What happens at the end of the main sequence?

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

Eventually, as stars age, they evolve away from the main sequence to become red giants or supergiants. The core of a red giant is contracting, but the outer layers are expanding as a result of hydrogen fusion in a shell outside the core. The star gets larger, redder, and more luminous as it expands and cools.

Why does the main sequence phase come to an end?

During most a star’s lifetime, the interior heat and radiation is provided by nuclear reactions in the star’s core. This phase of the star’s life is called the main sequence. When the star runs out of nuclear fuel, it comes to the end of its time on the main sequence.

What is the major source of the energy released during the explosion of a massive star?

Stars generate energy by the nuclear fusion of elements. Unlike the Sun, massive stars possess the mass needed to fuse elements that have an atomic mass greater than hydrogen and helium, albeit at increasingly higher temperatures and pressures, causing correspondingly shorter stellar life spans.

What will happen if a low massive main sequence star runs out?

When a main sequence star begins to run out of hydrogen fuel, the star becomes a red giant or a red super giant. THE DEATH OF A LOW OR MEDIUM MASS STAR After a low or medium mass or star has become a red giant the outer parts grow bigger and drift into space, forming a cloud of gas called a planetary nebula.

What is the final stage of existence for each type of star?

A planetary nebula is the final stage of a Sun-like star. As such, planetary nebulas allow us a glimpse into the future of our own solar system. A star like our Sun will, at the end of its life, transform into a red giant. Stars are sustained by the nuclear fusion that occurs in their core, which creates energy.

What will happen if a low massive main sequence?

Once a star has “turned on” it is known as a main sequence star. THE DEATH OF A LOW OR MEDIUM MASS STAR After a low or medium mass or star has become a red giant the outer parts grow bigger and drift into space, forming a cloud of gas called a planetary nebula.

Why is there a lower limit to the mass of a main sequence star?

Why is there a lower mass limit of 0.08 solar masses for main sequence stars? Objects below this mass are not hot enough to fuse hydrogen. More low mass main sequence stars are formed in molecular clouds and lower main sequence stars have much longer lifetimes than upper main sequence stars.

Why does the core of a massive star collapse?

Core collapse supernovae occur when the iron core of a massive star collapses due to the force of gravity. A shock generated by this process, collapse and bounce, lacks the energy needed to overcome dissipation due to iron dissociation and neutrino losses and will stall before reaching this surface.

Why does a star explode after collapsing?

It’s a balance of gravity pushing in on the star and heat and pressure pushing outward from the star’s core. When a massive star runs out of fuel, it cools off. This causes the pressure to drop. The collapse happens so quickly that it creates enormous shock waves that cause the outer part of the star to explode!

What happens to the energy output of a main sequence star?

So far we have assumed that a star on the main sequence maintains a constant energy output. In fact, as a main sequence star ages its luminosity increases slightly, resulting in it expanding and its outer layer cooling.

Are there high mass stars off the main sequence?

High-Mass Post-Main Sequence Evolution. Evolution of high-mass stars off the main sequence is an involved process and one still not fully understood. Such stars are rare and have very short lifespans relative to lower-mass stars.

How many years does the Sun spend on the main sequence?

Whilst our Sun will spend 10 billion years on the main sequence, a high-mass, ten solar-mass (10M Sun) star will only last 20 million years (2.0× 10 7 years) on the main sequence. A star with a only half the mass of Sun can spend 80 billion years on the main sequence.

How does nucleosynthesis occur in the main sequence stars?

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).