Question 1

Explain the two different forms of pressure that support the core of a low-mass main-sequence star and the core of a low-mass red giant star.

Accepted Answer

The core of a low-mass main-sequence sta

Question 2

The evolutionary cutoff between low- and high-mass stars occurs at approximately:

Accepted Answer

A) 1.5 M⨀ 
B) 1 M⨀ 
C) 3 M⨀ 
D) 5 M⨀ 
E) 10 M⨀ 
A) 1.5 M⨀ 
B) 1 M⨀ 
C) 3 M⨀ 
D) 5 M⨀ 
E) 10 M⨀

Question 3

If there were mixing processes in a main-sequence star with a radiative zone (there aren't)that churned up all the material in the interior,we would expect that the main-sequence lifetime would be _________ because _________.

Accepted Answer

A) shorter,because the star would turn into a giant faster 
B) shorter,because the star would burn hydrogen faster and have a higher luminosity 
C) longer,because helium nuclei have a higher mass than hydrogen nuclei 
D) shorter,because the star would never turn into a red giant 
E) longer,because more hydrogen would be available to burn 
A) shorter,because the star would turn into a giant faster 
B) shorter,because the star would burn hydrogen faster and have a higher luminosity 
C) longer,because helium nuclei have a higher mass than hydrogen nuclei 
D) shorter,because the star would never turn into a red giant 
E) longer,because more hydrogen would be available to burn

Question 4

Stars with masses similar to the Sun will lose approximately 30 percent of their mass before they become white dwarfs.

Accepted Answer

A) True 
 B)False

Question 5

Explain the significance of Roche lobes in a binary system.

Accepted Answer

The Roche lobe is an imaginary line of e

Question 6

Binary stars can evolve to become novae and supernovae because small differences in the stars' masses can mean large differences in their main-sequence lifetimes.

Accepted Answer

A) True 
 B)False

Question 7

You observe a 0.8 M⨀ white dwarf in a binary orbit around a main-sequence star of mass 1.4 M⨀.Which of the following is most likely the original mass of the star that became the white dwarf?

Accepted Answer

A) 0.5 M⨀ 
B) 1 M⨀ 
C) 0.8 M⨀ 
D) 1.4 M⨀ 
E) 3 M⨀ 
A) 0.5 M⨀ 
B) 1 M⨀ 
C) 0.8 M⨀ 
D) 1.4 M⨀ 
E) 3 M⨀

Question 8

A Type I supernova occurs when a white dwarf exceeds a mass of:

Accepted Answer

A) 0.8 M⨀ 
B) 1.4 M⨀ 
C) 2.3 M⨀ 
D) 5.4 M⨀ 
E) 10 M⨀ 
A) 0.8 M⨀ 
B) 1.4 M⨀ 
C) 2.3 M⨀ 
D) 5.4 M⨀ 
E) 10 M⨀

Question 9

As a white dwarf star gradually cools,its radius stays approximately constant.What is happening to the white dwarf's luminosity?

Accepted Answer

A) It stays the same. 
B) It increases. 
C) It increases then decreases periodically. 
D) It decreases. 
E) You can't tell from the information given. 
A) It stays the same. 
B) It increases. 
C) It increases then decreases periodically. 
D) It decreases. 
E) You can't tell from the information given.

Question 10

A nova is the result of which explosive situation?

Accepted Answer

A) mass transfer onto a white dwarf 
B) helium burning in a degenerate stellar core 
C) a white dwarf which exceeds the Chandrasekhar limit 
D) the collision of members of a binary system 
E) runaway nuclear reactions in the core 
A) mass transfer onto a white dwarf 
B) helium burning in a degenerate stellar core 
C) a white dwarf which exceeds the Chandrasekhar limit 
D) the collision of members of a binary system 
E) runaway nuclear reactions in the core

Question 11

The main-sequence lifetime of a star is given by the equation:

Accepted Answer

A) τ ∝ M/L 
B) τ ∝ L/M 
C) τ ∝ M2/L 
D) τ ∝ L2/L 
E) τ ∝ M/L2 
A) τ ∝ M/L 
B) τ ∝ L/M 
C) τ ∝ M2/L 
D) τ ∝ L2/L 
E) τ ∝ M/L2

Question 12

When a star burns hydrogen in a shell,it will never produce as much energy (per unit time)as when it burns hydrogen in the core because the core has a higher temperature.

Accepted Answer

A) True 
 B)False

Question 13

A Type I supernova can be as luminous as 10 billion L⨀.

