can a professional tell me in depth what stars are?

Question

please be specific id appreciate it thanx!

Answer 1

Birth of a Star

Protostars are stars that are about to be born. These are glowing clouds of interstellar gas and dust, which look like dark spots in the midst of light. Gravity causes every atom and every bit of dust to pull on every other one and all move to the center, causing the protostar to collapse. Having begun with a diameter of perhaps 1.5 trillion km, the protostar now shrinks at a very fast rate about 1,000 years, to a diameter of about 80 million km. Because the atoms move faster and faster as they fall toward the center, friction is created as they rub together and the temperature rises. The protostar starts at a temperature of about 100 K and over 1.000 years, rises to about 4,250 K. This heat causes the protostar to glow in with its own light, giving off even more light than our Sun even though it is not nearly as hot. After about 10,000 years, the protostar's surface temperature is up to about 4,500 K and it is now 100 times as luminous as the Sun; after another 100,000 years the temperature is 5,000 K even though the protostar has been shrinking the entire time and only gives off about 10 times the light of the Sun. There is little change in temperature over the next 10 million years but the brightness continues to drop as the protostar contracts. The next 20 million years is the last stage of the protostar's development where it equals the Sun in luminosity and its size becomes fixed at about 1.6 million km in diameter. 30 million years after the pocket of gas began to form, a star is born.






A star is any massive gaseous body in outer space, just like the Sun. Unlike a planet, a star generates energy through nuclear fusion and therefore emits light. All stars except the Sun appear as shining points in the nighttime sky that twinkle because of the effect of the Earth's atmosphere and their distance from us. The Sun is also a star, but it is close enough to Earth to appear as a disk instead, and to provide daylight.




A star is a brilliantly glowing sphere of hot gas whose energy is produced by an internal nuclear fusion process. Stars are contained in galaxies. A galaxy contains not only stars, but clouds of gas and dust. These clouds are called nebulae, and it is in a nebula where stars are born. In the nebula is hydrogen gas which is pulled together by gravity and starts to spin faster. Over millions of years, more hydrogen gas is pulled into the spinning cloud. The collisions which occur between the hydrogen atoms starts to heat the gas in the cloud. Once the temperature reaches 15,000,000 degrees Celsius, nuclear fusion takes place in the center, or core, of the cloud. The tremendous heat given off by the nuclear fusion process causes the gas to glow creating a protostar. This is the first step in the evolution of a star. The glowing protostar continues to accumulate mass. The amount of mass it can accumulate is determined by the amount of matter available in the nebula. Once its mass is stabilized, the star is known as a main sequence star. The new star will continue to glow for millions or even billions of years. As it glows, hydrogen is converted into helium in the core by nuclear fusion. The core starts to become unstable and it starts to contract. The outer shell of the star, which is still mostly hydrogen, starts to expand. As it expands, it cools and starts to glow red. The star has now reached the red giant phase. It is red because it is cooler than the protostar phase and it is a giant because the outer shell has expanded outward. All stars evolve the same way up to the red giant phase. The amount of mass a star has determines which of the following life cycle paths the star will take.


As a red giant, the hydrogen gas in the outer shell continues to burn as the temperature in the core continues to rise. At 200,000,000 degrees Celsius, the helium atoms fuse to form carbon atoms in the core. The last of the hydrogen gas in the outer shell is blown away to form a ring around the core. This ring is called a planetary nebula. When the last of the helium atoms in the core are fused into carbon atoms, the medium size star begins to die. Gravity causes the last of the star's matter to collapse inward and compact. This is the white dwarf stage which is extremely dense. White dwarfs shine with a white hot light but once all of their energy is gone, they die. The star has now reached the black dwarf phase.



MASSIVE STARS
Once massive stars reach the red giant phase, the core temperature continues to increase as carbon atoms are formed from the fusion of helium atoms. Gravity continues to pull together the carbon atoms in the core until the temperature reaches 600,000,000 degrees Celsius. At this temperature, carbon atoms form heavy elements such as oxygen and nitrogen. The fusion and production of heavy elements continues until iron starts to form. At this point, fusion stops and the iron atoms start to absorb energy. This energy is eventually released in a powerful explosion called a supernova. A supernova can light the sky up for weeks. The temperature in a supernova can reach 1,000,000,000 degrees Celsius. This high temperature can lead to the production of new elements which may appear in the new nebula that results after the supernova explosion. The core of a massive star that is 1.5 to 4 times as massive as our Sun ends up as a neutron star after the supernova. Neutron stars spin rapidly giving off radio waves. If the radio waves appear to be emitted in pulses (due to the star's spin), these neutron stars are called pulsars. The core of a massive star that has 10 or more times the mass of our Sun remains massive after the supernova. No nuclear fusion is taking place to support the core, so it is swallowed by its own gravity. It has now become a black hole which readily swallows any matter and energy that comes too near it. Some black holes have companion stars whose gases they pull off. As the gases are pulled down into the black hole, they heat up and give off energy in the form of X-rays. Black holes are detected by the X-rays which are given off as matter falls down into the hole.

Answer 2

A star is any massive gaseous body in outer space, just like the Sun. Unlike a planet, a star generates energy through nuclear fusion and therefore emits light. All stars except the Sun appear as shining points in the nighttime sky that twinkle because of the effect of the Earth's atmosphere and their distance from us. The Sun is also a star, but it is close enough to Earth to appear as a disk instead, and to provide daylight.

Answer 3

Quick and easy answer...
A star is a collection of gaseous hydrogen. SInce it is so massive the temperature and pressure can take 2 hydrogens and turn them into one helium atom. ( hydrogen has one proton, and helium has two) this process relaeses heat and other kinds of radiation (light, x-ray..) this process is called nuclear fusion. (its FUSING two hydrogens together). This starts a chain reaction which continues the process. The heliums can also get hydrogens added to them which would make lithium (3 protons) and every other naturally occuring element. In fact,scientists believe every piece of matter on earth (including you) are made from remains of old stars.

Answer 4

the closest star to us is our own sun. Inside there is nuclear fusion going on which produces all the heat and light, mostly hydrogen gas and some helium

Answer 5

I'm not a professional, if I were I would have to charge you for this answer. Anyway, stars are large balls of burning gasses, mostly Hydrogen.