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Ultra-Dense Galaxies In the Early Universe

Posted by kdawson on from the it's-little-it's-lovely-it-lights dept.

Science Daily is reporting on the characterization of a population of ancient galaxies, formed less than 3 billion years after the Big Bang, that are as massive as some modern galaxies but are only 1/20 the size. Each of the 9 compact galaxies found is less than 5,000 light-years across, and could fit comfortably inside the Milky Way's central hub (if you moved the supermassive black hole out first). The stars in these galaxies were 1/2 to 1 billion years old when observed and at least one generation of massive stars had already exploded as supernovae.

3 of 19 comments (clear)

  1. Just out of curiosity - how far away are they? by mmell · · Score: 4, Interesting
    Or - to put it more bluntly - how long ago did they look like that?

    If they're over thirteen million light-years distant, they might represent a tantalizing glimpse into the physics of galaxy formation shortly after the Big Bang - the presence of heavier-than-helium elements indicates that at least one round of (superheavy) star formation/destruction has taken place, but they could still be relatively good examples of galactic physics in the (then neonatal) Universe.

  2. Probably won't matter much by Moraelin · · Score: 2, Interesting

    The thing is, the rate of new star formation is decreasing over time.

    While technically there still is plenty of hydrogen left, the quantity of _free_ hydrogen (available for a new star) is becoming gradually more rare. More and more is locked inside old dead stars. Even a supernova doesn't eject all the matter in the star. A red giant only sheds the outer layer, or to put it other wise, does about as much to recycle the star as shedding does to recycle your dog ;)

    So basically if we're talking 100 billion years in the future -- which was the last number I heard for a universe where nothing is visible outside the galaxy -- there may be a rather extreme shortage of stars like the sun, and of civilizations trying to make contact with each other.

    --
    A polar bear is a cartesian bear after a coordinate transform.
  3. Imprecision Annoys by SWestrup · · Score: 2, Interesting

    Am I the only one annoyed by such an imprecise expression as "1/20th the size". One doesn't know from reading it if this is 1/20th the linear dimensions, or 1/20th the volume. (Turns out its the former, which makes it 1/8000th the volume, which is far more interesting.)