HST Observations of the Central-Cusp Globular Cluster NGC 6752. The Effect of Binary Stars on the Luminosity Function in the Core

We consider the effect of binary stars on the main-sequence luminosity functions observed in the core of globular clusters, with specific reference to NGC 6752. We find that mass segregation results in an increased binary fraction at fainter magnitudes along the main-sequence. If this effect is not taken into account when analyzing luminosity functions, erroneous conclusions can be drawn regarding the distribution of single stars, and the dynamical state of the cluster. In the core of NGC 6752, our HST data reveal a flat luminosity function, in agreement with previous results. However, when we correct for the increasing binary fraction at faint magnitudes, the LF begins to fall immediately below the turn-off. This effect appears to be confined to the inner core radius of the cluster.Comment: 10 pages, 3 figures Accepted to ApJ Lett Vol 513 Number

Desenvolver a autonomia na leitura em Inglês : um estudo de caso com recurso à hiperficção

Dissertação de mestrado em Educação (área de especialização em Supervisão Pedagógica em Ensino das Línguas Estrangeiras)O presente estudo de caso baseia-se numa experiência de auto-supervisão pedagógica no campo da didáctica do Inglês como língua estrangeira e reflecte um trajecto de investigação-acção da professora investigadora, no qual foram exploradas práticas de leitura extensiva com recurso à hiperficção, numa turma de 11º ano de escolaridade na Escola Secundária de Alberto Sampaio, em Braga, no ano lectivo de 2006/2007. Pretendeu-se avaliar potencialidades da hiperficção como recurso tecnológico ao serviço do desenvolvimento da autonomia na leitura extensiva, nomeadamente aos níveis da motivação, auto-avaliação e capacidade estratégica. Adoptou-se uma metodologia interpretativa, procurando-se avaliar a experiência de forma contextualizada e com base nas percepções dos participantes. Após um diagnóstico de representações e práticas de leitura dos alunos através de um questionário inicial, foram desenvolvidas actividades de leitura de um hipertexto que visavam promover competências de leitura e de auto-avaliação da leitura, tendo os alunos avaliado a experiência num questionário final. A recolha de informação para a avaliação do impacto da experiência foi feita através dos questionários inicial e final, de fichas de leitura e de auto-avaliação da leitura, e da observação de aulas. Os resultados demonstram as potencialidades do uso das tecnologias de informação e de comunicação ao serviço da promoção da autonomia na leitura em Inglês, revelando que a leitura extensiva de hiperficção com suporte em materiais didácticos adequados pode desenvolver competências de comunicação e de aprendizagem, tendo efeitos positivos na motivação dos alunos. A articulação entre a auto-supervisão e a didáctica da língua estrangeira constituiu um processo de desenvolvimento profissional para a professora investigadora, na medida em que lhe permitiu questionar e reconstruir teorias e práticas pedagógicas. Num plano mais geral, o estudo possibilitou uma reflexão aprofundada sobre a qualidade do ensino que as escolas podem oferecer e sobre o papel da reflexividade profissional na actualização permanente que o mundo actual exige aos professores como educadores.The present case study is based upon a pedagogical self-supervision experiment developed in the area of EFL didactics. It describes an action research project undertaken by the author as teacher researcher, in which she investigated the use of hyperfiction as a resource to support extensive reading, in a class of 11th grade students of English, at Alberto Sampaio Secondary School in Braga, during the school year of 2006/2007. The study aimed at understanding the educational value of hyperfiction as a technological resource in extensive reading classes, namely at the levels of student motivation, self-evaluation and strategic competence. An interpretative methodology was adopted, in an attempt to evaluate the pedagogical experiment in relation to its context, based upon the participants’ perceptions. After a diagnosis of students’ beliefs and practices related to reading through an initial questionnaire, reading activities adapted to hypertext were developed, aiming at the promotion of reading competences and self-evaluation of the reading process. The students assessed the whole experiment in a final questionnaire. The data to evaluate the impact of the experiment was collected through the initial and final questionnaires, reading worksheets, self-assessment records, and lesson observation grids. The results show that new technologies may promote autonomous reading in English, revealing that extensive reading of hyperfiction supported by adequate teaching materials may lead to the development of communication and learning competences, with positive effects on students’ motivation. The articulation between self-supervision and EFL didactics resulted in a process of professional development for the teacher researcher, allowing her to question and reconstruct pedagogical theories and practices. In a wider perspective, this study led to a deep reflection upon the quality of teaching provided by schools and about the role of professional reflectivity for the continuous updating that our contemporary world demands from teachers as educators

