Concept explainers
The text says a star does not change its mass very much during the course of its main-sequence lifetime. While it is on the main sequence, a star converts about 10% of the hydrogen initially present into helium (remember it’s only the core of the star that is hot enough for fusion). Look in earlier chapters to find out what percentage of the hydrogen mass involved in fusion is lost because it is converted to energy. By how much does the mass of the whole star change as a result of fusion? Were we correct to say that the mass of a star does not change significantly while it is on the main sequence?
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- In the H-R diagram we see that stellar masses__________ downward along the main sequence. At the upper end of the main sequence, the hot, luminous O stars can have masses as high as _________ or more times that of the Sun. On the lower end, cool, dim M stars may have as little as __________ times the mass of the Sun. Many more stars fall on the lower end of the main sequence than on the upper end, which tells us that _________stars are much more common than __________ stars.arrow_forwardSelect all of the statements about the main sequence stage in the life of a star that are TRUE: All stars spend the majority of their lives in the main sequence stage. Most stars lose a significant amount of mass while they are on the Main Sequence. Different stars spend a different amounts of time (number of years) in the main sequence stage, depending on the characteristics they were born with. Main sequence stars are rare in the Galaxy, so we are lucky to be living around one. During the main sequence stage, energy to power the star is provided by the fusion of hydrogen.arrow_forwardStar A and Star B are both on the main sequence. Star A is 63 times more luminous than Star B. What is the ratio of their main-sequence lifetimes? Hint: Refer to the stellar life expectancies equation, t* = M* L* = M* M*3.5 = 1 M*2.5 .arrow_forward
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