Main Question or Discussion Point
Why do the arms of spiral galaxies usually bifurcate? Is the visible matter in them moving in or out from the center?
2 armed galaxies are only one of many forms, many have multiple arms, many have none that can be easily identifiedWhy do the arms of spiral galaxies usually bifurcate? Is the visible matter in them moving in or out from the center?
One thing to keep in mind is that spiral arms in galaxies are "density waves" and not actual structures of the matter. They represent the area where many millions of stellar orbits reach their maximum distance from the galactic center of mass. At this point they are traveling the slowest and so "pile up" in the region producing the appearance of more stars than in-between the arms. But the individual stars in each arm are changing continuously.
Put another way, the arms are an illusion. They aren't like a whirlpool or anything like that.
First, thank you all for taking the time to answer my questions.The stars in a galaxy really are [were, given the finite speed of light] where they appear to be as Dave noted, however, Rex is correct in that they do not form and remain in spiral arms as they orbit a spiral galaxy. Their individual motions follow a density wave profile as illustrated here .
I'm curious what characteristic led you to that conclusion. I must be missing something because I just don't see it at all. I mean, I know that it's NOT, I'm just curious why you think it might be.Yes, an electrical type transformer in its form.
I think we're all confused why a galaxy seems related to an electrical transformer. Perhaps you could explain what you mean?Have I said something heretical? Is it not proper to assume the stars have arranged themselves so for a reason, and this may be worthy of our scrutiny?
No, the stars do not "arrange themselves". That puts an anthropomorphic spin on inanimate objects and thus is not science. Studying how the stars are arranged is certainly a valid (and interesting) field of study but let's not bring consciousness into it.Is it not proper to assume the stars have arranged themselves so for a reason, and this may be worthy of our scrutiny?
And you STILL have not explained this apparently nonsensical statement. Please do so.I may have been misunderstood by Mr. Phinds; spiral galaxies when considered over time seem to describe a form similar to an electrical transformer. I don't believe they are electrical transformers, although they may be. I'm trying to understand the reasons for the various forms galaxies take on as they transform one or more things into others. Their forms must follow their purposes.
Ah, where's the fun in that. It leaves me nothing to nitpick about.Mr. Phinds: please change "arrange themselves" to "are arranged".
Well, some of us here are just wading.Incidentally, my wife, who is also a heavenly body, agrees with you wholeheartedly that I'm nonsensical and not very scientific. I've informed her that someone who obviously resides in a very deep pool of knowledge agrees with her.