Telescope Catches Beautiful Outcome of Stellar Fight

The outcome of a stellar fight of the binary HD101584. The colors represent speed, going from blue (gas moving the fastest toward us) to red (gas moving the fastest away from us). Jets propel the material in blue and red. The stars are at the single bright dot at the center of the ring-like structure shown in green, which is moving with the same velocity as the system. Astronomers believe this ring has its origin in the material ejected as the lower mass star in the binary spiraled towards its red-giant partner. (ALMA [ESO/NAOJ/NRAO], Olofsson et al. Acknowledgement: Robert Cumming)
(CN) – Scientists have observed a faraway struggle between two stars that left both celestial bodies a little worse for wear.

In a study published Wednesday in Astronomy & Astrophysics, a team of astronomers reveal their discovery of a distant gaseous body, dubbed HD 101584, that appears to be the direct result of two stars engaged in what they call a remarkable cosmic fight. The team made their startling discovery using a collection of radio telescopes known as the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile, and the findings gleaned from the apparent battle could shed some much-needed light on the evolution of stars.

The team believes the struggle began when a large star ballooned to become red giant, a massive star form occurring relatively late in a star’s life cycle. The red giant then began to absorb a far smaller nearby star. Rather than allowing itself to be consumed by the red giant, however, the smaller star did something unexpected: it fought back.

Using great jets of gaseous material as a propellant, the smaller star spiraled toward the red giant and began to navigate around the giant’s outer layers. While not making any direct contact, the small star used its gas propellers to force the red giant into prematurely losing its protective outer layers, leaving behind only a hot and exposed inner core.

Astronomers report that while this process is not unheard of given that red giants are known to shed their outer layers and transform into white dwarfs toward the end of their lives, what makes this occurrence so unique is that this particular red giant lost its outer layers by force.

Hans Olofsson of the Chalmers University of Technology, Sweden, and leader of the study says astronomers are able to make these observations not only because this cosmic event took place quite recently, but also because the smaller star survived its aggressive encounter with the red giant.

“Our object is important in this context because the process started relatively recently, less than a thousand years ago, so that the ejected material remains around the system and its properties can be studied in detail,” Olofsson said in an email. “Another important fact is that the companion survived and stopped at some distance away from what remains of the red giant, and this means that we can estimate how much energy was liberated as the companion spiraled inwards and compare this with the kinetic energy of the ejected gas.”

The study notes the findings also provide some interesting perspectives to consider when looking at the life cycle of our own sun. In a few billion years, after our sun has exhausted its supply of gases, it will also shed its outer layers and become a white dwarf – not unlike the red giant at the heart of HD 101584 – though hopefully under far less combative circumstances.

Sofia Ramstedt, a co-author of the study from Uppsala University, Sweden, says the discovery could help researchers to better understand the complex, and occasionally unpredictable, life cycles of stars.

“Currently, we can describe the death processes common to many sun-like stars, but we cannot explain why or exactly how they happen,” Ramstedt said with the release of the study. “HD 101584 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 HD 101584 we can make the connection between the giant star it was before, and the stellar remnant it will soon become.”

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