HR Diagram

In November 2013 an object orbiting the sun seemed to disappear behind the sun. When a satellite did not detect the object, astronomers thought that the object had been destroyed when it passed close to the sun. However, when another satellite detected a small, bright object with a fan-shaped tail, astronomers proposed that the object was not destroyed.

What type of object were astronomers most likely observing?

• A comet

• An asteroid

• A meteor

• A nebula

Barnard's Star is about 5.9 light-years from the sun. The star has an approximate temperature of 2,800 K.

Based on the diagram, what spectral class does Barnard's Star belong to?

• Spectral class O

• Spectral class B

• Spectral class A

• Spectral class M

The Hertzsprung-Russell diagram shows how the sun is classified among the stars.

A star that is several thousand times brighter than the sun with a temperature lower than 4,000 K would be classified as -

• a main-sequence star in spectral class B

• a supergiant in spectral class K

• a main-sequence star in spectral class K or M

• a white dwarf in spectral class B

The universe has many different components. Which list places four components of the universe in the most likely order from smallest to largest?

• Planets, stars, galaxies, nebulae

• Nebulae, stars, planets, galaxies

• Galaxies, stars, planets, nebulae

• Planets, stars, nebulae, galaxies

Two stars are identified on the Hertzsprung-Russell diagram.

Based on this diagram, how do the characteristics of Star 1 and Star 2 compare?

• Star 1 is cooler and less bright than Star 2.

• Star 1 is hotter and brighter than Star 2.

• Star 1 is cooler and brighter than Star 2.

• Star 1 is hotter and less bright than Star 2.

Which of these correctly compares the masses of different objects in the universe?

• A moon has less mass than a star and more mass than the planet it orbits.

• A planet has less mass than a galaxy and more mass than the star it orbits.

• A galaxy has less mass than a moon and more mass than a planet.

• A star has less mass than a galaxy and more mass than a planet.

A Hertzsprung-Russell diagram is shown.

Based on this diagram, which type of stars would belong to spectral class M and have the highest luminosity?

• Main-sequence stars

• Giants

• White dwarfs

• Supergiants

Four students are asked to describe a nebula and a star. Their responses are shown in the table.

Which student described these two celestial bodies correctly?

• Student 1

• Student 2

• Student 3

• Student 4

The Milky Way galaxy is described as a disk of stars orbiting a central point on the disk. Which of these best explains why people on Earth cannot see the entire shape of the Milky Way?

• Earth is a part of this galaxy.

• Many more stars exist outside the galaxy.

• The stars in the center of the galaxy are extremely small.

• The center of the galaxy consists of a dense cluster of stars.

The Hertzsprung-Russell diagram shows how the brightness, surface temperature, and color of stars are related.

Which of these observations of Barnard's Star is most likely accurate?

• Barnard's Star is less bright than the sun, has a surface temperature below 3,800 K, and is red.

• Barnard's Star is less bright than the sun, has a surface temperature above 3,800 K, and is red.

• Barnard's Star is brighter than the sun, has a surface temperature below 5,300 K, and is yellow.

• Barnard's Star is brighter than the sun, has a surface temperature above 5,300 K, and is yellow.