Comments on: Giving Vega a spin

By: SFwriter

SFwriter — Thu, 23 Mar 2006 23:23:24 +0000

Blake Stacey Said:
“Itâ€™s all the sort of nonsense up with which we should not put.”

I always liked Winston Churchill!

By: Irishman

Irishman — Thu, 23 Mar 2006 22:56:31 +0000

In order for that to be the case, we would need to be aligned with the major axis of the ellipse. But there is no reason the major axis would stay constant. The distant objects would remain distant as they orbit, so the ellipse would rotate around Vega. Thus we would not see a circular projection for very long, it would quickly* become an ellipse.

*Quickly in astronomical terms. I don’t know how fast the disk material is orbiting.

By: Greg Wilson

Greg Wilson — Thu, 23 Mar 2006 22:54:36 +0000

My physics prof at UVa hated the word centrifugal and didn’t care too much about centripetal. His ideas were that centrifugal was just a result of inertia and that centripetal referred to too many separate forces, i.e. many things provide a centripetal force: it’s not “one” special force. I think these are teaching subtleties to help students understand.
I agree with my prof. and think that centrifugal is truly a fictitious force because if suddenly the centripetal force were to disappear, then the object flies off in a straight line at constant velocity until another force acts on it. If the centrifugal force was real, then the object should move in the direction of that force, i.e. if the gravitational force holding the star together (and providing the centripetal force) were to disappear, I don’t think particles would fly off toward the outside.
I do however understand that it’s sometimes beneficial when you’re thinking about a rotating frame of reference to use “centrifugal” but deep down, I feel that it’s fictitious.

By: Matt

Matt — Thu, 23 Mar 2006 17:32:25 +0000

I have a question tangential to the centri[fug|ped]al debate.

You mentioned that the apparently nearly circular disk of Vega’s system is evidence that we are looking nearly pole-on to a circular system — taken from the fact that if we looked obliquely at a circular system we’d see an ellipse.

Okay, so how do we know we aren’t looking at an elliptical system obliquely, yielding an almost-circle?

By: SFReader

SFReader — Thu, 23 Mar 2006 15:36:52 +0000

Another reason for Vega’s spin might be that it’s in the process of collapsing, or perhaps coalescing, which will be interesting for us, being so close. Although that’s not predicted by its place on the stellar life chart, is it?

By: HawaiiArmo

HawaiiArmo — Thu, 23 Mar 2006 09:11:23 +0000

I was thinking about the possibilities that arose regarding the current understanding of stellar evolution and how it applies to Vega’s extremely rapid angular spin. Apparently, some rotational force, some shock or another provides enough torque to cause a cold molecular cloud to condense and begin spinning. Perhaps Vega was located close to a supernova, and the energy imparted upon its inception resulted in the high rate of angular motion.
Does anyone else have any theories regarding the possible reason for Vega’s high rate of spin? Perhaps we can have an informal discussion, because I doubt there are any simulations that present Vega’s stellar origin in regards to this new data.

By: ioresult

ioresult — Thu, 23 Mar 2006 04:49:02 +0000

BA said: “Good thing I donâ€™t plan any Mars probes.”

Mixing pounds with newtons, that was waay bad!