306 research outputs found
Faint emission lines in the Galactic H II regions M16, M20 and NGC 3603
We present deep echelle spectrophotometry of the Galactic {\hii} regions M16,
M20 and NGC 3603. The data have been taken with the Very Large Telescope
Ultraviolet-Visual Echelle Spectrograph in the 3100 to 10400 \AA range. We have
detected more than 200 emission lines in each region. Physical conditions have
been derived using different continuum and line intensity ratios. We have
derived He, C and O abundances from pure recombination
lines as well as abundances from collisionally excited lines for a large number
of ions of different elements. We have obtained consistent estimations of the
temperature fluctuation parameter, {\ts}, using different methods. We also
report the detection of deuterium Balmer lines up to D (M16) and to
D (M20) in the blue wings of the hydrogen lines, which excitation
mechanism seems to be continuum fluorescence. The temperature fluctuations
paradigm agree with the results obtained from optical CELs and the more
uncertain ones from far IR fine structure CELs in NGC 3603, although, more
observations covering the same volume of the nebula are necessary to obtain
solid conclusions.Comment: 22 pages, 13 Tables, 7 Figures. Accepted for publication by MNRA
Face-to-Face vs. E-Learning Models in the COVID-19 Era: Survey Research in a Spanish University
This study shows the results of an autobiographical questionnaire of Spanish university students regarding two different educational models caused by the COVID-19 pandemic: face-to-face and e-learning. The aim is to discover their perceptions and opinions about their experiences during the learning process and what they have experienced during this global emergency and period of home confinement. The sample is made up of 100 students from the Primary Education Degree programme and the research was carried out through a qualitative study of the questionnaire. The results, divided into categories of each educational model, show the interpretation that the students make of the current reality and their own learning process. The most important aspect of the face-to-face learning model, according to 75% of the students, is direct communication with the teacher, and for 88% of them this model was effective. For the e-learning model, the flexible schedule, the economic savings and explanatory videos are the relevant ideas that the students express, with 68% stating that it was an effective model. The main conclusion is that the students prefer to continue with the face-to-face learning process (49%) rather than online teaching (7%) or, failing that, mixed or blended learning (44%), where the theoretical classes could be online and the practical classes could be face-to-face
A Teaching Experience for Prospective primary school Teachers: implementation of a geometric and measure activity
El presente documento relata una experiencia de clase en el área de
matemáticas en el Grado de Maestro de Educación Primaria en la Universidad
de Cádiz. Dicha experiencia consistió en la realización de un taller combinando
conocimientos y destrezas asociados a los ámbitos geométrico y de medida de
las matemáticas. En el cual se pretendÃa que los alumnos analizaran y reflexionaran acerca de los conocimientos relacionados con ambos ámbitos de las matemáticas para la resolución de una actividad cercana a la vida real, y desarrollaran
competencias necesarias para su futura profesión docente. En esta experiencia
de clase se trabaja desde una matemática realista contextualizada en la profesión
docente, alejándolo del modelo tradicional de enseñanza y estimulando a los
estudiantes para que construyan su propio conocimiento desde su particular
autonomÃa y experiencia. Se muestran las producciones de los estudiantes futuros
maestros de educación primaria y se ofrecen algunas conclusiones derivadas de
la actividad. Se presenta este trabajo como una contribución de buena práctica o
iniciativa de innovación docente a modo de experiencia motivadora para orientar
a otros docentes en el campo de la educación.: This document describes an experience of class in the mathematics
area in the Primary Education Degree at the University of Cádiz. Specifically,
in the subject of Mathematical Knowledge II. This experience consisted in the
realization of a workshop combining knowledge and skills associated with
the geometry and measure knowledge of the mathematics. In this workshop, the
students must analyse and reflect on the knowledge for the resolution of an
activity close to the reality, and they will develop necessary skills for their
future profession. In the classroom experience, we work from a realistic
mathematics contextualized in the teaching profession, moving it away from
the traditional teaching model and stimulating students to build their own
knowledge from your own autonomy and experience. The productions of
future primary school teachers are shown, and some conclusions derived from
the activity are offered. This work is presented as a contribution of good
practice or teaching innovation initiative like a motivating experience to guide
other teachers in the field of education.24 página
Gaia-ESO Survey: Gas dynamics in the Carina nebula through optical emission lines