Accepted Answer

A) True 
 B)False

Question 14

Asymptotic giant branch stars have high-mass loss rates because:

Accepted Answer

A) they are rotating quickly 
B) they have weak magnetic fields 
C) they have strong magnetic fields 
D) they have low surface gravity 
E) they have high surface temperatures 
A) they are rotating quickly 
B) they have weak magnetic fields 
C) they have strong magnetic fields 
D) they have low surface gravity 
E) they have high surface temperatures

Question 15

What types of chemical elements can low-mass stars contribute to the enrichment of the interstellar medium and how are they produced?

Accepted Answer

Low-mass stars can enrich the interstell

Question 16

If a main-sequence star's core temperature increased,fusion reaction rates would decrease because the protons would be moving faster.

Accepted Answer

A) True 
 B)False

Question 17

How can the core of a star be degenerate with respect to the electrons but nondegenerate with respect to the nuclei?

Accepted Answer

(1)Quantum mechanics says electrons take

Question 18

How long will a 2 M⨀ star live as a main-sequence star?

Accepted Answer

A) 12 million years 
B) 180 million years 
C) 1.8 billion years 
D) 12 billion years 
E) 18 billion years 
A) 12 million years 
B) 180 million years 
C) 1.8 billion years 
D) 12 billion years 
E) 18 billion years

Question 19

What is the shortest phase of evolution for a one solar mass star that we can visibly see?

Accepted Answer

The planetary nebula phase is

Question 20

Once the core of a low-mass main-sequence star runs out of hydrogen,fusion in the star stops until the core temperature is high enough for helium fusion to begin.

Accepted Answer

A) True 
 B)False

Exam 16: Evolution of Low-Mass Stars

Explain the two different forms of pressure that support the core of a low-mass main-sequence star and the core of a low-mass red giant star.

The evolutionary cutoff between low- and high-mass stars occurs at approximately:

If there were mixing processes in a main-sequence star with a radiative zone (there aren't)that churned up all the material in the interior,we would expect that the main-sequence lifetime would be _________ because _________.

Stars with masses similar to the Sun will lose approximately 30 percent of their mass before they become white dwarfs.

Explain the significance of Roche lobes in a binary system.

Binary stars can evolve to become novae and supernovae because small differences in the stars' masses can mean large differences in their main-sequence lifetimes.

You observe a 0.8 M⨀ white dwarf in a binary orbit around a main-sequence star of mass 1.4 M⨀.Which of the following is most likely the original mass of the star that became the white dwarf?

A Type I supernova occurs when a white dwarf exceeds a mass of:

As a white dwarf star gradually cools,its radius stays approximately constant.What is happening to the white dwarf's luminosity?

A nova is the result of which explosive situation?

The main-sequence lifetime of a star is given by the equation:

When a star burns hydrogen in a shell,it will never produce as much energy (per unit time)as when it burns hydrogen in the core because the core has a higher temperature.

A Type I supernova can be as luminous as 10 billion L⨀.

Asymptotic giant branch stars have high-mass loss rates because:

What types of chemical elements can low-mass stars contribute to the enrichment of the interstellar medium and how are they produced?

If a main-sequence star's core temperature increased,fusion reaction rates would decrease because the protons would be moving faster.

How can the core of a star be degenerate with respect to the electrons but nondegenerate with respect to the nuclei?

How long will a 2 M⨀ star live as a main-sequence star?

What is the shortest phase of evolution for a one solar mass star that we can visibly see?

Once the core of a low-mass main-sequence star runs out of hydrogen,fusion in the star stops until the core temperature is high enough for helium fusion to begin.

Why Learn Astronomy

Patterns in the Skymotions of Earth

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Tools of the Astronomer

The Birth and Evolution of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquid the Giant Planets

Planetary Adornments Moons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

Star Formation and the Interstellar Medium

Evolution of High-Mass Stars

Relativity and Black Holes

The Expanding Universe

Galaxies

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

Large-Scale Structure in the Universe

Life

Filters

If there were mixing processes in a main-sequence star with a radiative zone (there aren't)that churned up all the material in the interior,we would expect that the main-sequence lifetime would be _ because _.

You observe a 0.8 M_⨀ white dwarf in a binary orbit around a main-sequence star of mass 1.4 M_⨀.Which of the following is most likely the original mass of the star that became the white dwarf?

A Type I supernova can be as luminous as 10 billion L_⨀.

How long will a 2 M_⨀ star live as a main-sequence star?