The Ring Nebula

Ring Nebula, JWST

Sometimes a project becomes remarkable. Some years ago we started thinking about what to do with the James Webb Space Telescope, whenever it would become available. An idea was developed and we worked out what kind of data would be needed. It turned out to be feasible, so we proposed it.

That is harder than it sounds. JWST has ‘proposal deadlines’: about once a year people can send in their proposals. They have to be complete with a strong science case saying what would be learned from it and why that is important to current science. A detailed explanation is needed of what has been done before, what are the open questions, and how your observations will address those. The science case alone can be many pages. The observations need to be fully defined: which targets, which instruments, which filters or gratings, how long each, and of course why each of these. You calculate the overheads (how long will the telescope take to slew and acquire the target, how long does it take to change filters, what kind of calibration is needed, etc. A team is formed who can carry out the analysis. Hit the ‘submit’ button and wait.

JWST will get 10 times as many requests as it can accommodate. Panels of scientists read and judge the applications and pick the 5-10% best ones. After some months, the announcements arrive, with 90% or more of the applicants left disappointed.

We were lucky. The panels liked our idea and it would not take too much time to carry out – that means, typically 10-20 hours although some observations are shorter or longer. We did further preparations, submitted the final observational setups and waited again. Now JWST was launched and moved out to its location beyond the moon, far from Earth. It took 6 months before everything was working, all problems sorted out, and the ‘features’ of the instruments were understood. Science observations began in July 2022. It so turned out that our observations were among the very first to be scheduled. That was pure luck as at any time the telescope can only look at a part of the sky. If your target is not in there, you will have to wait until the Earth and Sun have moved out of the way. There was nothing for to do: the observations were set from the control centres by qualified people after extensive checking. We were not allowed anywhere near the telescope. After, the data us checked for quality and any mishaps, and if ok passed on to the proposers. For us, some of the data was taken in the first week of July, and a second set later in August.

The unfolding of JWST

The data turned out to be spectacular. But understanding all the idiosyncrasies took a long time. The Space Telescope institute developed software to calibrate the data and remove all problems. That took time. By January we were happy with the data and started work. It got busy. If you are wondering why so few posts here recently, I was (still am) a JWST captive.

The target of our observations was the Ring Nebula.It is a small object in the northern sky, discovered in the 18th century by Charles Messier and a few weeks later by Antoine Darquier, possibly because Messier told him. Darquier wrote about it and is therefore often credited with the discovery, but it has a number in the Messier catalogue (M57, to be precise). Neither was interested in it: they were hunting comets and it so happened one was near this little nebula. Darquier compared to a ‘fading planet’. The name stuck, and we still call it a ‘planetary nebula’

We now know some 3000 planetary nebulae in our Milky Way galaxy. They range in size from pinpricks looking like stars to nebulae appearing as large as the Moon. The collage below was made by David Frew, Ivan Bojicic and Quentin Parker at the University of Hong Kong. It shows the variety of shapes and sizes, scaled to their proper physical size in space. The range of structures is amazing. Messier and Darquier knew nothing about this. All they saw through their small telescope was a small cloud. The ring shape is though recognizable through even a small telescope. Using a telescope the size of JWST is definitely overkill.

So what are they? Clearly planetary nebulae have nothing to do with planets. It turns out, they are stars just after their death. The nebulae almost always have a faint star dead centre. That star is the cause of the nebula. The star is dead. It is still hot (very hot) and luminous, but that is from recent days. It has used up all its hydrogen and even helium and can generate no more energy. At the very end, in a moment of madness, sorry in a well-defined process of physics, it ejected its remaining envelope with all of its left-over fuel. Now it is sitting there, half the star it used to be, and is beginning a phase of cooling and fading that will last for the rest of the life of the Universe. Why so hot? That is because you are looking at the core of the star, a Fukushima without the shell. Why still luminous? That is because stars at the very end become very bright. Our Sun will become 6000 times brighter than it is now. Why so faint? That is because it is hot. All the energy is coming out in the far ultraviolet which we can’t see. But the energy it is radiating away cannot be replaced. It is on its final journey to nowhere.

