How did astronomers discover the relationship between spectral type and mass for main-sequence stars?
A. by using computer models of hydrogen fusion and stellar structure
B. by measuring stellar radii with very powerful telescopes
C. by comparing stars with the same spectral type but different luminosities
D. by measuring the masses and spectral types of main-sequence stars in binary systems
Answer:D
How did astronomers discover the relationship between spectral type and mass for main-sequence stars?
A. by using computer models of hydrogen fusion and stellar structure B. by measuring stellar radii with very powerful telescopes C. by comparing stars with the same spectral type but different luminosities D. by measuring the masses and spectral types of main-sequence stars in binary systems