Sun-like dying star is producing strange carbon rings while refuting modern theories

About 4.5 billion years ago, as the universe was expanding into what it is today, a hot ball of fire emerged out of a spinning cloud of dust from the solar nebula. Cut to 2022, scientists have discovered many such Sun-like stars which are out there in the universe, some emerging out of dust clouds while some are collapsing under their own weight. Some astronomers are currently observing one such star, which is at the last stage of its life and is behaving strangely.

V Hydrae, the star extraordinaire

Astronomers observing this star named V Hydrae or V Hya using the Atacama Large Millimeter/submillimeter Array (ALMA) came to know that it is a red giant star. What's more, is that this star is located about 1,300 light-years away and has the same mass as our sun. Although, one feature that is unique about V Hya is its companion. Unlike our sun, this red giant has a companion star that is too faint to see but is known to orbit V Hya every 8.5 years. According to astronomers, this sun-like entity has been categorised as a Mira Variable star meaning its brightness fluctuates approximately every 530 days. 

According to scientists, this is a common characteristic in dying stars as they consume heavier elements to survive, which causes a period of oscillation, resulting in heating and cooling of their core. Astronomers have also found the atmosphere of V Hya to be very sooty owing to the carbon fused in its core.

V Hya and our sun

By studying this unique star, astronomers are trying to better understand dying stars. As for V Hya, scientists have found six strange and thick rings of carbon which they say were ejected over the course of 1,200 years. According to ALMA observations, the star has been concluded to be an Asymptomatic Giant Branch (AGB) star, which is a stage almost 90% of stars have to go through. Until now, existing theories suggest that during the AGB period, a star sheds off its outer layers following which its core collapses into a white dwarf. Interestingly, V Hya suggests that this is not always the case.

According to existing theories, an ever-expanding nebula called planetary nebula is produced whenever a star sheds off its outer layers, however, the ALMA observations have shown no such sign around V Hya. Instead, the star is ejecting jets of gas perpendicular to the rings. For now, the astronomers will carry on with their observations to determine if this is common in most AGB stars or just V Hya. Scientists are eager to learn more about such an unusual star as they believe our sun is likely to have the same fate. The current generation and many subsequent ones, however, need not worry as this won't happen for the next five billion years. 

Image: ALMA (ESO/NAOJ/NRAO)/S. Dagnello (NRAO/AUI/NSF)