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Ancient stars made extraordinarily heavy elements, researchers find
- daveslash 3y agoI think it's interesting to speculate on how an alien civilization might develop technology, and in what order, if they were to originate on a planet with different ratios of elements than Earth, including access to these super heavy elements.
- ajross 3y agoThere is no reason to suspect any of these elements are stable. The paper seems to be alleging that they existed in quantity at the end of the r-process such that they produced otherwise hard to explain ratios of other stable nucleii (i.e. their fission products). If there were stable transuranic nucleii, we'd need to work very hard to explain why we can't find any in the universe.
- thsksbd 3y agoWell we know how stable many of them are - we've synthesized them and out them in our fire alarms
- Cockbrand 3y agoAndy Weir‘s novel Project Hail Mary explores this to some extent. Well, not super heavy elements, but heavier ones than the stuff we’re made of.
- philipkglass 3y agoAll of these super heavy elements are radioactive with short half lives, so they wouldn't be accessible as ores even on planets that formed close to these stars. The article refers to elements with atomic weights higher than 260, which would mean elements like lawrencium and rutherfordium; they all have half lives of less than a day. I have had a related thought about uranium, though. The fissile isotope that's useful for power generation and bombs, uranium 235, is only about 0.7% of uranium that's found on Earth. When uranium is formed in a supernova, there's actually more uranium 235 produced than uranium 238; this freshly produced uranium is about 62% U-235 [1]. The reason that U-235 is so rare on Earth is that U-235 decays faster than U-238 and our uranium is billions of years old. But if it's possible for a technological civilization to develop on a planet with much fresher uranium content, natural uranium there could contain a double-digit percentage of U-235. Under those conditions it would be easy to accidentally discover nuclear fission and naturally occurring reactors like Oklo [2] would be common. [1] https://world-nuclear.org/information-library/nuclear-fuel-cycle/uranium-resources/the-cosmic-origins-of-uranium.aspx https://world-nuclear.org/information-library/nuclear-fuel-c... [2] https://www.iaea.org/newscenter/news/meet-oklo-the-earths-two-billion-year-old-only-known-natural-nuclear-reactor https://www.iaea.org/newscenter/news/meet-oklo-the-earths-tw...
- chasil 3y agoIf the Cambrian explosion had happened sooner, then this would have been possible.
- cstross 3y agoThe Cambrian explosion was, however, constrained by the partial pressure of oxygen in the hydrosphere (and, indirectly, the atmosphere). And free O2 couldn't begin to build up in seawater until after the Great Oxygen Catastrophe when the crust and upper mantle was finally fully oxidized, mopping up all the unoxidized iron and other elements. (Which in turn killed off almost all previous life forms, which were methanogenic and to which oxygen was a deadly poison/metabolic waste product.) The speed with which this happened was in turn constrained by tectonic subduction ... it all turns out to be a knotty ball of string that took at least a couple of billion years to unwind.
- consp 3y ago> they all have half lives less than a day. Isn't it the case it is currently not possible to create any neutron heavy isotopes and that causes the half-lives to be on the low end?
- philipkglass 3y agoIsn't it the case it is currently not possible to create any neutron heavy isotopes and that causes the half-lives to be on the low end? All of these isotopes are neutron-heavy. Lawrencium 261 has 103 protons and 158 neutrons, for example. In fact, the only stable isotopes with fewer neutrons than protons are helium 3 and ordinary hydrogen (protium).
- saalweachter 3y agoI think he's referring to the way that eg lawrencium has a half-life that ~increases with the neutrons in the isotopes we've produced, from seconds for Lr-256 to hours for Lr-266. It isn't crazy to postulate, as a layman, that if we synthesized Lr-276, say, it might have a longer half-life. (Not that we expect that pattern to continue indefinitely, but still, have we discovered the most stable isotope of lawrencium yet?)