Aims. We present observations from the Gaia-ESO Survey in the lines of Hα, [N II], [S II], and He I of nebular emission in the central part of the Carina nebula. Methods. We investigate the properties of the two already known kinematic components (approaching and receding), which account for the bulk of emission. Moreover, we investigate the features of the much less known low-intensity high-velocity (absolute RV >50 km s) gas emission. Results. We show that gas giving rise to Hα and He I emission is dynamically well correlated with but not identical to gas seen through forbidden-line emission. Gas temperatures are derived from line-width ratios, and densities from [S II] doublet ratios. The spatial variation of N ionization is also studied, and found to differ between the approaching and receding components. The main result is that the bulk of the emission lines in the central part of Carina arise from several distinct shell-like expanding regions, the most evident found around η Car, the Trumpler 14 core, and the star WR25. These >shells> are non-spherical and show distortions probably caused by collisions with other shells or colder, higher-density gas. Some of them are also partially obscured by foreground dust lanes, while very little dust is found in their interior. Preferential directions, parallel to the dark dust lanes, are found in the shell geometries and physical properties, probably related to strong density gradients in the studied region. We also find evidence that the ionizing flux emerging from η Car and the surrounding Homunculus nebula varies with polar angle. The high-velocity components in the wings of Hα are found to arise from expanding dust reflecting the η Car spectrum. © ESO, 2016.This work was partly supported by the European Union FP7 programme through ERC grant number 320360 and by the Leverhulme Trust through grant RPG-2012-541Peer Reviewe
The Gaia-ESO Survey: pre-main-sequence stars in the young open cluster NGC 3293
Delgado, Antonio J. et. al.The young open cluster NGC3293 is included in the observing program of the Gaia-ESO survey (GES). The radial velocity values provided have been used to assign cluster membership probabilities by means of a single-variable parametric analysis. These membership probabilities are compared to the results of the photometric membership assignment of NGC3293, based on UBVRI photometry. The agreement of the photometric and kinematic member samples amounts to 65 per cent, and could increase to 70 per cent as suggested by the analysis of the differences between both samples. A number of photometric PMS candidate members of spectral type F are found, which are confirmed by the results from VPHAS photometry and SED fitting for the stars in common with VPHAS and GES data sets. Excesses at mid- and near-infrared wavelengths, and signs of H alpha emission, are investigated for them. Marginal presence of H alpha emission or infilling is detected for the candidate members. Several of them exhibit moderate signs of U excess and weak excesses at mid-IR wavelengths. We suggest that these features originate from accretion discs in their last stages of evolution.This work was partly supported by the European Union FP7 programme through ERC grant number 320360 and by the Leverhulme Trust through grant RPG-2012-541. We acknowledge the support from INAF and Ministero dell' Istruzione, dell' Universita' e della Ricerca (MIUR) in the form of the grant 'Premiale VLT 2012'. The results presented here benefit from discussions held during the Gaia-ESO workshops and conferences supported by the ESF (European Science Foundation) through the GREAT Research Network Programme. AJD, LS, EJA and MTC acknowledge financial support from the Spanish Ministerio de Economia y Competitividad, through grant AYA2013-40611-P. JLY acknowledges support from FCT (SFRH/BSAB/1423/2014 and UID/FIS/04434/2013). TM acknowledges financial support from Belspo for contract PRODEX GAIA-DPAC.Peer reviewe
The Gaia-ESO Survey: dynamics of ionized and neutral gas in the Lagoon nebula (M8)
We present a spectroscopic study of the dynamics of the ionized and neutral
gas throughout the Lagoon nebula (M8), using VLT/FLAMES data from the Gaia-ESO
Survey. We explore the connections between the nebular gas and the stellar
population of the associated star cluster NGC6530. We characterize through
spectral fitting emission lines of H-alpha, [N II] and [S II] doublets, [O
III], and absorption lines of sodium D doublet, using data from the
FLAMES/Giraffe and UVES spectrographs, on more than 1000 sightlines towards the
entire face of the Lagoon nebula. Gas temperatures are derived from line-width
comparisons, densities from the [S II] doublet ratio, and ionization parameter
from H-alpha/[N II] ratio. Although doubly-peaked emission profiles are rarely
found, line asymmetries often imply multiple velocity components along the line
of sight. This is especially true for the sodium absorption, and for the [O
III] lines. Spatial maps for density and ionization are derived, and compared
to other known properties of the nebula and of its massive stars 9 Sgr,
Herschel 36 and HD 165052 which are confirmed to provide most of the ionizing
flux. The detailed velocity fields across the nebula show several expanding
shells, related to the cluster NGC6530, the O stars 9 Sgr and Herschel 36, and
the massive protostar M8East-IR. The origins of kinematical expansion and
ionization of the NGC6530 shell appear to be different. We are able to put
constrains on the line-of-sight (relative or absolute) distances between some
of these objects and the molecular cloud. The large obscuring band running
through the middle of the nebula is being compressed by both sides, which might
explain its enhanced density. We also find an unexplained large-scale velocity
gradient across the entire nebula. At larger distances, the transition from
ionized to neutral gas is studied using the sodium lines.Comment: 26 pages, 31 figures, accepted on Astronomy and Astrophysics journa
- …