NEW VISIONS OF THE PAST – TECHNOLOGY AND THE CREATION OF MEMORY SPACE IN SOUTH AFRICAN MUSEUMS

Post-Apartheid South Africa is demanding a revised approach to the construction of museums and memory space, seeking to identify a new form of museum that assists in reflecting the history of Apartheid while facilitating community growth and commonality. This paper examines two differing approaches: The Apartheid Museum in Johannesburg; and The Red Location Museum near Port Elizabeth. Both museums present evolving solutions to the challenge of creating meaningful museum space and exemplify how design technology is responding to emerging questions of how to deal with recent and emotionally raw historical events. The Apartheid Museum follows the experientially based linear model to create a simulated sense of history incorporating persuasive architecture with digital technology. In so doing a slick, international package of the past is produced. In contrast, The Red Museum re-thinks the mode of construction, materiality and linear narrative tradition in museums to create a new kind of space, open and flexible, which is situated in the heart of the township it serves. Dignified and refined, this museum re-positions the past as an entity in the present, acknowledging and celebrating a uniquely African mode of understanding and conveying history. Both regarded as highly successful in their own right, the museums identify ways in which new technology can be applied in the construction of current historical narratives and reveal how technologies can be redirected to allow for the emergence of new perspectives. In this respect, architecture contributes to the construction of new political narratives, using space and technology to subtly convey emotive messages around historical events

Learning together: Lessons from a collaborative curriculum design project

Based on an action research project implemented at two South African universities, we argue that content and language integration (ICL) collaborative partnerships benefit not only from collaboration between language and content specialists, but in addition, from collaboration between language specialists, general education specialists and content specialists from a variety of disciplines. However, as we illustrate below, these benefits may be accompanied by substantial challenges. We make a further claim, for the value of a transformative approach towards collaboration for content and language integration, in which the teacher/researchers engage in their practice in a critical and reflexive manner, and by so doing, foster their own deep learning, as well as the deep learning of the students

Rematerialising Heritage

The Rocks is one of Sydney's premier tourist locations; its identity largely founded on the perception of it as a historically significant site. This perception is steeped in complex notions of the `authentic tourist experience offered at The Rocks, which arguably originates from the retention of some of the early streets and architectures of the area. However, implicit in the act of retention is also the act of deletion. Throughout the area of The Rocks, gaps exist. These are the spaces where buildings, houses, outhouses, lanes and indeed whole streets have been eradicated to make way for urban progress or to redefine areas of the city according to political or economic aims. Heritage here is constructed, not only from that which is retained and preserved but also from that which is deleted and destroyed. This paper seeks to examine the fate of one particular street in the Rocks Princes Street that was eradicated in 1927 to make way for the Sydney Harbour Bridge. The physical demolition of the street and subsequent erasure of any material sign of it has effectively allowed the street to disappear. The predominant historical narrative that results reveals the extent to which current notions of the past are fundamentally understood through the existence of the material artefact. Yet this paper argues that definitions of the past can be drawn, not only from the material or architectural object that operates as historical proof but also from the social, performative and touristic acts that might be undertaken around the object, the architecture or even its representation

Point X-ray sources in the SNR G 315.4-2.30 (MSH 14-63, RCW 86)

