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Stars in distant galaxies are typically more massive
- zionic 4y agoDoes this have implications for dark matter? The whole angle there is explaining “missing mass” right?
- hoyd 4y agoMy first thought too
- sgt101 4y agoI don't think so because many of the observations of the galaxys that make folks think that dark matter must be present (because the visible matter is not sufficient to make the galaxy stick together) are in the local group.
- pvg 4y agoThe research is about the distribution of stars in a galaxy, not mass that is missing or extra. Distant galaxies apparently have more massive stars than whatever widely used model says. From the article: Stars in distant galaxies are typically more massive than those in our "local neighborhood"
- phkahler 4y agoFunny thing about the missing mass. Papers will say "this could be explained by a dark matter Halo with this distibution". They assume it gravitationally affects regular matter the same way regular matter does. What is usually missing is 1) how dark matter interacts with dark matter 2) why it should have this particular distribution - dynamic model. Without those things, the explanation is IMHO worse than MOND because it doesnt make sense that some matter would end up with a completely different distribution. Oh and we cant actually detect it directly either, but trust us it must be there.
- gliptic 4y agoThis is not actually missing from the models. See for instance https://www.nature.com/articles/s41550-021-01598-4 https://www.nature.com/articles/s41550-021-01598-4
- ncmncm 4y agoThere is no reason for matter with very different interaction properties from the familiar stuff to have the same distribution. In particular, familiar stuff has ways to dispose of kinetic energy, allowing it to clump into our stars and planets, that might be unavailable to putative dark matter, making any dark matter more diffuse. Generally, you can start with the assumption that people working on dark matter hypotheses are not idiots. They might still be wrong, but if they are, they will be wrong in interesting and subtle ways, not obvious ones.
- phkahler 4y ago>> There is no reason for matter with very different interaction properties from the familiar stuff to have the same distribution. Sure there is. It has similar interaction with regular matter. Any other properties need to be defined and shown to produce this claimed distribution as a result of a dynamic process. Anything less and we can just say dark matter is fairy dust.
- ncmncm 4y ago"different interaction" != "similar interaction". Apparent effort to understand what you criticize may make your criticism seem worth more.
- phkahler 4y ago>> Generally, you can start with the assumption that people working on dark matter hypotheses are not idiots. Actually no I cant. When someone looks at galaxy rotation curves and is surprised they dont follow keplers laws, it activates the bozo bit in my mind.
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- Ralfp 4y agoIt doesn’t. Galaxies studied were very far from Milky Way and hence much older. This discovery shows that era of massive stars ended later in evolution of universe than we’ve assumed, not that we got mass of stars wrong. We still see younger galaxies with less massive stars not rotating as expected.
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- hexomancer 4y ago> Galaxies studied were very far from Milky Way and hence much older You mean younger, right?
- forgotusername6 4y agoLike looking at an old photograph of a child. Both older and younger at the same time.
- rsstack 4y agoWeird English quirk when you have relativistic distances: They are older in a sense that they aren't recent. They aren't older in a sense that they've existed for a longer time. (At least in the radiation we're seeing.)
- hoyd 4y agohttp://archive.today/poJee http://archive.today/poJee
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- Aardwolf 4y agoAssuming the universe is mainly uniform, why would distant galaxies have different starts than nearby ones? Is it related to time (the light from those farther away that reaches us being from the distant past)?
- disconcision 4y agodistant means younger means different composition (less heavy elements), dunno if that's the deal here though
- mrits 4y agoUnless we are the center of the universe I don't see how distant could mean younger
- Cthulhu_ 4y agoThat's an interesting one to think about; every galaxy moves away from every one, so (if I got this right) from every other galaxy's point of view, all the other galaxies are younger... or older, either / or I don't know anymore.
- ianai 4y agoLight and thus causality and information travel at a constant speed of "c." As far as we know, nothing can travel faster than "c" - other than the universe itself as in during the inflationary epoch. So the further out any observer would look the longer that light would have had to travel relative to that observer. Seeing something 3 billion light years away would mean the light took 3 billion years to arrive at the observer.
- Maursault 4y ago> As far as we know, nothing can travel faster than "c" What Relativity forbids is anything traveling as fast as c, as the increase in mass as c is approached would require infinite energy to reach. Relativity says absolutely nothing about faster than c, i.e. it does not forbid things such as the theoretical tachyon.
- naveen99 4y agothe earth has elements that were formed in previous generation of stars. I wonder if the sun is also not a first generation star.