The peculiar Horizontal Branch of NGC 2808

We present an accurate analysis of the peculiar Horizontal Branch (HB) of the massive Galactic globular cluster NGC 2808, based on high-resolution far-UV and optical images of the central region of the cluster obtained with HST. We confirm the multimodal distribution of stars along the HB: 4 sub-populations separated by gaps are distinguishable. The detailed comparison with suitable theoretical models showed that (i) it is not possible to reproduce the luminosity of the entire HB with a single helium abundance, while an appropriate modeling is possible for three HB groups by assuming different helium abundances in the range 0.24 < Y < 0.4 that are consistent with the multiple populations observed in the Main Sequence; (ii) canonical HB models are not able to properly match the observational properties of the stars populating the hottest end of the observed HB distribution, the so called "blue-hook region". These objects are probably "hot-flashers" , stars that peel off the red giant branch before reaching the tip and ignite helium at high effective temperatures. Both of these conclusions are based on the luminosity of the HB in the optical and UV bands and do not depend on specific assumptions about mass loss.Comment: Accepted for publication in the MNRAS (12 pages, 11 figures, 1 table

Wide Field Photometry of the Galactic Globular Cluster M22

We present wide field photometry of the Galactic Globular Cluster M~22 in the B, V and I passbands for more than 186,000 stars. The study is complemented by the photometry in two narrowband filters centered on H$_{\alpha}$ and the adjacent continuum, and by infrared J, H and K magnitudes derived from the 2 MASS survey for $\sim$2000 stars. Profiting from this huge database, we completely characterized the evolved stellar sequences of the cluster by determining a variety of photometric parameters, including new photometric estimates of the mean metallicity, reddening and distance to the cluster. In particular, from our multi-wavelength analysis, we re-examined the long-standing metallicity spread problem in M~22. According to our dataset, we conclude that most of the observed width of the red giant branch must be due to differential reddening, which amounts to a maximum of $\Delta E(B-V)\simeq0.06$, although the presence of a small metallicity spread cannot be completely ruled out. More specifically, the maximum metallicity spread allowed by our data is of the order of $\Delta$[Fe/H]$\simeq 0.1\div 0.2$ dex, i.e., not much more than what allowed by the photometric errors. Finally, we identified most of the known variable stars and peculiar objects in our field of view. In particular, we find additional evidence supporting previous optical identifications of the central star of the Planetary Nebula IRAS 18333-2357, which is associated with M~22.Comment: 15 pages, 16 figures, accepted for publication in MNRA

New pyrenocarpous lichens from NE Argentina

Five new species of corticolous pyrenocarpous lichens are described from tropical and subtropical forests in the Chaco and Misiones provinces in NE Argentina: Aspidothelium submuriforme with globose, grey ascomata and ascospores mostly 7-septate with 0–2 oblique longitudinal septa, 25–28 8–10 mm; Pyrenula inspersoleucotrypa, characterized by a thallus without pseudocyphellae, aggregated ascomata, an inspersed hamathecium, and ascospores of 17–20 65–80 mm with diamond-shaped lumina; Pyrenula punctoleucotrypa, which has a thallus with pseudocyphellae, aggregated ascomata in a conical pseudostroma, with fused ostioles, not inspersed hamathecium, and ascospores of 10–12 4–5 mm with rounded lumina; Strigula muriconidiata, containing immersed pycnidia with hyaline, densely muriform, ellipsoid conidia, 90–103 32–35 mm; Trypethelium globolucidum, forming sessile pseudostromata with black and whitish parts, an inspersed hamathecium, ascospores 13–19-septate, (65–)83–97 115–145 mm, lumina rounded to lentiform and containing lichexanthone.Fil: Aptroot, André. ABL Herbarium; Países BajosFil: Ferraro, Lidia Itati. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); ArgentinaFil: da Silva Cáceres, Marcela Eugenia . Universidade Federal de Sergipe; Brasi

Dwarf elliptical galaxies in Centaurus A group: stellar populations in AM 1339-445 and AM 1343-452

We study the red giant populations of two dE galaxies, AM 1339-445 and AM 1343-452, with the aim of investigating the number and luminosity of any upper asymptotic giant branch (AGB) stars present. The galaxies are members of the Centaurus A group (D~3.8 Mpc) and are classified as outlying (R~350 kpc) satellites of Cen A. The analysis is based on near-IR photometry for individual red giant stars, derived from images obtained with ISAAC on the VLT. The photometry, along with optical data derived from WFPC2 images retrieved from the HST science archive, enable us to investigate the stellar populations of the dEs in the vicinity of the red giant branch (RGB) tip. In both systems we find stars above the RGB tip, which we interpret as intermediate-age upper-AGB stars. The presence of such stars is indicative of extended star formation in these dEs similar to that seen in many, but not all, dEs in the Local Group. For AM 1339-445, the brightest of the upper-AGB stars have Mbol~-4.5 while those in AM 1343-452 have Mbol~-4.8 mag. These luminosities suggest ages of approximately 6.5+/-1 and 4+/-1 Gyr as estimates for the epoch of the last episode of significant star formation in these systems. In both cases the number of upper-AGB stars suggests that ~15% of the total stellar population is in the form of intermediate-age stars, considerably less than is the case for outlying dE satellites of the Milky Way such as Fornax and LeoI.Comment: 18 pages, 19 figures, A&A accepted; high resolution version available from: http://www.eso.org/~mrejkuba/CenA_dEs_I.pd