We report the results of a search for a point X-ray source (stellar remnant) in the southwest protrusion of the supernova remnant G 315.4-2.30 (MSH 14-63, RCW 86) using the archival data of the Chandra X-ray Observatory. The search was motivated by a hypothesis that G 315.4-2.30 is the result of an off-centered cavity supernova explosion of a moving massive star, which ended its evolution just near the edge of the main-sequence wind-driven bubble. This hypothesis implies that the southwest protrusion in G 315.4-2.30 is the remainder of a pre-existing bow shock-like structure created by the interaction of the supernova progenitor's wind with the interstellar medium and that the actual location of the supernova blast center is near the center of this hemispherical structure. We have discovered two point X-ray sources in the "proper" place. One of the sources has an optical counterpart with the photographic magnitude $13.38\pm0.40$, while the spectrum of the source can be fitted with an optically thin plasma model. We interpret this source as a foreground active star of late spectral type. The second source has no optical counterpart to a limiting magnitude $\sim 21$. The spectrum of this source can be fitted almost equally well with several simple models (power law: photon index $=1.87$; two-temperature blackbody: $kT_1 =0.11$ keV, $R_1 =2.34$ km and $kT_2 =0.71$ keV, $R_2 =0.06$ km; blackbody plus power law: $kT =0.07$ keV, photon index $=2.3$). We interpret this source as a candidate stellar remnant (neutron star), while the photon index and non-thermal luminosity of the source (almost the same as those of the Vela pulsar and the recently discovered pulsar PSR J 0205+6449 in the supernova remnant 3C 58) suggest that it can be a young "ordinary" pulsar.Comment: 7 pages, 6 figures,revised version accepted for publication in A&

Identification of the Mass Donor Star's Spectrum in SS 433

We present spectroscopy of the microquasar SS 433 obtained near primary eclipse and disk precessional phase Psi = 0.0, when the accretion disk is expected to be most ``face-on''. The likelihood of observing the spectrum of the mass donor is maximized at this combination of orbital and precessional phases since the donor is in the foreground and above the extended disk believed to be present in the system. The spectra were obtained over four different runs centered on these special phases. The blue spectra show clear evidence of absorption features consistent with a classification of A3-7 I. The behavior of the observed lines indicates an origin in the mass donor. The observed radial velocity variations are in anti-phase to the disk, the absorption lines strengthen at mid-eclipse when the donor star is expected to contribute its maximum percentage of the total flux, and the line widths are consistent with lines created in an A supergiant photosphere. We discuss and cast doubt on the possibility that these lines represent a shell spectrum rather than the mass donor itself. We re-evaluate the mass ratio of the system and derive masses of 10.9 +/- 3.1 Msun and 2.9 +/- 0.7 Msun for the mass donor and compact object plus disk, respectively. We suggest that the compact object is a low mass black hole. In addition, we review the behavior of the observed emission lines from both the disk/wind and high velocity jets.Comment: submitted to ApJ, 24 pages, 7 figure

Null Geodesics in Five Dimensional Manifolds

We analyze a class of 5D non-compact warped-product spaces characterized by metrics that depend on the extra coordinate via a conformal factor. Our model is closely related to the so-called canonical coordinate gauge of Mashhoon et al. We confirm that if the 5D manifold in our model is Ricci-flat, then there is an induced cosmological constant in the 4D sub-manifold. We derive the general form of the 5D Killing vectors and relate them to the 4D Killing vectors of the embedded spacetime. We then study the 5D null geodesic paths and show that the 4D part of the motion can be timelike -- that is, massless particles in 5D can be massive in 4D. We find that if the null trajectories are affinely parameterized in 5D, then the particle is subject to an anomalous acceleration or fifth force. However, this force may be removed by reparameterization, which brings the correct definition of the proper time into question. Physical properties of the geodesics -- such as rest mass variations induced by a variable cosmological ``constant'', constants of the motion and 5D time-dilation effects -- are discussed and are shown to be open to experimental or observational investigation.Comment: 19 pages, REVTeX, in press in Gen. Rel. Gra

