Lithium abundance in the metal-poor open cluster NGC 2243

Lithium is a fundamental element for studying the mixing mechanisms acting in the stellar interiors, for understanding the chemical evolution of the Galaxy and the Big Bang nucleosynthesis. The study of Li in stars of open clusters (hereafter OC) allows a detailed comparison with stellar evolutionary models and permits us to trace its galactic evolution. The OC NGC 2243 is particularly interesting because of its low metallicity ([Fe/H]=$-0.54 \pm0.10$ dex). We measure the iron and lithium abundance in stars of the metal-poor OC NGC 2243. The first aim is to determine whether the Li dip extends to such low metallicities, the second is to compare the results of our Li analysis in this OC with those present in 47 Tuc, a globular cluster of similar metallicity. We performed a detailed analysis of high-resolution spectra obtained with the multi-object facility FLAMES at the ESO VLT 8.2m telescope. Lithium abundance was derived through line equivalent widths and the OSMARCS atmosphere models. We determine a Li dip center of 1.06 $M_\odot$, which is much smaller than that observed in solar metallicity and metal-rich clusters. This finding confirms and strengthens the conclusion that the mass of the stars in the Li dip strongly depends on stellar metallicity. The mean Li abundance of the cluster is $\log n{\rm (Li)}=2.70$ dex, which is substantially higher than that observed in 47 Tuc. We estimated an iron abundance of [Fe/H]=$-0.54 \pm0.10$ dex for NGC 2243, which is similar (within the errors) to previous findings. The [$\alpha$/Fe] content ranges from $0.00\pm0.14$ for Ca to $0.20\pm0.22$ for Ti, which is low when compared to thick disk stars and to Pop II stars, but compatible with thin disk objects. We found a mean radial velocity of 61.9 $\pm$ 0.8 \kms for the cluster.Comment: 16 pages, 9 figures, Accepted for publication in Astronomy and Astrophysic

An overview of the mid-infrared spectro-interferometer MATISSE: science, concept, and current status

MATISSE is the second-generation mid-infrared spectrograph and imager for the Very Large Telescope Interferometer (VLTI) at Paranal. This new interferometric instrument will allow significant advances by opening new avenues in various fundamental research fields: studying the planet-forming region of disks around young stellar objects, understanding the surface structures and mass loss phenomena affecting evolved stars, and probing the environments of black holes in active galactic nuclei. As a first breakthrough, MATISSE will enlarge the spectral domain of current optical interferometers by offering the L and M bands in addition to the N band. This will open a wide wavelength domain, ranging from 2.8 to 13 um, exploring angular scales as small as 3 mas (L band) / 10 mas (N band). As a second breakthrough, MATISSE will allow mid-infrared imaging - closure-phase aperture-synthesis imaging - with up to four Unit Telescopes (UT) or Auxiliary Telescopes (AT) of the VLTI. Moreover, MATISSE will offer a spectral resolution range from R ~ 30 to R ~ 5000. Here, we present one of the main science objectives, the study of protoplanetary disks, that has driven the instrument design and motivated several VLTI upgrades (GRA4MAT and NAOMI). We introduce the physical concept of MATISSE including a description of the signal on the detectors and an evaluation of the expected performances. We also discuss the current status of the MATISSE instrument, which is entering its testing phase, and the foreseen schedule for the next two years that will lead to the first light at Paranal.Comment: SPIE Astronomical Telescopes and Instrumentation conference, June 2016, 11 pages, 6 Figure

Multiliteracies in local curricula:conceptual contextualizations of transversal competence in the finnish curricular framework

Abstract The international trend of competency-based curricula is evident in the curricular framework in Finland. In the latest effort of curricular reform, seven transversal competencies were introduced to the Finnish educational system. In this article, we analyse the ways in which multiliteracy as a transversal competency, presented in the Core Curriculum for Basic Education in Finland (2014), has been conceptually contextualized in local curricula. The study revealed that in most local curricula, the definition of multiliteracy was not contextualized within local settings. For the curricula in which contextualizations took place, most conceptual contextualizations focused on the level of practice (85%), level of definition (63%) and level of rationale (21%). Conceptual contextualizations were made through emphases, specifications, descriptions and expansions. The article contributes by highlighting the ways in which broadly defined competencies can be contextualized to local settings, offering new knowledge among growing extant literature on competency-based curricula. In addition to the contextualization process, the present study offers new insights into the ways in which the concept of multiliteracy can be understood

