Fast ray-tracing algorithm for circumstellar structures (FRACS) II. Disc parameters of the B[e] supergiant CPD-57 degrees 2874 from VLTI/MIDI data

Context. B[e] supergiants are luminous, massive post-main sequence stars exhibiting non-spherical winds, forbidden lines, and hot dust in a disc-like structure. The physical properties of their rich and complex circumstellar environment (CSE) are not well understood, partly because these CSE cannot be easily resolved at the large distances found for B[e] supergiants (typically greater than or similar to 1 kpc). Aims. From mid-IR spectro-interferometric observations obtained with VLTI/MIDI we seek to resolve and study the CSE of the Galactic B[e] supergiant CPD-57 degrees 2874. Methods. For a physical interpretation of the observables (visibilities and spectrum) we use our ray-tracing radiative transfer code (FRACS), which is optimised for thermal spectro-interferometric observations. Results. Thanks to the short computing time required by FRACS (<10 s per monochromatic model), best-fit parameters and uncertainties for several physical quantities of CPD-57 degrees 2874 were obtained, such as inner dust radius, relative flux contribution of the central source and of the dusty CSE, dust temperature profile, and disc inclination. Conclusions. The analysis of VLTI/MIDI data with FRACS allowed one of the first direct determinations of physical parameters of the dusty CSE of a B[e] supergiant based on interferometric data and using a full model-fitting approach. In a larger context, the study of B[e] supergiants is important for a deeper understanding of the complex structure and evolution of hot, massive stars.

A binary engine fuelling HD 87643's complex circumstellar environment Determined using AMBER/VLTI imaging

Context. The star HD 87643, exhibiting the ""B[e] phenomenon"", has one of the most extreme infrared excesses for this object class. It harbours a large amount of both hot and cold dust, and is surrounded by an extended reflection nebula. Aims. One of our major goals was to investigate the presence of a companion in HD87643. In addition, the presence of close dusty material was tested through a combination of multi-wavelength high spatial resolution observations. Methods. We observed HD 87643 with high spatial resolution techniques, using the near-IR AMBER/VLTI interferometer with baselines ranging from 60 m to 130 m and the mid-IR MIDI/VLTI interferometer with baselines ranging from 25 m to 65 m. These observations are complemented by NACO/VLT adaptive-optics-corrected images in the K and L-bands, and ESO-2.2m optical Wide-Field Imager large-scale images in the B, V and R-bands. Results. We report the direct detection of a companion to HD 87643 by means of image synthesis using the AMBER/VLTI instrument. The presence of the companion is confirmed by the MIDI and NACO data, although with a lower confidence. The companion is separated by similar to 34 mas with a roughly north-south orientation. The period must be large (several tens of years) and hence the orbital parameters are not determined yet. Binarity with high eccentricity might be the key to interpreting the extreme characteristics of this system, namely a dusty circumstellar envelope around the primary, a compact dust nebulosity around the binary system and a complex extended nebula suggesting past violent ejections.

Concessão Douro Litoral A32/IC2: passagens inferiores pré-fabricadas no sistema arco "Techspan" e muros ala de suporte de terras no sistema "Terra Armada": ponte sobre o rio Antuã: aplicação da tecnologia "Freyssinet"

O presente relatório visa apresentar o trabalho desenvolvido pelo estagiário na empresa Freyssinet – Terra Armada, S.A. (FTA). O relatório traduz o acompanhamento do estagiário na construção e aplicação da tecnologia Terra Armada em duas passagens inferiores, bem como o acompanhamento dos trabalhos efectuados pela empresa FTA no que diz respeito à aplicação da tecnologia Freyssinet na ponte sobre o rio Antuã, estando ambas as obras abordadas inseridas no Lote 8 – “A32/IC2 Oliveira de Azeméis/IP1 (S. Lourenço) trecho 2 e 3 – a cargo da empresa Alves Ribeiro S.A.. Com a construção dos trechos 2 e 3 da A32 surgiu a necessidade de se restabelecerem algumas ligações, o que fez com que após estudadas as soluções passíveis de serem utilizadas, se tivesse optado pela construção de túneis a céu aberto na execução dos restabelecimentos. Descreve-se neste documento a metodologia utilizada e as tecnologias patenteadas pela empresa Terra Armada, sendo estas compostas pelos Arcos “Techspan” e muros de ala executados com recurso à tecnologia “Terra Armada”. Em relação à ponte sobre o rio Antuã inserida no trecho 2 da empreitada de construção da A32, foi construída com recurso a cimbre auto-lançável e betonada in situ, havendo a necessidade de aplicação de tecnologias patenteadas pela Freyssinet no que diz respeito às actividades de pré-esforço, aparelhos de apoio nas ligações entre o tabuleiro e os pilares e juntas de dilatação na ligação do tabuleiro aos encontros. Apresentam-se os procedimentos de montagem e aplicação das tecnologias anteriormente referidas. No presente relatório estão descritos e explicados detalhadamente os trabalhos executados pela FTA, nomeadamente a aplicação da tecnologia “Terra Armada” no que diz respeito à construção das passagens inferiores, e a aplicação da tecnologia “Freyssinet” aplicada aquando da construção da ponte sobre o rio Antuã.

