Mysterious Death of Carbon-Rich Star Plays Out Like Six-Ring Circus

Artist’s Conception V Hydrae

Scientists have observed, for the first time, the mysterious death throes of a carbon-rich asymptotic branch star (AGB). V Hydrae’s final act is characterized by the mass ejection of matter into space, resulting in the slow expansion of six rings and the formation of two hourglass-shaped structures shown here in this artist’s conception. Credit: ALMA (ESO/NAOJ/NRAO)/S. Dagnello (NRAO/AUI/NSF)

Scientists studying V Hydrae (V Hya) have witnessed the star’s mysterious death throes in unprecedented detail. Using the Atacama Large Millimeter/submillimeter Array (ALMA) and data from the Hubble Space Telescope (HST), the team discovered six slowly-expanding rings and two hourglass-shaped structures caused by the high-speed ejection of matter out into space. The results of the study are published in The Astrophysical Journal.

V Hya is a carbon-rich asymptotic giant branch (AGB) star located approximately 1,300 light-years from Earth in the constellation Hydra. More than 90-percent of stars with a mass equal to or greater than the Sun evolve into AGB stars as the fuel required to power nuclear processes is stripped away. Among these millions of stars, V Hya has been of particular interest to scientists due to its so-far unique behaviors and features, including extreme-scale plasma eruptions that happen roughly every 8.5 years and the presence of a nearly invisible companion star that contributes to V Hya’s explosive behavior.

V Hydrae

The carbon-rich star V Hydrae is in its final act, and so far, its death has proved magnificent and violent. Scientists studying the star have discovered six outflowing rings (shown here in composite), and other structures created by the explosive mass ejection of matter into space. Credit: ALMA (ESO/NAOJ/NRAO)/S. Dagnello (NRAO/AUI/NSF)

“Our study dramatically confirms that the traditional model of how AGB stars die—through the mass ejection of fuel via a slow, relatively steady, spherical wind over 100,000 years or more—is at best, incomplete, or at worst, incorrect,” said Raghvendra Sahai, an astronomer at NASA’s Jet Propulsion Laboratory, and the principal researcher on the study. “It is very likely that a close stellar or substellar companion plays a significant role in their deaths, and understanding the physics of binary interactions is both important across astrophysics and one of its greatest challenges. In the case of V Hya, the combination of a nearby and a hypothetical distant companion star is responsible, at least to some degree, for the presence of its six rings, and the high-speed outflows that are causing the star’s miraculous death.”

Mark Morris, an astronomer at UCLA and a co-author on the research added, “V Hydra has been caught in the process of shedding its atmosphere—ultimately most of its mass—which is something that most late-stage red giant stars do. Much to our surprise, we have found that the matter, in this case, is being expelled as a series of outflowing rings. This is the first and only time that anybody has seen that the gas being ejected from an AGB star can be flowing out in the form of a series of expanding ‘smoke rings.’”

Dying Carbon-Rich Star V Hya

Scientists studying the dying carbon-rich star V Hya have discovered six slowly expanding rings forming as the star expels its matter. Shown here in composite, these outflowing rings and the diffuse arc structure of the sixth ring are moderately visible in the 12CO carbon isotope emission line, and become well-defined in views of the 13CO carbon isotopes. These rings are part of a previously unknown story about the death of stars, and are helping scientists to unravel what happens in the “final act.” Credit: ALMA (ESO/NAOJ/NRAO)/S. Dagnello (NRAO/AUI/NSF)

The six rings have expanded outward from V Hya over the course of roughly 2,100 years, adding matter to and driving the growth of a high-density flared and warped disk-like structure around the star. The team has dubbed this structure the DUDE, or Disk Undergoing Dynamical Expansion.

“The end state of stellar evolution—when stars undergo the transition from being red giants to ending up as white dwarf stellar remnants—is a complex process that is not well understood,” said Morris. “The discovery that this process can involve the ejections of rings of gas, simultaneous with the production of high-speed, intermittent jets of material, brings a new and fascinating wrinkle to our exploration of how stars die.”

Sahai added, “V Hya is in the brief but critical transition phase that does not last very long, and it is difficult to find stars in this phase, or rather ‘catch them in the act. We got lucky and were able to image all of the different mass-loss phenomena in V Hya to better understand how dying stars lose mass at the end of their lives.”

