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How Big is a Quasar

  • 07-09-2007 7:32am
    #1
    The Hill Billy
    Registered Users, Registered Users 2 Posts: 22,818 ✭✭✭✭


    I saw this on APOD yesterday & it got me thinking...

    How big or bright must a quasar be for it to be visible at 12.7 billion light years? Apart from a couple of foreground stars every other object in the pic is a galaxy. Do quasars emit a galactic amount of light?


Comments

  • #2
    pred racer
    Registered Users, Registered Users 2 Posts: 4,384 ✭✭✭pred racer


    quasars are a galaxy!, they are an active galactic nucleus, with large amounts of matter orbiting and being consumed by a massive black hole.


  • #3
    Mahatma coat
    Banned (with Prison Access) Posts: 6,869 ✭✭✭Mahatma coat


    The other site seems to suggest that Quasars consume Galaxies, so that'd be a lot of energy then


  • #4
    The Hill Billy
    Registered Users, Registered Users 2 Posts: 22,818 ✭✭✭✭The Hill Billy


    Silly me - I should have done a bit more research first.

    According to Wikipedia - they can be as small as a few light hours - based on changes in luminosity.
    Wikipedia wrote:
    Quasars are found to vary in luminosity on a variety of time scales. Some vary in brightness every few months, weeks, days, or hours. This evidence has allowed scientists to theorize that quasars generate and emit their energy from a very small region, since each part of the quasar would have to be in contact with other parts on such a time scale to coordinate the luminosity variations. As such, a quasar varying on the time scale of a few weeks cannot be larger than a few light-weeks across.


  • #5
    User45701
    Registered Users, Registered Users 2 Posts: 6,905 ✭✭✭User45701


    Quazars are not as much about size as they are brightness i mean a quazar that is a unimaginable distance away can shine brighter than alpha centurai which is our closest star


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