This is the thing you guys have been waited for a long time, and now it has arrived.

"It" is my blog, of course. :)

I know I said this over on your blog instead of here... so as not to diminish how cool that is:

YAY :)

Thanks. :)

I have accomplished surprisingly lot there in last few months. I now have quite a good body of posts there, so perhaps I should now start paying attention to the PR side, as I have currently only about one visitor per day. ;) Well, it's just little against my nature to go to every forum I find to make some posts practically asking them to look at my blog...

Internet searches seem to find my "redshift components" post quite a lot, so it is becoming the popular one of my posts.

There's a new post available:

Knut Lundmark - extragalactic distance scale

It continues my series on astronomy history, and this one was very interesting character; pre-Hubble redshift-distance relation etc.

I realised that in order to get some traffic from google, I need to make entries of the really exciting systems, so here's the entry on NGC 7603:

http://arijmaki.wordpress.com/2010/04/10/ngc-7603-the-discordant-redshift-system/

very cool

Do you know anything about the redshift of light coming from the bridge itself?

It's probably not possible to isolate, but I would think there would be some "new stuff residue" at the trailing edge, within the parent galaxy.

Do you know anything about the redshift of light coming from the bridge itself?

Yes, Lopez-Corredoira & Gutierrez estimated it to be 0.030 - about the same as the main galaxy.

It's probably not possible to isolate, but I would think there would be some "new stuff residue" at the trailing edge, within the parent galaxy.

It would be difficult, but might be possible with some big telescope with lot of observing time. I cannot see that happening any time soon, though.

so if the bridge matter is about the same age as the main galaxy (by Arpian redshift view) does that mean the event that creates the new galaxy (implosion or explosion) takes place after the ejection?

Gotta throw some aether conjencture in here too - I should note that when I throw the term aether around, I'm not referring to any particular theory, just the idea that "space" is composed of very tiny little buggers that haven't been acknowledged yet. Anyway...so a dense bunch of matter is ejected from the parent galaxy (for reasons I'll ingnore at the moment) and suddenly finds itself in a very low pressure area (with respect to matter) or a very high pressure area (with respect to aether). You could view it as matter coming apart very quickly (explosion) or aether rushing inward very quickly, pushing the matter along with it (implosion).

Ed said:

so if the bridge matter is about the same age as the main galaxy (by Arpian redshift view) does that mean the event that creates the new galaxy (implosion or explosion) takes place after the ejection?

I guess that might be one way looking at it, but I think the suggestion here is that the ejection has dragged material from the main galaxy. I have my own doubts about that, though. The two objectsin the bridge bother me; if this would be en ejection event where 3 objects have been ejected at different times, then why should all of them be so precisely in the same ejection path? It doesn't make sense in such a dynamic environment, it's just too perfect.

good point. there might be a very good reason they're all lined up, but you'd have to know a lot more about the ejection events to evaluate it.  Is it also possible that the two objects in the bridge aren't actually in the bridge, just superimposed?

The idea of new matter being formed and then being ejected (or simultaneously) doesn't sound right though. Wouldn't that be an extremely violent event? I imagine that would cause a lot more disruption in the parent galaxy than an ejection that then explodes or implodes.

My own thinking, based not so much on research as a very active imagination, is that these ejections might be caused when the galaxy gets close to a very strong magnetic field line. If there happens to be a large enough concentration of heavy metals in the wrong place at the wrong time, they get ripped out.

If the galaxy encountered one of these lines periodically, at the same orientation, that might explain the alignment. Of course, whatever was emitting the magnetic field lines would have to be enormous.

yet another possibility, I suppose, is that the younger galaxy happened to form near the older galaxy,  and isn't its offspring, just drawing off some of the material. 

Here's a fairly recent image:

[url=http://hostedby.us/art/pictures/DISTSUNS/NGC7603.JPG][/url]

To the totally untrained eye, there does seem to be a lot of commotion going on at the center of the "parent"

Ed said:

Is it also possible that the two objects in the bridge aren't actually in the bridge, just superimposed?

I think so. Some time ago I performed a rough calculation of the chance projection probability for the two so that I counted similar looking objects within certain radius from NGC 7603 using the SDSS image of the system. There are quite a few similar looking objects around NGC 7603 and the probability for the two being within the bridge area wasn't very low, i.e. it seemed like a real option that they are just chance projections (I don't remember the actual numbers). However, this kind of approach is far from conclusive because it is likely that not all similar looking objects are actually similar objects. Lopez-Corredoira & Gutierrez have presented similar calculation but using spectroscopically determined objects and they arrived to quite low probability.