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

Odd radio circles and their environment

Odd Radio Circles (ORCs) are unexpected faint circles of diffuse radio emission discovered in recent wide deep radio surveys. They are typically about one arcmin in diameter, and may be spherical shells of synchrotron emission about a million light years in diameter, surrounding galaxies at a redshift of ∼0.2–0.6. Here we study the properties and environment of the known ORCs. All three known single ORCs either lie in a significant overdensity or have a close companion. If the ORC is caused by an event in the host galaxy, then the fact that they tend to be in an overdensity, or have a close companion, may indicate that the environment is important in creating the ORC phenomenon, possibly because of an increased ambient density or magnetic field

WTF? : discovering the unexpected in next-generation radio continuum surveys

Most major discoveries in astronomy have come from unplanned discoveries made by surveying the Universe in a new way, rather than by testing a hypothesis or conducting an investigation with planned outcomes. Next generation radio continuum surveys such as the Evolutionary Map of the Universe (EMU: the radio continuum survey on the new Australian SKA Pathfinder telescope), will significantly expand the volume of observational phase space, so we can be reasonably confident that we will stumble across unexpected new phenomena or new types of object. However, the complexity of the instrument and the large data volumes mean that it may be non-trivial to identify them. On the other hand, if we don't, then we may be missing out on the most exciting science results from EMU. We have therefore started a project called “WTF”, which explicitly aims to mine EMU data to discover unexpected science that is not part of our primary science goals, using a variety of machine-learning techniques and algorithms. Although targeted specifically at EMU, we expect this approach will have broad applicability to astronomical survey data

Radio-continuum jets around the peculiar galaxy pair ESO 295-IG022

We report new radio-continuum observations with the Australia Telescope Compact Array (ATCA) of the region surrounding the peculiar galaxy pair ESO 295-IG022 at the centre of the poor cluster Abell S0102. We observed this cluster at wavelengths of λ=20/13 and 6/3 cm with the ATCA 6 km array. With these configurations, we achieved a resolution of ~2" at 3 cm which is sufficient to resolve the jet-like structure of ~3' length detected at 20 cm. From our new high resolution images at 6 and 3 cm we confirm the presence of a double jet structure, most likely originating from the northern galaxy (ESO 295-IG022-N), bent and twisted towards the south. We found the spectral index of the jet to be very steep (α=-1.32). No point source was detected that could be associated with the core of ESO 295-IG022-N. On the other hand, ESO 295-IG022-S does not show any jet structure, but does show a point radio source. This source has variable flux and spectral index, and appears to be superposed on the line-of-sight of the jets (seen at 20-cm) originating from the northern galaxy ESO 295-IG022-N. Finally, regions of very high and somewhat well ordered polarisation were detected at the level of 70%

X-ray spectroscopy of potential small Magellanic Cloud type Ia supernova remnants and their environments

We examine three supernova remnants in the SMC, IKT 5 (supernova remnant (SNR) 0047-73.5), IKT 25 (SNR 0104-72.3), and DEM S 128 (SNR 0103-72.4), which are designated as Type Ia in the literature due to their spectra and morphology. This is troublesome because of their asymmetry, a trait not usually associated with young Type Ia remnants. We present Chandra X-ray Observatory data on these three remnants and perform a maximum likelihood analysis on their spectra. We find that the X-ray emission is dominated by interactions with the interstellar medium. In spite of this, we find a significant Fe overabundance in all three remnants. Through examination of radio, optical, and infrared data, we conclude that these three remnants are likely not Type Ia SNRs. We detect potential point sources that may be members of the progenitor systems of both DEM S 128 and IKT 5, which could suggest these could be Fe-rich core-collapse remnants

Radio-continuum study of the supernova remnants in the large magellanic cloud - an SNR with a highly polarised breakout region - SNR J0455-6838

We present the results of new moderate resolution ATCA observations of SNR J0455-6838. We found that this SNR exhibits a mostly typical appearance with rather steep and curved α=-0.81±0.18 and D=43x31±1 pc. Regions of high polarisation were detected, including unusually strong (~70%) region corresponding to the northern breakout. Such a strong polarisation in breakout regions has not been observed in any other SNR

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

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

Optical spectra of radio planetary nebulae in the Large Magellanic Cloud

We present 11 spectra from 12 candidate radio sources co-identified with known planetary nebulae (PNe) in the Large Magellanic Cloud (LMC). Originally found in Australia Telescope Compact Array (ATCA) LMC surveys at 1.4, 4.8 and 8.64 GHz and confirmed by new high resolution ATCA images at 6 and 3 cm (4″/2″), these complement data recently presented for candidate radio PNe in the Small Magellanic Cloud (SMC). Their spectra were obtained using the Radcliffe 1.9-meter telescope in Sutherland (South Africa). All of the optical PNe and radio candidates are within 2″ and may represent a population of selected radio bright sample only. Nebular ionized masses of these objects are estimated to be as high as 1.8 M⊙, supporting the idea that massive PNe progenitor central stars lose much of their mass in the asymptotic giant branch (AGB) phase or prior. We also identify a sub-population (33%) of radio PNe candidates with prominent ionized iron emission lines