Dramatic events are afoot in the constellation of Centaurus: A stellar fight to the death. Although the HD101584 star system appears in our sky as one bright light, it actually consists of two stars which are so close together they form a binary system — and one is cannibalizing the other.
Most stars follow a well-known life cycle: After forming and starting hydrogen fusion as a main sequence star, like our sun, they then change color and become red giants when their fuel runs out. Eventually, a red giant will either shed its outer layers to leave behind a core called a white dwarf, or, if it is large enough, it can explode as a supernova and leave behind a neutron star or a black hole.
But HD101584 is different. There, one of the stars had grown so large in its red giant phase that it engulfed the other, swallowing it whole. The smaller star began spiraling toward the larger one, coming close to its core without actually colliding. And this process triggered an outburst from the larger star, in which it threw off its outer layers.
This unusual occurrence has impacted the life cycles of the larger star. “The star system HD101584 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,” lead author Hans Olofsson of the Chalmers University of Technology in Gothenburg, Sweden, explained in a statement.
This fight has left its mark on the system too, with layers of gas spread across the region and the core of the larger star now left exposed. Jets of gas created by the interactions of the two stars spewed outward, which can be seen in the rings of gas traveling out from the nebula.
Studying this particular system with the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder Experiment (APEX) is giving astronomers new insights into how stars die.
“Currently, we can describe the death processes common to many sun-like stars, but we cannot explain why or exactly how they happen,” co-author Sofia Ramstedt from Uppsala University in Uppsala, Sweden, said in the same statement.
“HD101584 gives us important clues to solve this puzzle since it is currently in a short transitional phase between better studied evolutionary stages. With detailed images of the environment of HD101584 we can make the connection between the giant star it was before, and the stellar remnant it will soon become.”
The findings are published in the journal Astronomy & Astrophysics.