The 69 ms Radio Pulsar Near the Supernova Remnant RCW 103

We report the detection of the radio pulsar counterpart to the 69 ms X-ray pulsar discovered near the supernova remnant RCW 103 (G332.4-0.4). Our detection confirms that the pulsations arise from a rotation-powered neutron star, which we name PSR J1617-5055. The observed barycentric period derivative confirms that the pulsar has a characteristic age of only 8 kyr, the sixth smallest of all known pulsars. The unusual apparent youth of the pulsar and its proximity to a young remnant requires that an association be considered. Although the respective ages and distances are consistent within substantial uncertainties, the large inferred pulsar transverse velocity is difficult to explain given the observed pulsar velocity distribution, the absence of evidence for a pulsar wind nebula, and the symmetry of the remnant. Rather, we argue that the objects are likely superposed on the sky; this is reasonable given the complex area. Without an association, the question of where is the supernova remnant left behind following the birth of PSR J1617-5055 remains open. We also discuss a possible association between PSR J1617-5055 and the gamma-ray source 2CG 333+01. Though an association is energetically plausible, it is unlikely given that EGRET did not detect 2CG 333+01.Comment: 18 pages, 2 encapsulated Postscript figures, uses AAS LaTeX style files. Accepted for publication in The Astrophysical Journal Letter

Formation of a disk-structure and jets in the symbiotic prototype Z And during its 2006-2010 active phase

We present an analysis of spectrophotometric observations of the latest cycle of activity of the symbiotic binary Z And from 2006 to 2010. We estimate the temperature of the hot component of Z And to be \approx 150000 - 170000 K at minimum brightness, decreasing to \approx 90000 K at the brightness maximum. Our estimate of the electron density in the gaseous nebula is N_{e}=10^{10}-10^{12} cm^{-3} in the region of formation of lines of neutral helium and 10^6-10^7 cm^{-3} in the region of formation of the [OIII] and [NeIII] nebular lines. A trend for the gas density derived from helium lines to increase and the gas density derived from [OIII] and [NeIII] lines to simultaneously decrease with increasing brightness of the system was observed. Our estimates show that the ratios of the theoretical and observed fluxes in the [OIII] and [NeIII] lines agree best when the O/Ne ratio is similar to its value for planetary nebulae. The model spectral energy distribution showed that, in addition to a cool component and gaseous nebula, a relatively cool pseudophotosphere (5250-11 500 K) is present in the system. The simultaneous presence of a relatively cool pseudophotosphere and high-ionization spectral lines is probably related to a disk-like structure of the pseudophotosphere. The pseudophotosphere formed very rapidly, over several weeks, during a period of increasing brightness of Z And. We infer that in 2009, as in 2006, the activity of the system was accompanied by a collimated bipolar ejection of matter. In contrast to the situation in 2006, the jets were detected even before the system reached its maximum brightness. Moreover, components with velocities close to 1200 km/s disappeared at the maximum, while those with velocities close to 1800 km/s appeared.Comment: 18 pages, 19 figures, Accepted for publication in Astronomy Report

The detailed optical light curve of GRB 030329

(Abridged) We present densely sampled BVRI light curves of the optical transient associated with the gamma-ray burst GRB 030329, the result of a coordinated observing campaign conducted at five observatories. Augmented with published observations of this GRB, the compiled optical dataset contains 2687 photometric measurements, obtained between 78 minutes and 79 days after the burst. We show that the underlying supernova 2003dh evolved faster than, and was probably somewhat fainter than the type Ic SN 1998bw, associated with GRB 980425. We find that our data can be described by a broken power-law decay perturbed by a complex variable component. The early- and late-time decay slopes are determined to be ~1.1 and ~2, respectively. Assuming this single power-law model, we constrain the break to lie between ~3 and ~8 days after the burst. This simple, singly-broken power-law model, derived only from the analysis of our optical observations, may also account for available multi-band data, provided that the break happened ~8 days after the burst. The more complex double-jet model of Berger et al. provides a comparable fit to the optical, X-ray, mm and radio observations of this event. We detect a significant change in optical colors during the first day. Our color analysis is consistent with a cooling break frequency sweeping through the optical band during the first day. The light curves of GRB 030329 reveal a rich array of variations, superposed over the mean power-law decay. We find that the early variations are asymmetric, with a steep rise followed by a relatively slower (by a factor of about two) decline. The variations maintain a similar time scale during the first four days, and then get significantly longer.Comment: 14 pages, 12 figures, accepted for publication in ApJ with minor changes. See the GRB030329 Data Treasury at http://wise-obs.tau.ac.il/GRB030329