Astronomy
1st Edition
ISBN: 9781938168284
Author: Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher: OpenStax
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Chapter 22, Problem 33E
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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Chapter 22 Solutions
Astronomy
Ch. 22 - Compare the following stages in the lives of a...Ch. 22 - What is the first event that happens to a star...Ch. 22 - Astronomers find that 90% of the stars observed in...Ch. 22 - Describe the evolution of a star with a mass...Ch. 22 - Describe the evolution of a star with a mass...Ch. 22 - A star is often described as “moving” on an HR...Ch. 22 - On which edge of the main sequence band on an HR...Ch. 22 - How do stars typically “move” through the main...Ch. 22 - Certain stars, like Betelgeuse, have a lower...Ch. 22 - Gravity always tries to collapse the mass of a...
Ch. 22 - Why are star clusters so useful for astronomers...Ch. 22 - Would the Sun more likely have been a member of a...Ch. 22 - Suppose you were handed two HR diagrams for two...Ch. 22 - Referring to the HR diagrams in Exercise 22.13,...Ch. 22 - The nuclear process for fusing helium into carbon...Ch. 22 - Pictures of various planetary nebulae show a...Ch. 22 - Describe the two “recycling” mechanisms that are...Ch. 22 - In which of these star groups would you mostly...Ch. 22 - Explain how an HR diagram of the stars in a...Ch. 22 - Where did the carbon atoms in the trunk of a tree...Ch. 22 - What is a planetary nebula? Will we have one...Ch. 22 - Is the Sun on the zero-age main sequence? Explain...Ch. 22 - How are planetary nebulae comparable to a...Ch. 22 - Which of the planets in our solar system have...Ch. 22 - Would you expect to find an earthlike planet (with...Ch. 22 - In the HR diagrams for some young clusters, stars...Ch. 22 - If the Sun were a member of the cluster NGC 2264,...Ch. 22 - If all the stars in a cluster have nearly the same...Ch. 22 - Suppose a star cluster were at such a large...Ch. 22 - Suppose an astronomer known for joking around told...Ch. 22 - Stars that have masses approximately 0.8 times the...Ch. 22 - Automobiles are often used as an analogy to help...Ch. 22 - The text says a star does not change its mass very...Ch. 22 - The text explains that massive stars have shorter...Ch. 22 - You can use the equation in Exercise 22.34 to...Ch. 22 - You can estimate the age of the planetary nebula...Ch. 22 - If star A has a core temperature T, and star B has...
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- According to the text, a star must be hotter than about 25,000 K to produce an H II region. Both the hottest white dwarfs and main-sequence O stars have temperatures hotter than 25,000 K. Which type of star can ionize more hydrogen? Why?arrow_forwardA star begins its life with a mass of 5 MSunbut ends its life as a white dwarf with a mass of 0.8 MSun. List the stages in the star’s life during which it most likely lost some of the mass it started with. How did mass loss occur in each stage?arrow_forwardThis star has a mass of 3.3 MSun. What is the main sequence lifetime of this star? You may assume that the lifetime of the sun is 1010 yr.arrow_forward
- Let's calculate how much mass will be lost by the Sun 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 that it is only the core of the star that is hot enough for fusion). During nuclear fusion, the Sun converts about 0.7% of the core hydrogen mass into energy. The total mass of the Sun is 2 × 1030 kg. How many kilograms of mass will be converted to energy during the main sequence stage of the Sun's life? What is the ratio of this lost mass to the Earth's mass (6 × 1024 kg)? In other words, how many Earths of mass will be turned into energy?arrow_forwardThis star has a mass of 3.3 MSun. What is the main sequence lifetime of this star? You may assume that the lifetime of the sun is 1010 yr. Hint: The simple relation is that lifetime is proportional to mass divided by luminosity. If you use these quantities in solar masses and solar luminosities, then this relation tells you how many times longer than the Sun the star will live.arrow_forwardObservations show that stellar luminosity, L, and mass, M, are related by L x M3.5 for main sequence stars. Obtain an expression that relates the main sequence life time and the mass of a star. You should assume that the luminosity is constant throughout a star's main sequence life time, and that the amount of mass converted into energy by a star while it is on the main sequence is given by AM main sequence life time of a 20 Solar mass star given that the Sun is expected to spend 1010 years on the main sequence. Comment on the significance of your answer. fM, where f is a constant. Estimate thearrow_forward
- 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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