How Big is a Quasar

The Hill Billy

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?

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.

Mahatma coat

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

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.

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