Changes in mood state and recovery-stress perception after an HRV-guided running program in untrained women

To determine the effects of HRV-guided running training on mood state and recovery-stress factors in untrained women. Thirty untrained women were randomized into two groups. The CG performed a pre-defined training program while the HRVG completed their running training regarding the intensity distribution according to the parasympathetic activity. The questionnaires of perception of recovery-stress and mood state were answered pre and post-training. The CG reported reduced emotional stress (-0.8±1.3), conflicts/pressure (-0.8±0.8), and increased sleep quality (0.9±1.1), personal acceptance (0.9±1.6), self-regulation (0.8±1.3), specific recovery mean (0.6±0.9), and total recovery mean (0.4±0.7). The HRVG reported decreased general stress (-0.5±0.8), emotional stress (-0.7±1.2), social stress (-0.8±1.0), lack of energy (-0.8±0.8), general stress mean (-0.5±0.8), and increased self-regulation (0.7±1.1). This group also decreased tension (-2.8±3.7), depression (-2.7±4.2), anger (-2.8±4.4) and fatigue (-2.7±3.7) and TMD (-10.7±14.2). HRVG reduced negative scales of mood state and stress factors that were not observed in the controls.Determinar los efectos del entrenamiento de carrera guiado por la VFC sobre el estado de ánimo y los factores de recuperación-estrés en mujeres no entrenadas. Treinta mujeres sin entrenamiento fueron separadas en dos grupos al azar. El GC realizó un programa de entrenamiento predefinido, mientras que el GVFC completó su entrenamiento de carrera con respecto a la distribución de intensidad según la actividad parasimpática. Los cuestionarios de percepción de recuperación-estrés y estado de ánimo se respondieron antes y después del entrenamiento. El GC presentó una reducción del estrés emocional (-0,8±1,3), conflictos / presión (-0,8±0,8) y una mayor calidad del sueño (0,9±1,1), aceptación personal (0,9±1,6), autorregulación (0,8±1,3), media de recuperación específica (0,6±0,9) y media de recuperación total (0,4±0,7). El GVFC presentó una disminución del estrés general (-0,5±0,8), estrés emocional (-0,7±1,2), estrés social (-0,8±1,0), falta de energía (-0,8±0,8), media de estrés general (-0,5±0,8), y aumento de la autorregulación (0,7±1,1). Hubo disminución de la tensión (-2,8±3,7), depresión (-2,7±4,2), ira (-2,8±4,4), fatiga (-2,7±3,7) y TAT (-10,7±14,2) en el GVFC. El GVFC mejoró el estado de ánimo y factores de estrés que no se observaron en los controles.Determinar os efeitos do treinamento de corrida guiado pela VFC sobre o estado de humor e fatores de recuperação-estresse em mulheres não-treinadas. Trinta mulheres não-treinadas foram randomizadas em dois grupos. O GC realizou um programa de treinamento pré-definido, enquanto que o GVFC completou seu treinamento de corrida no que diz respeito à distribuição das intensidade segundo a atividade parassimpática. Os questionários de percepção da recuperação-estresse e estado de humor foram respondidos antes e após o programa de treinamento. O GC apresentou redução do estresse emocional (-0,8±1,3), conflitos/pressão (-0,8±0,8) e uma maior qualidade do sono (0,9±1,1), aceitação pessoal (0,9±1,6), auto-regulação (0,8±1,3), média da recuperação específica (0,6±0,9) e média da recuperação total (0,4±0,7). O GVFC apresentou diminuição do estresse geral (-0,5±0,8), estresse emocional (-0,7±1,2), estresse social (-0,8±1,0), falta de energia (-0,8±0,8), média do estresse geral (-0,5±0,8), e aumento da auto-regulação (0,7±1,1). Houve diminuição da tensão (-2,8±3,7), depressão (-2,7±4,2), raiva (-2,8±4,4), fadiga (-2,7±3,7) e THT (-10,7±14,2) no GVFC. O GVFC reduziu as escalas negativas de humor e fatores de estresse que não foram observados nos controles

