Topic: Space Pictures This Week: Lunar Sunrise, Saturn Slice, More

[sam]

A black hole two billion times as massive as the sun spits out jets of radiation in an artist's impression of ULAS J1120 0641, the most distant quasar yet discovered. The object was described in this week's issue of the journal Nature.

http://news.nationalgeographic.com/news/2011/06/pictures/110630-best-space-pictures-stars-quasar-titan-saturn-moon-lunar-151-science/

[Simon]

2 billion times the sun?  It's just beyond our imaginations, isn't it?

[sam]

yes.. when you put things into scale its just amazing;: e.g. http://vlad.bailescu.ro/wp-content/uploads/2008/10/planet_and_stars_scale_comparison.jpg

[Clive]

That's mass don't forget Simon - not size.  Though I'm sure Sam could do a back of an envelope calculation on size in comparison to our Sun.

[sam]

oh yes, mass it was. Ummm. I could do a calculation but would have to make a few assumptions about the contents of the star and the spectral age.

For stars like the Sun the radius is closely related to the the Mass - actually not far off 1:1, its actually R ~ M^(0.78) so a star 2 times the mass of the Sun would be 1.717 larger. For a star 2billion times larger, its much different and hence this relation would fall apart. Different physics going on inside it.

Black hole are exceedingly small. This is a quasar and hence would be smaller than the Sun.

[Simon]

[sam]

  I could be worse. I thought I was quite straight forward there.

Maybe this is better: http://en.wikipedia.org/wiki/Quasar

[Simon]

I'll look later. 

[Clive]

Mass and size are difficult concepts for most people, but you gave a good explanation.   

[sam]

maybe too much maths.

[Clive]

Can't see how you could have got away with less.   

[sam]

Ummm...

Most of the time mass is proportional to radius but in the case of extreme objects this is not the case. In red giants the radius is much larger due to convection currents. In the case of neutrons stars its much smaller because of the strong force holding it all together.

How's that.No maths.

[Clive]