Lujien terästen hitsauksen kehittäminen

Työn teoriaosuudessa käsitellään lujia hitsattavia teräksiä sekä niiden hitsauksessa huomioitavia erityispiirteitä. Työssä esitellään hitsattavuuden arviointiin kehitettyjä teoreettisia menetelmiä sekä otetaan kantaa hitsauksen suoritustekniikkaan ja lisäainevalintaan. Myös lujien terästen hitsauksessa tyypilliset hitsausvirheet on käsitelty tässä työssä. Työn kokeellisessa osassa selvitettiin metsäteknologian tuotteita valmistavan metalliyrityksen käyttämien lujien terästen hitsattavuus ja hitsauksen esivalmistelujen tarpeellisuus. Kokeelliseen osioon kuului myös sopivan lisäainelangan valinta sekä tarkempaan tarkasteluun valitun esimerkkituotteen hitsien laadun selvittäminen. Tutkimuksissa käytettyjä menetelmiä olivat makro- ja mikrohietutkimus, hitsausliitoksen poikittainen vetokoe, Vickersin kovuuskoe ja murtokoe. Tarkasteluissa peilautuu myös hitsauksen automatisoinnin vaikutukset lujien terästen hitsaukseen. Kokeellisessa osiossa huomattiin nuorrutettujen terästen pehmeneminen liian suurella lämmöntuonnilla. Termomekaanisesti valssatut teräkset ovat paremmin hitsattavissa kuin nuorrutetut ja karkaistut teräkset. Kyseessä olevassa yrityksessä hitsattavien materiaalien paksuudet ovat pääsääntöisesti niin ohuita, ettei korotettua työlämpötilaa tarvita. Alilujat lisäaineet soveltuvat hitsauslisäaineeksi tuotantokäyttöön muutamia tuotekohtaisia poikkeuksia lukuun ottamatta.

Fractografia quantitativa: relações entre tenacidade e o comportamento fractal em ligas metálicas

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

The relationship between gamma Cassiopeiae's X-ray emission and its circumstellar environment

gamma Cas is the prototypical classical Be star and is recently best known for its variable hard X-ray emission. To elucidate the reasons for this emission, we mounted a multiwavelength campaign in 2010 centered around four XMM-Newton observations. The observational techniques included long baseline optical interferometry (LBOI) from two instruments at CHARA, photometry carried out by an automated photometric telescope and H alpha observations. Because gamma Cas is also known to be in a binary, we measured radial velocities from the H alpha line and redetermined its period as 203.55 +/- 0.20 days and its eccentricity as near zero. The LBOI observations suggest that the star's decretion disk was axisymmetric in 2010, has an system inclination angle near 45 degrees, and a larger radius than previously reported. In addition, the Be star began an "outburst" at the beginning of our campaign, made visible by a brightening and reddening of the disk during our campaign and beyond. Our analyses of the new high resolution spectra disclosed many attributes also found from spectra obtained in 2001 (Chandra) and 2004 (XMM-Newton). As well as a dominant hot (approximate to 14 keV) thermal component, the familiar attributes included: (i) a fluorescent feature of Fe K even stronger than observed at previous times; (ii) strong lines of N VII and Ne XI lines indicative of overabundances; and (iii) a subsolar Fe abundance from K-shell lines but a solar abundance from L-shell ions. We also found that two absorption columns are required to fit the continuum. While the first one maintained its historical average of 1 x 10(21) cm(-2), the second was very large and doubled to 7.4 x 10(23) cm(-2) during our X-ray observations. Although we found no clear relation between this column density and orbital phase, it correlates well with the disk brightening and reddening both in the 2010 and earlier observations. Thus, the inference from this study is that much (perhaps all?) of the X-ray emission from this source originates behind matter ejected by gamma Cas into our line of sight.