Question

How does galaxy composition typically relate to the age of the stars in the galaxy?(1 point)
Responses

Stars form from dust and gas, so galaxies with younger stars typically consist of higher proportions of dust and gas than other galaxies.
Stars form from dust and gas, so galaxies with younger stars typically consist of higher proportions of dust and gas than other galaxies.

Star formation consumes dust and gas, so galaxies where stars are oldest typically consist of higher proportions of dust and gas than other galaxies.
Star formation consumes dust and gas, so galaxies where stars are oldest typically consist of higher proportions of dust and gas than other galaxies.

Star formation and the presence of young stars is common across galaxies, regardless of the proportions of dust and gas present.
Star formation and the presence of young stars is common across galaxies, regardless of the proportions of dust and gas present.

Star aging emits gas and dust, so galaxies with

Answer 1

Stars form from dust and gas, so galaxies with younger stars typically have higher proportions of gas and dust than galaxies dominated by older stars. (Spiral and irregular galaxies tend to be gas‑rich and star‑forming; ellipticals are gas‑poor and dominated by old stars.)