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Thread: Possible antistars?

  1. #1
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    Possible antistars?

    Stars made of antimatter could lurk in the Milky Way
    https://www.sciencenews.org/article/...pace-astronomy
    If true, the preliminary find might mean some antimatter survived to the present day
    SHARKS (crossed out) MONGEESE (sic) WITH FRICKIN' LASER BEAMS ATTACHED TO THEIR HEADS

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    Tom, don't get your hopes up. The original paper is basically just setting upper limits for the number of antistars, but indicates that the most likely number is zero, but they are going through the calculations of determining how many could exist without our knowing. The 14 sources they indicate are likely to be neutron stars, or perhaps some other highly energetic AND magnetic bodies that produce electron-positron pairs and separate them.
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    Very unlikely, but it would be amazing. I wonder if any of these stars are moving really fast?

    (Iím thinking of the plot of a Larry Niven story - Flatlander.)

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    Ka-Boom

    Seems unlikely, but interesting. What would an antistar supernova look like? Even worse, what would a collision with a normal star be like?

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    Quote Originally Posted by John Mendenhall View Post
    Seems unlikely, but interesting. What would an antistar supernova look like? Even worse, what would a collision with a normal star be like?
    An antistar supernova would look like a normal supernova, except for the high levels of gamma radiation where the cloud starts sweeping normal matter in the interstellar medium. The fact that we've never detected an anti-Iron nucleus as a cosmic ray tells me there probably haven't been any anti-supernovae within 100 million light years of here. Your point about a collision with a normal star is interesting. It should release about 5000 to 10,000 times as much energy as a Type 1a supernova... but even if stars and antistars were mixed evenly, it should almost never happen.
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    If antistars exist, they could have antiplanets with antilife. Make sure not to hug them if you meet one.

    I have a feeling any antimatter that survived past the Big Bang is so scarce there isn't enough of it to form antistars. But, maybe if a part of the universe does have a large amount of antimatter, could there be entire antigalaxies?

    Another crazy thought. When the Big Bang happened, perhaps it formed 2 universes, like 2 lobes expanding out in opposite "directions", one made of primarily matter (the one we exist in) and the other primarily antimatter. Of course, whatever life exists in that anti-universe would see their version of matter as the "normal" kind and our kind as "anti"-matter.

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    Quote Originally Posted by antoniseb View Post
    Tom, don't get your hopes up. The original paper is basically just setting upper limits for the number of antistars, but indicates that the most likely number is zero, but they are going through the calculations of determining how many could exist without our knowing. The 14 sources they indicate are likely to be neutron stars, or perhaps some other highly energetic AND magnetic bodies that produce electron-positron pairs and separate them.
    Never mind the antistars, how could we possibly miss the giant clouds of antimatter they formed from?
    If any antistars exist anywhere, it seems like they'd have to be in antigalaxies somewhere very far from any normal-matter galaxies.

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    Quote Originally Posted by cjameshuff View Post
    Never mind the antistars, how could we possibly miss the giant clouds of antimatter they formed from?
    If any antistars exist anywhere, it seems like they'd have to be in antigalaxies somewhere very far from any normal-matter galaxies.
    Exactly!
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    In Flatlander, the star is said to possibly be from outside the Milky Way Galaxy.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Noclevername View Post
    In Flatlander, the star is said to possibly be from outside the Milky Way Galaxy.
    Yep, that’s why I was wondering if any of the candidates were moving really fast in my earlier post.. In Flatlander the star is moving extremely fast and thought to be originally from outside the galaxy.

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    Quote Originally Posted by Noclevername View Post
    In Flatlander, the star is said to possibly be from outside the Milky Way Galaxy.
    That still leaves the question of how it got here without being accompanied by other antimatter dust, gas, and stars from wherever it came from, and how wherever that is is avoiding similar clouds of normal matter from the Milk Way, Andromeda, their various satellites, etc.

    Realistically, a better explanation would be that it's from another universe entirely.

