Question 1

Stars that lie in different places on the main sequence of the H-R diagram differ from each other mainly by having different:

Accepted Answer

Stars on the main sequence differ mainly by their mass, which affects their temperature, luminosity, and other properties. Other factors, such as composition and internal structure, may also contribute to differences among stars, but mass is the primary determinant. Radial velocity and formation history are not directly related to the position of stars on the H-R diagram.

Question 2

A star that is quite hot and has a very small radius compared to most stars is called

Accepted Answer

A white dwarf is the correct choice because it is a very hot star with a small radius; it is the remnant of a low-mass star that has exhausted all of its nuclear fuel. A main-sequence star is a typical star that is fusing hydrogen in its core to produce energy, while an O-type star is a very massive, hot star. A red giant is a star that has evolved beyond the main sequence and has expanded and cooled down, and an M-type star is a low-mass, cool star. None of these choices fit the description of a hot star with a small radius as well as a white dwarf.

Question 3

Imagine that powerful telescopes in the future give us a truly representative sampling of all the stars in the Sun's cosmic neighborhood. Where on the H-R diagram would most of the stars in our immediate vicinity lie?

Accepted Answer

Most stars in the Sun's cosmic neighborhood, and indeed in the galaxy, are red dwarfs. These stars are smaller, cooler, and less luminous than the Sun, placing them in the lower right of the H-R (Hertzsprung-Russell) diagram among the least luminous main sequence stars.

Question 4

A team of astronomers discovers one of the most massive stars ever found. If this star is just settling down in that stage of its life where it will be peacefully converting hydrogen to helium in its core, where will we find it on the H-R diagram?

Accepted Answer

If the star is settling down in the stage of peacefully converting hydrogen to helium, it is a main sequence star. Since it is one of the most massive stars ever found, it would be near the top of the main sequence, located in the upper left of the H-R diagram.

Question 5

One of your good friends who is on a diet asks you to point out the stars with the smallest mass on an H-R diagram that you are studying. Where are you sure to find the stars with the lowest mass on any H-R diagram?

Accepted Answer

The stars with the lowest mass on an H-R diagram are found at the bottom right of the main sequence. This area represents stars that are cooler and less luminous, characteristics of lower mass stars.

Question 6

A white dwarf, compared to a main sequence star with the same mass, would always be:

Accepted Answer

A white dwarf is the remnant core of a star after it has exhausted all its nuclear fuel. As a result, its outer layers have been expelled into space leaving only a hot, dense core behind. This means that a white dwarf would be smaller in diameter compared to a main sequence star with the same mass.

Question 7

Where on the H-R Diagram would we find stars that look red when seen through a telescope?

Accepted Answer

Red stars are cooler than blue or white stars, and on the Hertzsprung-Russell (H-R) Diagram, cooler stars are found on the right side. The left side of the diagram is reserved for hotter, blue and white stars.

Question 8

Measurements show a certain star has a very high luminosity (100,000 x the Sun's) while its temperature is quite cool (3500^o K). How can this be?

Accepted Answer

This star has a very high luminosity despite its cool temperature, which means it must be very large in size. This is possible because the star is in a later stage of its life cycle, possibly a red giant or supergiant. The other choices are not supported by the given information.

Question 9

Astronomers identify the main sequence on the H-R diagram with what activity in the course of a star's life?

Accepted Answer

The main sequence on the H-R diagram is a diagonal line that shows stars fusing hydrogen into helium in their cores. This is the stage where the majority of stars spend most of their lives.

Quiz 18: The Stars: a Celestial Census

Stars that lie in different places on the main sequence of the H-R diagram differ from each other mainly by having different:

A star that is quite hot and has a very small radius compared to most stars is called

Imagine that powerful telescopes in the future give us a truly representative sampling of all the stars in the Sun's cosmic neighborhood. Where on the H-R diagram would most of the stars in our immediate vicinity lie?

A team of astronomers discovers one of the most massive stars ever found. If this star is just settling down in that stage of its life where it will be peacefully converting hydrogen to helium in its core, where will we find it on the H-R diagram?

One of your good friends who is on a diet asks you to point out the stars with the smallest mass on an H-R diagram that you are studying. Where are you sure to find the stars with the lowest mass on any H-R diagram?

A white dwarf, compared to a main sequence star with the same mass, would always be:

Where on the H-R Diagram would we find stars that look red when seen through a telescope?

Measurements show a certain star has a very high luminosity (100,000 x the Sun's) while its temperature is quite cool (3500^o K) . How can this be?

Astronomers identify the main sequence on the H-R diagram with what activity in the course of a star's life?

Quiz 18: The Stars: a Celestial Census

Stars that lie in different places on the main sequence of the H-R diagram differ from each other mainly by having different:

A star that is quite hot and has a very small radius compared to most stars is called

Imagine that powerful telescopes in the future give us a truly representative sampling of all the stars in the Sun's cosmic neighborhood. Where on the H-R diagram would most of the stars in our immediate vicinity lie?

A team of astronomers discovers one of the most massive stars ever found. If this star is just settling down in that stage of its life where it will be peacefully converting hydrogen to helium in its core, where will we find it on the H-R diagram?

One of your good friends who is on a diet asks you to point out the stars with the smallest mass on an H-R diagram that you are studying. Where are you sure to find the stars with the lowest mass on any H-R diagram?

A white dwarf, compared to a main sequence star with the same mass, would always be:

Where on the H-R Diagram would we find stars that look red when seen through a telescope?

Measurements show a certain star has a very high luminosity (100,000 x the Sun's) while its temperature is quite cool (3500o K) . How can this be?

Astronomers identify the main sequence on the H-R diagram with what activity in the course of a star's life?

Measurements show a certain star has a very high luminosity (100,000 x the Sun's) while its temperature is quite cool (3500^o K) . How can this be?