2020

The WR 147 system seen by VLA

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An article published in “The Astrophysical Journal Letters” reports a study of the WR 147 system, and in particular of one of the two stars that form it that is now reaching the end of its life, a massive star that is a very hot giant which belongs to the category of Wolf-Rayet stars. A team of researchers used the VLA radio telescope to study the radio emissions from this star, detecting very strong stellar winds colliding with those of its companion, another giant star but not yet at the end of its life. This phenomenon generates very powerful vortices of materials that look like cosmic pinwheels.

GW Orionis seen by ALMA and SPHERE (Image ALMA (ESO/NAOJ/NRAO), ESO/Exeter/Kraus et al.)

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An article published in the journal “Science” reports a research on the characteristics of the circumstellar disk of the GW Orionis system, or GW Ori, warped by the action of the three stars that form it. A team of researchers used the AMBER and later GRAVITY and SPHERE instruments mounted on ESO’s VLTI and the ALMA radio telescope to observe the disk’s twisted shapes and the three rings into which it’s divided, which are misaligned. The innermost ring is made up of an amount of materials estimated to be about 30 times the Earth’s mass, so planets could form. The goal of the studies of this triple system is to understand if planets with stable orbits can form in its rings, a step forward to understand this type of processes in double or multiple systems.

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.

The galaxy TXS 0128+554 seen by VLBA at various frequencies (Image Lister, et al.; Sophia Dagnello, NRAO/AUI/NSF)

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An article published in “The Astrophysical Journal” reports a study of the galaxy TXS 0128+554 and in particular of the jets of particles emitted by the supermassive black hole at its center that form two lobes that appear to have different ages. A team of researchers led by Matthew Lister of Purdue University used the Very Long Baseline Array (VLBA) and NASA’s Chandra X-ray Observatory to observe the jets of materials and gamma-ray emissions. The conclusion is that the jets started about 80 years ago, stopped and then started again about 10 years ago.