We are studying those shells, the nebulae that the star ejected. Where do all those amazing structures come from? Stars are round, so why these nebulae? The solar wind does not look like that. How does the material in the nebulae change? We see different colours throughout – why? And finally, how and why does the star eject so much mass? They only ever do it at the very end.

The images of the Ring Nebulae are fantastic. They have higher resolution than the Hubble Space telescope (at least some of the images we have do) and show very different aspects.

This is the Hubble image of the Ring Nebula. It shows the vibrant colours, but also details of the structure. The colours come from different elements. The nebula is ionized by the star and becomes a plasma. (Think the inside of lightning.) The hottest gas is closest to the star and is bright in oxygen which shines blue-green. Further out the gas is a bit cooler and there it shines mainly in nitrogen and hydrogen, which looks red. Of course we can make the images any colour we want, but we often (not always) try to stay close to the natural colours.

Around the ring you can see several fainter, broken rings, forming a halo. In the main ring you can see a few dark clumps, dense enough that they absorb light from behind them. And in the centre one can see that dying star.

The JWST images show the nebula differently, different from how we have ever seen it before.

JWST NIRcam image. Credit: Roger Wesson et al

So what do we see? Can’t tell you. We have more images that are not yet public. But some details are obvious. The ring is very broken here. (It isn’t really a ring but a torus that we see almost pole-on.) Clumps are everywhere. I counted 25,000 clumps. We used a software program designed to find clumps – it counted 17,000. I think my number is better. We estimate that half of the gas in the ring is in those clumps. We have ideas on how the clumps formed. They are so dense that the gas inside is shielded from the hot star and has started to form molecules. Some have started to form short tails, becoming like planet-sized comets. The halo shows a wealth of structure. One of these is a series of hundred of spikes or rays, pointing directly away from the star. They seem illuminated by light coming through holes in the shell. But we don’t see the holes.

What does it mean for us? Well, it is good entertainment, I guess. But there is a point of personal interest. Some of the gas in the shell becomes cool enough to condense. About 1% consists of condensable materials, such as silicon and iron. They form small dust grains. Those dust grains travel with the gas and in some 10,000 years will become part of interstellar space. And perhaps a few hundred million years later, they find themselves, much changed but still with a core that came from the planetary nebula, in a region where new stars form. Now they have an important role to play. For while the gas forms the star, the dust clumps together and grows bigger. And bigger. Eventually, it forms planets. Our Earth formed in this way. And there is more. The material ejected by the star contained products of its nuclear burning. When helium fuses, it produces carbon. Much of the carbon in space comes from here, from stars like the one forming the Ring Nebula. The Earth managed to capture a thin cover of carbon. Add some water and you get hydrocarbons. Add nitrogen, and you get the building blocks of life. Eventually, you get us, complete with a nice planet to live on and a nice star right next door to keep us warm.

This is the process we are studying, an ever richer cycle of matter in space where stars form, die and new stars form enriched by the debris, now with a consortium of planets. One day they too will die and add their ashes to the Universe, renewing the cycle. It has been called (thanks, Xander) a galactic ecology.

And this is what we are studying. That dead star in the Ring Nebula is leaving us a legacy. And by studying the Ring Nebula perhaps we can understand this ecology a little better. I am only a part of a team (and everything was awesome). Other people did much of the work and deserve the credit. But it has been a rewarding experience.

Albert, August 2023

A proposal to build another JWST out of lego.

309 thoughts on “The Ring Nebula

    • I saw this earlier today, it bears several more viewings.
      The creator equivocated about exactly where he was standing to fly the drone…

    • A fitting tribute to a fascinating volcanic episode… I have really enjoyed watching this eruption from birth to death, it is so lovely to have this memory of it. Many thanks for posting it Tomas as I also had not seen it.

