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About how long did the Sun spend in the protostar phase of its life?
Q25: Which of these statements does NOT describe
Q43: X-ray bursters emit occasional and intense bursts
Q60: Thermonuclear reactions convert hydrogen into helium in
Q93: What is the ratio of the brightnesses
Q109: The shell of a planetary nebula is
Q125: A binary system contains a neutron star
Q157: There are several mechanisms that can trigger
Q206: Supernovae have been detected<br>A) in both the
Q218: Which of these four spectral classifications signifies
Q230: What is the reason that the edge