Why do stars in the central bulge have a lower metallicity than stars in the disk?
What will be an ideal response?
Stars in the central bulge formed first, out of material found early in the Universe's history that was mostly hydrogen and helium. Many stars in the disk are younger, and formed after stellar evolution had enriched the interstellar medium with heavier elements. Since metals were present in the materials that formed disk stars, disk stars have a higher metallicity.
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A hot pizza contains __________
Fill in the blank(s) with correct word
What electric charge is characteristic for an ion of S?
a. 6+ b. 0 c. 2– d. 2+
The cutting cord on a gas-powered weed cutter is 0.20 m in length. If the motor rotates at the rate of 20 rev/s, what is the tangential speed of the end of the cord?
a. 628 m/s c. 19 m/s b. 25 m/s d. 63 m/s
How does the explosion of a nuclear bomb provide evidence for the theory of relativity?
A) The bomb converts rest-mass energy into thermal energy in accord with E = mc2, which is part of the theory of relativity. B) The mass of the bomb when it explodes is much greater than its normal mass. C) The bomb causes things in its vicinity to move at high speeds, allowing scientists to measure effects of time dilation. D) The bomb shortens the lifetimes of all people who happen to be near it when it detonates.