How did astronomers discover the relationship between spectral type and mass for main sequence stars?
A) by measuring stellar radii with very powerful telescopes
B) by measuring the masses and spectral types of main-sequence stars in binary systems
C) by using computer models of hydrogen fusion and stellar structure
D) by comparing stars with the same spectral type but different luminosities
B
You might also like to view...
A 1800 kg car moving at 20 m/s hits an initially uncompressed spring with a spring constant of 
The maximum compression of the spring is
A. 0.40 m. B. 0.60 m. C. 0.80 m. D. 1.0 m. E. 1.2 m.
An Earth satellite in close orbit circles Earth in about an hour and a half. How long would a satellite located as far away as the Moon take to orbit Earth?
A) the same hour and a half B) less than an hour and a half C) about 28 days D) need more information E) none of the above
An image is formed by a converging lens. Suppose the bottom half of the lens in covered, as shown
What happens to the image?
In a parallel RLC circuit, where IR = IR, max sin(?t), the current through the capacitor, IC, is
A. IC = ?IC, max sin(?t). B. IC = IC, max sin(?t). C. IC = ?IC, max cos(?t). D. IC = IC, max cos(?t). E. IC = IC, max tan(?t).