The three-dimensional structure of the Eta Carinae Homunculus

We investigate, using the modeling code SHAPE, the three-dimensional structure of the bipolar Homunculus nebula surrounding Eta Carinae, as mapped by new ESO VLT/X-Shooter observations of the H2 $\lambda=2.12125$ micron emission line. Our results reveal for the first time important deviations from the axisymmetric bipolar morphology: 1) circumpolar trenches in each lobe positioned point-symmetrically from the center and 2) off-planar protrusions in the equatorial region from each lobe at longitudinal (~55 degrees) and latitudinal (10-20 degrees) distances from the projected apastron direction of the binary orbit. The angular distance between the protrusions (~110 degrees) is similar to the angular extent of each polar trench (~130 degrees) and nearly equal to the opening angle of the wind-wind collision cavity (~110 degrees). As in previous studies, we confirm a hole near the centre of each polar lobe and no detectable near-IR H2 emission from the thin optical skirt seen prominently in visible imagery. We conclude that the interaction between the outflows and/or radiation from the central binary stars and their orientation in space has had, and possibly still has, a strong influence on the Homunculus. This implies that prevailing theoretical models of the Homunculus are incomplete as most assume a single star origin that produces an axisymmetric nebula. We discuss how the newly found features might be related to the Homunculus ejection, the central binary and the interacting stellar winds. We also include a 3D printable version of our Homunculus model.Comment: 14 pages, 7 color figures, 1 interactive 3D figure (Figure 5, requires Adobe Reader), published in MNRAS. A 3D printable version of our Homunculus model can be downloaded from http://svs.gsfc.nasa.gov/vis/a010000/a011500/a011568/Eta_Car_Homunuculus_3D_model.zip or from the 'Supporting Information' link in the electronic version of the MNRAS articl

A highly-ionized region surrounding SN Refsdal revealed by MUSE

Supernova (SN) Refsdal is the first multiply-imaged, highly-magnified, and spatially-resolved SN ever observed. The SN exploded in a highly-magnified spiral galaxy at z=1.49 behind the Frontier Fields Cluster MACS1149, and provides a unique opportunity to study the environment of SNe at high z. We exploit the time delay between multiple images to determine the properties of the SN and its environment, before, during, and after the SN exploded. We use the integral-field spectrograph MUSE on the VLT to simultaneously target all observed and model-predicted positions of SN Refsdal. We find MgII emission at all positions of SN Refsdal, accompanied by weak FeII* emission at two positions. The measured ratios of [OII] to MgII emission of 10-20 indicate a high degree of ionization with low metallicity. Because the same high degree of ionization is found in all images, and our spatial resolution is too coarse to resolve the region of influence of SN Refsdal, we conclude that this high degree of ionization has been produced by previous SNe or a young and hot stellar population. We find no variability of the [OII] line over a period of 57 days. This suggests that there is no variation in the [OII] luminosity of the SN over this period, or that the SN has a small contribution to the integrated [OII] emission over the scale resolved by our observations.Comment: 5 pages, 4 figures, accepted for publication in A&

Birefringence in nonlinear anisotropic dielectric media

Light propagation is investigated in the context of local anisotropic nonlinear dielectric media at rest with the dielectric coefficients $\epsilon^\mu{}_\nu = \epsilon^\mu{}_\nu (\vec{E},\vec{B})$ and constant $\mu$, in the limit of geometrical optics. Birefringence was examined and the general conditions for its occurrence were presented. A toy model is exhibited, in which uniaxial birefringent media with nonlinear dielectric properties could be driven by external fields in such way that birefringence may be artificially controlled. The effective geometry interpretation is also addressed.Comment: 5 pages, 1 figur

Porta-enxertos afetam a susceptibilidade de laranjeira Pêra ao Ácaro-da-Falsa-Ferrugem Phyllocoptruta oleivora (Acari: Eryiophidae).

