An analysis of the Hygiea asteroid family orbital region

(10) Hygiea is the fourth largest asteroid of the main belt, by volume and mass, and it is the largest member of its family, that is made mostly by low-albedo, C-type asteroids, typical of the outer main belt. Like many other large families, it is associated with a 'halo' of objects, that extends far beyond the boundary of the core family, as detected by traditional hierarchical clustering methods (HCM) in proper element domains. Numerical simulations of the orbital evolution of family members may help in estimating the family and halo family age, and the original ejection velocity field. But, in order to minimize the errors associated with including too many interlopers, it is important to have good estimates of family membership that include available data on local asteroid taxonomy, geometrical albedo and local dynamics. For this purpose, we obtained synthetic proper elements and frequencies of asteroids in the Hygiea orbital region, with their errors. We revised the current knowledge on asteroid taxonomy, including Sloan Digital Sky Survey-Moving Object Catalog 4th release (SDSS-MOC 4) data, and geometric albedo data from Wide-field Infrared Survey Explorer (WISE) and Near-Earth Object WISE (NEOWISE). We identified asteroid family members using HCM in the domain of proper elements (a, e, sin (i)) and in the domains of proper frequencies most appropriate to study diffusion in the local web of secular resonances, and eliminated possible interlopers based on taxonomic and geometrical albedo considerations. To identify the family halo, we devised a new hierarchical clustering method in an extended domain that includes proper elements, principal components PC1, PC2 obtained based on SDSS photometric data and, for the first time, WISE and NEOWISE geometric albedo. Data on asteroid size distribution, light curves and rotations were also revised for the Hygiea family. The Hygiea family is the largest group in its region, with two smaller families in proper element domain and 18 families in various frequencies domains identified in this work for the first time. Frequency groups tend to extend vertically in the (a, sin (i)) plane and cross not only the Hygiea family but also the near C-type families of Themis and Veritas, causing a mixture of objects all of relatively low albedo in the Hygiea family area. A few high-albedo asteroids, most likely associated with the Eos family, are also present in the region. Finally, the new multidomains hierarchical clustering method allowed us to obtain a good and robust estimate of the membership of the Hygiea family halo, quite separated from other asteroids families halo in the region, and with a very limited (about 3 per cent) presence of likely interlopers. © 2013 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society.

Composição de cores através da calibração radiométrica e fotométrica de LEDs: Teoria e experimento

In the present work, the basic concepts of radiometric, photometric and colorimetric calibration are presented, which were applied to three light-emitting diodes (LEDs) used to compose the different color sensations that the human eye perceives in the visible region of the electromagnetic spectrum. In this sense, an experimental setup comprising a LED drive circuit and a home-made integrating sphere was assembled for the initial radiometric and photometric calibration as well as to obtain a set of intensity and spectral combinations associated to different colorimetric CIE (Commission Internationale de l'Eclairage) coordinates. The reader can, therefore, understand, in a simple manner, the process of color composition inside a color monitor or display picture element (pixel ). © Sociedade Brasileira de Física.

Matrix effect on butyltin analysis of sediments and fish tissues by GC-PFPD

Butyltin (BTs) quantification in environmental matrices can be affected by interfering species found primarily in complex matrices,such as sediment and biota tissues. This study investigated matrix effects in analytical procedures for butyltin (TBT,DBT and MBT) quantification and speciation in sediments and in two fish tissues (gill and liver) by gas chromatography with pulsed flame photometric detection (GC-PFPD) analysis. Unlike sediment samples,tissues exhibited a significant matrix effect,thus,the quantification should be made by curve over matrix to avoid quantification errors and loss of analytical accuracy. © 2013 Sociedade Brasileira de Química.

Extração de rodovias utilizando SNAKES

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo da estabilidade do anel de Jano e Epimeteu

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estimativas de parâmetros cosmológicos para o Dark Energy Survey

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudos sobre a ocorrência de compostos organoestânicos em sedimentos marinhos superficiais na costa do estado de São Paulo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Analysis of 25 mutual eclipses and occultations between the Galilean satellites observed from Brazil in 2009

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Dynamical evolution of V-type asteroids in the central main belt

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Differential organotin sensitivity in two Leucozonia species from a ship traffic area in southeastern Brazil

Tributyltin exposure is the primary cause of imposex development in gastropods, making them excellent bioindicators. The present research represents the first examination of butyltin (BT) contamination in surface sediments associated with imposex in Leucozonia nassa and L. ocellata in a harbour complex area in Espirito Santo, southeastern Brazil. The objectives of this study were to evaluate the organotin pollution in the area and to assess the sensitivity of both species to BT pollution through imposex development. Specimens were collected between 2007 and 2010 and the sediments were sampled in 2007. Imposex intensity was evaluated based on the percentage of imposexed females, the relative penis length index (RPLI) and the average value of the vas deferens sequence index (VDSI). BTs were analysed using gas chromatography equipped with a pulsed flame photometric detector (PFPD). The results demonstrated the occurrence of elevated concentrations of BTs in the sediment ranging from 383.7 to 7172.9 ng Sn g(-1), indicating a severe contamination of the area, which was confirmed by the biological monitoring results. Our findings also indicated that L. ocellata is a less sensitive species than L. nassa and that this differential sensitivity plays a key role in the distributions of the populations of both species in the studied area.

The triple near-Earth asteroid (153591) 2001 SN263: an ultra-blue, primitive target for the Aster space mission

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Implementação de aparato experimental para medição de instabilidades tipo Roll Waves em fluidos não- newtonianos

Pós-graduação em Engenharia Mecânica - FEIS

Avaliação de compostos modelos visando propor um método de diferenciação de matéria orgânica lábil e recalcitrante em ambientes aquáticos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Experimental setup for measuring roll waves on laminar open channel flows

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of residential energy-saving lamps on the attraction of nocturnal insects

Many species of insects display a disposition to move towards light. As a consequence, nocturnal artificial lighting often contributes to an increase in insect population among humans. We tested the hypothesis that residential white lamps can evoke significantly different attraction to insects even when their light outputs are nearly indistinguishable to humans. In a two-choice experiment using insect traps equipped with either a compact fluorescent or a LED light source with similar photometric specifications, about three times more insects were captured in the trap with a compact fluorescent lamp than in the LED trap. The results suggest that LED lamps are preferable to compact fluorescent lamps when the objective is to avoid attracting nocturnal insects to households.