MEERKAT, SALT spectrum from X-ray to UV to radio wavelengths,” “This study was one of the first to involve co- said Laura Driessen, a PhD student at The University ordination between two of South Africa’s major of Manchester who led this work. astronomy facilities and shows the way for future and a mystery stellar event work.” Professor Ben Stappers from The University Patrick Woudt, Professor and Head of the Astronomy of Manchester said, “The properties of this system Department at the University of Cape Town said, don’t easily fit into our current knowledge of binary MeerKAT and SALT combine for the very first time to discover and “Since the inauguration in July or flaring stars and so may identify a unique and previously-unseen flare of radio emission from 2018 of the South African represent an entirely new a binary star in our Galaxy. MeerKAT radio telescope, source class. ”The MeerKAT the ThunderKAT project on “This study was one telescope is sweeping MeerKAT has been monitoring the sky for sources that parts of the southern skies of the first to involve vary on timescales from cientists using the MeerKAT radio a binary system; where two objects orbit each other to study the variable radio co-ordination milliseconds to years, and will telescope and the Southern African approximately every 22 days. emission from known significantly improve human Large Telescope (SALT) have compact binary stars, such as between two understanding of the variable combined forces for the first time to While the cause of the flaring and the exact nature of accreting black holes. radio sky. The discovery discover and identify a unique and the stars that make up the system is still uncertain, of South Africa’s of this new transient with Spreviously-unseen flare of radio emission from a it is thought to be associated with an active corona The excellent sensitivity MeerKAT demonstrates how major astronomy binary star in our Galaxy. – the hot outermost part of the brighter star. The and the wide field of view powerful this telescope will be source of the observed activity is located in the of the MeerKAT telescope, facilities and shows in the search for further new The MeerKAT radio telescope in the Northern Cape southern constellation of Ara and was found to be combined with the repeat transient events. of South Africa discovered the object which rapidly in the same place as a giant star about two times as ThunderKAT observations of the way for brightened by more than three times over a period of massive as the Sun. The star’s orbital motion was various parts of the southern future work.” Rob Adam, Managing three weeks. discovered and measured using optical observations skies, allows us to search Director of the South African with the SALT. the skies for new celestial Radio Astronomy Observatory This is the first new transient source discovered phenomena that exhibit - Dr David Buckley (SARAO) said: “Once again with MeerKAT and scientists hope it is just the tip Fortuitously, the star is sufficiently bright to have also variable or short-lived radio we see the potential of the of an iceberg of transient events to be discovered been monitored by optical telescopes for the last 18 emission.” MeerKAT telescope in finding with the telescope in future. Astronomers call an years and is seen to vary in brightness every three interesting and possibly new astronomical event “transient” when it lasts only for weeks, matching the orbital period “This source Dr David Buckley from the astrophysical phenomena, as a short time, it may appear or disappear, or become was discovered just a couple of weeks after I joined South African Astronomical Observatory, who leads well as the power of the multi-wavelength approach fainter or brighter over seconds, days, or even the team, it was amazing that the first MeerKAT the SALT transient follow-up programme, which to the analysis of observations.” years. These events are important as they provide images I worked on had such an interesting source followed up on the discovery, commented, “This is a a glimpse of how stars live, evolve, and die. Using in them. Once we found out that the radio flares perfect example of where co-ordinated observations an assortment of telescopes around the globe, the coincided with a star, we discovered that the star across different wavelengths were combined to give https://www.nrf.ac.za/media-room/news/meerkat-and-salt-combine-

researchers determined that the source of the flare is emits across almost the entire electromagnetic SARAO a holistic view of a newly discovered object. solve-mystery-stellar-event

14 January 2020 | SCIENCE MATTERS SCIENCE MATTERS | January 2020 15