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    Quote Originally Posted by cjameshuff View Post
    That still leaves the question of how it got here without being accompanied by other antimatter dust, gas, and stars from wherever it came from, and how wherever that is is avoiding similar clouds of normal matter from the Milk Way, Andromeda, their various satellites, etc.

    Realistically, a better explanation would be that it's from another universe entirely.
    Stars sometimes are ejected from a galaxy by various mechanisms. A number of hypervelocity stars have been found going too fast to be held by the galaxy’s gravity. S5-HVS1 is a better known example, after interacting with Sagittarius A* is moving out with great velocity. A rogue star may not be accompanied by much else aside from maybe some gravitationally bound planets.

    I’m also curious what might be left of antimatter clouds after this many billions of years. Antimatter clouds that might have managed a couple of generations of stars in the early universe might have been disrupted later interacting with matter (presumably there would still have to be much less antimatter than matter in order for us to exist).

    Mind you, I think this is extremely unlikely but I don’t want to discount it entirely.

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    Quote Originally Posted by Van Rijn View Post
    Stars sometimes are ejected from a galaxy by various mechanisms. A number of hypervelocity stars have been found going too fast to be held by the galaxy’s gravity. S5-HVS1 is a better known example, after interacting with Sagittarius A* is moving out with great velocity. A rogue star may not be accompanied by much else aside from maybe some gravitationally bound planets.

    I’m also curious what might be left of antimatter clouds after this many billions of years. Antimatter clouds that might have managed a couple of generations of stars in the early universe might have been disrupted later interacting with matter (presumably there would still have to be much less antimatter than matter in order for us to exist).

    Mind you, I think this is extremely unlikely but I don’t want to discount it entirely.
    The existence of rogue stars is precisely the problem. There's nothing special about stars that makes them uniquely capable of escaping a galaxy, and an antimatter galaxy would be constantly spraying its surroundings with rogue antimatter stars, planets, planetoids, dust, and molecules of gas, while encountering the same from its normal-matter neighbors. And then there's the matter of most galaxies having formed by a long history of galactic merger events, which would be rather noticeable if they ever involved matter and antimatter galaxies merging together.

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    Quote Originally Posted by cjameshuff View Post
    ...which would be rather noticeable if they ever involved matter and antimatter galaxies merging together.
    Astronomy loves an understatement.

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    Quote Originally Posted by VQkr View Post
    Astronomy loves an understatement.
    The thing is, when galaxies merge the individual stars donít really collide, so I donít think there would be something catastrophic. But the clouds would be colliding, so you should be able to see x-ray emissions from the border.


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    Quote Originally Posted by Jens View Post
    The thing is, when galaxies merge the individual stars don’t really collide, so I don’t think there would be something catastrophic. But the clouds would be colliding, so you should be able to see x-ray emissions from the border.
    Ignoring dark matter, a substantial fraction of a typical galaxy's mass (10+% for the Milky Way) is in interstellar gas, which is constantly being regenerated as stars shed mass through their solar wind or explode at the end of their lives, plus a potential hot gas halo with mass equal to the rest of the stars and gas together. There'd be a bit more than some x-ray emissions from the border.

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    Quote Originally Posted by cjameshuff View Post
    There'd be a bit more than some x-ray emissions from the border.
    Would there be enough energy released to alter the trajectory of the colliding galaxies? Push them back apart or disrupt them, for example?

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    Quote Originally Posted by VQkr View Post
    Would there be enough energy released to alter the trajectory of the colliding galaxies? Push them back apart or disrupt them, for example?
    Even if one galaxy were antimatter and one matter, all the radiation resulting would likely still be a tiny fraction of what would be needed to measurably change the course of a whole galaxy. The radiation would also be released omnidirectionally, so if it could move any stars they'd be going off in all directions.
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    Discover Magazine article
    https://www.discovermagazine.com/the...to-solving-the
    'Where Did The Universe's Antimatter Go? Scientists Inch Closer To Solving The Mystery.'

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