From tin trunk to world-wide memory : the making of the Bleek collection

Includes bibliographical references (leaves 107-115).This research sketches the history of the Bleek-L1oyd collection by documenting the cataloguing and archiving of material which has occurred in the years subsequent to the recording of the original manuscripts and certain related material during the closing decades of the nineteenth century. It attempts to track the processes by which material elements (notebooks, manuscripts, printed documents, artefacts, objects and original artworks, correspondence, newspaper clippings, pamphlets, books, photographs, paintings) became consolidated - or separated - as part of the making of what is now known as the Bleek-L1oyd archive. In addition, this research examinesthe various projects of knowledge production and writing which have emanated from the archive in the 80 years since a small part of the notebook texts, edited by Lucy Lloyd, was published in 1911. In particular, I examine ways in which the notebook texts have been deployed in the service of emerging and established academic disciplines including philology, "native studies", folklore and anthropology, archaeology and rock art interpretation. In more recent times, the Bleek collection provides a case study of the archive reconstituted for the new nation, serving not only as a site for the recovery of lost or hidden histories, but also as location for an international, redemptive celebration of indigenous identitie

Expanded Very Large Array observations of the H66{\alpha} and He66{\alpha} recombination lines toward MWC 349A

We have used the greatly enhanced spectral capabilities of the Expanded Very Large Array to observe both the 22.3 GHz continuum emission and the H66{\alpha} recombination line toward the well-studied Galactic emission-line star MWC 349A. The continuum flux density is found to be 411 $\pm$ 41 mJy in good agreement with previous determinations. The H66{\alpha} line peak intensity is about 25 mJy, and the average line-to-continuum flux ratio is about 5%, as expected for local thermodynamic equilibrium conditions. This shows that the H66{\alpha} recombination line is not strongly masing as had previously been suggested, although a moderate maser contribution could be present. The He66{\alpha} recombination line is also detected in our observations; the relative strengths of the two recombination lines yield an ionized helium to ionized hydrogen abundance ratio y+ = 0.12 $\pm$ 0.02. The ionized helium appears to share the kinematics of the thermally excited ionized hydrogen gas, so the two species are likely to be well mixed. The electron temperature of the ionized gas in MWC 349A deduced from our observations is 6,300 $\pm$ 600 K.Comment: Accepted for publication in ApJ

Urban Atmospherics

In this article, we consider how an atmospheric attunement to place enables new ways of writing place. Specifically, we draw on fieldwork conducted in Johannesburg and reflect on the outcome of a remote, collective writing process pursued during months of lockdown, when our attention was dominated by talk of air and virality. We think about how our fieldwork provided us with an unsettling preview of the atmospheric anxieties to come, of a time when the very idea of the urban harboured an unseen and largely uncalibrated threat. Having developed a digital StoryMap as a way to host our written reflections, we also assess the importance of our cross-disciplinary method, especially when it comes to sensing and responding to these atmospheric circulations in less anxious, more critical terms

SMA Imaging of the Maser Emission from the H30α\alpha Radio Recombination Line in MWC349A

We used the Submillimeter Array to map the angular distribution of the H30$\alpha$ recombination line (231.9 GHz) in the circumstellar region of the peculiar star MWC349A. The resolution was 1\farcs2, but because of high signal-to-noise ratio we measured the positions of all maser components to accuracies better than 0\farcs01, at a velocity resolution of $1 kms$. The two strongest maser components (called high velocity components) at velocities near -14 and $32 kms$ are separated by 0\farcs048 \pm 0\farcs001 (60 AU) along a position angle of 102 \pm 1\arcdeg. The distribution of maser emission at velocities between and beyond these two strongest components were also provided. The continuum emission lies at the center of the maser distribution to within 10 mas. The masers appear to trace a nearly edge-on rotating disk structure, reminiscent of the water masers in Keplerian rotation in the nuclear accretion disk of the galaxy NGC4258. However, the maser components in MWC349A do not follow a simple Keplerian kinematic prescription with $v \sim r^{-1/2}$, but have a larger power law index. We explore the possibility that the high velocity masers trace spiral density or shock waves. We also emphasize caution in the interpretation of relative centroid maser positions where the maser is not clearly resolved in position or velocity, and we present simulations that illustrate the range of applicability of the centroiding method.Comment: 23 pages with 9 figures (two of these figures are vertically aligned as Figure 4) submitted to the Astrophysical Journa

Extremely broad radio recombination maser lines toward the high-velocity ionized jet in Cepheus A HW2

We present the first detection of the H40a, H34a and H31a radio recombination lines (RRLs) at millimeter wavelengths toward the high-velocity, ionized jet in the Cepheus A HW2 star forming region. From our single-dish and interferometric observations, we find that the measured RRLs show extremely broad asymmetric line profiles with zero-intensity linewidths of ~1100 kms-1. From the linewidths, we estimate a terminal velocity for the ionized gas in the jet of >500 kms-1, consistent with that obtained from the proper motions of the HW2 radio jet. The total integrated line-to-continuum flux ratios of the H40a, H34a and H31a lines are 43, 229 and 280 kms-1, clearly deviating from LTE predictions. These ratios are very similar to those observed for the RRL maser toward MWC349A, suggesting that the intensities of the RRLs toward HW2 are affected by maser emission. Our radiative transfer modeling of the RRLs shows that their asymmetric profiles could be explained by maser emission arising from a bi-conical radio jet with a semi-aperture angle of 18 deg, electron density distribution varying as r^(-2.11) and turbulent and expanding wind velocities of 60 and 500 kms-1.Comment: 6 pages, 2 figures, 3 tables, accepted for publication in ApJ

