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  1. #11
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    There is a super massive black hole at the center of the Milky Way -- astronomers have been tracking stars for several decades now circling an unseen point in space-- several of the stars have completed full orbits around this object of GREAT mass which cannot be seen.

    VIDEO: How scientists used stars to identify black hole at the centre of the Milky Way | Mail Online

    BBC NEWS | Science & Environment | Black hole confirmed in Milky Way

    This is WAY beyond theoretical-- we can actually observe these stars and calculate the mass of the unseen super massive black hole that they are circling.
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  2. #12
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    Quote Originally Posted by CelestialDNA View Post
    That's what I have been trying to figure out all along. Somehow scientists are obsessed about blackholes and string theory none of which can be truly proven.
    Hold it right there!!

    In science, nothing is ever "proven". A theory might be proved FALSE, if there is evidence that contradicts it. It is never proven true. That's why we call it a theory, rather than a fact. If there is evidence that supports the theory, then that's all - evidence supports the theory.

    The old "That's not proven" thing is a red herring employed by anti-scientists to support their conspiracy theories.

    In this case, evidence supports the existence of black holes.
    A black star on the other hand could definately exist. As mentioned several times in my previous posts such a star needs to have at least 485 times the mass of our sun. I derived that number by taking our suns escape velocity and dividing it by the speed of light.
    "Could definitely exist"????

    Show me your calculations that indicate that a star of 485 solar masses would be stable. While we are at it, show me your calculation of how escape velocity relates to mass. Can you even point out the incorrect assumption you made? I'll overlook the fact that, in translating your calculation into English, you inverted it.

    Sorry, if you want to play in the science field, you have to learn the rules.

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  3. #13
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    Quote Originally Posted by KeithBC View Post
    Hold it right there!!

    In science, nothing is ever "proven". A theory might be proved FALSE, if there is evidence that contradicts it. It is never proven true. That's why we call it a theory, rather than a fact. If there is evidence that supports the theory, then that's all - evidence supports the theory.

    The old "That's not proven" thing is a red herring employed by anti-scientists to support their conspiracy theories.

    In this case, evidence supports the existence of black holes.

    "Could definitely exist"????

    Show me your calculations that indicate that a star of 485 solar masses would be stable. While we are at it, show me your calculation of how escape velocity relates to mass. Can you even point out the incorrect assumption you made? I'll overlook the fact that, in translating your calculation into English, you inverted it.

    Sorry, if you want to play in the science field, you have to learn the rules.
    Well first off all I'm not here to start a brawl and sorry if I offended ur scientific knowledge by stating that I do not agree with the above mentioned theories. I'm not a physicist hence I posted my suggestion on an astronomy board vs publishing it in a scientific paper. I cannot tell whether the star would be stable. But why don't u show me any calculations to prove the opposite? You seem to keep asking me questions which I have already talked answered numerous times. How does escape velocity relate to mass? Go to Wikipedia type "escape velocity" that will give u the escape velocity of the earth and the sun. Then find out the speed of light (also from Wikipedia) and divide that by suns escape velocity. That will give u the mass of a black star relative to the mass of our sun. Meaning a star whose escape velocity is the speed of light. That isn't really rocket science buddy- it's called a bit of common sense.

  4. #14
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    Hi CelestialDNA.

    Welcome to the Astronomy Forum.

    Your hypothesis of an undetectable dark star, not a black hole, with a mass is great enough to prevent light for escaping, is just that; your hypothesis. In science the onus of proof lies on the party proposing a hypothesis, not the outside world. If you strongly believe in your hypothesis, then get to work. Get some physics and math books and start studying until you have the knowledge to analyze your hypothesis yourself. When you get there you will know why the answer to your question is "your hypothesis is false."

    A debate is great and are perfectly acceptable on the forum. But you also must add your part; not simply unilaterally reject any argument with which you do not agree simply because you do not care for the answer. This is what we define as covert trolling. This is your first and last warning on the subject of trolling.
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  5. #15
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    Quote Originally Posted by CelestialDNA View Post
    I cannot tell whether the star would be stable.
    Yet you stated that it could definitely exist. You didn't know that, you made it up.
    How does escape velocity relate to mass? Go to Wikipedia type "escape velocity"...
    And if you go there and look at the relationship between escape velocity and mass, you will find that it is not linear. A ratio of escape velocities of 485x does not mean a ratio of masses of 485x. It means a ratio of masses of 235,000 because escape velocity is proportional to the square root of the mass. You made an incorrect assumption that escape velocity was linearly related to mass. It is not.

    That isn't really rocket science, buddy- it's called mathematical competence. It is a basic requirement for doing science.

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  6. #16
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    Not to pile on, but you also complete miss the effect of radius on escape velocity from the surface of a star. The escape velocity from the "surface" of Betelgeuse is 0.00015% of that from the surface of the sun, despite being 19 times as massive.

    We have a half decent understanding of how stars form, and while we occasionally observe a star that seems to be over the Eddington limit (especially very metal poor ones), it seems to hold. A star with 485 solar masses could not form, because the more massive the star is the higher the luminosity. Above a point, the radiation pressure overcomes the gravity of the star and new gas cannot accrete and is blown away.

    Even outside of that, by it's nature a star fuses light elements into heavier ones, releasing energy in the process. If by some miracle four 120 solar mass stars merged to produces a single star, you still wouldn't see a "dark star".

    From the wikipedia article on Hypergiants
    Stability

    As luminosity of stars increases greatly with mass, the luminosity of hypergiants often lies very close to the Eddington limit, which is the luminosity at which the force of the star's gravity equals the radiation pressure outward. This means that the radiative flux passing through the photosphere of a hypergiant may be nearly strong enough to lift off the photosphere. Above the Eddington limit, the star would generate so much radiation that parts of its outer layers would be thrown off in massive outbursts; this would effectively restrict the star from shining at higher luminosities for longer periods.

    A good candidate for hosting a continuum-driven wind is Eta Carinae, one of the most massive and luminous stars ever observed. With an estimated mass of around 130 solar masses and a luminosity four million times that of the Sun, astrophysicists speculate that Eta Carinae may occasionally exceed the Eddington limit.[2] The last time might have been a series of outbursts in 1840-1860, reaching mass loss rates much higher than our current understanding of what stellar winds would allow.[3]
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