Question

1. what is the general relationship between mass and lifetime for a star on the main sequence? (1) a stars mass has no effect on its lifetime (2) only medium - mass stars like our sun have long lifetimes (3) the more massive a star is, the longer its lifetime (4) the more massive a star is, the shorter its lifetime is 17) which of the following spectral classes represents the hottest temperatures (1) g (2) a (3) o (4) m 18) which cosmic event is responsible for the creation of elements heavier than iron, such as gold and uranium? (1) the collapse of a star into a white dwarf (2) the formation of a red giant (3) nuclear fusion in the core of a sun - like star (4) a supernova explosion 19) the star aldebaran is classified as a giant. it is much more luminous than the sun, but its surface temperature is significantly cooler. what physical property accounts for its high luminosity? (1) its high mass (2) its rapid rotation (3) its very large radius (4) its proximity to earth

Explanation:

• Question 16: More massive stars burn fuel faster, so they have shorter lifetimes.
• Question 17: The spectral class order from hottest to coolest is O, B, A, F, G, K, M.
• Question 18: Supernova explosions create elements heavier than iron.
• Question 19: Luminosity \(L=\sigma T^{4}4\pi R^{2}\) (Stefan - Boltzmann law). If \(T\) (temperature) is lower but \(L\) (luminosity) is higher, \(R\) (radius) must be large.

Answer:

1. (4) the more massive a star is, the shorter its lifetime is
2. (3) O
3. (4) a supernova explosion
4. (3) its very large radius