Chapter 33, Problem 4TC

Solution

To determine: The rank in order of increasing age of a white dwarf, a protostar, a red giant, a yellow medium-sized star.

Answer:

The rank in order of increasing age is a protostar < a red giant < a yellow medium-sized star < white dwarf.

Explanation:

The life span of a protostar depends on its size, but it is shorter as compared to the sequence and cannot exceed 1 million years.

A red giant is a highly bright and low-mass star of life span 10's to 100's of millions of years, but the lifespan of a red giant star cannot exceed 1 billion years.

Our Sun is considered as a medium-sized yellow star with a life span of $\text{around}8-14\text{billion}\text{years}$ and a very small yellow star can survive up to trillions of years.

The life span of the white dwarf is calculated to be longer than the current age of the universe. The average life span of a dwarf star varies from $10\text{billion}\text{years}$ to $100\text{billion}\text{years}$ .

Conclusion:

Therefore, the rank in order of increasing age is a protostar < a red giant < a yellow medium-sized star < white dwarf.