The distance to the Fornax Dwarf Spheroidal Galaxy

A large multicolour, wide-field photometric database of the Fornax dwarf spheroidal galaxy has been analysed using three different methods to provide revised distance estimates based on stellar populations in different age intervals. The distance to Fornax was obtained from the Tip of the Red Giant Branch measured by a new method, and using the luminosity of Horizontal Branch stars and Red Clump stars correc ted for stellar population effects. Assuming a reddening $E(B-V)=0.02$, the following distance moduli were derived: $(m-M)_0=20.71 \pm 0.07$ based on the Tip of the Red Giant Branch, $(m-M)_0=20.72 \pm 0.06$ from the level of the Horizontal Branch, and $(m-M)_0=20.73 \pm 0.09$ using the Red Clump method. The weighted mean distance modulus to Fornax is $(m-M)_0=20.72 \pm 0.04$. All these measurements agree within the errors, and are fully consistent with previous determinations and with the distance measurements obtained in a companion paper from near-infrared colour-magnitude diagrams.Comment: Accepted for publication on Monthly Notices of the Royal Astronomical Societ

On the alpha-element gradients of the Galactic thin disk using Cepheids

We present new homogeneous measurements of Na, Al and three alpha-elements (Mg, Si, Ca) for 75 Galactic Cepheids. The abundances are based on high spectral resolution (R ~ 38,000) and high signal-to-noise ratio (S/N ~ 50-300) spectra collected with UVES at ESO VLT. The current measurements were complemented with Cepheid abundances either provided by our group (75) or available in the literature, for a total of 439 Galactic Cepheids. Special attention was given in providing a homogeneous abundance scale for these five elements plus iron (Genovali et al. 2013, 2014). In addition, accurate Galactocentric distances (RG) based on near-infrared photometry are also available for all the Cepheids in the sample (Genovali et al. 2014). They cover a large fraction of the Galactic thin disk (4.1 <= RG <= 18.4 kpc). We found that the above five elements display well defined linear radial gradients and modest standard deviations over the entire range of RG. Moreover, the [element/Fe] abundance ratios are constant across the entire thin disk; only the Ca radial distribution shows marginal evidence of a positive slope. These results indicate that the chemical enrichment history of iron and of the quoted five elements has been quite similar across the four quadrants of the Galactic thin disk. The [element/Fe] ratios are also constant over the entire period range. This empirical evidence indicates that the chemical enrichment of Galactic Cepheids has also been very homogenous during the range in age that they cover (~10-300 Myr). Once again, [Ca/Fe] vs. log(P) shows a (negative) gradient, being underabundant among youngest Cepheids. Finally, we also found that Cepheid abundances agree quite well with similar abundances for thin and thick disk dwarf stars and they follow the typical Mg-Al and Na-O correlations.Comment: 25 pages, 11 figures, 5 table

The Carina Project. VIII. The {\alpha}-element abundances

We have performed a new abundance analysis of Carina Red Giant (RG) stars from spectroscopic data collected with UVES (high resolution) and FLAMES/GIRAFFE (high and medium resolution) at ESO/VLT. The former sample includes 44 RGs, while the latter consists of 65 (high) and ~800 (medium resolution) RGs, covering a significant fraction of the galaxy's RG branch (RGB), and red clump stars. To improve the abundance analysis at the faint magnitude limit, the FLAMES/GIRAFFE data were divided into ten surface gravity and effective temperature bins. The spectra of the stars belonging to the same gravity/temperature bin were stacked. This approach allowed us to increase by at least a factor of five the signal-to-noise ratio in the faint limit (V>20.5mag). We took advantage of the new photometry index cU,B,I introduced by Monelli et al. (2014), as an age and probably a metallicity indicator, to split stars along the RGB. These two stellar populations display distinct [Fe/H] and [Mg/H] distributions: their mean Fe abundances are -2.15$\pm$0.06dex (sig=0.28), and -1.75$\pm$0.03dex (sig=0.21), respectively. The two iron distributions differ at the 75% level. This supports preliminary results by Lemasle et al. (2012) and by Monelli et al. (2014). Moreover, we found that the old and intermediate-age stellar populations have mean [Mg/H] abundances of -1.91$\pm$0.05dex (sig=0.22) and -1.35$\pm$0.03dex (sig=0.22); these differ at the 83% level. Carina's {\alpha}-element abundances agree, within 1sigma, with similar abundances for field Halo stars and for cluster (Galactic, Magellanic) stars. The same outcome applies to nearby dwarf spheroidals and ultra-faint dwarf galaxies, in the iron range covered by Carina stars. Finally, we found evidence of a clear correlation between Na and O abundances, thus suggesting that Carina's chemical enrichment history is quite different than in the globular clusters.Comment: 21 pages, 19 figures, 11 tables, accepted for publication in A&