An international team led by astronomers Gyula Józsa, Michelle Cluver, and Thomas Jarrett has utilized the South African MeerKAT telescope to discover a mysterious chain of hydrogen gas clouds the size of a massive galaxy. Indeed, the accumulation of so much elemental hydrogen without associated stellar components is the largest yet discovered. Appearing at the edge of a relatively massive group of galaxies, there is the possibility that the cloud chain is gas stripped from group-member galaxies, but it may also be primordial and gravitationally drawn into the group through a cosmic filament pathway. Whatever the case, MeerKAT is proving to be a ground-breaking telescope, and this "dark" cloud discovery should soon be followed by many such discoveries in the exciting days ahead.

The arrival of mainstream virtual-reality (VR) headsets and increased GPU power, as well as the availability of versatile development tools for video games, has enabled scientists to deploy such technology to effectively interrogate and interact with complex data. In this paper we present development and results from custom-built interactive VR tools, called the iDaVIE suite, that are informed and driven by research on galaxy evolution, cosmic large-scale structure, galaxy-galaxy interactions, and gas/kinematics of nearby galaxies in survey and targeted observations. In the new era of Big Data ushered in by major facilities such as the SKA and LSST that render past analysis and refinement methods highly constrained, we believe that a paradigm shift to new software, technology and methods that exploit the power of visual perception, will play an increasingly important role in bridging the gap between statistical metrics and new discovery. We have released a beta version of the iDaVIE software system that is free and open to the community.

Mid-infrared photometry and measured global properties of the 100 largest galaxies in the sky is presented, including the well-studied Magellanic Clouds, Local Group galaxies M31 and M33, the Fornax and Virgo Galaxy Cluster giants, and many of the most spectacular Messier objects (e.g., M51 and M83). This is the first release of a larger catalog of extended sources as imaged in the mid-infrared, called the WISE Extended Source Catalogue (WXSC).

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We present MeerKAT neutral hydrogen (HI) observations of the Fornax A group, that is likely falling into the Fornax cluster for the first time. Our HI image is sensitive to 1.4 × 1019 atoms cm−2 over 44.1 km s−1, where we detect HI in 10 galaxies and a total of (1.12 ± 0.02) × 109 Msol of HI in the intra-group medium (IGM). We search for signs of pre-processing in the 12 group galaxies with confirmed optical redshifts that reside within the sensitivity limit of our HI image. The central, massive galaxy in our group (NGC 1316) underwent a 10:1 merger ∼ 2 Gyr ago, and ejected 6.6 – 11.2 × 108 Msol of HI that we detect as clouds and streams in the IGM, some forming coherent structures up to ∼ 220 kpc in length. We also detect giant (∼ 100 kpc) ionised hydrogen (Hα) filaments in the IGM, likely from cool gas being removed (and subsequently ionised) from an infalling satellite. The Hα filaments are situated within the hot halo of NGC 1316 and there are localised regions that contain HI. We speculate that the Hα and multi-phase gas is supported by magnetic pressure (possibly assisted by the NGC 1316 AGN), such that the hot gas can condense and form HI that survives in the hot halo for cosmological timescales.

We present the global scaling relations between the neutral atomic hydrogen gas, the stellar disk and the star forming disk in a sample of 228 nearby galaxies that are both spatially and spectrally resolved in HI line emission. We have used HI data from the Westerbork survey of HI in Irregular and Spiral galaxies (WHISP) and Mid Infrared (3.4μm, 11.6 μm) data from the Wide-field Infrared Survey Explorer (WISE) survey, combining two datasets that are well-suited to such a study in terms of uniformity, resolution and sensitivity. We utilize a novel method of deriving scaling relations for quantities enclosed within the stellar disk rather than integrating over the HI disk and and the global scaling relations to be tighter when defined for enclosed quantities. We also present new HI intensity maps for the WHISP survey derived using a robust noise rejection technique along with corresponding velocity fields.

We present the beta release of iDaVIE-v, a new Virtual Reality software for data cube exploration. The beta release of iDaVIE-v (immersive Data Visualisation Interactive Explorer for volumetric rendering) is planned for release in early 2021. iDaVIE-v has been developed through the Unity game engine using the SteamVR plugin and is compatible with all commercial headsets. It allows the visualization, exploration and interaction of data for scientific analysis. Originally developed to serve the HI Radio Astronomy community for HI source identification, the software has now completed the alpha testing phase and is already showing capabilities that will serve the broader astronomical community and more. iDaVIE-v has been developed at the IDIA Visualisation Lab (IVL) based at the University of Cape Town in collaboration with the Italian National Institute for Astrophysics (INAF) in Catania.

We present a detailed study of emission-line systems in the Galaxy And Mass Assembly (GAMA) G23 region, making use of Wide-field Infrared Survey Explorer (WISE) photometry that includes carefully measured resolved sources. After applying several cuts to the initial catalog of ∼41,000 galaxies, we extract a sample of 9809 galaxies. We then compare the spectral diagnostic Baldwin, Philips & Terlevich (BPT) classification of 1154 emission-line galaxies (38% resolved in W1) to their location in the WISE color-color diagram, leading to the creation of a new zone for mid-infrared "warm" galaxies located 2σ; above the star-forming sequence, below the standard WISE active galactic nucleus (AGN) region. Based on our findings, we have created a new diagnostic: [W1 - W2] versus [N II]/[Hα], which has the virtue of separating SF from AGNs and high-excitation sources. It classifies 3 to ∼5 times more galaxies than the classic BPT.

Using mid-infrared star formation rate and stellar mass indicators in WISE, we construct and contrast the relation between star formation rate and stellar mass for isolated and paired galaxies. Our samples comprise a selection of AMIGA (Analysis of the interstellar Medium in Isolated GAlaxies; isolated galaxies) and pairs of ALFALFA (Arecibo Legacy Fast ALFA) galaxies with HI detections such that we can examine the relationship between HI content (gas fraction, HI deficiency) and galaxy location on the main sequence (MS) in these two contrasting environments. We derive for the first time an HI scaling relation for isolated galaxies using WISE stellar masses, and thereby establish a baseline predictor of HI content that can be used to assess the impact of environment on H I content when compared with samples of galaxies in different environments.

(24 minutes, VR or Fulldome, 4K or 8K unidirectional) Rising Star takes you on an astronomical journey from our beginnings through the development of astronomy research in South Africa and looks at what the future of astronomy holds for the country. In addition to introducing multi-wavelength and multi-messenger astronomy, it highlights the many remarkable facilities hosted in South Africa along with some of their latest results. The film is accessible to all ages and aims to excite both South African and International audiences about South African astronomy and inspire the next generation of astronomers in the country. As the first of its kind to be produced in Africa, Rising Star hopes to stimulate the production of many more locally produced planetarium films from multidisciplinary fields, with the goal of popularising Africa’s numerous scientific achievements.

A galaxy group catalogue for the recently-completed 2MASS Redshift Survey (2MRS) is presented, consisting of 3022 groups, and 44572 redshifts, including 1041 new measurements for galaxies mostly located within the Zone of Avoidance. The catalogue is generated by using a novel, graph-theory based, modified version of the Friends-of-Friends algorithm. The results and graph-theory methods presented in this paper have been thoroughly interrogated against previous 2MRS group catalogues by making use of cutting-edge visualization techniques and the immersive visualisation facilities of the IDIA Vislab.