What happens during the main sequence phase of a star?

What happens during the main sequence phase of a star?

When the protostar starts fusing hydrogen, it enters the “main sequence” phase of its life. Stars on the main sequence are those that are fusing hydrogen into helium in their cores. The radiation and heat from this reaction keep the force of gravity from collapsing the star during this phase of the star’s life.

What happens to the most massive stars when they end their main sequence?

Eventually, a main sequence star burns through the hydrogen in its core, reaching the end of its life cycle. At this point, it leaves the main sequence. Stars smaller than a quarter the mass of the sun collapse directly into white dwarfs. White dwarfs no longer burn fusion at their center, but they still radiate heat.

What happens to the outer surface of a star during the red giant phase?

As the core collapses, the shell of plasma surrounding the core becomes hot enough to begin fusing hydrogen itself. As fusion in this shell begins, the extra heat causes the outer layers of the star to expand dramatically, and the surface extends up to several hundred times beyond the former size of the star.

What does a massive star become in the end?

A massive star ends with a violent explosion called a supernova. The matter ejected in a supernova explosion becomes a glowing supernova remnant.

What happens during the main sequence phase of a star quizlet?

On the main sequence, a high mass stars fuses hydrogen to helium in its core via the CNO cycle. Once hydrogen is depleted in the core of the star, hydrogen begins fusing in a shell around the inert helium core, creating a red supergiant.

Which of the following occurs in a main sequence star?

Nucleosynthesis and Fusion Reactions. Nucleosynthesis simply refers to the production of nuclei heavier than hydrogen. This occurs in main sequence stars through two main processes, the proton-proton chain and the CNO cycle (carbon, nitrogen, oxygen).

Why do main sequence stars become giants?

When the hydrogen in the centre of a star runs out, the star begins to use hydrogen further out from its core. This causes the outer layers of the star to expand and cool. Over time, the star grows to more than 400 times its original size. As the star cools, it changes colour and glows redder.

What can result from the death of a very massive star?

When a high-mass star has no hydrogen left to burn, it expands and becomes a red supergiant. While most stars quietly fade away, the supergiants destroy themselves in a huge explosion, called a supernova. The death of massive stars can trigger the birth of other stars.

How does a massive star change at the end of the main stable period?

A larger star with more mass will go on making nuclear reactions, getting hotter and expanding until it explodes as a supernova. An exploding supernova throws hot gas into space.

What process happens in red giant star once they leave the stage of main sequence star this is how three helium 4 are converted into carbon?

The triple-alpha process is a set of nuclear fusion reactions by which three helium-4 nuclei (alpha particles) are transformed into carbon.

What does a star become after a red giant?

Once at the red giant stage, a star might stay that way for up to a billion years. Then the star will slowly contract and cool to become a white dwarf: Earth-sized, ultra-dense star corpses radiating a tiny fraction of their original energy.

When the Sun goes from the main sequence to the red giant stage?

The Sun will exit the main sequence in approximately 5 billion years and start to turn into a red giant. As a red giant, the Sun will grow so large that it will engulf Mercury, Venus, and possibly Earth, maybe even Mars and part or all of the asteroid belt.

What are the two end possibilities of massive stars?

But if your star is massive enough, you might not get a supernova at all. Another possibility is direct collapse, where the entire star just goes away, and forms a black hole. Still another is known as a hypernova, which is far more energetic and luminous than a supernova, and leaves no core remnant behind at all.

Why do some massive stars become neutron stars?

UNIVERSITY PARK, Pa. — When the most massive stars die, they collapse under their own gravity and leave behind black holes; when stars that are a bit less massive than this die, they explode and leave behind dense, dead remnants of stars called neutron stars.

How does a massive star turn into a red supergiant?

A red supergiant occurs when a moderately massive star — perhaps 8–40 solar masses in size — exhausts its hydrogen fuel, evolves off of the main sequence, and transitions to fusing helium within its core. As this occurs, the star’s radius expands, causing its temperature to plummet.

What is the main phase of a star?

The main sequence phase is the stage in development where the core temperature reaches the point for the fusion to commence. In this process, the protons of hydrogen are converted into atoms of helium.

What is the main phase of a star?

The main sequence phase is the stage in development where the core temperature reaches the point for the fusion to commence. In this process, the protons of hydrogen are converted into atoms of helium.

What happens to a star when it leaves the main sequence?

One-Solar Post-Main Sequence Evolution. Stars such as our Sun move off the main sequence and up the red giant branch (RGB), fusing hydrogen into helium in hydrogen shell burning. A very short helium flash sees the start of helium core fusion and the star moves along the horizontal branch (HB).

What does the main sequence represent?

The main sequence on the H-R diagram defines a sequence of mass, with luminosity and mass related by L = M3.5. Main sequence stars are all in the first stage of stellar evolution, the stage between formation and the end of hydrogen fusion in the core.