The star ? Pegasi (in the constellation Pegasus, the Flying Horse) has a spectral luminosity class of B8 V, giving it a surface temperature of about 12,000 K. According to Table 19-1 of Universe, 11th ed., the expected main-sequence lifetime of ? Pegasi is:
?
?
A)about 400,000 years.
B)about 400 million years.
C)much greater than 800 million years.
D)not defined in any way by the above information.

Question

The star ? Pegasi (in the constellation Pegasus, the Flying Horse) has a spectral luminosity class of B8 V, giving it a surface temperature of about 12,000 K. According to Table 19-1 of Universe, 11th ed., the expected main-sequence lifetime of ? Pegasi is:
?
 ?
A)about 400,000 years. 
B)about 400 million years. 
C)much greater than 800 million years. 
D)not defined in any way by the above information.

Quizplus · Accepted Answer

The expected main-sequence lifetime of a star is primarily determined by its mass. Based on its spectral luminosity class, ζ Pegasi has a mass of about 2.5 solar masses, which corresponds to a main-sequence lifetime of about 400 million years.

The Star ? Pegasi (In the Constellation Pegasus, the Flying