Outflow and accretion detections in the young stellar object IRAS 04579+4703

We present Submillimeter Array observations of the young stellar object IRAS 04579+4703 in the 1.3 mm continuum and in the 12CO(2-1), 13CO(2-1) and C18O(2-1) lines. The 1.3 mm continuum image reveals a flattened structure with a mass of 13 Msun. The 12CO(2-1) line map and position-velocity (PV) diagram, together with the broad wing (full width=30 km/s of 12CO(2-1)) line, clearly show that there is an outflow motion, which originates from an embedded massive YSO in this region. The lengths of the blue-shifted and red-shifted lobes are 0.14 pc and 0.13 pc respectively. The total gas mass, average dynamical timescale and mass entrainment rate of the outflow are 1.8 Msun, 1.7*10^4 yr and 1.1*10^(-4) Msun/yr, respectively. The flattened morphology of the continuum source perpendicular to the outflow direction, and the velocity gradient seen in the spectra of C18O(2-1) taken from different locations along the major axis of the continuum source, suggest the presence of an accretion disk in this region.Comment: 4 pages, 4 figures, accepted by A&A Letter

A detailed study of the accretion disk surrounding the high-mass protostar NGC 7538S

We present deep high angular resolution observations of the high-mass protostar NGC 7538S, which is in the center of a cold dense cloud core with a radius of 0.5 pc and a mass of ~2,000 Msun. These observations show that NGC 7538S is embedded in a compact elliptical core with a mass of 85 - 115 Msun. The star is surrounded by a rotating accretion disk, which powers a very young, hot molecular outflow approximately perpendicular to the rotating accretion disk. The accretion rate is very high, ~ 1.4 - 2.8 10^-3 Msun yr^-1. Evidence for rotation of the disk surrounding the star is seen in all largely optically thin molecular tracers, H13CN J = 1-0, HN13C J = 1-0, H13CO+ J = 1-0, and DCN J = 3-2. Many molecules appear to be affected by the hot molecular outflow, including DCN and H13CO+. The emission from CH3CN, which has often been used to trace disk rotation in young high-mass stars, is dominated by the outflow, especially at higher K-levels. Our new high-angular resolution observations show that the rotationally supported part of the disk is smaller than we previously estimated. The enclosed mass of the inner, rotationally supported part of the disk (D ~ 5", i.e 14,000 AU) is ~ 14 - 24 Msun.Comment: Accepted by ApJ; 20 pages, 20 figure

Zooming towards the Event Horizon - mm-VLBI today and tomorrow

Global VLBI imaging at millimeter and sub-millimeter wavelength overcomes the opacity barrier of synchrotron self-absorption in AGN and opens the direct view into sub-pc scale regions not accessible before. Since AGN variability is more pronounced at short millimeter wavelength, mm-VLBI can reveal structural changes in very early stages after outbursts. When combined with observations at longer wavelength, global 3mm and 1mm VLBI adds very detailed information. This helps to determine fundamental physical properties at the jet base, and in the vicinity of super-massive black holes at the center of AGN. Here we present new results from multi-frequency mm-VLBI imaging of OJ287 during a major outburst. We also report on a successful 1.3mm VLBI experiment with the APEX telescope in Chile. This observation sets a new record in angular resolution. It also opens the path towards future mm-VLBI with ALMA, which aims at the mapping of the black hole event horizon in nearby galaxies, and the study of the roots of jets in AGN.Comment: 6 pages, to appear in 11th European VLBI Network Symposium, ed. P. Charlot et al., Bordeaux (France), October 9-12, 201

Resolving the inner jet structure of 1924-292 with the EVENT HORIZON TELESCOPE

We present the first 1.3 mm (230 GHz) very long baseline interferometry model image of an AGN jet using closure phase techniques with a four-element array. The model image of the quasar 1924-292 was obtained with four telescopes at three observatories: the James Clerk Maxwell Telescope (JCMT) on Mauna Kea in Hawaii, the Arizona Radio Observatory's Submillimeter Telescope (SMT) in Arizona, and two telescopes of the Combined Array for Research in Millimeterwave Astronomy (CARMA) in California in April 2009. With the greatly improved resolution compared with previous observations and robust closure phase measurement, the inner jet structure of 1924-292 was spatially resolved. The inner jet extends to the northwest along a position angle of $-53^\circ$ at a distance of 0.38\,mas from the tentatively identified core, in agreement with the inner jet structure inferred from lower frequencies, and making a position angle difference of $\sim 80^{\circ}$ with respect to the cm-jet. The size of the compact core is 0.15\,pc with a brightness temperature of $1.2\times10^{11}$\,K. Compared with those measured at lower frequencies, the low brightness temperature may argue in favor of the decelerating jet model or particle-cascade models. The successful measurement of closure phase paves the way for imaging and time resolving Sgr A* and nearby AGN with the Event Horizon Telescope.Comment: 6 pages, 4 figures, accepted for publication in ApJ