bending mode of water vapor, with the shape of the spectrum suggesting water vapor temperatures > 500 K, though some of these spectra also show indications of an absorption band, likely from another molecule. This water vapor emission contrasts with the absorption from warm water vapor seen in the spectrum of the FU Orionis star V1057 Cyg. The other six of the thirteen stars have spectra showing a strong absorption band, peaking in strength at 5.6-5.7 microns, which for some is consistent with gaseous formaldehyde (H2CO) and for others is consistent with gaseous formic acid (HCOOH). There are indications that some of these six stars may also have weak water vapor emission. Modeling of these stars' spectra suggests these gases are present in the inner few AU of their host disks, consistent with recent studies of infrared spectra showing gas in protoplanetary disks.Comment: 33 pages, 9 figures, to appear in the 20 August, 2014, V791 - 2 issue of the Astrophysical Journa

Análise bioquímica do carbono foliar em plantas de eucalipto submetidas a estresses hídrico e nutricional.

Resumo: Neste trabalho são apresentados os resultados preliminares das análises foliares de carbono não estrutural (açúcares, aminoácidos, ácidos orgânicos e amido) e estrutural (lignina e celulose) obtidas num plantio experimental de Eucalyptusgrandisde 3 anos de implantação. As árvores receberam dois níveis de adubação potássica (0 e 17,4 g K m-2 na forma de KCl) e foram submetidas a dois regimes hídricos (100% e 33% da precipitação). Abstract: This work presents the preliminary results about the foliar nonstructural carbon (sugars, aminoacids, organic acids and starch) and structural carbon content (lignin and cellulose) in a three years old Eucalyptus grandisexperimental area. The trees were subjected to two levels of potassium fertilization (0 and 17.4 g K m-2 applied as KCl) as well as two levels of water availability (100% and 33% of rainfall)

Quantum matrix algebra for the SU(n) WZNW model

The zero modes of the chiral SU(n) WZNW model give rise to an intertwining quantum matrix algebra A generated by an n x n matrix a=(a^i_\alpha) (with noncommuting entries) and by rational functions of n commuting elements q^{p_i}. We study a generalization of the Fock space (F) representation of A for generic q (q not a root of unity) and demonstrate that it gives rise to a model of the quantum universal enveloping algebra U_q(sl_n), each irreducible representation entering F with multiplicity 1. For an integer level k the complex parameter q is an even root of unity, q^h=-1 (h=k+n) and the algebra A has an ideal I_h such that the factor algebra A_h = A/I_h is finite dimensional.Comment: 48 pages, LaTeX, uses amsfonts; final version to appear in J. Phys.

Efeitos da disponibilidade hídrica e de potássio na alocação de carbono em plantas de eucalipto marcadas com 13C-CO2.

Resumo: Neste trabalho são apresentados os resultados da alocação do carbono (C) recentemente assimilado em árvores de eucalipto submetidas a diferentes tratamentos com relação à disponibilidade hídrica (chuva normal e exclusão de 33%) e fertilização de potássio (0 e 4,5 Kmol ha-1 na forma de KCl), utilizando-se o método da marcação com 13C-CO2 (13C pulse labelling). Observou-se que o aumento da velocidade de crescimento das árvores aumenta a partição do C fixado na madeira e a implicação prática desta constatação, considerando-se a produção de uma quantidade fixa de madeira, é que o consumo de recursos será menor maximizando-se a produtividade numa pequena área, ao contrário de plantações pouco produtivas ocupando áreas maiores. Abstract: This work presents the results about the carbon allocation ( 13 C pulse labelling) in a three years old Eucalyptus grandis experimental area, where the trees were subjected to two levels of potassium fertilization (0 and 4.5 Kmol ha -1 applied as KCl) as well as two levels of water availability (normal rainfall and exclusion of 33% of rainfall). The observed increase in the growth velocity of the trees enhanced the C partition in the wood. Therefore the resources consumption for the production of a fixed amount of wood will be lower in a smaller and more productive area than in a less productive larger plantation

Tropical Isabella grape juices: bioactive compounds and antioxidant power depends on harvest season.

Grapes are important sources of antioxidants compounds and one of the most used varieties to elaborate juices is 'Isabel', or 'Isabella', as it is called in North-America. This study aimed to evaluate the antioxidant activity of Isabella grape juices from the tropical semi-arid climate produced in Brazil on March and September, 2010. Total phenolics and anthocyanins were determined, as well as the antioxidant capacity by DPPH, FRAP and hydrophilic ORAC methods. Test T was used to compare statistical difference at 5% of significance level. As expected, the results showed that the season can play a significant role on phenolics content and antioxidant power. Polyphenols content in juices varied from 82.9 ± 0.92 to 102.2 ± 1.59 mg GAE 100 mL-1 and anthocyanins content ranged from 44.3 ± 2.01 to 129.5 ± 2.82 mg cyanidin-3-glucoside 100 mL-1. Regression analyses showed a high correlation of antioxidant capacity and anthocyanins content. Grapes from Sao Francisco River Valley demonstrated to be a good source of antioxidant for human diet

The Spitzer Infrared Spectrograph Survey of T Tauri Stars in Taurus

We present 161 Spitzer Infrared Spectrograph (IRS) spectra of T Tauri stars and young brown dwarfs in the Taurus star-forming region. All of the targets were selected based on their infrared excess and are therefore surrounded by protoplanetary disks; they form the complete sample of all available IRS spectra of T Tauri stars with infrared excesses in Taurus. We also present the IRS spectra of seven Class 0/I objects in Taurus to complete the sample of available IRS spectra of protostars in Taurus. We use spectral indices that are not significantly affected by extinction to distinguish between envelope-and disk-dominated objects. Together with data from the literature, we construct spectral energy distributions for all objects in our sample. With spectral indices derived from the IRS spectra we infer disk properties such as dust settling and the presence of inner disk holes and gaps. We find a transitional disk frequency, which is based on objects with unusually large 13-31 mu m spectral indices indicative of a wall surrounding an inner disk hole, of about 3%, and a frequency of about 20% for objects with unusually large 10 mu m features, which could indicate disk gaps. The shape and strength of the 10 mu m silicate emission feature suggests weaker 10 mu m emission and more processed dust for very low mass objects and brown dwarfs (spectral types M6-M9). These objects also display weaker infrared excess emission from their disks, but do not appear to have more settled disks than their higher-mass counterparts. We find no difference for the spectral indices and properties of the dust between single and multiple systems.NASANASA through JPL/CaltechNASA through the Spitzer Space TelescopeNational Science Foundation AST-0544588, 0901947Pennsylvania State UniversityEberly College of SciencePennsylvania Space Grant ConsortiumNSFAstronom