In the News: Strange Ring Galaxy

[CraigS]

Here we go ..one for the Astrophotographers ..

"Image: A Strange Ring Galaxy"
http://www.physorg.com/news202133035.html

"On the outside is a ring dominated by bright blue stars, while near the center lies a ball of much redder stars that are likely much older. Between the two is a gap that appears almost completely dark."
...
"Hoag's Object spans about 100,000 light years and lies about 600 million light years away toward the constellation of the Snake (Serpens). Coincidentally, visible in the gap (at about one o'clock) is yet another ring galaxy that likely lies far in the distance".

? Two birthing phases ??
Lets see the galaxy modellers work that one out !

Cheers

[astroron (Ron)]

Hoag's Object was the subject of APOD on the 22 August
http://antwrp.gsfc.nasa.gov/apod/ap100822.html
Still it is an amazing object

[renormalised (Carl)]

Yes, this one is a toughy.....in most cases of ring galaxies, there's an obvious collisional cause as there is usually an associated companion nearby, e.g. the Cartwheel (PGC2248), but in this case (and in some others) there's no companion to be seen. Although, if a collision happened long enough ago, there's a good chance you may not see one because it's moved on and/or the companion may have been absorbed in the collision.

Your hunch about two birthing phases maybe right, Craig, but objects like this need further study (no doubt Alex will have the answers...as usual).

Or, as they summise, it may have something to do with a previously existing central bar.

What's neat here, is that you have another ring galaxy behind Hoag's that you can see between the ring and the nucleus

[astroron (Ron)]

Originally Posted by renormalised

Yes, this one is a toughy.....in most cases of ring galaxies, there's an obvious collisional cause as there is usually an associated companion nearby, e.g. the Cartwheel (PGC2248), but in this case (and in some others) there's no companion to be seen. Although, if a collision happened long enough ago, there's a good chance you may not see one because it's moved on and/or the companion may have been absorbed in the collision.

Your hunch about two birthing phases maybe right, Craig, but objects like this need further study (no doubt Alex will have the answers...as usual).

Or, as they summise, it may have something to do with a previously existing central bar.

What's neat here, is that you have another ring galaxy behind Hoag's that you can see between the ring and the nucleus

Yes Carl, What a coincidence What are the chances of this happening again

[renormalised (Carl)]

Originally Posted by astroron

Yes Carl, What a coincidence What are the chances of this happening again

There's a reasonable chance that the formation of a ring galaxy could happen at any stage in a galaxy's formation. If it's through collisional processes, then you have a good chance of it happening if the geometry of the collision allows it. It would have to be a head on, or near head on collision in order to generate the shockwaves that would create such a galaxy. You probably have about a 1-2% chance of it occurring. If it's a formation of a polar ring, then they occur in around 5-10% of interacting galaxies, and similarly the shape of the ring is due to the geometry of the interaction between the galaxies (plus the gravitational and other effects, of course).

If the ring is formed through the general formation processes of the galaxy, then that is a different matter altogether. They still aren't sure how that occurs but they have some hypotheses...namely those ones that I have already stated. However, there maybe other processes at work, but the least likely is some EM influence as proposed by EU. There's no evidence for it. The evidence for powerful EM forces at work (as is proposed) would be so obvious, you couldn't miss it, even in a cursory examination.

As for the other ring galaxy behind Hoag's....just coincidence, no more or no less. Given the numbers of galaxies in existence, there would be bound to be a few chance alignments such as this. You should know that as well as I do.

[astroron (Ron)]

Lighten up Carl that was just a fun remark
I know that these things happen, but it is still a rare thing to get images of the occurrence
I have seen Thousands of images of galaxies, Quite a few ring galaxies among them but Non with another ring galaxy inside it

[renormalised (Carl)]

I know Ron. I'm probably still touchy over Jarva's escapades and I have other things to do besides. Which I will now get into and finish off before the deadline passes on Monday!!!

Plus I have a roaring headache from being in front of the computer too much

[CraigS]

Interesting discussion, guys. I haven't had a chance to do much reading on this one but the thoughts going thru my mind are on things like:

i) What does the gravity field look like in the dark ring part ?
ii) How does this effect the objects in the outer core and the inner/outer parts of the ring ?
iii) How is the halo effected ? and what role has the notorious DM played in the structure formation or maintenance of the structure geometry ? Can we get a lens on this one (eg: for the ring galaxy visible inside it) and what more info can this tell us about the shape of the Halo ?
iv) What can we predict will happen to this galaxy in the next few MYrs ? Can we predict the expansion rates of the inner & outer bits & can we measure them now ? What do these measurements tell us ?

Man I could go forever ...
v) How does this one impact on current Galaxy models ?
vi) Does it contain an SMBH in the core ?

Oh well, apologies for that. I get excited about this kind of stuff when I read about something unusual .. I don't expect anyone to answer all of the above .. I'll just have to get back to more reading I guess, but my mind can't just stop at the awe of the image .. (just thought I'd share my thoughts on it all .. ugly as these thoughts may be).


Cheers & Rgds.

[renormalised (Carl)]

Everything that you have mentioned there is up for grabs, so to speak, Craig. A lot of work needs to be done before we understand what is going on there. But all your questions are very important and very relevant.

I have an idea....why don't you do a course in Astronomy. Do a masters then onto a PhD. You've got a keen interest in it and it'd seem a shame not to capitalise on it