Abstract. We present far-infrared (FIR) continuum observations of the deeply embedded source IRAS 16293-2422 performed with the Long Wavelength Spectrometer (LWS) on-board the Infrared Space Observatory (ISO). We also report 450 and 850 µm mapping observations done with the Submillimetre Common-User Bolometer Array (SCUBA) at the James Clerk Maxwell Telescope (JCMT). We combined these observations with IRAS and other JCMT data available in the literature to construct a complete spectral energy distribution (SED) of the source. A spherically symmetric dusty envelope model was used to reproduce the SED and to characterize the circumstellar matter around the object. We call attention to the fact that when using models such as the one presented here, one needs spatial information about the object to distinguish between different possible fits to the SED. A comparison between the intensity profiles at 450 and 850 µm obtained from the SCUBA observations and the profiles predicted by the model allowed us to constrain the size of the envelope and its density distribution. The SED and the 850 µm intensity profile of the source are consistent with a centrally peaked power law dust density distribution of the form ρ(r) ∝ r −p with p = 1.5−2, with a radius R env = 3000−3250 AU, defining a very compact circumstellar envelope. We estimate a bolometric luminosity L bol = 36 L , an envelope mass M env = 3.4 M , and a submillimetre to bolometric luminosity ratio L submm /L bol = 1.9%, confirming that the source shows a submillimetre excess characteristic of Class 0 sources.

Abstract. In the present paper we present JHK photometric results of the young embedded cluster NGC 2316. We construct the cluster radial profile from which we determine a radius of 0.63 pc. We find 189 ± 29 cluster members in an extinction limited sub-sample of the survey, 22 ± 19 of which are possibly substellar. An average extinction of 4.5 visual magnitudes is derived using (H − K) colours of control fields. This extinction is due to the presence of residual parental molecular cloud. NGC 2316 presents 16% source fraction of excess emission which is consistent with other results from clusters with an age of 2−3 Myr. This age is consistent with the distribution of sources in the colour-magnitude diagram when compared to theoretical isochrones, and the overall shape of the cluster KLF. The substellar population of the cluster is similar or smaller than that observed for other embedded clusters and the stellar objects dominate the cluster membership.

Resumo: Tendo em vista a necessidade do mercado brasileiro por ligantes que minimizem a prematura falência estrutural dos revestimentos nas vias urbanas, a modificação do cimento asfáltico de petróleo (CAP 50/70) constitui uma excelente opção tecnológica. Nesta pesquisa utilizou-se 2% p/p do copolímero de estireno-butadieno-estireno (SBS) e 2% p/p de fibra natural da casca dos frutos de Couepia edulis (Prance), conhecida como castanha de cutia, material vegetal com característica de reforço e biodisponibilidade na região Amazônica. Os efeitos oxidativos e térmicos, bem como as características físicas dos materiais asfálticos modificados, foram estudados e comparados ao ligante convencional, utilizando-se ensaios estabelecidos pela Agência Nacional de Petróleo, Gás Natural e Biocombustíveis (ANP) e análise térmica -termogravimetria (TG), a fim de determinar as propriedades de degradação e estabilização térmica. Os resultados para os ligantes modificados, confrontados ao ligante tradicional, apresentaram: maior resistência ao envelhecimento, melhorias evidenciadas pelo aumento da consistência, ponto de amolecimento, além da excelente estabilidade térmica em toda faixa de temperatura de utilização (10 °C a 80 °C) e aplicação (130 °C a 170 °C) dos cimentos asfálticos de petróleo, fornecendo uma opção ao pavimento regional. Palavras-chave: Copolímero SBS, fibras naturais, asfalto modificado, Amazonas, Couepia edulis, castanha de cutia. Effect of Addition of Plant Material (Fiber of Cutia Chesnut) and Polymer (SBS) on the Properties of Asphalt Binder (CAP 50/70)Abstract: There is a need in the Brazilian market for asphalt binders that minimize premature structural failure of the coatings on urban roads, and the modification of asphalt cement oil (CAP 50/70) is an excellent option. In this research we used 2% w/w of the styrene -butadiene-styrene (SBS) copolymer and 2% w/w of natural fiber from Couepia edulis (Prance), known as cutia chesnut, which is a plant from the Amazon region with strengthening properties. The oxidative and thermal effects, as well as the physical characteristics of the asphalt modified materials, were studied and compared to the conventional binder, using the tests set by the National Agency of Petroleum, Natural Gas and Biofuels (ANP) and thermal analysis -thermogravimetry (TG) to determine the properties of thermal degradation and stabilization. In comparison with the traditional binders, the modified ones exhibited increased resistance to aging, evidenced by an increase in consistency, softening point and excellent thermal stability in the whole range of operating (10 °C to 80 °C ) and application (130 °C to 170 °C) temperatures for the asphalt cement oil, providing an option for regional pavements. Keywords: SBS copolymer, fibers, modified asphalt, Amazon, Couepia edulis, cutia chestnut. IntroduçãoO cimento asfáltico de petróleo, distribuído pelas refinarias de petróleo, é fornecido ao mercado consumidor atendendo às características exigidas pela Agência Nacional de Petróleo, Gás Natural e B...

No abstract

No abstract