O debate sobre os métodos de ensino nos liceus portugueses (anos 30 a 60 do século XX)

Congresso realizado nos dias 6 a 9 de Maio de 2014, em Toluca, MéxicoA presente comunicação tem como objetivo refletir sobre os métodos de ensino, ao nível do ensino secundário, tal como são propostos e debatidos por educadores e professores em duas das grandes revistas pedagógicas consagrados a esse nível de ensino e ligadas a um importante contexto de formação de professores – o Liceu Normal de Pedro Nunes situado em Lisboa. Estamos a falar do Boletim do Liceu Normal de Lisboa Pedro Nunes (1932-1938) e de Palestra. Revista de pedagogia e cultura (1957-1973).info:eu-repo/semantics/publishedVersio

Radio-continuum study of MCSNR J0536-7038 (DEM L249)

We present a detailed radio-continuum study on Australia Telescope Compact Array (ATCA) observations of Large Magellanic Cloud (LMC) supernova remnant (SNR), MCSNR J0536-7038. This Type Ia SNR follows a horseshoe morphology, with a size 32 pc × 32 pc (1-pc uncertainty in each direction). It exhibits a radio spectrum α=-0.52±0.07 between λ=73 and 6 cm. We report detections of regions showing moderately high fractional polarisation at 6 cm, with a peak value of 71±25 % and a mean fractional polarisation of 35±8 %. We also estimate an average rotation measure across the remnant of -237 rad m-2. The intrinsic magnetic field appears to be uniformly distributed, extending in the direction of the two brightened limbs of the remnant

A multi-wavelength look at the young plerionic supernova remnant 0540-69.3

We present a study of the plerionic supernova remnant 0540-69.3 in the LMC in X-ray, radio, optical, and infrared. We find that the shell of 0540-69.3 is characterized in the X-ray by thermal nonequilibrium plasma with depleted Mg and Si abundances and a temperature of kT ∼ 0.7 keV. This thermal emission is superimposed with synchrotron emission in several regions. Based on X-ray spectra and on morphological considerations in all surveyed wavebands, we conclude that the shell is expanding into a clumpy and highly inhomogeneous medium. In one region of the shell we find an overabundance of Ne, suggesting the presence of ejecta near the edge of the remnant. We also see evidence for reheating of material via a reverse shock originating from the interaction of the supernova blast wave with a particularly dense cloud in the surrounding medium. Finally, we perform the first detailed study of the "halo" region extending 1.2-2.2 pc from the central pulsar. We detect the presence of thermal and nonthermal spectral components but do not find evidence for mixing or ejecta. We conclude that the thermal component is not a counterpart to similar optical and infrared halos and that it is most likely due to the projection of shell material along the line of sight

Optical discovery and multiwavelength investigation of supernova remnant MCSNR J0512-6707 in the Large Magellanic Cloud

We present optical, radio and X-ray data that confirm a new supernova remnant (SNR) in the Large Magellanic Cloud (LMC) discovered using our deep Hα imagery. Optically, the new SNR has a somewhat filamentary morphology and a diameter of 56×64 arcsec (13.5×15.5 pc at the 49.9 kpc distance of the LMC). Spectroscopic follow-up of multiple regions show high [S II]/Hα emission-line ratios ranging from 0.66 ± 0.02 to 0.93 ± 0.01, all of which are typical of an SNR. We found radio counterparts for this object using our new Australia Telescope Compact Array (ATCA) 6 cm pointed observations as well as a number of available radio surveys at 8640 MHz, 4850 MHz, 1377 MHz and 843 MHz. With these combined data we provide a spectral index α≈−0.5 between 843 and 8640 MHz. Both spectral line analysis and the magnetic field strength, ranging from 124 to 184 μG, suggest a dynamical age between ∼2200 and∼4700 yr. The SNR has a previously catalogued X-ray counterpart listed as HP 483 in the ROSAT Position Sensitive Proportional Counter (PSPC) catalogue

XMM-Newton observations of 30 Dor C in the Large Magellanic Cloud

The 30 Dor C superbubble (SB) in the Large Magellanic Cloud is notable for its bright shell of non-thermal X-ray emission. The southeastern region is also known to exhibit significant thermal emission with metal enhancements indicating the presence of a supernova remnant (SNR). However, a detailed treatment and characterisation of the thermal emission has not yet been performed. In this work, we present the analysis of the ample XMM-Newton data available for 30 Dor C (flarefiltered exposure times of 420 ks EPIC-pn, 556 ks EPIC-MOS1, 614 ks EPIC-MOS2) to attempt to isolate and identify any X-ray emission due to an SNR. In addition, an analysis of the nonthermal emission will be presented and discussed in the context of emission mechanisms previously suggested in the literature (i.e., non-thermal bremsstrahlung and synchrotron). Two SNRs were found to be contributing to the thermal emission in 30 Dor C. The most apparent is manifest as a prominent arc in the 1-2 keV energy range, which shows strong emission lines of α-process elements in its spectrum, consistent with a core-collapse remnant. Its X-ray morphology points to a location outside the SB. The second SNR is likely an interior SNR interacting with the shell wall

Supernova remnants in the Magellanic Clouds

We present an ongoing study of the complete sample of supernova remnants (SNRs) and candidates in the Magellanic Clouds. 108 objects in both Clouds are considered to be either SNR or reliable candidates. This represents the most complete sample of all known SNRs in any galaxy. It therefore allows us to study SNR population properties such as the age-diameter (Age-D) relation. Here, we show that this Age-D relation is strongly dependant on the local environment in which SNRs are residing

