September 2020

Artistic concept of two black holes that are about to merge (Image courtesy Mark Myers, ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav))

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Two articles, one published in the journal “Physical Review Letters” and one in “The Astrophysical Journal Letters”, report various aspects of an analysis of the data collected by the LIGO and Virgo Collaborations on the merger between two black holes of which the gravitational waves have been detected in the event cataloged as GW190521. The two black holes involved had masses out of the ordinary, estimated at 66 and 85 times the Sun’s, for a total mass of about 150-151 times the Sun’s. The black hole produced has a mass estimated at 142 times the Sun’s, which means that about 9 solar masses were turned into energy during that event to form an intermediate-mass black hole, the first observed at its birth.

Artist's concept of a protostar attracting gas (Image courtesy A. Mark Garlick )

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An article published in the journal “Nature” reports the results of observations of the very young TW Hydrae system in which for the first time the columns of materials that contribute to the formation of new stars have been directly observed. A team of researchers part of the GRAVITY collaboration that runs the instrument with that name mounted on ESO’s VLTI in Chile used it to obtain the best details ever studying TW Hydrae. This star has yet to complete its formation, so these observations provide new details on those processes.