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

Small-spatial scale variations of nebular properties and the abundance discrepancy in three Galactic HII regions

We present results of long-slit spectroscopy in several slit positions that cover different morphological structures of the central parts of three bright Galactic HII regions: M8, M17 and NGC7635. We study the spatial distributions of a large number of nebular parameters such as the extinction coefficient, line fluxes, physical conditions and ionic abundances at the maximum spatial resolution attainable with our instrumentation. Particularly, our goal is to study the behaviour of the abundance discrepancy factor of O^{2+}, ADF(O^{2+}), defined as the logarithmic difference of the O^{2+} abundances derived from collisionally excited and recombination lines. We find that the ADF(O^{2+}) remains fairly constant along the slit positions of M8 and M17. In the case of NGC7635, we only detect the OII recombination lines in the integrated spectrum along the whole slit, where the ADF(O^{2+}) reaches a remarkably high value of about 0.59 dex. We compare our results with previous ones obtained for the Orion Nebula. We find several evidences that suggest the presence of a candidate to Herbig-Haro object in M8.Comment: 18 pages, 9 figures. Table A1 available only in the online version. Accepted for publication in MNRAS