The European Southern Observatory (ESO) has spread an image of the spectacular trail left by a ‘fight to the death’ between two stars. It is a peculiar gas cloud that originated in the stellar binary system HD101584 and has been detected by an international team of astronomers using the Atacama Large Millimeter / submillimeter Array (ALMA), located in Chile.
The gas cloud arose when the dying main star of the system expanded to become a red giant, enveloping the other, of lesser mass. Astronomers determined that what happened in HD101584 was somewhat similar to a stellar struggle.
As the main star became a red giant, it grew enough to wrap its mate. On the other hand, the smallest star shifted in a spiral towards the giant’s core, but did not collide with it. On the contrary, this maneuver caused the largest star to explode, dispersing its gas layers and exposing its core, clarifies the ESO.
The ‘death process’
Like people, stars change with age and ultimately die. For the Sun and similar stars, this change will lead to a phase in which, having burned all the hydrogen in its nucleus, it will expand to become a large and bright red giant star. Finally, the dying Sun will lose its outer layers, leaving behind its core: a hot, dense star called a white dwarf.
“The star system HD101584 is special, in the sense that this ‘death process’ ended prematurely and dramatically when a nearby low-mass companion star was swallowed by the giant, ” said Hans Olofsson of the Chalmers University of Technology (Sweden), who directed the work.
According to astronomers, the complex structure of the gas in the nebula HD101584 is due to the spiral path of the smaller star towards the red giant, as well as the gas jets that formed in that process. As a fatal blow to the already defeated layers of gas, these jets moved through the previously expelled material, forming the gas rings and the bright bluish and reddish spots seen in the nebula.
Clues that help solve the puzzle
Scientists hope that this ‘stellar struggle’ will help us to better understand the final evolution of stars like the Sun. For now, “we can describe the death processes of stars, but we cannot explain why or how they exactly happen. HD101584 gives us important clues to solve this puzzle since, currently, it is in a short phase of transition between evolutionary stages that have been better studied, “said Sofia Ramstedt of the University of Uppsala (Sweden).
“With detailed images of the environment of HD101584 we can make the connection between the giant star that was before and the stellar remnant it will soon become,” he added.