On average how long does a star live

It is now a M ain Sequence Star. Stage 5 - A star of one solar mass remains in main sequence for about 10 billion years, until all of the hydrogen has fused to form helium. Stage 6 - The helium core now starts to contract further and reactions begin to occur in a shell around the core.

Stage 7 - The core is hot enough for the helium to fuse to form carbon. The outer layers begin to expand, cool and shine less brightly. The expanding star is now called a Red Giant. Stage 8 - The helium core runs out, and the outer layers drift of away from the core as a gaseous shell, this gas that surrounds the core is called a Planetary Nebula.

The core becomes a W hite Dwarf the star eventually cools and dims. When it stops shining, the now dead star is called a Black Dwarf. Massive stars have a mass 3x times that of the Sun.

August 19, July 29, July 06, Nancy Grace Roman's Legacy. May 20, Ask a Question. Average Stars Become White Dwarfs For average stars like the Sun, the process of ejecting its outer layers continues until the stellar core is exposed. This dead, but still ferociously hot stellar cinder is called a White Dwarf. White dwarfs, which are roughly the size of our Earth despite containing the mass of a star, once puzzled astronomers - why didn't they collapse further?

What force supported the mass of the core? Quantum mechanics provided the explanation. Pressure from fast moving electrons keeps these stars from collapsing. The more massive the core, the denser the white dwarf that is formed. Thus, the smaller a white dwarf is in diameter, the larger it is in mass! These paradoxical stars are very common - our own Sun will be a white dwarf billions of years from now. White dwarfs are intrinsically very faint because they are so small and, lacking a source of energy production, they fade into oblivion as they gradually cool down.

This fate awaits only those stars with a mass up to about 1. Above that mass, electron pressure cannot support the core against further collapse. Such stars suffer a different fate as described below. White Dwarfs May Become Novae If a white dwarf forms in a binary or multiple star system, it may experience a more eventful demise as a nova. Nova is Latin for "new" - novae were once thought to be new stars.

Today, we understand that they are in fact, very old stars - white dwarfs. If a white dwarf is close enough to a companion star, its gravity may drag matter - mostly hydrogen - from the outer layers of that star onto itself, building up its surface layer. When enough hydrogen has accumulated on the surface, a burst of nuclear fusion occurs, causing the white dwarf to brighten substantially and expel the remaining material.

Within a few days, the glow subsides and the cycle starts again. Sometimes, particularly massive white dwarfs those near the 1. Supernovae Leave Behind Neutron Stars or Black Holes Main sequence stars over eight solar masses are destined to die in a titanic explosion called a supernova. This means that it is in the most stable part of its life, converting the hydrogen present in its core into helium. For a star the size of ours, this phase lasts a little over 8 billion years.

Our solar system is just over 4. In a star, gravitational force pulls all the gases towards the centre. When the star has hydrogen to burn, the creation of helium produces enough outward pressure to balance out the gravitational pull. But when the star has nothing left in the core to burn, gravitational forces take over.

Eventually that force compresses the centre of the star to such a degree that it will start burning hydrogen in a small shell around the dead core, which is still full of helium. The process of compression in the centre allows the outer regions of the star to expand outwards. During the two billion years of its red giant phase, its hot core becomes coated in the ashes of helium from the layer burning above it. A carbon-burning red giant star gives off nearly 10 times the energy it did as a dwarf star.

In only a few hundred million years, the red giant burns through its helium and collapses again. This fuses a layer of helium above the hotter carbon core, which creates enough heat to boil the outer gases of the star so fiercely so as to expand beyond its ability to keep hold of itself.

However, the dwarf star does not have enough mass to crush the carbon core into heavier elements, and the core stops fusing. A hot core of carbon atoms holds together, thanks to gravity, but resists crushing itself, thanks to the pressure of the spaces inside the atoms. We call this delicate balancing act a white dwarf. The expanding outer gases eventually fly away, leaving the exposed white dwarf to gradually cool into a black dwarf. A white dwarf is stable as long as it is no more than 1.

If it gains enough gas to tip over the balance mass, the white dwarf will detonate, leaving behind only an ever-expanding fireworks display of exploding star matter. The core of a giant star is under extreme and constant pressure from the weight of itself. Its atoms fuse furiously to give off the huge amounts of energy needed to buoy its heavy burden of gas.

As a result, giants shine fiercely, blue- and white-hot, and streaming out particles in huge winds. These particles give off radio waves, and radio telescopes have picked up the signals of giant stars throughout our Galaxy. Its core fuses its available hydrogen into helium in about , years. Then, it needs only a couple of hundred years to compress and make carbon, then oxygen, and silicon before building iron deep inside its core.

The energy of this frantic fusion pours into its huge atmosphere, boiling it into red supergiant. Only the most massive hypergiant stars fuse fast enough to remain blue-hot on their surfaces. Red supergiants shudder in brightness as their balancing act falters between burning phases. Yet, they continue to stream out particles as their cores furiously fuse to heavier and heavier elements, and our radio telescopes see eruptions from their surfaces as they churn through their fuel.