Which star has completed its life cycle?

Answer 1

Stars are born in nebulae. Huge clouds of dust and gas collapse under gravitational forces, forming protostars. These young stars undergo further collapse, forming main sequence stars.

Stars expand as they grow old. As the core runs out of hydrogen and then helium, the core contacts and the outer layers expand, cool, and become less bright. This is a red giant or a red super giant (depending on the initial mass of the star). It will eventually collapse and explode. Its fate is determined by the original mass of the star; it will become either a black dwarf, neutron star, or black hole.

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Answer 2

There is 2 main ways:

Low mass stars:

Nebula, Protostar, Main Sequence, Red Giant, White Dwarf.

(Red Dwarfs skip the Red Giant stage).

High mass stars:

Nebula, Protostar, Main Sequence, Supergiant, Supernova/Hypernova, Neutron star or Black hole.

Answer 3

It depends entirely on the star's mass. The more mass, the faster it lives and dies. Giants like Arcturus and Betelgeuse are probably within thousands of years of their collapses.

Tiny red dwarfs could still be shining (weakly) trillions of years from now.

Stars like our Sun live for about 10 billion years as "Main Sequence" stars before changing into red giants and then into white dwarfs. So, the Sun is about halfway through its life on the "Main Sequence".

Answer 4

By "typical", I'll assume you mean a star of about solar mass or below. Really big stars work a little differently.

It starts as a cloud of dust and gas that collapses in on itself. Gravity compresses the lump in the center until it reaches a temperature and pressure that allows for hydrogen fusion. The star then burns more or less steadily until it runs out of hydrogen in the core. This causes a couple of things to happen. The first is that gravity compresses the star further to the point that hydrogen fusion can begin outside the core (where there is still hydrogen left). This increases the temperature and makes the star expand dramatically. Towards the end of this process, as hydrogen begins to run out in this outer shell as well, the star will collapse again, and for a star like the Sun it will collapse to the point where it gets hot enough to fuse helium to carbon. This will happen quickly ("helium flash"), and blow the outer layers of the star off into a planetary nebula. The core will become a white dwarf, which will slowly cool.

Stars more than about 2.5 times as massive as the Sun begin burning helium before the core becomes degenerate, which is a smoother process and allows for the accumulation of a carbon core. When the helium is all gone, another collapse occurs and initiates carbon burning. In really massive stars, the elements go up the chain by one alpha particle as a time successively... carbon to oxygen to neon to magnesium to silicon to sulfur to argon to calcium to titanium to chromium to iron to nickel, each phase taking less time than the previous one, but at nickel the sequence ends. Adding an alpha particle to nickel to make zinc actually requires energy rather than releasing it, so the star collapses very quickly. For stars this massive, the collapse is more than can be withstood by electron degeneracy pressure and the core collapses into a neutron star or, for even more massive stars, a black hole, liberating a tremendous amount of energy and blowing off the outer layers in a spectacular supernova explosion.

Answer 5

any star that doesnt exist anymore. once the star has completed the life cycle, it dies and you cant see it any more. but this dying would happen millions of years before we noticed the light has gone out.

Answer 6

The life cycle of a star is made up of six parts. They include the nebula, star, red giant, red dwarf, white dwarf and supernova.

Answer 7

The average life span of a small and medium sized star is 10 billion years. But massive stars die earlier than this time period.

Answer 8

Life cycle of a sun like star.

A sun like star will start out as a nebula to a protostar to a main sequence star to a red giant and into a white dwarf and will simply fade out.

Answer 9

Nebula > Star > Red Giant > Red Dwarf > White Dwarf > Supernova > Neutron Star > Black Hole.

Answer 10

first: protostar

second: birth of star

third: main sequence

forth: red giant/super giant

fifth: white dwarf/black hole