- eloff 4y agoIt definitely is not a first generation star. It's only about 5 billion years old, while the universe is almost 14 billion years old. Not only does earth have elements formed in older stars, so do all the planets in the solar system and our own sun.
- sulam 4y agoThe sun is absolutely not a first generation star. It is approximately one third the current best estimated age of the universe (4.6B vs 13.8B years).
- pohl 4y agoThe sun is estimated to have formed less than 5B years ago. The universe is roughly 13B and change years old, and the first stars started forming only 100M years after the beginning. There's absolutely no way it could be a first generation star.
- ncmncm 4y agoThe first-generation stars are imagined to have lasted only a few million years before going supernova and (because of their size) becoming black holes. We can never be certain, of course, because they are all long gone. Like, 13 billion years gone. The James Webb telescope is hoped to see back nearly that far back, but not likely near enough to catch any of them.
- Zigurd 4y agoThe entire solar system precipitated out of the same interstellar dust, which has to contain the remnants of previous generations of stars, including collided neutron stars, in order for there to be heavy elements beyond iron.
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- DelightOne 4y agoImplications for the lifetime of suns?
- kabdib 4y agoIt's a power law. Increased mass more than proportionally decreases the lifetime of a star. (A star with 100 X the mass of our sun would last about a million years).
- ianai 4y agoThat sort of sounds like a "sorting" process or something like survivor bias. The conditions were more likely to produce pockets of material dense and large enough to produce the larger, shorter living stars the earlier back in the universe. i.e. as Time progresses forward the stars which remain are those with more burn time and thus less mass. Otherwise would require some forces to exist which pull mass back together to counter the overall expansion of the universe.
- codingbeer 4y agoAlbert, the graduate student behind this work, was also in the news just a week ago with another cool discovery, see https://nbi.ku.dk/english/news/news22/danish-astrophysics-student-discovers-link-between-global-warming-and-locally-unstable-weather/ https://nbi.ku.dk/english/news/news22/danish-astrophysics-st... Edit: and this from last year https://nbi.ku.dk/english/news/news21/danish-student-solves-how-the-universe-is-reflected-near-black-holes/ https://nbi.ku.dk/english/news/news21/danish-student-solves-...
- ffhhj 4y ago》This “total” temperature can also be described as a sum of temperatures on coarse (large) scales, temperatures on finer scales, even finer scales, etc. On large scales we see the well-known climate changes. Albert Sneppen’s study documents that the temperature differences become stronger on small scales (credit: Albert Sneppen). 》In other words, climate change makes the differences in temperature grow locally — and with large temperature differences come even more extreme weather patterns. Makes a lot of sense.
- joebob42 4y agoHe "discovered" this? This has been my understanding of how this all worked for years, unless there's some subtlety I'm missing here.
- akeck 4y agoI don't think he discovered the conclusion per se. I think he discovered an analytical path to an already known/suspected conclusion via a novel application of cosmology math to planetary climate.
- labster 4y agoIt’s been common knowledge in atmospheric science for the past 20 years (based on personal knowledge, it’s probably decades longer). Not only does it shake out of climate models, but it’s intuitive that more heat to redistribute will increase the amplitude of all the wave-like properties of the atmosphere.
- samstave 4y agoWhy does “heavier” mean something when talking about a mass suspended in the vacuum of space? Does the mass and resultant gravitational force attenuate the same ratio for small vs big stars? Also, how do super dense neutron stars work - in the sense that atoms (and neutrons) are “mostly empty space” — are the particles in the atoms compressed closer together? Or does an atom of one substance at the center of a star have the same mass/volume as an atom of the same, either floating by itself or say, on earths surface?
- colechristensen 4y ago"Weight" words and "mass" words get used interchangeably because it usually becomes obvious which one is meant based on context. Here, obviously we're talking about stellar mass. You can't really talk about the "volume" of an atom because the distance between one atom and the next closest atom really depends on the bulk material and isn't just atoms sorted into their one fixed size but is a balance of various forces. A neutron star isn't made of atoms, but is, in a sense, one enormous atom or just a nucleus (but it's more complex than that). Mostly neutrons with some electrons and protons mixed in not separated into atoms which repel each other but in a super dense fluid of particles packed about as closely as particles in the nucleus of a normal atom. http://astro.vaporia.com/start/neutronmatter.html http://astro.vaporia.com/start/neutronmatter.html
- antisthenes 4y agoCould this just be a luminosity effect? Larger [More massive] stars are typically more luminous. Could be that there is a selection bias towards them. since they are the only ones that can be detected from that far away.