Do we have a true picture of galaxy types?

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Offline jeffreyH

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Do we have a true picture of galaxy types?
« on: 25/06/2015 02:20:45 »
If we take a cylinder 299, 792, 458 meters long with stripes of alternate colours painted along its length and have it rotating at 1 revolution per second then the stripes would appear like those on a barbers pole. This is simply due to the speed of light. The light from the end nearer to the observer arrives 1 second before that from the other end. Since galaxies are typically light years across we may have an incorrect view of the shapes they form. The effects of the internal gravitation on light may also give us a skewed picture of their rotation.

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Offline Colin2B

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Re: Do we have a true picture of galaxy types?
« Reply #1 on: 25/06/2015 17:35:04 »
Just thinking that these galaxies are a long way away. Do you know what the movement of the far side would be relative to near side during time for light to transverse. Just wondering how that relates to resolving power of the observers?
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Offline jeffreyH

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Re: Do we have a true picture of galaxy types?
« Reply #2 on: 26/06/2015 12:47:50 »
The problem is there is a variation in the gravitational field passing through the galaxy. This is going to affect light but will be variable depending upon the position. Near the central black hole this will be extreme. I have no idea if I am right or not. This may all have been taken into account by astronomers. The question came to me while reading Longair's Galaxy Formation.