  1. On the topic of magma maficness vs. eruption explosiveness, might I venture a hypothesis?

    First, we have to distinguish true explosions (so, basically, strombolian, vulcanian, and plinian eruptions, the ultra-plinian HTHH/Krakatoa type events, phreatic blasts, and whatever it is that Etna does that makes those sky-high fountains) from false explosions (dome collapses, pelean eruptions, and other non-plinian sources of pyroclastic flows).

    We then find that “grey” eruptions divide into three broad groups: ones with a plinian/ultra-plinian component or else maar formation, pelean eruptions without such a phase, and dome collapse type activity. The third actually is related to more viscous magma, especially if combined with steep slopes, so is mainly a stratovolcano thing. Pure-pelean eruptions can be mafic and occur because the roof of the magma chamber falls right in: if an outward-dipping fault develops, the roof can just drop straight down. This is buoyancy driven and becomes “grey” from sheer effusion rate. It’s like a pot boiling over in the kitchen and spilling across the surrounding landscape. Highly destructive but not actually an explosion. The vulcanian, plinian, and more aggressive strombolian eruptions and their scaled-up kin, plus maar blasts, all have a single thing in common: water. The magma is rich not just in gases in general, but water vapor in particular; or else there is magma-water interaction, such as in maar formation events. Subduction volcanoes are given to these because the melt is enriched in water derived from subducted seawater. Intraplate volcanoes and those at divergent boundaries are water-poor and don’t tend to explode … not even Yellowstone, which alternates between effusing anything from basalt to rhyolite nonexplosively and having the caldera lid cave in catastrophically. Is there any evidence for plinian eruptions at Yellowstone, or just pelean eruptions and “red” eruptions?

    What makes water so explosive? It’s probably two things. One, water has a huge specific heat, so hot water holds a vast amount of thermal energy that can abruptly convert to kinetic energy if the water is depressurized fast and boils abruptly, causing heat energy to go into providing the heat of evaporation. Second, water is one of the last gases to exsolve, so it waits until the magma is nearing the surface and then comes out all at once, rather than emerging more gradually starting at a greater depth. So this large release of energy happens rapidly and close to the surface, rather than, say, two kilometers down in the case of CO2.

    One thing that would be predicted from this is that mafic volcanoes will explode harder when they do explode, because the magma temperature tends to be much higher, and thus the heat energy content in the water. This explains why the really colossal blasts, like Krakatau and HTHH, occurred in basaltic volcanoes. There the water could hold a monstrous amount of energy, converting from supercritical water at 1100C to steam at a few hundred C in moments and all of the remaining energy turned into expansion of the steam cloud. Kaboom. Compare St. Helens whose water content may have been at “merely” six or seven hundred degrees when it exsolved. So, if a mafic volcano has a water-rich magma chemistry, however mafic, look out!

    • Nice hypothesising! Although I ‘m not fully sure about everything. Krakatau 1883 was a dacite eruption. And the most violent eruptions in terms of ignimbrite extent are the rhyolite eruptions of the Taupo Volcanic Zone and some other locations, like the Taupo Ignimbrite, or the supreme Kidnappers Ignimbrite.

    • We have to divide between three general types of explosive eruptions:
      1. “Wet” explosive eruptions: Phreatomagmatic/phreatic eruptions. Maar, Surtseyan (incl. glacier surtseyan) and phreato-strombolian, phreato-plinian eruptions. Also explosive ocean entries of lava flows. Everything that’s explosive by heat/water and magma/water interaction belongs to these “wet” explosive type.
      2. Viscousity driven explosions: Viscous magma/lava blocks the exit of magma to the surface. Pressure rises until the block is crashed and the whole volcanic “Bottle” explodes like Pinatubo, St. Helens and Vesuvius 79. Usually this type of explosions is plininan, but it can also be sub-plinian, pelean or vulcanian.
      3. Gas driven explosivity: Sometimes magma is very gasrich and can by itself cause explosive eruptions if the pressure of the surrounding rocks decreases below a certain level. Hector had an arcticle about volcanoes like this in southern Germany (Hegau). Also Etna sometimes does explosive eruptions of this type, if new magma rises very quick from the mantle. Even Stromboli’s major explosive eruptions can be seen as part of this type. It can do maar eruptions, strombolian, vulcanian, pliniian.