A citricultura é uma das atividades agrícolas mais importantes do Estado de Sergipe, principalmente na Região Centro-Sul, a qual engloba 14 municípios (IBGE, 2009). A Embrapa Tabuleiros Costeiros, em parceria com a Embrapa Mandioca e Fruticultura e a Empresa de Desenvolvimento Agropecuário de Sergipe - Emdagro está pesquisando novas cultivares copa e porta-enxertos de citros para o estado de Sergipe, no entanto, não existem estudos sobre sua susceptibilidade a pragas. Diferentes genótipos de plantas respondem de forma específica ao ataque de pragas. Alguns genótipos podem ser menos preferidos por pragas para a alimentação, oviposição ou abrigo (antixenose), ou podem interferir negativamente na biologia da praga (antibiose) (GALLO et al., 2002; ORIANI et al., 2011). É possível, ainda, que um genótipo apresente uma combinação de antixenose e antibiose. A determinação do grau de resistência é relativa e sempre baseada na comparação entre genótipos

One-dimensional collision carts computer model and its design ideas for productive experiential learning

We develop an Easy Java Simulation (EJS) model for students to experience the physics of idealized one-dimensional collision carts. The physics model is described and simulated by both continuous dynamics and discrete transition during collision. In the field of designing computer simulations, we discuss briefly three pedagogical considerations such as 1) consistent simulation world view with pen paper representation, 2) data table, scientific graphs and symbolic mathematical representations for ease of data collection and multiple representational visualizations and 3) game for simple concept testing that can further support learning. We also suggest using physical world setup to be augmented complimentary with simulation while highlighting three advantages of real collision carts equipment like tacit 3D experience, random errors in measurement and conceptual significance of conservation of momentum applied to just before and after collision. General feedback from the students has been relatively positive, and we hope teachers will find the simulation useful in their own classes. 2015 Resources added: http://iwant2study.org/ospsg/index.php/interactive-resources/physics/02-newtonian-mechanics/02-dynamics/46-one-dimension-collision-js-model http://iwant2study.org/ospsg/index.php/interactive-resources/physics/02-newtonian-mechanics/02-dynamics/195-elastic-collisionComment: 6 pages, 8 figures, 1 table, 1 L. K. Wee, Physics Education 47 (3), 301 (2012); ISSN 0031-912

Desempenho da copa de Laranjeira Jafa em diferentes porta - enxertos.

região Nordeste do Brasil responde por aproximadamente 10% da produção nacional de citros, constituindo-se na segunda maior região produtora do país, com 121.498 hectares de área colhida, na safra 2012, produzindo 1.858.781 milhão de toneladas de frutas, com rendimento médio de 15,3 toneladas/hectare, considerado baixo (IBGE, 2014)

Produção de diferentes cultivares de laranjas, limas ácidas e tangerinas em combinação com Limoeiro Cravo .

A região do Nordeste do Brasil detém a maior área de cultivo de citros em clima tropical do Mundo, concentrando seus pomares nos Estados da Bahia e Sergipe. O cultivo de citros nesta região baseia-se na combinação laranjeira ?Pera? [Citrus sinensis (L.) Osbeck] - limoeiro ?Cravo? (C. limonia Osbeck) (PRUDENTE et al., 2004)

Produtividade de variedades copa de citros em combinação com Limoeiro Cravo no Território Sul de Sergipe.

A região Nordeste responde por aproximadamente 10% da produção nacional de citros, constituindo-se na segunda maior região produtora do país, com mais de 118 mil hectares cultivados produzindo cerca de 1,7 milhão de toneladas de citros (IBGE, 2011). Dentre os estados nordestinos produtores, o destaque fica com a Bahia e Sergipe, com 90% de toda área plantada, ou seja, com 55,8 mil e 53 mil hectares plantados, respectivamente. A atividade citrícola na região nordestina tem baseado seus pomares em um número restrito de variedades, concentrando-se na laranjeira Pêra (C. sinensis) como cultivar copa. A citricultura sergipana é um claro exemplo desta situação, em que cerca de 95% de seus pomares assentam-se na referida laranjeira doce (PRUDENTE; SILVA, 2006)