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A 20 solar mass star will stay on the main sequence for 10 million years, yet its iron core canexist for only a:
Q29: How would Ptolemy explain the rising of
Q73: What is meant by a cosmological distance?
Q74: Harvard woman astronomer discovered the period- luminosity
Q105: The instability strip shows that not all
Q110: The Copernican Principle notes that we are
Q112: The RR Lyrae stars all have periods
Q118: Compared to a hydrogen atom where the
Q128: Within the boundaries of the constellations Coma
Q149: Two stars have the same absolute magnitude,
Q160: Describe the cycle of life and death