V Hydrae Star Chart

V Hydrae is a carbon-rich star located 1,300 light-years away in the constellation Hydra. It is the subject of recent observations revealing the violent deaths of stars, which include, in the case of V Hya, explosive ejections of plasma into space that shape the structural environment around the star. Credit: IAU and Sky & Telescope

In addition to a full set of expanding rings and a warped disk, V Hya’s final act features two hourglass-shaped structures—and an additional jet-like structure—that are expanding at high speeds of more than half a million miles per hour (240 km/s). Large hourglass structures have been observed previously in planetary nebulae, including MyCn 18 —also known as the Engraved Hourglass Nebula—a young emission nebula located roughly 8,000 light-years from Earth in the southern constellation of Musca, and the more well-known Southern Crab Nebula, an emission nebula located roughly 7,000 light-years from Earth in the southern constellation Centaurus.

Sahai said, “We first observed the presence of very fast outflows in 1981. Then, in 2022, we found a jet-like flow consisting of compact plasma blobs ejected at high speeds from V Hya. And now, our discovery of wide-angle outflows in V Hya connects the dots, revealing how all these structures can be created during the evolutionary phase that this extra-luminous red giant star is now in.”

Due to both the distance and the density of the dust surrounding the star, studying V Hya required a unique instrument with the power to clearly see matter that is both very far away and also difficult or impossible to detect with most optical telescopes. The team enlisted ALMA’s Band 6 (1.23mm) and Band 7 (.85mm) receivers, which revealed the star’s multiple rings and outflows in stark clarity.

“The processes taking place at the end stages of low mass stars, and during the AGB phase in particular, have long fascinated astronomers and have been challenging to understand,” said Joe Pesce, an astronomer and NSF program officer for NRAO/ALMA. “The capabilities and resolution of ALMA are finally allowing us to witness these events with the extraordinary detail necessary to provide some answers and enhance our understanding of an event that happens to most of the stars in the Universe.”

Sahai added that the incorporation of infrared, optical, and ultraviolet data into the study created a complete multi-wavelength picture of what might be one of the greatest shows in the Milky Way, at least for astronomers. “Each time we observe V Hya with new observational capabilities, it becomes more and more like a circus, characterized by an even bigger variety of impressive feats. V Hydrae has impressed us with its multiple rings and acts, and because our own Sun may one day experience a similar fate, it has us at rapt attention.”

Research

  • “The rapidly evolving AGB star, V Hya: ALMA finds a multi-ring circus with high velocity outflow,” Sahai et al, (2022), The Astrophysical Journal, preprint: arXiv:2202.09335

Resources

  • “Discovery of very high velocity outflow in V Hydra – Wind from an accretion disk in a binary?” Sahai, R. & Wannier, P. G. (1988), Astronomy & Astrophysics, ADS: 1988A&A…201L…9S
  • “V Hydrae: the missing link between spherical red giants and bipolar planetary nebulae? Radio observations of the molecular envelope,” Kahane et al (1996), Astronomy & Astrophysics, ADS: 1996A&A…314..871K
  • “A collimated, high-speed outflow from the dying star V Hydrae,” Sahai et al (2003), Nature, 426, 261, DOI: 10.1038/nature02086
  • “High-velocity bipolar outflow and disklike envelope in the carbon star V Hydrae,” Hirano et al (2004), The Astrophysical Journal, DOI: 10.1086/424382
  • “High-Speed Bullet Ejections during the AGB to Planetary Nebula Transition: HST Observations of the Carbon Star, V Hydrae,” Sahai, R., Scibelli, S., & Morris, M.R. (2016), The Astrophysical Journal, DOI: 10.3847/0004-637x/827/2/92

8 Comments on "Mysterious Death of Carbon-Rich Star Plays Out Like Six-Ring Circus"

  1. Mike Pollock | March 29, 2022 at 4:52 am | Reply

    This is hardly the death of a star. This is the beginning of the life of a solar system. Those rings are no different than the ones that circle Saturn or the ring of planets that circle our Sun. The process is always the same. All celestial objects begin their lives as masses of quark plasma which is invisible and can make shapes. This is the plasma black holes are made of. This mass is creating the system that will orbit its central mass for the next billions of years. It is obvious that it isn’t dying because of the plentiful invisible energy it still produces. Eventually, based on the violent impacts this system may receive, it will create planets just as our solar system has done. That is the significant of the separate rings that have already been created. Parts of the system are now visible because quark plasma starts generating visible light as it cools by forming neutrons on the surface of masses.

