How do Stars function ?

The life cycle of a star depends on its mass. Once a star begins its fusion, it enters the main sequence and maintains its hydrostatic equilibrium for billions of years. Very massive stars glow with blue light and expend their fuel more quickly, finally collapsing as gravity compresses the remaining matter.

This collapse often results in a supernova that ejects the star’s material into space. Smaller stars undergo this type of collapse, but they do not always explode.

Every star on the main sequence eventually expends its fuel and begins a process of collapsing and expanding into a red giant before collapsing into a a white dwarf.

Neutron stars are city-size stellar objects with a mass about 1.4 times that of the sun. Born from the explosive death of another, larger stars, these tiny objects pack quite a punch. Let's take a look at what they are, how they form, and how they vary.

When stars four to eight times as massive as the sun explode in a violent supernova, their outer layers can blow off in an often-spectacular display, leaving behind a small, dense core that continues to collapse.

Gravity presses the material in on itself so tightly that protons and electrons combine to make neutrons, yielding the name "neutron star." [Supernova Photos: Great Images of Star Explosions]

Some neutron stars have jets of materials streaming out of them at nearly the speed of light. As these beams pan past Earth, they flash like the bulb of a lighthouse. Scientists called them pulsars after their pulsing appearance. Normal pulsars spin between 0.1 and 60 times per second, while millisecond pulsars can result as much as 700 times per second.

When X-ray pulsars capture the material flowing from more massive companions, that material interacts with the magnetic field to produce high-powered beams that can be seen in the radio, optical, X-ray or gamma-ray spectrum.

As material within a pulsar accelerates within the magnetosphere of a pulsar, the neutron star produces gamma-ray emission. The transfer of energy in these gamma-ray pulsars slows the spin of the star.

The average neutron star boasts a powerful magnetic field. Earth's magnetic field is around 1 gauss, and the sun's is around a few hundred gauss, according to astrophysicist Paul Sutter. But a neutron star has a trillion-gauss magnetic field.

All stars begin from clouds of cold molecular hydrogen that gravitationally collapse. As they cloud collapses, it fragments into many pieces that will go on to form individual stars.

The material collects into a ball that continues to collapse under its own gravity until it can ignite nuclear fusion at its core

star would just continue collapsing for millions of years until it became its smallest possible size; maybe as a neutron star. But there is a pressure pushing back against the gravitational collapse of the star: light

The nuclear fusion at the core of a star generates a tremendous amount of energy. The photons push outward as they make their journey from inside the star to reach the surface; a journey that can take 100,000 years.

When stars become more luminous, they expand outward becoming red giants. And when they run out of light pressure, they collapse down into white dwarfs.

If you could collect all the stars together and put them in piles, the biggest pile, by far, would be the red dwarfs. These are stars with less than 50% the mass of the Sun.

The color of stars can range from red to white to blue. Red is the coolest color; that’s a star with less than 3,500 Kelvin. Stars like our Sun are yellowish white and average around 6,000 Kelvin.

The hottest stars are blue, which corresponds to surface temperatures above 12,000 Kelvin. So the temperature and color of a star are connected. Mass defines the temperature of a star.

It might look like all the stars are out there, all by themselves, but many come in pairs. These are binary stars, where two stars orbit a common center of gravity.

there are other systems out there with 3, 4 and even more stars. Just think of the beautiful sunrises you’d experience waking up on a world with 4 stars around it.

Speaking of red giants, or in this case, red supergiants, there are some monster stars out there that really make our Sun look small. A familiar red supergiant is the star Betelgeuse in the constellation Orion.

These giants can have as much as 150 times the mass of the Sun, and put out a ferocious amount of energy. For example, one of the most massive stars we know of is Eta Carinae, located about 8,000 light-years away.

This star is thought to have 150 solar masses, and puts out 4 million times as much energy. While our own Sun has been quietly burning away for billions of years, and will keep going for billions more, Eta Carinae has probably only been around for a few million years.

astronomers are expecting Eta Carinae to detonate as a supernovae any time now. When it does go off, it would become the brightest object in the sky after the Sun the Moon. It would be so bright you could see it during the day, and read from it at night.