      • All of your exploders in categories 2 and 3 seem to be subduction volcanoes, so have water-rich magmas. I expect the category 2 cases amount to a boiler failure: there’s a head of steam (or supercritical water) under the plug when it fails. A plinian eruption is basically a scaled-up shotgun blast, or a whole series of them, aimed (usually) straight up (but see e.g. St. Helens, where it went sideways, to devastating effect).

        Most explosions in Iceland appear to be from magma interacting with water (often in the form of ice). Hekla’s explosive throat-clearings may be an exception. I wonder if its magma chemistry contains extra water, from some source, compared to the “dry” MORB/hotspot magmas predominant elsewhere in Iceland.

        • Hekla does have weird magma, not sure of the water content but the fluorine is also weird, Icelandic magmas are usually very low in halogens and high in sulfur, very similar to Hawaii. But the basaltic volcanism in the immediate area around Hekla is not abnormal at all for the area, to me this really only leaves extensive crustal contamination and melting as a cause. Hekla is an evolved central volcano too despite being young and without a magma chamber at a shallow depth, so another reason to suspect contamination, as well as a possible second source too.

  2. Kilauea is inflating enthusiastic again. Uwekahuna is going up at over 1 microradian per day. Has a new surge hit? Things were starting to slow down a little since the late June-early July surge, but it looks like things could be ramping up again. Although I might be a bit impatient to say this after only two days of increased deformation. Mauna Loa’s DLP earthquakes have mostly calmed down, although there was one this week so not entirely. Mauna Loa is playing its usual game of inflating for a month or so and then deflating rapidly although not as much as the preceding inflation.

    • Did you see that the ERZ connector is finally active again? Still small in comparison to the SWRZ connector but it is definitely there. Interestingly though it only seems to extend to Puhimau crater where the caldera fault is, and where a sizable quake happened that was visible as a small jump on the U’ekahuna tiltmeter. Seems like something just broke in that direction.

      So now we have the lake getting higher and prone to fast violent fissure eruptions, and now both of the rifts are starting to activate. Your reseatch and prediction of 950 meters lake elevation to get rift eruptions might be pretty spot on. The lake is apparently at 920 metets now, so it is not unlikely to get 30 meters higher in the next year at the rate things are going now.

      • Yes, saw that, although I don’t think the Keanakakoi-Puhimau area flaring is something new. I would want to see earthquakes down to Mauna Ulu.

      • Maybe the whole Caldera is inflating and pushing the upper RZ. I see that earthquakes happen on a line from Halema’uma’u to Kilauea Iki. The next eruption can be a fissure line through the whole caldera like 1982.

  3. There is a small glowing patch of lava visible in the lower right corner on the MBL wide field camera.
    It became visible around 23:40 once the mist had cleared.

  4. There is also a faint glow from a possible steam vent at the base or Keilir. It could also be a reflection or human activity.
    A shallow quake of 0.135 km. was registered near Keilir yesterday morning.

  5. What is the upper limit for rock planets? How large can rock planets with volcanism be? In our Solar System Earth is the largest rock planet, but there may be stars with larger rock planets.

    The gas planets like Jupiter and Saturn do no volcanism. Why is the solid core not able to create any magma?

