ALMA | ESO | NAOJ | NRAO | 2020 Feb 05
Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner, have spotted a peculiar gas cloud that resulted from a confrontation between two stars. One star grew so large it engulfed the other which, in turn, spiralled towards its partner provoking it into shedding its outer layers.
- This new ALMA image shows the outcome of a stellar fight: a complex and stunning gas environment surrounding the binary HD 101584. The colors represent speed, going from blue — gas moving the fastest towards us — to red — gas moving the fastest away from us. Jets, almost along the line of sight, propel the material in blue and red. The stars in the binary are located at the single bright dot at the centre of the ring-like structure shown in green, which is moving with the same velocity as the system as a whole along the line of sight. Astronomers believe this ring has its origin in the material ejected as the lower mass star in the binary spiralled towards its red-giant partner. Credit: ALMA (ESO/NAOJ/NRAO), Olofsson et al (2019 A&A). Acknowledgement: Robert Cumming
Like humans, stars change with age and ultimately die. For the Sun and stars like it, this change will take it through a phase where, having burned all the hydrogen in its core, it swells up into a large and bright red-giant star. Eventually, the dying Sun will lose its outer layers, leaving behind its core: a hot and dense star called a white dwarf.
“The star system HD 101584 is special in the sense that this ‘death process’ was terminated prematurely and dramatically as a nearby low-mass companion star was engulfed by the giant,” said Hans Olofsson ...
Thanks to new observations with ALMA, complemented by data from the ESO-operated Atacama Pathfinder EXperiment (APEX), Olofsson and his team now know that what happened in the double-star system HD 101584 was akin to a stellar fight. As the main star puffed up into a red giant, it grew large enough to swallow its lower-mass partner. In response, the smaller star spiralled in towards the giant’s core but didn’t collide with it. Rather, this maneuver triggered the larger star into an outburst, leaving its gas layers dramatically scattered and its core exposed. ...
HD 101584: Circumstellar Characteristics and Evolutionary Status ~ H. Olofsson et al