- thsksbd 3y agoA more interesting question is if an alien race can exist with ratios that differ considerably from the ones on earth. Outside of carbon chemistry your ability to create replicable life plummets. Biologists may speculate if non carbon life is possible, but there's no doubt it would be limited. Arsenic or silicon just don't have the chemical complexity carbon does. As for super heavy elements - the elements alien races would have access to wouldn't be that different from ours. Heavy nuclei are terribly radioactive and thus short lived. The article points our elements heavier than 260 are too short lived, but on astronomical (and biological) scales anything past 238 (ie Uranium) is short lived. Past Uranium (which we have on Earth naturally), only Pu-244 is relatively long lived. Its half life is 81 million years vs. U-238 at 2 billion years. 81 million sounds like a long time, but the alien race has to evolve intelligence. We've been evolving for about 4 billion years, or 40 halvings of Pu-244 initial (anyway low) concentration. 2^-40 is a small number. By comparison U-238 has halved only twice on Earth since evolution started. To illustrate, if the entire Sun were made of Pu-244 and the entirety of the remaining Pu-244 were put on Earth after 4 billion years, the concentration would be less than 1 part per million per mass.
- blacksmith_tb 3y agoThere's been recent talk of finding a new island of stability[1] though I don't think we imagine those super-heavy elements would have half-lives of more than thousands of years (so probably not very handy for alien engineers). 1: https://en.wikipedia.org/wiki/Island_of_stability#Possible_natural_occurrence https://en.wikipedia.org/wiki/Island_of_stability#Possible_n...
- thsksbd 3y agoYea, and it is super cool to think that, but either 1. the kinetic barrier is impossibly large that even novas cant cross it, or 2. the "stable" elements are not very long lived in astronomical time scales. Probably both are true, either way, it's a wash - no super heavy elements for alien races to play with.
- scotty79 3y ago> Outside of carbon chemistry your ability to create replicable life plummets. Biologists may speculate if non carbon life is possible, but there's no doubt it would be limited. Arsenic or silicon just don't have the chemical complexity carbon does. Best argument for carbon I've seen so far is that despite carbon being just 0.02% of all elements on earth it became preferred engine of life. Although I can't rule out that under different temperature, pressures and radiation some other element might be preferred if it's reasonably abundant somewhere. In my opinion if there's mostly stable, reasonable energy gradient somewhere life will find a way if possible.
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- jylam 3y agoIsn't there a probable island of stability, with very heavy, stable elements ?
- Sharlin 3y agoPossible, not probable. It’s a cool idea but even if the island is theoretically possible and there’s some real astrophysical process that could actually synthetize such nuclei, they’d likely still be only "stable" relative to other superheavy elements. That is, half-lifes from seconds to years or something like that rather than microseconds.
- jylam 3y agoOk, looked back at some stuff I read, and yes we are talking about half-lives of a couple of years at most. Disappointing, but thank you :)
- NoMoreNicksLeft 3y agoIn later years, I thought it had changed to "relatively stable"... as in elements that have half-lives in minutes rather than in milliseconds.
- Nevermark 3y agoWater worlds intrigue me. All the elements and heat vents you might need for life. But how do you develop the technology for an escape velocity civilization in a medium so corrosive and viscous? Super Earths are a likely source of water worlds, since the same percentage of water volume (~ to radius^3) results in much deeper oceans at the surface (~ to radius^2). The greater gravity would create even more hurdles. How do you hit escape velocity if your fuel to orbit is to heavy to lift itself? First orbital vehicle might have to be nuclear. Problem 1: Develop a civilization with a sustained technology runway in a medium that corrodes, relentlessly saps temperature gradients, creates immense pressure at its solid floor, etc. Problem 2: Create floating platforms and colonize their ocean surface. Problem 3: Develop atmospheric flight, from their bobbing surface colonies, with heavy water filled planes. Problem 4: Develop orbital flight with water filled space craft. Problem 5: Develop sustainable water filled living environments off planet, as first step to going beyond. And do this before their star or other cause finishes them off!
- didgeoridoo 3y agoHa, given that this is cosmologists talking, I assumed “extraordinarily heavy” meant… like, beryllium. Element 260 was a nice surprise.
