What is a galaxy's bulge?

Answer 1

It's the central part of a galaxy, where there is a much higher concentration of older stars, dust, and other luminous objects.

The reason it is denoted a bulge, is because the high luminosity stands out from the rest of the galaxy and looks like it is bulging outwards. Here's an artistic rendition that is probably a bit inaccurate, but illustrates the concept because it is fairly exaggerated.

It is also commonly accepted that most galaxies contain a supermassive black hole which resides in this central bulge.

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Answer 2

Declan Carroll

Usually located at the center of a galaxy, the bulge is a central, dense, spherical structure made of stars, gas, and dust.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.