Density waves and star formation in grand design spirals

HII regions in the arms of spiral galaxies are indicators of recent star-forming processes. They may have been caused by the passage of the density wave or simply created by other means near the arms. The study of these regions may give us clues to clarifying the controversy over the existence of a triggering scenario, as proposed in the density wave theory. Using H$\alpha$ direct imaging, we characterize the HII regions from a sample of three grand design galaxies: NGC5457, NGC628 and NGC6946. Broad band images in R and I were used to determine the position of the arms. The HII regions found to be associated with arms were selected for the study. The age and the star formation rate of these HII regions was obtained using measures on the H$\alpha$ line. The distance between the current position of the selected HII regions and the position they would have if they had been created in the centre of the arm is calculated. A parameter, T, which measures whether a region was created in the arm or in the disc, is defined. With the help of the T parameter we determine that the majority of regions were formed some time after the passage of the density wave, with the regions located `behind the arm' (in the direction of the rotation of the galaxy) the zone they should have occupied had they been formed in the centre of the arm. The presence of the large number of regions created after the passage of the arm may be explained by the effect of the density wave, which helps to create the star-forming regions after its passage. There is clear evidence of triggering for NGC5457 and a co-rotation radius is proposed. A more modest triggering seems to exist for NGC628 and non significant evidence of triggering are found for NGC6946.Comment: 10 pages, 20 figures, accepted for publication in A&

The oxygen abundance gradient in M101: the reliability of the P method

We present the oxygen abundance determination for 90 HII regions in the inner parts of the grand design galaxy M101. The abundances were derived employing the P method (Pilyugin 2001a). A comparison is made with previous determinations using another calibration and direct measurements of electron temperature to derive the oxygen abundance. The results show agreement with the abundances derived from the electron temperature method and also show that the older calibration is not as accurate as the P method.Comment: 4 pages, 3 figures. Accepted for publication in A&

Study of star-forming galaxies in SDSS up to redshift 0.4: I. Metallicity evolution

The chemical composition of the gas in galaxies versus cosmic time provides a very important tool for understanding galaxy evolution. Although there are many studies at high redshift, they are rather scarce at lower redshifts. However, low redshift studies can provide important clues about the evolution of galaxies, furnishing the required link between local and high redshift universe. In this work we focus on the metallicity of the gas of star-forming galaxies at low redshift, looking for signs of chemical evolution. To analyze the metallicity contents star-forming galaxies of similar luminosities and masses at different redshifts. With this purpose, we present a study of the metallicity of relatively massive (log(M_star/M_sun)>10.5) star forming galaxies from SDSS--DR5 (Sloan Digital Sky Survey--Data Release 5), using different redshift intervals from 0.04 to 0.4. We used data processed with the STARLIGHT spectral synthesis code, correcting the fluxes for dust extinction, estimating metallicities using the R_23 method, and segregating the samples with respect to the value of the [NII]6583/[OII]3727 line ratio in order to break the R_23 degeneracy selecting the upper branch. We analyze the luminosity and mass-metallicity relations, and the effect of the Sloan fiber diameter looking for possible biases. By dividing our redshift samples in intervals of similar magnitude and comparing them, significant signs of metallicity evolution are found. Metallicity correlates inversely with redshift: from redshift 0 to 0.4 a decrement of ~0.1 dex in 12+log(O/H) is found.Comment: 11 pages, 9 figures, Accepted for publication in A&

Wavelength self-calibration and sky subtraction for Fabry–Pérot interferometers: applications to OSIRIS

We describe techniques concerning wavelength calibration and sky subtraction to maximize the scientific utility of data from tunable filter instruments. While we specifically address data from the Optical System for Imaging and low Resolution Integrated Spectroscopy instrument (OSIRIS) on the 10.4-m Gran Telescopio Canarias telescope, our discussion is generalizable to data from other tunable filter instruments. A key aspect of our methodology is a coordinate transformation to polar coordinates, which simplifies matters when the tunable filter data are circularly symmetric around the optical centre. First, we present a method for rectifying inaccuracies in the wavelength calibration using OH sky emission rings. Using this technique, we improve the absolute wavelength calibration from an accuracy of ∼5 to 1 Å, equivalent to ∼7 per cent of our instrumental resolution, for 95 per cent of our data. Then, we discuss a new way to estimate the background sky emission by median filtering in polar coordinates. This method suppresses contributions to the sky background from the outer envelopes of distant galaxies, maximizing the fluxes of sources measured in the corresponding sky-subtracted images. We demonstrate for data tuned to a central wavelength of 7615 Å that galaxy fluxes in the new sky-subtracted image are ∼37 per cent higher, versus a sky-subtracted image from existing methods for OSIRIS tunable filter data

Relatório de Estágio da Prática de Ensino Supervisionada

A elaboração deste relatório tem como propósito a realização de uma reflexão crítica, consistente e fundamentada de toda a experiência profissional durante a Prática de Ensino Supervisionada. A PES visa a integração do estudante estagiário no exercício da vida profissional de forma progressiva e orientada, em contexto real, desenvolvendo competências profissionais que promovam um desempenho crítico e reflexivo, tem como finalidade formar professores/educadores promotores de um ensino de qualidade. O presente relatório encontra-se organizado em três capítulos. O primeiro referente ao “Enquadramento Institucional – Organização e Administração Escolar”, em que a primeira parte remete para a organização do sistema educativo e os aspetos a ter em conta, como as Orientações Curriculares para a Educação Pré-Escolar e o Currículo, Orientações e Programas para o 1º CEB. A segunda parte diz respeito à Caraterização Socioeconómica e Psicopedagógica da turma. No que concerne ao segundo capítulo, “Descrição do Processo de Prática de Ensino Supervisionada”, este integra a experiência de ensino/aprendizagem no Pré-Escolar e 1º CEB. O terceiro capítulo diz respeito ao aprofundamento do tema escolhido “O Jogo no Processo de Ensino e Aprendizagem da Matemática no Pré-Escolar” e é apresentada uma prática docente relacionada com a superação do mesmo. Para finalizar este capítulo, foi realizado um inquérito por questionário, em quatro distritos de Portugal (dois no litoral e dois no interior), com o objetivo de recolher informações sobre as conceções de outros educadores de infância relativamente a esta temática. O jogo é fundamental na vida da criança e faz parte do seu quotidiano, quer como atividade espontânea, quer como atividade orientada. É um meio para melhorar as relações, o crescimento e o desenvolvimento das crianças a vários níveis: moral, cognitivo, físico e social. O jogo exerce um papel importante no crescimento da criança em idade pré-escolar e é uma ferramenta fulcral no seu desenvolvimento e cabe ao educador transformá-lo num recurso para que haja uma aprendizagem global da criança, criando um ambiente favorável à imaginação, à criação, à descoberta, à reflexão, à construção do conhecimento e que lhe possibilite um prazer e uma vontade em aprender e querer aprender mais Matemática, porque ao jogarem, as crianças podem experimentar uma forma diferente de adquirir conhecimentos através de atividades interessantes, motivadoras, desafiadoras e prazerosas, como são as utilizadas com o jogo