FSQ #1 Unit 7: The Universe

Which of the following statements is true regarding white dwarf stars?

• White dwarf stars have low surface temperatures and low absolute brightness.

• White dwarf stars have low surface temperatures and high absolute brightness.

• White dwarf stars have high surface temperatures and low absolute brightness.

• White dwarf stars have high surface temperatures and high absolute brightness.

Answer explanation

White dwarf stars are remnants of stars that have exhausted their nuclear fuel. They are very hot, with high surface temperatures, but due to their small size, they have low absolute brightness.

There are two bright stars in a constellation. One of the stars appears red and the other star appears blue. Which of the following is the best explanation for the difference in the stars' color?

• The blue star must be moving toward Earth and the red star away from Earth.

• The red star must be moving toward Earth and the blue star away from Earth.

• The red star must have a greater surface temperature compared to the blue star.

• The blue star must have a greater surface temperature compared to the red star.

Answer explanation

The blue star must have a greater surface temperature compared to the red star. Stars emit different colors based on their temperatures, with hotter stars appearing blue and cooler stars appearing red.

When measuring the brightness of a star, what is a limitation of using apparent magnitude rather than absolute brightness?

• Apparent magnitude does not use the star's color or temperature.

• Apparent magnitude is only theoretical, thus its value cannot be directly measured with equipment.

• Apparent magnitude does not take into account the fact that not all stars are the same distance from Earth.

• Apparent magnitude is only on a comparative scale that determines how bright a star looks from a theoretical distance of 32 light-years from Earth.

Answer explanation

The correct choice highlights that apparent magnitude does not account for the varying distances of stars from Earth, which affects how bright they appear. This limitation can lead to misinterpretations of a star's true brightness.

Which of the following statements is NOT true regarding main sequence stars?

• Red giant stars are part of the main sequence group.

• Most stars visible from Earth are main sequence stars.

• As surface temperature increases, absolute brightness increases.

• Main sequence stars are primarily composed of hydrogen and helium gas.

Answer explanation

Red giant stars are not part of the main sequence; they represent a later stage in stellar evolution after a star has exhausted its hydrogen fuel. Main sequence stars are primarily in the hydrogen-burning phase.

Which of the following statements is true about the relationship between galaxies and stars?

• A galaxy contains many stars.

• A star contains many galaxies.

• A star contains only one galaxy.

• A galaxy contains only one star.

Answer explanation

The correct statement is that a galaxy contains many stars. Galaxies are vast systems made up of billions of stars, along with gas, dust, and dark matter, while the other options incorrectly describe the relationship.

NGC 1232 is a spiral galaxy about twice the size of our Milky Way Galaxy. It is located about 100 million light-years from Earth. Which of the following best explains why the physical properties of these two galaxies are similar?

• The temperatures of the stars within each galaxy are all identical.

• The two galaxies have the same shape and both orbit the same star.

• The two galaxies formed from the same materials and in the same way.

• All of the stars making up each galaxy are at the same stage of their life cycles as the Sun.

Answer explanation

The two galaxies formed from the same materials and in the same way, leading to similar physical properties despite their size difference. Other options do not accurately describe the relationship between the galaxies.

Due to the size of the Universe and the number of galaxies and stars in it, scientists must devise indirect ways to study it. Which of these represents the best way for scientists to study the Universe?

• Scientists should create a graph showing a comparison of the relative sizes of all the galaxies and stars.

• Scientists should develop a gridded map and then number the known galaxies and stars and record their locations.

• Scientists should build a physical model that demonstrates the relative sizes and locations of all known galaxies and stars.

• Scientists should make a computer model of known galaxies and stars that allows for unknowns and modify it as new discoveries are made.

Answer explanation

The best way for scientists to study the Universe is by making a computer model of known galaxies and stars. This allows for flexibility to incorporate unknowns and adapt as new discoveries are made, enhancing understanding.