Ks-band (2.14 micron) imaging of southern massive star formation regions traced by methanol masers

We present deep, wide-field, Ks-band (2.14 micron) images towards 87 southern massive star formation regions traced by methanol maser emission. Using point-spread function fitting, we generate 2.14 micron point source catalogues towards each of the regions. For the regions between 10 degrees and 350 degrees galactic longitude and galactic latitude +/- 1 degree, we match the 2.14 micron sources with the GLIMPSE point source catalogue to generate a combined 2.14 to 8.0 micron point source catalogue. We provide this data for the astronomical community to utilise in studies of the stellar content of embedded clusters.Comment: Accepted PASA. Full version including figures available from http://www.cfa.harvard.edu/~slongmor/snl_iris2_withfigs.pd

Constructing sonified haptic line graphs for the blind student: first steps

Line graphs stand as an established information visualisation and analysis technique taught at various levels of difficulty according to standard Mathematics curricula. It has been argued that blind individuals cannot use line graphs as a visualisation and analytic tool because they currently primarily exist in the visual medium. The research described in this paper aims at making line graphs accessible to blind students through auditory and haptic media. We describe (1) our design space for representing line graphs, (2) the technology we use to develop our prototypes and (3) the insights from our preliminary work

Research in COVID-19 times: The way forward

The COVID-19 pandemic has had a major impact on research at universities. Universities around the world, including in South Africa, have been or are still closed as part of national lockdown strategies. Students have not been attending classes or doing hands-on experimental work, and students and academics have been working from home. Many thousands of students have had their university education interrupted, and for them, the resumption of learning programmes online, and where possible in research laboratories, is critically important. There is no question that as we emerge from lockdown we will not be entering a world that resembles a ‘norm’ as lived in the pre-COVID-19 era, and many changes will be required. Here we discuss the importance of research, the urgency to get things up and running again, and strategies that will need to be implemented to ensure that research activities continue. At the same time, it is necessary to ensure that students and staff are not exposed to risk in their research endeavours, which will require the development and implementation of risk management plans

Understanding person acquisition using an interactive activation and competition network

Face perception is one of the most developed visual skills that humans display, and recent work has attempted to examine the mechanisms involved in face perception through noting how neural networks achieve the same performance. The purpose of the present paper is to extend this approach to look not just at human face recognition, but also at human face acquisition. Experiment 1 presents empirical data to describe the acquisition over time of appropriate representations for newly encountered faces. These results are compared with those of Simulation 1, in which a modified IAC network capable of modelling the acquisition process is generated. Experiment 2 and Simulation 2 explore the mechanisms of learning further, and it is demonstrated that the acquisition of a set of associated new facts is easier than the acquisition of individual facts in isolation of one another. This is explained in terms of the advantage gained from additional inputs and mutual reinforcement of developing links within an interactive neural network system. <br/

The molecular environment of massive star forming cores associated with Class II methanol maser emission

Methanol maser emission has proven to be an excellent signpost of regions undergoing massive star formation (MSF). To investigate their role as an evolutionary tracer, we have recently completed a large observing program with the ATCA to derive the dynamical and physical properties of molecular/ionised gas towards a sample of MSF regions traced by 6.7 GHz methanol maser emission. We find that the molecular gas in many of these regions breaks up into multiple sub-clumps which we separate into groups based on their association with/without methanol maser and cm continuum emission. The temperature and dynamic state of the molecular gas is markedly different between the groups. Based on these differences, we attempt to assess the evolutionary state of the cores in the groups and thus investigate the role of class II methanol masers as a tracer of MSF.Comment: 5 pages, 1 figure, IAU Symposium 242 Conference Proceeding

A Large Mass of H2 in the Brightest Cluster Galaxy in Zwicky 3146

We present the Spitzer/IRS mid-infrared spectrum of the infrared-luminous (L_{IR}=4e11 L_sun) brightest cluster galaxy (BCG) in the X-ray-luminous cluster Z3146 (z=0.29). The spectrum shows strong aromatic emission features, indicating that the dominant source of the infrared luminosity is star formation. The most striking feature of the spectrum, however, is the exceptionally strong molecular hydrogen (H2) emission lines, which seem to be shock-excited. The line luminosities and inferred warm H2 gas mass (~1e10 M_sun) are 6 times larger than those of NGC 6240, the most H2-luminous galaxy at z <~ 0.1. Together with the large amount of cold H2 detected previously (~1e11 M_sun), this indicates that the Z3146 BCG contains disproportionately large amounts of both warm and cold H2 gas for its infrared luminosity, which may be related to the intracluster gas cooling process in the cluster core.Comment: 13 pages, 3 figures, 1 table; Accepted for publication in ApJ

