Artificial Intelligence
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What causes the bar in a barred-spiral galaxy?


The bar in a barred-spiral galaxy is thought to be caused by a gravitational instability in the galactic disk. This instability can be triggered by interactions with neighboring galaxies, or by the internal dynamics of the galaxy itself. As the bar rotates, it exerts gravitational forces on the surrounding gas and stars, causing them to move along the bar's structure. This creates a more elongated central region in the galaxy, giving it a "barred" appearance.