Unit 4 Review

All stars begin as a __________?

• giant
• black hole
• white dwarf
• nebula

Nebula's are mixtures of gases and what?

• clouds
• stars
• tiny particles
• dust

Two stars are identified on the Hertzsprung-Russell diagram below.

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

Star brightness is defined in terms of apparent magnitude. Apparent magnitude is how bright the star appears from Earth.

How does the brightness of white dwarfs compare to the brightness of the Sun?

• The Sun is less bright than white dwarfs.

• White dwarfs are less bright than the Sun

• White dwarfs and the Sun have the same brightness

• White dwarfs are not seen from Earth, therefore you can not compare the brightness.

Our Sun is one of the many stars that has been classified as average. Its luminosity and its temperature place it in the middle of the ___ area of the H-R diagram.

• Main Sequence

• White Dwarf

• Red Giant

• Super giant

According to the diagram, which of these types of stars has the greatest luminosity?

• Hot white dwarf

• Hot main sequence star

• Cool super giant

• Cool giant

Most of the stars in the universe fit onto one of the four areas on this Hertzsprung-Russell diagram.

Which area of the diagram represents the Supergiants?

• Area M

• Area X

• Area P

• Area Z

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-sequenced 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

Most of the space in the universe is empty. Part of the reason for the emptiness of space is that the matter in the universe is gravitationally attracted to other pieces of matter. Most matter in the universe gets pulled into one of the many massive systems held together by the gravitational pull of black holes. These massive systems can be millions of light-years wide and contain millions of stars and planets.

What do scientists call these massive systems?

• Solar Systems

• Nebulae

• Galaxies

• Planetary Systems

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.