Star+Births

A star is formed from the condensation of a hot cloud of gas and dust in space. When the cloud gets hot and dense enough, fusion—the combination of hydrogen atoms into helium atoms—begins to occur, producing starlight. Depending on the size of the cloud, a single star, a binary star (a system of two stars that orbit around a common center of gravity), or a cluster of stars may be formed. The main phase of a star's life lasts as long as a star has plenty of hydrogen fuel. A star enters the final 10 percent of its life once its hydrogen supply runs low. What happens next is determined by the size of the star. An average-sized star, like our sun, will spend its final phase as a red giant. In the red giant phase, the star takes on a reddish color and its diameter expands by ten to one thousand times its original size. from enotes.com

[]

[]

this is a good pic of nebulae

Our galaxy, along with many others, contains many large clouds of gas and dust, mostly made up of hydrogen. These clouds are called "nebulae." If the cloud becomes large enough, then its own gravity begins to overcome the gas pressure, and the cloud can begin to collapse. As the cloud collapses, gravity, temperature, and pressure increase, until the cloud has collapsed enough to raise the temperature to that required to fuse (burn) the hydrogen. Once that fusion begins, the energy released halts the contraction, and the outer layers of gas are blown away. What's left is an incandescent ball of mostly hydrogen, set aglow by the fusion reactions in its core: a star. from []

[]

Stars are born within the clouds of dust and scattered throughout most galaxies. A familiar example of such as a dust cloud is the Orion Nebula, revealed in vivid detail in the adjacent image, which combines images at visible and infrared wavelengths measured by NASA's Hubble Space Telescope and Spitzer Space Telescope. Turbulence deep within these clouds gives rise to knots with sufficient mass that the gas and dust can begin to collapse under its own gravitational attraction. As the cloud collapses, the material at the center begins to heat up. Known as a protostar, it is this hot core at the heart of the collapsing cloud that will one day become a star. Three-dimensional computer models of star formation predict that the spinning clouds of collapsing gas and dust may break up into two or three blobs; this would explain why the majority the stars in the Milky Way are paired or in groups of multiple stars. As the cloud collapses, a dense, hot core forms and begins gathering dust and gas. Not all of this material ends up as part of a star — the remaining dust can become planets, asteroids, or comets or may remain as dust. In some cases, the cloud may not collapse at a steady pace. In January 2004, an amateur astronomer, James McNeil, discovered a small nebula that appeared unexpectedly near the nebula Messier 78, in the constellation of Orion. When observers around the world pointed their instruments at __<span style="background-attachment: initial; background-clip: initial; background-color: transparent; background-origin: initial; background-position: 100% 0%; background-repeat: no-repeat no-repeat; border: 0px initial initial; color: #993302; display: inline; font-size: 13px; font-style: inherit; font-weight: inherit; margin: 0px; outline-color: initial; outline-style: initial; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 20px; padding-top: 0px; vertical-align: baseline;">[|McNeil's Nebula] __, they found something interesting — its brightness appears to vary. Observations with NASA's Chandra X-ray Observatory provided a likely explanation: the interaction between the young star's magnetic field and the surrounding gas causes episodic increases in brightness.

Stars are born in clouds of dust called nebulae. Movement deep within the clouds can force the dust to collapse under its own gravitational attraction. As it collapses the matter at the centre of the gravitational pull begins to heat up. This hot core is called a ‘protostar’. This is at the centre of the collapsing cloud and will one day become a star. Scientists predict that these spinning clouds of collapsing dust and gas break up into two or three blobs; this is why many stars are grouped into groups of multiple stars. As the cloud collapses, the core collects dust and gas by not all of these remains as the star; some of it becomes planets, asteroids, comets or may just remain as dust and gas. During this stage the brightness begins to vary and the newly born stars’ magnetic field increases in brightness.

this will be put on the slides

media type="youtube" key="9BDrK5IJI0o?fs=1" height="745" width="960"