"Irregularities in the density of the gas causes a net gravitational force that pulls the gas molecules closer together. Some astronomers think that a gravitational or magnetic disturbance causes the nebula to collapse. As the gases collect, they lose potential energy, which results in an increase in temperature.
As the collapse continues, the temperature increases. The collapsing cloud separates into many smaller clouds, each of which may eventually become a star. The core of the cloud collapses faster than the outer parts, and the cloud begins to rotate faster and faster to conserve angular momentum. When the core reaches a temperature of about 2,000 degrees Kelvin, the molecules of hydrogen gas break apart into hydrogen atoms. Eventually the core reaches a temperature of 10,000 degrees Kelvin, and it begins to look like a star when fusion reactions begin. When it has collapsed to about 30 times the size of our sun, it becomes a protostar.
When the pressure and temperature in the core become great enough to sustain nuclear fusion, the outward pressure acts against the gravitational force. At this stage the core is about the size of our sun. The remaining dust envelope surrounding the star heats up and glows brightly in the infrared part of the spectrum. At this point the visible light from the new star cannot penetrate the envelope. Eventually, radiation pressure from the star blows away the envelope and the new star begins its evolution. The properties and lifetime of the new star depend on the amount of gas that remains trapped. A star like our sun has a lifetime of about 10 billion years and is just middle-aged, with another five billion years or so left. "
source: http://www.sciam.com/article.cfm?id=how-is-a-star-born
It formed the sun.
fatigue
the answer is rotational force
All bodies that have mass, have gravity. The Helix Nebula is a large planetary nebula and will have "loads" of gravity.
Atelectasis is a partial collapse of the lung caused by failure of the parenchymal (functional) lung tissue due to disease (i.e., COPD). Pneumothorax is the collapse of the lung due to mechanical causes (i.e., traumatic injury, violent coughing).
A nebula IS a cloud of dust and gas loosely held together by gravity.
Gravity.
pickles
a nebula is the cloud of radioactive material dust smoke and debris caused by an exploding start, a nebula happens after a nova or super nova..and somtimes the collapse of a start causes black holes too in which case you wont see a nebula because the massive amount of gravity in the black holes sucks everything in, but yes a nebula is the cloud left over from an exploding star
A nebula does not directly turn into a white dwarf. A nebula will collapse to form stars. Low to medium mass stars become white dwarfs after they die. Some are the result of a supernova and do not collapse, they merely dissipate over time. The Crab Nebula is the most prominent example of this.
No. A star forms when gravity causes a nebula to collapse. As the gas compresses it heats up. eventually, the heat and pressure ignite nuclear fusion.
Gravitational collapse of a protostellar nebula.
"Primordial nebula" is a name used to describe a region of gas in space which is undergoing gravitational collapse, and which will eventually form a star.
helium and hydrogen gases
No. Stars are born when nebulae collapse, not when they expand.
An explosion from outside the nebula
The two main factors that cause a nebula to develop into a star are gravity and heat. Gravity pulls the gas and dust in the nebula together, causing it to collapse under its own gravity. As the collapse continues, the temperature and pressure in the core of the collapsing nebula increase, eventually reaching a point where nuclear fusion ignites, and a star is born.
An explosion from outside the nebula