    • You have no idea what you are talking about. Notice the title “Carbon Rich Star”? That means that the star is at the end of its nuclear fusion run, as all of its fusible elements have been converted to heavier elements getting closer and closer to the end of exothermic fusion events with the generation of Iron-56. Based on your comments I find it laughable that you seem to think that you know better than these astrophysicists and some random guy like me who at least understands the R and S processes or nuclear fusion. I have no idea what you think you mean saying that black holes are mae of plasma. What comes right before a black hole in terms of mass density? A neutron star, a star where the gravity is so intense that the electrons are forced into bonding with the protons making neutrons, all neutrons. And when all there is is neutrons, then there isn’t any plasma as by definition, plasma is free electrons and nuclei bouncing around with such great energies that gravity seems irrelevant. You state that it isn’t dying because of the invisible energy? Well how do you know there is energy if it is invisible. You sound like some kind of psychiatric patient who thinks they are smarter than everyone. Deluded. Dunning Krueger effect in vivo eh?

      • Martard, you have no idea what you’re talking about.
        What kind of star looks like that? What kind of star has rings? The carbon is in the rings where the matter has cooled enough to create the carbon. When I say invisible, I mean optically invisible. Didn’t you notice which telescopes wer used to examine this system?
        I want to sound confusing to you because everything you think is wrong. Do you understand black holes? Do you understand the force that causes gravity? Do you understand supernovae? Do you understand how a universe fits in a neutrino? Do you understand why fusion isn’t giving science what they thought it would?
        The answer to all those questions is no because of the incredibly lacking theory you believe in. You don’t have any idea why those rings are there. You don’t know how that carbon got there. All you know is the Big Bang theory and all I know is all the laws it breaks to exist. That’s why you find my comment so confusing. Didn’t you even read the article?

        “Our study dramatically confirms that the traditional model of how AGB stars die—through the mass ejection of fuel via a slow, relatively steady, spherical wind over 100,000 years or more—is at best, incomplete, or at worst, incorrect”

        You act like everything is perfect when it isn’t. That’s why you can’t fathom the thought of a different theory explaining what they can’t. Get over it. That is how paradigm shifts work.

        • Mike Pollock | March 30, 2022 at 1:22 am | Reply

          Also martard, let me explain this to you.
          You think a neutron star comes before a black hole? You think there was a neutron star before the black hole in the center of our galaxy. Why? Black holes are minimum entropy objects. After the neutron star created our black holes, where did all the other matter come from? Why didn’t the black hole simply suck in all of the galaxy?
          Why do you think a black hole is in the center of our galaxy and the stars nearest to it are neutron stars and blue stars? It’s called entropy and it only goes one way. Black holes eventually cool to neutron stars. Neutron stars cool to blue stars. Blue stars cool to yellow stars. Yellow stars cool to orange stars. Orange stars cool to red stars. Red stars cool to brown stars. Brown stars cool to planets. All the while, quark plasma is giving the star the energy to do all of it. It’s called the conservation of energy where kinetic energy turns to potential energy. You think gravity created everything when it was actually a massive collision in space that frated all the energy we see. That’s why you have no idea how the the force of gravity is created.

          • Ah conspiracy theorist who thinks they can disprove relativity…… Lol, I wouldn’t have said anything to you if I had known you were the science equivalent of a trump supporter. Let me guess, all of these nucleosynthetic occurrences probably happened in the past 10,000 years in order to satisfy your bronze ago goat herder mythology too right? I mean what is the point of learning things over decades if you can just make it up as you go along. Please explain your version of the R and S process please. Also list out your version of the weak, strong and nuclear forces. I want to see it here first before you win the intergalactic nobel prize. Lololooll, great entertainment at the least. But again, why are you not writing articles for this publication if you know so much better?

          • Mike Pollock | March 30, 2022 at 6:01 am |

            So maytard, you DIDN’T read the article. Ok. Enough said.

  2. Babu lives in a fantasy world.

  3. Wow, and therefore god, the most implausible of theories hailed as supreme. How about the universe is a complex thing about which we can only speculate through very limited observational lenses. And as we try to understand, we learn. That is what I read.

    Science and faith both end in the same place, wherever you feel comfortable stopping asking questions. Science satisfies those who want to know more, religion satisfies those who are content to know less. Spend a lifetime trying to prove/disprove the last observation, or spend a lifetime trying to prove/disprove the next observation. What is, simply is. With that the scientist and theologian become the same person.

    When you take into account the universe may be very large or small (all very relative), one thing is relatively certain from at least our perspective, compared to us, it is quite vast, and likely contains not much aside from our selves that care for our explanations of it.

    So science or faith? “Science does not explain the whole universe!”
    That in a nutshell is an excellent argument, until you attribute it to even less evidence…

Leave a Reply to Martard Cancel reply

Email address is optional. If provided, your email will not be published or shared.