Life Cycle of a Star - v2

Front

What type of stars burn Hydrogen as fuel?

Back

Main Sequence

Answer explanation

Main Sequence stars, the correct answer, are in a stable phase of their life cycle where they burn Hydrogen as fuel. This process, known as nuclear fusion, provides the energy that makes stars shine. Other types of stars like Red Giants, White Dwarfs, and Red Supergiants are in different stages of their life cycle and do not primarily burn Hydrogen.

Front

A white dwarf is the final stage for _________ mass stars like our Sun.

Back

small/medium

Answer explanation

A white dwarf is the final evolutionary stage of stars that have a similar mass to our Sun, or smaller. These are classified as small to medium mass stars. Larger or super massive stars follow a different evolutionary path, often ending in a supernova explosion or forming a black hole.

Front

Which type of stars are fusing Helium and heavier elements?

Back

Red Giants

Answer explanation

Red Giants are the type of stars that are fusing Helium and heavier elements. In their core, these stars have exhausted their hydrogen fuel and have begun to fuse helium into heavier elements such as carbon and oxygen. This process is different from Main Sequence, White Dwarfs, and Blue Giants, making Red Giants the correct answer to the question.

Front

We consider these stars 'dead' because they no longer are carrying out fusion in their cores. Options: White Dwarfs, Red Giants

Back

White Dwarfs

Answer explanation

The question asks why certain stars are considered 'dead' due to the cessation of fusion in their cores. The correct answer is 'White Dwarfs'. White Dwarfs are stars that have exhausted the nuclear fuel in their cores and thus, no longer carry out fusion. They are essentially stellar remnants, hence considered 'dead'. The other options, Red Dwarfs, Red Giants, and Brown Dwarfs, are different types of stars at various stages of their life cycle.

Front

A main sequence star is composed mostly of what gas?

Back

Hydrogen

Answer explanation

A main sequence star, like our Sun, is primarily composed of Hydrogen. This is because Hydrogen is the most abundant element in the universe and the primary fuel for nuclear fusion in stars. The fusion of Hydrogen atoms creates Helium, releasing energy in the process. This energy is what makes stars shine. The other options, Carbon and Iron, are produced in later stages of a star's life and in smaller quantities.

Front

Where does a star begin its life?

Back

Stellar Nebula

Answer explanation

A star begins its life in a Stellar Nebula, not in a Black Hole, Galaxy, or Solar System. Stellar Nebulae are the birthplaces of stars, where dense regions within the nebula collapse under gravity, creating stars. This is why the correct answer to the question is 'Stellar Nebula'.

Front

Main sequence stars will become red giants (or supergiants) when they run out of which fuel?

Back

Hydrogen

Answer explanation

Main sequence stars, like our Sun, primarily fuse hydrogen to form helium in their cores. This process releases energy that causes the star to shine. When the hydrogen fuel in the core is exhausted, the star expands and cools, becoming a red giant or supergiant. Therefore, the correct answer is 'Hydrogen'.

Front

What spectacular event follows the red super giant phase for a large or massive star when it starts fusing iron in its core?

Back

Supernova

Answer explanation

A large or massive star, after the red super giant phase, starts fusing iron in its core. This process leads to a spectacular event known as a Supernova. This is not the Big Bang, which is the event that led to the formation of the universe. Nor is it a Planetary Nebula, which is the final stage of a low or medium mass star. Therefore, the correct answer to the question is 'Supernova'.

Front

The path a star takes during its life cycle depends solely on its _____.

Back

mass

Answer explanation

The path a star takes during its life cycle is determined by its mass. The mass of a star determines its rate of fusion, its lifespan, and ultimately, the end state of the star. It does not depend on its temperature, luminosity, or location.

Front

As the mass of a star increases, its life expectancy __________ because it burns fuel more rapidly.

Back

decreases

Answer explanation

The life expectancy of a star is inversely proportional to its mass. As the mass of a star increases, it burns fuel more rapidly, which shortens its lifespan. Therefore, the correct answer to the question is 'decreases'. This is because a star with a higher mass will have a shorter life expectancy due to its faster fuel consumption.