Does a black hole become a normal star again?

  • Stars which exceed the Tolman-Oppenheimer-Volkoff limit can become a black hole.

    What happens to star after it becomes a black hole?
    Does it regain its status of star?

    Chandrasekhar limit is only std. max. mass of white dwarf...

  • John Davis

    John Davis Correct answer

    8 years ago

    There's several ways this question could be answered, but they all come down to an emphatic "no" - a black hole will not return to being a main sequence star. The simplest way to see this is probably that a black hole has a much higher entropy than a star or even another type of stellar remnant of even vaguely similar mass and so there simply could not exist a spontaneous process by which a black hole develops back into a star.

    A black hole once formed will stay a black hole, however it is believed that the Hawking process will lead to the black hole eventually evaporating. The time scale for evaporation though of a stellar remnant black hole is mindbogglingly long and they will not evaporate until long after stellar formation has ceased in the Universe.

    A very long time indeed. Hawking radiation won't even be a consideration until the influx of mass/energy into the black hole drops below the rate at which Hawking radiation dissipated mass/energy. For a stellar black hole, even the incoming photons from the Microwave Background Radiation swamp Hawking radiation. The universe will have to get a lot older and a lot colder before black holes (except for tiny ones) stop gaining mass.

    For anyone who doesn't want to do the math, he's a very convenient Hawking Radiation and Black Hole calculator: - I can't swear to it's accuracy though. (and this doesn't take into account background radiation input, so, that changes the time a bit)

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Content dated before 7/24/2021 11:53 AM

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