The spectroscopic evolution of the recurrent nova T Pyxidis during its 2011 outburst. II.The optically thin phase and the structure of the ejecta in recurrent novae

We continue our study of the physical properties of the recurrent nova T Pyx, focussing on the structure of the ejecta in the nebular stage of expansion during the 2011 outburst. The nova was observed contemporaneously with the Nordic Optical Telescope (NOT), at high resolution spectroscopic resolution (R ~ 65000) on 2011 Oct. 11 and 2012 Apr. 8 (without absolute flux calibration), and with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope, at high resolution (R ~ 30000) on 2011 Oct. 10 and 2012 Mar. 28 (absolute fluxes). We use standard plasma diagnostics (e.g. [O III] and [N II] line ratios and the H$\beta$ line fluxes) to constrain electron densities and temperatures. Using Monte Carlo modeling of the ejecta, we derive the structure and filling factor from comparisons to the optical and ultraviolet line profiles. The ejecta can be modeled using an axisymmetric conical -- bipolar -- geometry with a low inclination of the axis to the line of sight, i=15+/-5 degrees, compatible with published results from high angular resolution optical spectro-interferometry. The structure is similar to that observed in the other short orbital period recurrent novae during their nebular stages. We show that the electron density scales as $t^{-3}$ as expected from a ballistically ejected constant mass shell; there is no need to invoke a continuing mass outflow following the eruption. The derived mass for the ejecta with filling factor f ~ 3%, M_ej ~ 2E-6$M_sun is similar to that obtained for other recurrent nova ejecta but inconsistent with the previously reported extended optically thick epoch of the explosion. We suggest that the system underwent a common envelope phase following the explosion that produced the recombination event. Implications for the dynamics of the recurrent novae are discussed. (truncated)Comment: accepted for publication in A&A (10 Nov. 2012), 10 pgs, 16 fig

Estoques de carbono e nutrientes e macrofauna invertebrada em argissolo sob sistemas agroflorestais e agricultura de corte e queima no norte do Piauí.

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The spectroscopic evolution of the γ\gamma-ray emitting classical nova Nova Mon 2012. I. Implications for the ONe subclass of classical novae

Nova Mon 2012 was the first classical nova to be detected as a high energy $\gamma$-ray transient, by Fermi-LAT, before its optical discovery. We study a time sequence of high resolution optical echelle spectra (Nordic Optical Telescope) and contemporaneous NOT, STIS UV, and CHIRON echelle spectra (Nov 20/21/22). We use [O III] and H$\beta$ line fluxs to constrain the properties of the ejecta. We derive the structure from the optical and UV line profiles and compare our measured line fluxes for with predictions using Cloudy with abundances from other ONe novae. Mon 2012 is confirmed as an ONe nova. We find E(B-V)=0.85$\pm$0.05 and hydrogen column density $\approx 5\times 10^{21}$ cm$^{-2}$. The corrected continuum luminosity is nearly the same in the entire observed energy range as V1974 Cyg, V382 Mon, and Nova LMC 2000 at the same epoch after outburst. The distance, about 3.6 kpc, is quite similar to V1974 Cyg. The line profiles can be modeled using an axisymmetric bipolar geometry for the ejecta with various inclinations of the axis to the line of sight, 60 \le i \le 80 degrees, an opening angle of \approx$70 deg, inner radius$\Delta R/R(t)\approx 0.4$for permitted lines and less filled for forbidden lines. The filling factor$f\approx 0.1-0.3$implying M(ejecta)$\leq 6\times 10^{-5}$M$_\odot$. The ONe novae appear to comprise a single physical class with bipolar high mass ejecta, similarly enhanced abundances, and a common spectroscopic evolution within a narrow range of luminosities. The detected$\gamma$-ray emission may be a generic phenomenon, common to all ONe novae, possibly to all classical novae, and connected with acceleration and emission processes within the ejecta (abstract severely truncated).Comment: Submitted to A&A 9/1/2013; Accepted 27/2/2013 (in press

Endogenous territorial development in mountain environments: the case of the territory of the Alto Camaquã, Brazil.

The territory of Alto Camaquã, in the southern state of Rio Grande do Sul ‐ Brazil, it has been highlighted by the strengthening of family livestock from associative process based on the construction of collective territorial mark that identifies the production with the landscape socially constructed of local mountain environments

Sistemas agroflorestais: efeitos na dinâmica de nutrientes e na macrofauna invertebrada da serapilheira.

Sistemas agroflorestais: efeitos na dinâmica de nutrientes e na macrofauna invertebrada da serapilheira; Sistemas agroflorestais: objetivos e benefícios; Serapilheira como fonte de nutrientes nos SAFs; Macrofauna invertebrada como indicador de qualidade do solo.bitstream/item/95222/1/DOC1710001.pd

Influência da cobertura morta no desenvolvimento de fruteiras tropicais.

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Mapeamento de microbacias para subsidiar ações de restauração ecológica e pagamento por serviços ambientais no contexto do projeto Produtor de Água do Rio Descoberto, DF.

Este trabalho objetivou o mapeamento do uso e da cobertura do solo, dos passivos ambientais em APP e avaliação do potencial de regeneração natural, em duas microbacias do Rio Descoberto – DF. A análise espacial do uso e da cobertura mostrou que 62,3% da área está ocupada vegetação nativa e silvicultura. As microbacias totalizaram 193,94 ha de APP, dos quais 46,26 ha apresentaram passivo ambiental, necessitando de ações de restauração ecológica. Do total de passivo ambiental, 20,25 ha, localizados em pastagem, apresentaram baixo potencial de regeneração natural. As demais áreas de passivo ambiental apresentaram maior potencial de regeneração natural em função do menor tamanho e distância da fonte de propágulos. O potencial de regeneração das áreas, subsidia a seleção de estratégias de intervenção para fins de restauração ecológica, visando ampliar a prestação de serviços ambientais e seu futuro pagamento no âmbito do Projeto Produtor de Água do Rio Descoberto