The death of a larger star, for example, around 10 times as bright as the sun, results in a supernova explosion, the biggest explosion we humans have ever seen. And supernova explosions happen in a matter of seconds.
Eventually the cycle of star birth and death will come to an end. Gravity will have won, a victory delayed by the ability of stars to call on the resources of nuclear fusion. But ultimately, gravity will reduce all stars to a super-dense state as black holes, neutron stars or cold white dwarfs.
Stars do explode, and when that happens they're known as supernovae. A supernova creates an explosion billions of times brighter than our sun, with enough energy to outshine its own galaxy for weeks.
One Star's End is a Black Hole's Beginning
Most black holes form from the remnants of a large star that dies in a supernova explosion. (Smaller stars become dense neutron stars, which are not massive enough to trap light.)
When the helium fuel runs out, the core will expand and cool. The upper layers will expand and eject material that will collect around the dying star to form a planetary nebula. Finally, the core will cool into a white dwarf and then eventually into a black dwarf. This entire process will take a few billion years.
Stars heavier than eight times the mass of the Sun end their lives very suddenly. When they run out of fuel, they swell into red supergiants. They try to keep alive by burning different fuels, but this only works for a few million years. Then they blow themselves apart in a huge supernova explosion.
Planetary nebulae are illuminated for around 10,000 years before the central star begins to cool and shrink to become a white dwarf. When this happens, the star's light drastically diminishes and ceases to excite the surrounding gas, so the nebula fades from view.
At the end of their lives, sunlike stars metamorphose into glowing shells of gas – perhaps shaped by unseen companions. Billions of years from now, as our Sun approaches the end of its life and helium nuclei begin to fuse in its core, it will bloat dramatically and turn into what's known as a red giant star.
We Can See Protoplanetary Disks
Also, there appears to be a very young star that has formed out of the remnants of Supernova 1987A, making it the youngest star we've yet seen.
When two stars merge slowly, they can create a new, brighter star called a blue straggler. If two stars traveling at a fast pace hit, they'll likely leave behind only hydrogen gas. Stars that collide with a black hole are ultimately consumed.
The Death Star is a space station and superweapon featured in the Star Wars space-opera franchise. Constructed by the autocratic Galactic Empire, the Death Star is capable of annihilating entire planets into rubble, and serves to enforce the Empire's reign of terror.
The stars seem to twinkle in the night sky due to the effects of the Earth's atmosphere. When starlight enters the atmosphere, it is affected by winds in the atmosphere and areas with different temperatures and densities. This causes the light from the star to twinkle when seen from the ground.
The most massive stars can burn out and explode in a supernova after only a few million years of fusion. A star with a mass like the Sun, on the other hand, can continue fusing hydrogen for about 10 billion years.
On the other hand, supernovae have been seen by the naked eye throughout human history. These are the death throes of stars, and are extremely bright. So not only is the light coming from the star just as it dies, but it also might be substantially farther away than most stars.
Using our knowledge of the death rate in the entire Milky Way, the death rate for visible stars works out at about one star every 10,000 years or so. Given that all those stars are closer than 4,000 light-years, it is unlikely – though not impossible – that any of them are already dead.
When it starts to die, the Sun will expand into a red giant star, becoming so large that it will engulf Mercury and Venus, and possibly Earth as well. Scientists predict the Sun is a little less than halfway through its lifetime and will last another 5 billion years or so before it becomes a white dwarf.
Stars form from collapsing clouds of gas and dust.
These dust-thick regions of star birth are often dark and opaque. The Eagle Nebula, depicted in one of the Hubble Space Telescope's most famous images, is a stellar nursery, but what we see of it in visible light looks like dense cloud pillars.
Because stars are so far away, it takes years for their light to reach us. Therefore, when you look at a star, you are actually seeing what it looked like years ago. It is entirely possible that some of the stars you see tonight do not actually exist anymore. Public Domain Image, source: NASA.
A star is a huge glowing ball of hot gas. Deep inside its core, hydrogen atoms smash together, forming helium and releasing huge amounts of energy that heats the gas. This is called nuclear fusion, and it's why a star shines. As the hot gas pushes outward, it opposes the inward pull of gravity.
With no fuel left to burn, the hot star radiates its remaining heat into the coldness of space for many billions of years. In the end, it will just sit in space as a cold dark mass sometimes referred to as a black dwarf.
Watching a doomed star
The explosion sends the stellar guts spewing away at 20 million mph (10,000 kilometers per second) in a fireball that's a billion times brighter than the sun, the researchers say.
Once the core of a white dwarf has stopped contracting, it can exceed temperatures of around 100,000 Kelvin (around 100,000 degrees Celsius and 180,000 degrees Fahrenheit).
An explosion of a nearby star might leave Earth and its surface and ocean life relatively intact. But any relatively nearby explosion would still shower us with gamma rays and other high-energy radiation. This radiation could cause mutations in earthly life.
They made observations via the European Space Agency's (ESA) (opens in new tab) Hipparcos satellite and estimated that HD140283 — or Methuselah as it's commonly known — was a staggering 16 billion years old. Such a figure was rather baffling.