Lord of the Rings: A Kinematic Distance to Circinus X-1 from a Giant X-Ray Light Echo

Circinus X-1 exhibited a bright X-ray flare in late 2013. Follow-up observations with Chandra and XMM-Newton from 40 to 80 days after the flare reveal a bright X-ray light echo in the form of four well-defined rings with radii from 5 to 13 arcminutes, growing in radius with time. The large fluence of the flare and the large column density of interstellar dust towards Circinus X-1 make this the largest and brightest set of rings from an X-ray light echo observed to date. By deconvolving the radial intensity profile of the echo with the MAXI X-ray lightcurve of the flare we reconstruct the dust distribution towards Circinus X-1 into four distinct dust concentrations. By comparing the peak in scattering intensity with the peak intensity in CO maps of molecular clouds from the Mopra Southern Galactic Plane CO Survey we identify the two innermost rings with clouds at radial velocity ~ -74 km/s and ~ -81 km/s, respectively. We identify a prominent band of foreground photoelectric absorption with a lane of CO gas at ~ -32 km/s. From the association of the rings with individual CO clouds we determine the kinematic distance to Circinus X-1 to be $D_{Cir X-1} = 9.4^{+0.8}_{-1.0}$ kpc. This distance rules out earlier claims of a distance around 4 kpc, implies that Circinus X-1 is a frequent super-Eddington source, and places a lower limit of $\Gamma \gtrsim 22$ on the Lorentz factor and an upper limit of $\theta_{jet} \lesssim 3^{\circ}$ on the jet viewing angle.Comment: 20 pages, 21 figures, Astrophysical Journal, in prin

Shocked molecular hydrogen towards the Tornado nebula

We present near-infrared and millimetre-line observations of the Tornado nebula (G357.7-0.1). We detected 2.12 micron_m H2 1-0 S(1) line emission towards the suspected site of interaction with a molecular cloud revealed by the presence of an OH(1720 MHz) maser. The distribution of the H2 emission is well correlated with the nonthermal radio continuum emission from the Tornado, and the velocity of the H2 emission spans over 100 km/s, which both imply that the H2 emission is shock excited. We also detected millimetre-lines from 12CO and 13CO transitions at the velocity of the maser, and mapped the distribution of the molecular cloud in a 2 x 2 arcmin^2 region around the maser. The peak of the molecular cloud aligns well with an indentation in the nebula's radio continuum distribution, suggesting that the nebula's shock is being decelerated at this location, which is consistent with the presence of the OH(1720 MHz) maser and shocked H2 emission at that location.Comment: 10 pages, 8 figures, minor changes, accepted to MNRA

Insights into rapid explosive volcanic processes from ground- and space-based intraday SO2 flux measurements

Observations of volcanic degassing yield insights into the sub-surface magmatic processes which control volcanic activity during both quiescent and eruptive phases. By combining information on volcanic gas flux with constraints on original dissolved volatile contents the volume of degassing magma can be determined. Comparisons between the volume of degassing magma, erupted volume, and ground deformation allow mass balance calculations to be performed, providing insight into the shallow volcanic plumbing system dynamics. For these reasons there is great interest in improving the quality and frequency of volcanic gas flux measurements. Ultraviolet and infrared remote sensing techniques allow determination of SO2 column amounts within volcanic plumes. By calculating SO2 column amounts in a profile orthogonal to the plume-wind direction and multiplying the integrated SO2 cross section by the wind speed the SO2 emission rate can be retrieved. There are currently three main approaches for determining volcanic SO2 fluxes; (i) ground-based mini-DOAS systems, (ii) ground-based SO2 imaging cameras, and (iii) satellite-based infrared and ultraviolet imaging. Here we examine SO2 fluxes obtained by the Flux Automatic Measurement (FLAME) network of scanning mini-DOAS instruments installed at Mt. Etna and by the MODIS instrument aboard the NASA EOS satellite AQUA during the 2006 eruption of Mt. Etna, Sicily, Italy. Mt. Etna produced a highly variable eruptive activity from the South-East crater, characterised by explosive sequences, which could be either ash-rich or ash-poor, lava effusion, partial flank collapse and periods of quiescence. We examined intraday variations in SO2 flux measured with FLAME and MODIS during both ash-rich and ash-poor explosive phases. In general, good agreement was found between the datasets. Of particular interest was the successful recalculation and validation of temporal variations in SO2 flux recorded in a single image from MODIS. By examining the temporal evolution of gas emissions our results provide insight in the eruption mechanism driving the explosive activity