Comment on Think twice before gifting someone an M dwarf this holiday season

raspberriesareyummy@lemmy.world ⁨4⁩ ⁨weeks⁩ ago

• eager_eagle@lemmy.world ⁨4⁩ ⁨weeks⁩ ago

  that’s not the sun

  Recent astrophysical models suggest that red dwarfs of 0.1 M☉ may stay on the main sequence for some six to twelve trillion years, […]

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  • raspberriesareyummy@lemmy.world ⁨4⁩ ⁨weeks⁩ ago

    that’s not the sun

    Yeah I missed that reference, as it is an artist’s impression it didn’t occur to me this could be any other star since the last format of this meme that I saw was still using something on the planet Earth as subject of the joke.

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• AmosBurton_ThatGuy@lemmy.ca ⁨4⁩ ⁨weeks⁩ ago

  To add onto the comments that you’ve already received, red dwarfs of approximately 0.8 - 0.25 solar masses are thought to be fully convective. So they mix all of their hydrogen fuel down into the core throughout their lives. More massive stars have different layers, the sun has a radiative zone above its core that is so dense it can take hundreds of thousands of years for a photon to get from the core to being released as light. More massive stars are too dense to mix all the hydrogen down into their cores and so end their lives with a lot of unspent hydrogen that gets ejected during the end of the stars life instead of being used as fuel in the core.

  Another fun fact is that it’s thought that stars more massive than our sun have an exterior radiative layer rather than a convectional outer layer and so they wouldn’t have the “granules” that we see on the surface of the sun. They would instead be one “solid” shining surface.

  God I love space. So fascinating.

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• peoplebeproblems@midwest.social ⁨4⁩ ⁨weeks⁩ ago

  The other two have corrected you on the lifespan of red dwars.

  However, it’s actually pretty neat to understand why small stars have exceptionally long lifespans, and big ones are very short: it’s because of the limitations of quantum tunneling and nuclear fusion, vs mass.

  In order for a star to generate any light, it needs a shit ton of energy. The only way to get this epic shit ton of energy is nuclear fusion. Because of physics, massive particles are attracted to eachother because of gravity. Heavier masses attract more particles. As the particles start piling up on top of eachother, they generate heat because they are also being repelled by other forces (namely electromagnetism). Heat is really a particles kinetic energy - the amount of energy of its movement.

  At a certain point, hydrogen fuses to Helium, helium fuses, then heavier elements like carbon, oxygen and nitrogen, all the way up to Iron.

  Each time a specific fuel runs out, there is a small to large explosion as the force compressing the particles is less than the force repelling the particles. Depending on how massive the star is, this could happen very quickly, or not at all. Red dwarfs don’t usually have the mass required to fuse more helium, so the fusion reaction continues forever until the gravitational forces are in equilibrium with the e&m forces. In bigger stars, the rate of fuel being consumed increases with mass, so you burn through each fuel quicker. In a star hypothetically large enough, it’s possible that the mass is enormous enough for it to consume all of its fuel in short succession, and instead of even getting a black hole, the star completely blows itself apart.

  Which leads to other really crazy things - like the question on supermassive black holes in the center of galaxies. How did they form if stars of a certain size would blow themselves to smitherings?

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  • raspberriesareyummy@lemmy.world ⁨4⁩ ⁨weeks⁩ ago

    The other two have corrected you on the lifespan of red dwarfs.

    *They corrected me on which star the meme was about.

    Either way, thanks for the mention of a theory of a second, “dark” big bang - that was an interesting web research just now.

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    • peoplebeproblems@midwest.social ⁨4⁩ ⁨weeks⁩ ago

      Yeah it’s relatively new. James Web telescope has the potential to help a ton with physics.

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  • SparrowHawk@feddit.it ⁨4⁩ ⁨weeks⁩ ago

    Couldn’t it be that the center of newlyborn galaxies are massive enough that many black holes form and then the black holes merge together, creating one supermassive black hole?

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    • peoplebeproblems@midwest.social ⁨4⁩ ⁨weeks⁩ ago

      That’s a whole different discussion, which is why I left the question there.

      The answer is likely no. Galaxies, unlike a good chunk of stars, are almost as old as the universe itself. The youngest observed galaxy has actually been found to have stellar signatures that give it an age of 1 billion to 10 billion years, and I suspect James Web will find more, inevitably confirming it too formed at the same time as more other galaxies.

      The supermassive black holes are quite likely primordial black holes - they came into existence shortly after the big bang (and there is debate on which big bang they formed with - yes, there is a working theory that there were two the conventional big bang, and a dark matter big bang).

      The problem with black hole mergers being the source of them is that space is huge. When the Milky Way Collides with Andromeda, it’s very possible that no stars, let alone the supermassive black holes, interact between galaxies. They will possibly change shape but due to the gravitational interaction of the two galaxies dark matter.

      A lot of theories are waiting on data from James Web. The really interesting part, is that the further back in time we look - we still see galaxies that have formed. As I mentioned earlier with the two big bang theories is that there is now some thought that the universe isn’t as finite as well believe, but it is cyclical. We are aware of the heat death of the universe, where the space between individual particles is too great to sustain an interaction. We have two possible ages of the universe, shortly apart from eachother.

      Current research is looking at the relationship between particle chirality, the mystery between matter and anti-matter imbalance, the distribution of dark matter, and primordial black holes to see if it can be linked together. One of the more popular theories right now is that dark matter is likely a class of weakly interacting massive particles that we know a lot of characteristics of, but need something orders of magnitude stronger than the LHC to produce it.

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      • SparrowHawk@feddit.it ⁨4⁩ ⁨weeks⁩ ago

        Wow, thank for the very detailed reply, I am so excited to be fortunate enough that maybe in my lifetime someone will find out just a little bit more of these questions.

        I wonder if the difference between near and far stops making sense when the universe reaches total heat death. Maybe it’s just a senseless guess, but what if that’s how a singularity is born? When a universe dies?

        It feels more religious than scientific to say but given how we observe that nothing is created or destroyed but rather is changed, why shouldn’t it apply to a Universe?

        I really like the way the videogame Outer Wilds tackles this question, using scientific knowledge as a basis to pose a more philosophical question about the life and death of a universe

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• HakFoo@lemmy.sdf.org ⁨4⁩ ⁨weeks⁩ ago

  I though dwarf stars had far longer lifespans than solar-type stars, and conversely the largest giants last only tens of millions of years.

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  • raspberriesareyummy@lemmy.world ⁨4⁩ ⁨weeks⁩ ago

    see above - missed that it wasn’t supposed to be our sun.

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  • peoplebeproblems@midwest.social ⁨4⁩ ⁨weeks⁩ ago

    You are correct. I don’t know what evidence we have of super sized stars, but beyond a certainly limit, stars can burn through their fuel faster than it can condense.

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