The death throes of a red giant star have been seen in unprecedented clarity by astronomers, exhibiting an unusual trait. V Hydrae (or V Hya for short) was a star that ejected six different rings of material. The exact mechanism in which these intriguing “smoke rings” develop is still unknown. V Hya is an asymptotic giant branch (AGB) star with a lot of carbon. It’s in the constellation Hydra, some 1,300 light-years away from the Earth. So far, due to its unique behaviour and properties, including incredibly big plasma explosions that occur every 8 years or so, V Hya has piqued the interest of scientists amid millions of stars.
This discovery was made by scientists from the University of California, Los Angeles (UCLA) and NASA’s Jet Propulsion Laboratory (JPL). It has the potential to upend current models for this late stage of stellar evolution and shed more light on the Sun’s fate.
The researchers discovered that the carbon-rich star had ejected six gradually increasing molecular rings and an hourglass-shaped structure that is rapidly expelling matter into space, indicating that the star is undergoing rapid evolution as it approaches its end.
The findings were published in The Astrophysical Journal.
“This is the first and only time that a series of expanding rings has been seen around a star that is in its death throes — a series of expanding ‘smoke rings’ that we have calculated are being blown every few hundred years,” Mark Morris, a UCLA professor of physics and astronomy and a co-author of the study, was quoted as saying in a UCLA press release.
The study was conducted using the Atacama Large Millimeter/submillimeter Array, known as ALMA, and data from the Hubble Space Telescope.
Morris went on to add that they had caught this dying star “in the process of shedding its atmosphere”, as is typical of late-stage red giant stars. However, to the surprise of the researchers, they discovered “that the matter, in this case, is being expelled as a series of rings”.
The researchers also saw high-speed gas blasts ejected in two different directions, perpendicular to the rings.
Talking about the mechanism that produced these rings, though Morris said it was unknown, he went on to add that it might be “related to the presence of orbiting companion stars”.
“But it is difficult to explain that given the few-hundred-year interval between ring ejections,” Morris said.
The finding suggests that earlier assumptions regarding star deaths may be incorrect, according to Raghvendra Sahai, an astronomer at JPL and the study’s primary author. “Our study dramatically reveals that the traditional model of how AGB stars die — through the mass ejection of fuel via a slow, relatively steady, spherical wind over 1,00,000 years or more — is at best, incomplete, or at worst, incorrect,” said Sahai.
