The Integral Field View of the Orion Nebula

This paper reviews the major advances achieved in the Orion Nebula through the use of integral field spectroscopy (IFS). Since the early work of Vasconcelos and collaborators in 2005, this technique has facilitated the investigation of global properties of the nebula and its morphology, providing new clues to better constrain its 3D structure. IFS has led to the discovery of shock-heated zones at the leading working surfaces of prominent Herbig-Haro objects as well as the first attempt to determine the chemical composition of Orion protoplanetary disks, also known as proplyds. The analysis of these morphologies using IFS has given us new insights into the abundance discrepancy problem, a long-standing and unresolved issue that casts doubt on the reliability of current methods used for the determination of metallicities in the universe from the analysis of H II regions. Results imply that high-density clumps and high-velocity flows may play an active role in the production of such discrepancies. Future investigations based on the large-scale IFS mosaic of Orion will be very valuable for exploring how the integrated effect of small-scale structures may have impact at larger scales in the framework of star-forming regions.Comment: 15 pages, 8 figures. Review paper published in Advances in Astronomy as part of the special issue "Metals in 3D: A Cosmic View from Integral Field Spectroscopy". More information: http://dx.doi.org/10.1155/2014/27932

La educación en valores: propuesta didáctica en La clé sur la porte de Marie Cardinal

Cet article propose un rapprochement de la littérature française à travers un texte de La clé sur la porte de Marie Cardinal. On prétend réaliser une proposition didactique dont le but soit que les élèves de Baccalauréat pratiquent l’analyse du texte et qu’ils développent des compétences telles que la compréhension écrite et l’expression orale et écrite. Finalement, la littérature sera présentée comme véhicule pour renforcer l’éducation en valeurs

Integral field spectroscopy of selected areas of the Bright Bar and Orion-S cloud in the Orion Nebula

We present integral field spectroscopy of two selected zones in the Orion Nebula obtained with the Potsdam Multi-Aperture Spectrophotometer (PMAS), covering the optical spectral range from 3500 to 7200 A and with a spatial resolution of 1". The observed zones are located on the prominent Bright Bar and on the brightest area at the northeast of the Orion South cloud, both containing remarkable ionization fronts. We obtain maps of emission line fluxes and ratios, electron density and temperatures, and chemical abundances. We study the ionization structure and morphology of both fields, which ionization fronts show different inclination angles with respect to the plane of the sky. We find that the maps of electron density, O+/H+ and O/H ratios show a rather similar structure. We interpret this as produced by the strong dependence on density of the [OII] lines used to derive the O+ abundance, and that our nominal values of electron density-derived from the [SII] line ratio-may be slightly higher than the appropriate value for the O+ zone. We measure the faint recombination lines of OII in the field at the northeast of the Orion South cloud allowing us to explore the so-called abundance discrepancy problem. We find a rather constant abundance discrepancy across the field and a mean value similar to that determined in other areas of the Orion Nebula, indicating that the particular physical conditions of this ionization front do not contribute to this discrepancy.Comment: 15 pages, 10 figures. Accepted for publication in MNRA