    • Indeed the larger a rocky planet is the slower it will cool and the more radioactive heating because of increased volume, so much more volcanism beacuse of that

      Rocky explanets of 10 Earth masses are certain and have been discovered and woud only have 2x Earth gravity so 5 Earth masses woud only yeild 1,5 G with an earthlike composition and only a bit larger than Earth

      10 Earth masses with an earthlike composition woud yeild insane volcanism with increased internal heating ..

      But there are also supermassive terestrial planets thats been discovered some with 40 Earth masses and 4G.. souch objects Maybe having a thick outer atmosphere but some have been suggested to have thinner enveloples.
      Souch woud be giant magma oceans by sheer internal heating I guess

    • Jupiter haves around 20 to 30 Earth masses of sillicate materials mixed in, so at Jupiters very center ( the core is diffuse and very large and gets enriched in heavy elements the further you go in ) at the Jupiter center you may find ultracompressed jovian magma at 24 000 c perhaps even liquid iron.

      But most of Jupiter is liquid metallic hydrogen with lots of sillicate atoms mixed in, and gets pure hydrogen the further from the center you go of Jupiter, Jupiter is mostly gas but there is lots of other stuff inside there .. it sourely swallowed some rocky super earths in its youth

      Jupiters deep interior is a mess there is everything there

      • Jupiter is so hot inside, that it supposedly causes a lot of convection in the atmosphere, that may have similarities to mantle convection. Should we regard the gas layers as something between atmosphere and mantle?

      • Most of the mantle is liquid hydrogen only gassy on top but yes thats likey correct

        I have always wondered what it woud be like to fly in Jupiters upper atmosphere, just above the clouds .. I know that hydrogen will scatter blue light so jovian dayskies woud likley be blue.

        Most of the upper clouds woud probaly look like sheets of cirrostratus, cirrus, with isolated Cumulunimbus towers If you flew above them and the horizon woud be immensely distant because of Jupiters immense size

        In the evening you woud see Jupiters own shadow cast itself on its clear blue upper atmosphere just like it does on Earth ( the fact thats its No surface below woud be disturbing! ) but No idea really what it woud look like

    • I asked this question once, I think in hindsight the limit might just be the electron degeneracy pressure in the core. So in a crazy way the upper limit is the Chandarsekar limit because the planet would become a white dwarf.

      A neutron star is also, technically, a planet. It has a solid surface and a compositionally stratified interior, and a crust with mountains and quakes, although I dont know if they have volcanoes. I dont think it should matter that the ‘solid’ is held together by gravity not electromagnetism. But Albert will probably have many things to say about this 🙂

      In real life the two planets around Kepler 277 are in the range of 70 earth masses and physically between Earth and Neptune in size. Kepler 277b, the more massive of the two, is 87 Earth masses and 2.2 radii.
      There is also a white dwarf that was stripped to its crystaline core by its companion that turned into a pulsar. It is the mass of Jupiter in a volume a bit smaller than Neptune, so it could theoretically be solid with a distinct surface but calling this a terrestrial planet is a bit of a stretch, at least it is not the same sort of thing as the Earth, or the above examples.

    • Kepler 277b Is an Ultra Mercury I guess a sickly large iron core with a relativly thin mantle ( still deeper than Earths mantle ) composed of ultrahigh-pressure phases of magnesium silicates that woud be the materials for magma

      It must have some insane volcanism I guess because of its enormous mass 🙂 lots of heat trapped inside. Woud the core be entirely liquid? its sourely extremely hot because of its size .. or perhaps a solid inner core is possible?

      • I would think it is so large the core is compressed solid most of the way, volcanism might only happen in the same depth range as it does on Earth with the rest of the mantle being held in a rigid state under gravity. But that is without doing any calculations so take with a grain of salt 🙂

        Also, ‘sickly’ isnt an adjective for describing magnitude of scale, better words would be ‘enormous’ or ‘gigantic’. 🙂

    • There has been a number of shallow quakes over the past 4 days. I have this down as a future VEI7+ system so it’ll be interesting to see how it develops, though I suspect we’ll only see another 1953-esque eruption or two in our lifetimes.

  6. Hofsjökull wants to remind us it isn’t dead. Very probably just geothermal movements.

    • More earthquakes now. Has the eruption gone off shore a bit?

      • Can see the earthquakes on odf drumplot. Odf tremor has jumped up as well.

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