H-R Diagram SLA Questions

What does the H-R diagram plot on its axes?

• Distance and luminosity

• Temperature and size

• Luminosity and surface temperature

• Mass and brightness

Answer explanation

The H-R diagram plots luminosity on the vertical axis and surface temperature on the horizontal axis. This allows astronomers to classify stars and understand their evolution based on these two key properties.

What color are the hottest stars on the H-R diagram?

• Red

• Yellow

• Blue

• Orange

Answer explanation

The hottest stars on the H-R diagram are blue. This is because blue stars have higher temperatures compared to red, yellow, and orange stars, which are cooler. Therefore, blue is the correct answer.

Where are most stars located on the H-R diagram?

• The upper left

• The lower left

• The main sequence

• The supergiant region

Answer explanation

Most stars are found on the main sequence of the H-R diagram, which runs diagonally from the upper left (hot, bright stars) to the lower right (cool, dim stars). This region contains about 90% of all stars.

Which stage of a star’s life involves hydrogen fusion in its core?

• White dwarf

• Supernova

• Main sequence

• Red giant

Answer explanation

The main sequence stage of a star's life is characterized by hydrogen fusion in its core, where hydrogen atoms combine to form helium, releasing energy that powers the star.

Tags

NGSS.HS-ESS1-1

What kind of star is our Sun classified as?

• A white dwarf

• A G-type main sequence star

• A red giant

• A supergiant

Answer explanation

The Sun is classified as a G-type main sequence star, also known as a G dwarf. This classification is based on its temperature, size, and luminosity, distinguishing it from white dwarfs, red giants, and supergiants.

What happens when a star runs out of hydrogen in its core?

• It immediately becomes a supernova

• It begins fusing helium

• It stops emitting light

• It moves to the main sequence

Answer explanation

When a star runs out of hydrogen in its core, it can no longer fuse hydrogen and begins fusing helium instead. This process leads to changes in the star's structure and energy output, marking a new phase in its lifecycle.

Tags

NGSS.HS-ESS1-1

NGSS.HS-PS1-8

Where on the H-R diagram are white dwarfs found?

• Upper right

• Lower left

• Top center

• Top left

Answer explanation

White dwarfs are found in the lower left region of the H-R diagram. This area represents stars that are hot but have low luminosity, characteristic of the final stage of stellar evolution for stars like our Sun.

Which type of star is the largest and brightest?

• Main sequence

• Supergiants

• Red dwarfs

• White dwarfs

Answer explanation

Supergiants are the largest and brightest type of stars, significantly larger than main sequence stars and much more luminous than red dwarfs and white dwarfs. They can outshine entire galaxies.

What element is primarily fused during the main sequence stage?

• Helium

• Carbon

• Hydrogen

• Iron

Answer explanation

During the main sequence stage of a star's life, hydrogen is primarily fused into helium through nuclear fusion. This process releases a significant amount of energy, which powers the star.

Tags

NGSS.HS-ESS1-1

NGSS.HS-PS1-8

What unit is used to measure a star’s surface temperature on the H-R diagram?

• Celsius

• Fahrenheit

• Kelvin

• Lumens

Answer explanation

The H-R diagram uses Kelvin to measure a star's surface temperature, as it is an absolute temperature scale that starts at absolute zero, making it suitable for astronomical measurements.