Monilukutaidot paikallisissa opetussuunnitelmissa

Informaatiotutkimuksen päivät 2018

On the lithium dip in the metal poor open cluster NGC 2243

Lithium is a key element for studying the mixing mechanisms operating in stellar interiors. It can also be used to probe the chemical evolution of the Galaxy and the Big Bang nucleosynthesis. Measuring the abundance of Lithium in stars belonging to Open Clusters (hereafter OC) allows a detailed comparison with stellar evolutionary models. NGC 2243 is particularly interesting thanks to its relative low metallicity ([Fe/H]=-0.54 ± 0.10 dex). We performed a detailed analysis of high-resolution spectra obtained with the multi-object facility FLAMES at the VLT 8.2m telescope. Lithium abundance has been measured in 27 stars. We found a Li dip center of 1.06 M☉, which is significantly smaller than that observed in solar metallicity and metal-rich clusters. This finding confirms and strengthens the conclusion that the mass of the stars in the Li dip strongly depends on stellar metallicity. The mean Li abundance of the cluster is log n(Li) = 2.70 dex, which is substantially higher than that observed in 47 Tue. We derived an iron abundance of [Fe/H]=-0.54±0.10 dex for NGC 2243, in agreement (within the errors) with previous findings. <P /

Monilukutaito koodin purkajana:ehdotus laaja-alaiseksi ohjelmoinnin pedagogiikaksi

Tiivistelmä Tässä artikkelissa esitetään malli laaja-alaisesta ohjelmoinnin pedagogiikasta. Digitalisaation myötä algoritmit lävistävät yhä useampia elämänalueita ja sekä koulussa että sen ulkopuolella oppilaita hallitaan, ohjataan ja kontrolloidaan koodin ja algoritmien avulla. Tätä valta-asetelmaa ei kuitenkaan käsitellä perusopetuksessa vaan perusopetuksen opetussuunnitelman perusteissa ohjelmointi tarjotaan oppilaille näennäisen arvovapaina päättelyharjoituksina. Tilanne on ristiriidassa osallistumista, demokratiaa ja vaikuttamista korostavien opetussuunnitelmaperusteiden linjausten kanssa. Artikkelissa esitämme, että ohjelmoinnin moniulotteisempi käsittely onnistuu laajentamalla ymmärrystä ohjelmoinnista laajan tekstikäsityksen mukaisesti tekstitapahtumana ja koodista sosiomateriaalisena tekstinä, jolla on aina yhteiskunnallisia ja sosiaalisia seuraamuksia. Teoreettisesti artikkeli tukeutuu erityisesti monilukutaidon pedagogiikkaan, joka tarjoaa sekä pedagogisen viitekehyksen että konkreettisia välineitä siihen, miten ohjelmointiin liittyviä yhteiskunnallisia kysymyksiä kuten kriittistä toimijuutta algoritmisessa ja dataistuneessa mediaympäristössä voidaan käsitellä osana perusopetusta

Toward accurate radial velocities with the fiber-fed GIRAFFE multi-object VLT spectrograph.

International audienceWe describe briefly the Data-Reduction of the VLT fiber-fed multi-object GIRAFFE spectrograph - part of the VLT FLAMES facility. We focus on specific features of GIRAFFE - the simultaneous wavelength calibration - and their impact on the data-reduction strategy. We describe the implementation of the global physical model and we compare the results obtained with the simulated, laboratory and preliminary data. We discuss the influence of critical parameters, the overall accuracy of the wavelength solution, and the stability and the robustness of the global model approach. We address the accuracy of radial velocity measurements illustrated by solar spectra obtained during the Preliminary Acceptance in Europe

Detector upgrade for FLAMES: GIRAFFE gets red eyes

GIRAFFE is an intermediate resolution spectrograph covering a wavelength range from 360-930nm and fed by optical fibers as a part of FLAMES, the multi-object fiber facility mounted at the ESO VLT Kueyen. For some time we sought a new detector for GIRAFFE spectrograph to boost the instrument's red QE (Quantum E.ciency) capabilities, while still retaining very good blue response. We aimed also at reducing the strong fringing present in the red spectra. The adopted solution was an e2v custom 2-layer AR (Anti-Re.ection) coated Deep Depletion CCD44-82 CCD. This device was made in a new e2v Technologies AR coating plant and delivered to ESO in mid 2007 with performance that matches predictions. The new CCD was commissioned in May 2008.Here we report on the results

Detector upgrade for FLAMES: GIRAFFE gets red eyes

GIRAFFE is an intermediate resolution spectrograph covering a wavelength range from 360-930nm and fed by optical fibers as a part of FLAMES, the multi-object fiber facility mounted at the ESO VLT Kueyen. For some time we sought a new detector for GIRAFFE spectrograph to boost the instrument's red QE (Quantum E.ciency) capabilities, while still retaining very good blue response. We aimed also at reducing the strong fringing present in the red spectra. The adopted solution was an e2v custom 2-layer AR (Anti-Re.ection) coated Deep Depletion CCD44-82 CCD. This device was made in a new e2v Technologies AR coating plant and delivered to ESO in mid 2007 with performance that matches predictions. The new CCD was commissioned in May 2008.Here we report on the results