Mysterious death of carbon star plays out like six-ring circus —

Scientists finding out V Hydrae (V Hya) have witnessed the star’s mysterious dying throes in unprecedented element. Utilizing the Atacama Massive Millimeter/submillimeter Array (ALMA) and knowledge from the Hubble House Telescope (HST), the workforce found six slowly-expanding rings and two hourglass-shaped constructions brought on by the high-speed ejection of matter out into area. The outcomes of the examine are revealed in The Astrophysical Journal.

V Hya is a carbon-rich asymptotic large department (AGB) star situated roughly 1,300 light-years from Earth within the constellation Hydra. Greater than 90-percent of stars with a mass equal to or higher than the Solar evolve into AGB stars because the gasoline required to energy nuclear processes is stripped away. Amongst these tens of millions of stars, V Hya has been of explicit curiosity to scientists as a result of its so-far distinctive behaviors and options, together with extreme-scale plasma eruptions that occur roughly each 8.5 years and the presence of an almost invisible companion star that contributes to V Hya’s explosive conduct.

“Our examine dramatically confirms that the standard mannequin of how AGB stars die — by way of the mass ejection of gasoline through a gradual, comparatively regular, spherical wind over 100,000 years or extra — is at greatest, incomplete, or at worst, incorrect,” stated Raghvendra Sahai, an astronomer at NASA’s Jet Propulsion Laboratory, and the principal researcher on the examine. “It is vitally possible {that a} shut stellar or substellar companion performs a big position of their deaths, and understanding the physics of binary interactions is each essential throughout astrophysics and considered one of its biggest challenges. Within the case of V Hya, the mix of a close-by and a hypothetical distant companion star is accountable, at the very least to some extent, for the presence of its six rings, and the high-speed outflows which can be inflicting the star’s miraculous dying.”

Mark Morris, an astronomer at UCLA and a co-author on the analysis added, “V Hydra has been caught within the technique of shedding its environment — finally most of its mass — which is one thing that almost all late-stage pink large stars do. A lot to our shock, we have now discovered that the matter, on this case, is being expelled as a collection of outflowing rings. That is the primary and solely time that anyone has seen that the fuel being ejected from an AGB star will be flowing out within the type of a collection of increasing ‘smoke rings.'”

The six rings have expanded outward from V Hya over the course of roughly 2,100 years, including matter to and driving the expansion of a high-density flared and warped disk-like construction across the star. The workforce has dubbed this construction the DUDE, or Disk Present process Dynamical Growth.

“The top state of stellar evolution — when stars bear the transition from being pink giants to ending up as white dwarf stellar remnants — is a fancy course of that’s not nicely understood,” stated Morris. “The invention that this course of can contain the ejections of rings of fuel, simultaneous with the manufacturing of high-speed, intermittent jets of fabric, brings a brand new and interesting wrinkle to our exploration of how stars die.”

Sahai added, “V Hya is within the temporary however important transition section that doesn’t final very lengthy, and it’s tough to search out stars on this section, or fairly ‘catch them within the act. We obtained fortunate and had been capable of picture all the totally different mass-loss phenomena in V Hya to higher perceive how dying stars lose mass on the finish of their lives.”

Along with a full set of increasing rings and a warped disk, V Hya’s remaining act options two hourglass-shaped constructions — and an extra jet-like construction — which can be increasing at excessive speeds of greater than half 1,000,000 miles per hour (240 km/s). Massive hourglass constructions have been noticed beforehand in planetary nebulae, together with MyCn 18 — also referred to as the Engraved Hourglass Nebula — a younger emission nebula situated roughly 8,000 light-years from Earth within the southern constellation of Musca, and the extra well-known Southern Crab Nebula, an emission nebula situated roughly 7,000 light-years from Earth within the southern constellation Centaurus.

Sahai stated, “We first noticed the presence of very quick outflows in 1981. Then, in 2022, we discovered a jet-like move consisting of compact plasma blobs ejected at excessive speeds from V Hya. And now, our discovery of wide-angle outflows in V Hya connects the dots, revealing how all these constructions will be created throughout the evolutionary section that this extra-luminous pink large star is now in.”

On account of each the space and the density of the mud surrounding the star, finding out V Hya required a novel instrument with the facility to obviously see matter that’s each very distant and in addition tough or unimaginable to detect with most optical telescopes. The workforce enlisted ALMA’s Band 6 (1.23mm) and Band 7 (.85mm) receivers, which revealed the star’s a number of rings and outflows in stark readability.

“The processes going down on the finish phases of low mass stars, and throughout the AGB section specifically, have lengthy fascinated astronomers and have been difficult to know,” stated Joe Pesce, an astronomer and NSF program officer for NRAO/ALMA. “The capabilities and determination of ALMA are lastly permitting us to witness these occasions with the extraordinary element vital to offer some solutions and improve our understanding of an occasion that occurs to a lot of the stars within the Universe.”

Sahai added that the incorporation of infrared, optical, and ultraviolet knowledge into the examine created a whole multi-wavelength image of what may be one of many biggest reveals within the Milky Approach, at the very least for astronomers. “Every time we observe V Hya with new observational capabilities, it turns into an increasing number of like a circus, characterised by a good greater number of spectacular feats. V Hydrae has impressed us with its a number of rings and acts, and since our personal Solar could someday expertise an identical destiny, it has us at rapt consideration.”