Question

Explain the steps of the life cycle of a star. Beginning with a nebula and ending with old age/death of a star, explain each step in a star’s life cycle. @hello1213

Answer 1

@agleich

Answer 2

SOLAR MASS STAR --
Planetary nebula
Protostar
Main Sequence Star
Red Giant
White Dwarf

MASS 1.5 TIMES SUN --
Planetary nebula
Protostar
Main Sequence
Supernova
Neutron star

MASS 10 TIMES SUN --
Planetary nebula
Protostar
Main Sequence Red Giant
Supernova
Black hole

Answer 3

Stars are born in a region of high density Nebula, and condenses into a huge globule of gas and dust and contracts under its own gravity. A region of condensing matter will begin to heat up and start to glow forming Protostars. If a protostar contains enough matter the central temperature reaches 15 million degrees centigrade. At this temperature, nuclear reactions in which hydrogen fuses to form helium can start. The star begins to release energy, stopping it from contracting even more and causes it to shine. It is now a Main Sequence Star. 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. The helium core now starts to contract further and reactions begin to occur in a shell around the core. 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. 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 remaining core (thats 80% of the original star) is now in its final stages. The core becomes a White Dwarf the star eventually cools and dims. When it stops shining, the now dead star is called a Black Dwarf.

Answer 4

http://answers.yahoo.com/question/index?qid=20120608111757AAaGYGp

Answer 5

Did you get it.

Answer 6

@Taylor_Westwood

Answer 7

Well I gotta leave in a bit so, bye

Answer 8

@hello1213 so that's the answer

Answer 9

http://answers.yahoo.com/question/index?qid=20120608111757AAaGYGp

Answer 10

I got it from yahoo.com

Answer 11

this is also from yahoo.com
A nebula full of gas and dust begins to coalesce due to gravity. The particles in the cloud begin to orbit the center; and start bumping into each other and sticking, collecting to form clumps of material.

As the mass in the center begins to increase, pulling in more & more gas, the core begins to heat due to the pressure created by gravity. Eventually, the pressure and temperature are both high enough to generate the spark of fusion, creating the star, converting the lightest element - hydrogen - into the next heaviest element - Helium.

Small stars, Red Dwarfs, burn slowly for tens to hundreds of billions of years. Stars like our Sun - yellow dwarfs - will last about 10 billion years. The larger the star, the shorter it's life. As you increase the mass of a star, it will burn through it's fuel faster.

How a star dies depends on it's mass.

Small stars will begin to run out of fuel, hydrogen, and the reaction that keeps the star 'inflated' will stop. Stars like our sun will condense, increasing the pressure (and heat) in it's core, and the helium in it's core will briefly begin to fuse into carbon. This cause our sun to swell up to form a red giant, extending the atmosphere of the sun far beyond where it is not - consuming Mercury, then Venus, and finally the Earth.
After a few hundred thousand years, the outer layers of the sun will be blown off & away, leaving nothing but it's very hot, non-fusing core. It'll be about the size of Earth, and it's called a white dwarf. It'll cool over billions of years.

Medium size stars - 3 to 5 solar masses and a little larger - have enough mass in them that they can start fusing additional elements. So, after a core of helium has formed inside these stars as a result of fusing hydrogen, the helium will begin to fuse into carbon. If enough mass exists again, the carbon will fuse into calcium, and so on. These stars 'live' for about 1/4 to 1/2 the age our sun will obtain, figure a couple of billion to 5 billion years or so.
When the core of these stars begin to produce iron - that's the last element that *can* be produced inside a star, *and* release energy. Elements heavier than iron *take* energy to produce... so once iron begins to form inside the star - it's getting ready to die.
When the fusion reaction stops on these massive stars - they collapse in on themselves, suddenly. It only takes seconds. The huge, sudden *overpressure* on the core blasts outward, blowing the star up - it's called a supernova. The blast occurs outside the inner core, blasting *out* the outer layers of the star, and *imploding* it's core.

The core gets crushed by the explosion - so much so, that the free electrons are crushed into the protons of it's atoms - creating a mass of nothing but neutrons. If you look at anything around you, your computer, your desk, the phone on your desk - it's mostly empty space, because atoms are about 99.9999% empty space. But, the material of a neutron star is nothing but neutrons - there *is* no empty space - each neutron is right next to other neutrons. It's so dense, that a teaspoon of this material is as massive as the Empire State Building.

In even *more* massive stars, the collapse doesn't have to stop at the neutron star phase... it can continue, until there's so much mass in such a small space, that it forms a black hole, a singularity. It's a nearly infinitely massive, nearly dimensionless point in space.

Answer 12

I posted the link.

Answer 13

Now give me a medal!