XMM-Newton observations of the supernova remnants [HP99] 1139 and 1RXS J053353.6-720404 in the Large Magellanic Cloud

Supernova remnants (SNRs) are of vital importance to the physical and chemical evolution of the interstellar medium (ISM). The expanding shell of the remnants imparts kinetic energy to the surrounding ISM as well as enriching it with the metals fused in the cores of their progenitor stars. Thus, an understanding of these objects is crucial to the understanding of star formation and matter recycling in galaxies. We have been studying SNRs in the Magellanic Clouds (MCs) in greater detail using combined optical, radio, and X-ray observations. The X-ray selected candidate SNRs 1RXS J053353.6-720404 and [HP99] 1139 were observed by XMM-Newton in May 2012. Both candidates are readily confirmed as bona fide X-ray SNRs due to their soft thermal emission and morphology. [HP99] 1139 is also notable due to the bright Fe-rich gas in its interior, a feature observed in several evolved LMC SNRs and is typical of a Type Ia SN progenitor. In this poster we present the detailed analysis of these remnants, including a comparison of the X-ray emission to multiwavelength data to better understand their spectral and morphological properties

Studies of shock-heated interstellar plasma

Supernova remnants (SNRs), interstellar bubbles, and superbubbles are generated either by stellar winds, by one or multiple stellar explosions, or by a combination of these and are driven by the expansion of strong shock waves propagating into the interstellar medium (ISM). The evolution of SNRs and bubbles as well as the distribution of the hot phase of the ISM can be studied best in soft X-ray line and continuum emission, since these plasmas are very hot (106 – 107 K). We present recent results of our studies of SNRs and superbubbles in the nearby galaxies, in particular in the Large Magellanic Cloud. In addition, we will discuss the prospects of ISM research with the eROSITA telescope onboard the Spectrum-RG satellite scheduled for launch in 2015

XMM-Newton observation of SNR J0533-7202 in the Large Magellanic Cloud

Aims. We present an X-ray study of the supernova remnant SNR J0533-7202 in the Large Magellanic Cloud (LMC) and determine its physical characteristics based on its X-ray emission. Methods. We observed SNR J0533-7202 with XMM-Newton (background flare-filtered exposure times of 18 ks EPIC-pn and 31 ks EPIC-MOS1, EPIC-MOS2). We produced X-ray images of the supernova remnant, performed an X-ray spectral analysis, and compared the results to multi-wavelength studies. Results. The distribution of X-ray emission is highly non-uniform, with the south-west region much brighter than the north-east. The detected X-ray emission is correlated with the radio emission from the remnant. We determine that this morphology is most likely due to the supernova remnant expanding into a non-uniform ambient medium and not an absorption effect. We estimate the remnant size to be 53.9 (±3.4) × 43.6 (±3.4) pc, with the major axis rotated ~64° east of north. We find no spectral signatures of ejecta emission and infer that the X-ray plasma is dominated by swept up interstellar medium. Using the spectral fit results and the Sedov self-similar solution, we estimate the age of SNR J0533-7202 to be ~17-27 kyr, with an initial explosion energy of (0.09-0.83) × 1051 erg. We detected an X-ray source located near the centre of the remnant, namely XMMU J053348.2-720233. The source type could not be conclusively determined due to the lack of a multi-wavelength counterpart and low X-ray counts. We found that it is likely either a background active galactic nucleus or a low-mass X-ray binary in the LMC. Conclusions. We detected bright thermal X-ray emission from SNR J0533-7202 and determined that the remnant is in the Sedov phase of its evolution. The lack of ejecta emission prohibits us from typing the remnant with the X-ray data. Therefore, the likely Type Ia classification based on the local stellar population and star formation history reported in the literature cannot be improved upon

Multiwavelength study of the newly confirmed supernova remnant MCSNR J0527-7104 in the Large Magellanic Cloud

Context. The Large Magellanic Cloud (LMC) hosts a rich and varied population of supernova remnants (SNRs). Optical, X-ray, and radio observations are required to identify these SNRs, as well as to ascertain the various processes responsible for the large array of physical characteristics observed. Aims. In this paper we attempted to confirm the candidate SNR [HP99] 1234, identified in X-rays with ROSAT, as a true SNR by supplementing these X-ray data with optical and radio observations. Methods. Optical data from the Magellanic Cloud Emission Line Survey (MCELS) and new radio data from the Molonglo Observatory Synthesis Telescope (MOST), in addition to the ROSAT X-ray data, were used to perform a multiwavelength morphological analysis of this candidate SNR. Results. An approximately ellipsoidal shell of enhanced [S II] emission, typical of an SNR ([S II]/H alpha > 0.4), was detected in the optical. This enhancement is positionally coincident with faint radio emission at lambda = 36 cm. Using the available data we estimated the size of the remnant to be similar to 5.1' x 4.0' (similar to 75 pc x 59 pc). However, the measurement along the major-axis was somewhat uncertain due to a lack of optical and radio emission at its extremities and the poor resolution of the X-ray data. Assuming this SNR is in the Sedov phase and adopting the ambient mass density of 1.2 x 10(-25) g cm(-3) measured in a nearby H II region, an age estimate of similar to 25 kyr was calculated for a canonical initial explosion energy of 10(51) erg. However, this age estimate should be treated cautiously due to uncertainties on the adopted parameters. Analysis of the local stellar population suggested a type Ia event as a precursor to this SNR, however, a core-collapse mechanism could not be ruled out due to the possibility of the progenitor being a runaway massive star. Conclusions. With the detection of X-ray, radio and significant optical line emission with enhanced [S II], this object was confirmed as an SNR to which we assign the identifier MCSNR J0527-7104