This H-R diagram shows the life track of a 1 MSun star from the time it first becomes a main-sequence star. Which numbered point represents the star when it has both hydrogen-fusing and helium-fusing shells around an inert carbon core?
A) Point 1
B) Point 2
C) Point 3
D) Point 4
D) Point 4
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As global warming continues, weather patterns will change causing
A) some parts of the Earth's landmass to become warmer while other parts will experience more extreme winters. The ocean temperatures will continue to rise B) only the oceans to become warmer while the landmasses will become colder C) only the landmasses to become warmer while the oceans will become colder D) all parts of the Earth's surface will become warmer
Why are Cepheid variables important?
A) Cepheid variables are stars that vary in brightness because they harbor a black hole. Therefore, they provide direct evidence for black holes. B) Cepheids variables are supermassive stars that are on the verge of becoming supernovae. Therefore they allow us to choose candidates to watch if we hope to observe a supernova. C) Cepheids variables are a type of irregular galaxy, much more common in the early universe. Therefore they help to understand how galaxies formed. D) Cepheids variables are pulsating stars whose pulsation periods are directly related to their true luminosities. Therefore they can be used as distance indicators.
Why didn't elements heavier than helium form in the first minutes of creation?
A) When He-4 was formed, the expansion cooled the cosmos below 100 million K. B) The first generation of stars used them up too quickly to observe them. C) The electrons slowed down enough to be captured into orbits by protons. D) There was not enough matter in the universe at that time. E) Only Type I supernovae can produce iron and heavier elements.
Nimbus means
a. "poorly formed.". b. "curl.". c. "heap.". d. none of these.