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Massive Stars and their approximate Size

Astronomers have found massive stars in the early universe, primarily located in distant galaxies that formed shortly after the Big Bang. These regions are often studied through advanced telescopes capable of observing very distant light, such as the Hubble Space Telescope and the upcoming James Webb Space Telescope. In terms of size, these monster stars can have diameters ranging from about 100 to over 300 times that of our Sun. The Sun’s diameter is approximately 1.4 million kilometers (about 864,000 miles), so these massive stars could be approximately 140 million to over 420 million kilometers (about 87 million to 261 million miles) in diameter.
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What ionized the universe?

The sparsely distributed hot gas that exists in the space between galaxies, the intergalactic medium, is ionized. The question is, how? Astronomers know that once the early universe expanded and cooled enough, hydrogen (its main constituent) recombined into neutral atoms. Then, once newly formed massive stars began to shine in the so-called "era of reionization," their extreme ultraviolet radiation presumably ionized the gas in processes that continue today. One of the key steps, however, is not well understood, namely the extent to which the stellar ionizing radiation escapes from the galaxies into the IGM. Only if the fraction escaping was high enough during the era of reionization could starlight have done the job, otherwise some other significant source of ionizing radiation is required. That might imply the existence of an important population of more exotic objects like faint quasars, X-ray binary stars, or perhaps even decaying/annihilating particles.

from Astronomy News - Space News, Exploration News, Earth Science News, Earth Science https://ift.tt/2CwQs9V
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