- WendyTheWillow 3y agoSimilarly, I saw this and thought, "Didn't we know this already?" I was taught this literally a few weeks ago in my "Astronomy for non-STEM majors" class. But then yeah, 260 is a big number, heh.
- varjag 3y agoWasn't the accepted model that formation of these happens only in supernova events?
- Sharlin 3y agoThe article is talking about the r-process, so it’s still supernovas (either core-collapse or more likely neutron star collision) that would have forged these elements. Ancient or not, a stably burning star isn’t going to synthetize nuclei heavier than iron in non-negligible quantities.
- antognini 3y agoSome elements are believed to only form from neutron star mergers.
- rdlw 3y agoAtomic mass 260 != element 260. Bismuth-209 has atomic mass ~209 but is element 83 (123 neutrons add the extra mass). An atomic mass of 260 probably means about... 100-120 protons? That's a guess from eyeballing this chart: https://en.wikipedia.org/wiki/List_of_elements_by_stability_of_isotopes https://en.wikipedia.org/wiki/List_of_elements_by_stability_... Still very cool, but not (far) outside of what has been synthesized.
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- borissk 3y agoIMHO there are probably ways for heavy elements to form without neutron stars or supernova explosions. We have so much of these heavy elements in the crust of the Earth (and they tend to fall down towards the center when a planet is formed).
- adamiscool8 3y agoSo Bob Lazar was right after all, the aliens might have naturally sourced moscovium for their anti-gravity generators! [0][1] [0] https://ui.adsabs.harvard.edu/abs/2004AIPC..699.1230A/abstract https://ui.adsabs.harvard.edu/abs/2004AIPC..699.1230A/abstra... [1] https://science.howstuffworks.com/space/aliens-ufos/element-115.htm#pt4 https://science.howstuffworks.com/space/aliens-ufos/element-...
- whoopdedo 3y agoHow ancient are we talking here? Was there a time when the size of the universe was large enough to form stars but still much denser than it is today? That meant there was "more" matter available to those stars for crunch into large atoms.
- waynecochran 3y agoI am thinking these are the first stars formed after the Big Bang (when there was only Hydrogen and Helium and some Lithium), but those stars don't live very long.
- everdrive 3y agoThis just not a necessary fact that making the heavier elements takes more time, and so the more recent stars cannot make such heavy elements?
- antognini 3y agoNo. The massive stars that produce these elements have very brief lives. What's different is that the metallicity of later stars is higher than earlier stars. In essence, the earliest stars were formed from gas that had virtually no metals in them and because of that could grow much larger. But after their death, they polluted the ISM with metals which prevented later generations from becoming as massive.
- SpaceManNabs 3y ago[flagged]
- DonHopkins 3y ago[flagged]
- stainablesteel 3y agoi've always wondered if much heavier nuclei produce different kinds of radiation not seen prior that produces things like dark matter
- dr_dshiv 3y agoWhat “causes” spontaneous decay? Neutrons can cause fission — can protons also cause it? Can anything else facilitate or inhibit nuclear decay?
- nobodyandproud 3y ago“We don’t know” or “it’s spontaneous” is the definitive answer for what gives an unstable atom its nudge. https://physics.stackexchange.com/questions/497589/what-triggers-a-nuclear-decay#497599 https://physics.stackexchange.com/questions/497589/what-trig... https://www.thoughtco.com/why-radioactive-decay-occurs-608649 https://www.thoughtco.com/why-radioactive-decay-occurs-60864... I personally don’t like the answer that it’s “spontaneous”, but I vaguely grok that any explanation has to step beyond QM/QCD as we know it. There are hidden variable QM interpretations that exist, but marrying them with Special Relativity appears to be difficult. There are even more exotic hidden variables theories like https://physics.stackexchange.com/questions/515720/what-is-the-whole-idea-behind-retrocausality-in-quantum-mechanics https://physics.stackexchange.com/questions/515720/what-is-t... but none of these variables are measurable with regards to making predictions on decay. I’m also way out of my field so I may be wrong here.