Third spiral in opposite direction?
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by
bundrew
When I look at this image, I see three spiral arms: the two obvious ones, but then just above the end of the bottom arm is another, stubbier arm that appears to be rotated in the opposite direction! It almost looks like pincers or something. Is that perhaps part of some tidal debris or merger remnant? Maybe it's just a weird alignment? Or is there a process that can form another arm going in the opposite direction of the other spiral arms?
Posted
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by
klmasters
scientist, admin
We certainly know there are galaxies in which some stars rotate one way, and others go the other way (called "counter rotating discs"), but I think it'd be hard to create the spiral pattern for any length of time in two senses.
If that small edge on disc to the right of the main galaxy is a satellite (rather than background), or the round one at the lower right even, then the spur you see could definitely be related to tidal interactions.
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