Birth of a Star

The stages of how a star’s life begins. By: McKenna F

Stage One- The Interstellar Cloud

• Area of interstellar dust and gas that is more concentrated than the surrounding interstellar medium.

• All stars form from these clouds of dust and gas, called nebulae.

• In the first million years of its life, the star is hidden from view inside the nebulae it formed in.

Stage Two- Clouds Collapse

• Triggered Star Formation – Clouds can also start to

become unstable because of the interference other electric forces (like exploding supernovae) located near them in space.

• Spontaneous Star Formation– When the molecules inside

these clouds of interstellar dust and gas become unstable the cloud starts to develop a gravitational pull.

–In either situation the gases and dust of the nebula start to collapse and compress.

Stage Three- Protostar• A protostar is a

collection of dust and gas, joined together by this compression and gravitational pull.

• All these molecules are moving and releasing energy.

• This release of energy generates heat and light, causing the protostar to glow.

• Protostars are often hard to see because they are still hidden in the nebula but can be using infrared cameras.

Stage Four- AccretionProtostars exist where the gravitational pull is equal to the pressure of the gases.

This gravitational pull attracts more molecules, fragments and bits of interstellar medium.

When the gases start to compress, the combined effect generates a higher gravitational pull.

Evolution of A Protostar• The protostar starts

at a temperature of about 100 Kelvin

• After 1.000 years this temperature has

risen to about 4,250 Kelvin.

• It takes about 100,000 years to go from 4,250 to 4,500

Kelvin. • After another

100,000 years the temperature is 5,000

Kelvin.

• During this time the brightness

heightened at 100 times that of the sun, but as the star grows the brightness drops.

• Over the next 20 million years protostar's

developments to where it equals the Sun in luminosity

and its size becomes fixed at about 1.6

million km in diameter.

• It only took what 30 million years…

Stage Five

Stage Six- Nuclear Fission

• While the protostar is attaining dust, gas, and increasing in pressure, size and gravitational pull the core to become very concentrated and very dense.

• When to many hydrogen atoms are too close together at very high temperatures, they go through nuclear fusion and fuse together.

• Once this process starts, the protostar has become and actual star.

Stage Seven- Main Sequence Star• During this the stage of nuclear fusion

(about 90% of the star’s life) it is classified as a main sequence star.

Sources• http://gallery.spitzer.caltech.edu/Imagegallery/image.php?image_name=sig06-021• http://library.thinkquest.org/21008/data/star/birth.htm• http://sscws1.ipac.caltech.edu/Imagegallery/subcat.php?cat=Astronomical%20Images&

subcat=Star%20Formation• http://outreach.physics.utah.edu/labs/star_life/starlife_proto.html• http://en.wikipedia.org/wiki/Star_formation• http://en.wikipedia.org/wiki/Circumstellar_disc• http://www.geocities.com/CapeCanaveral/Launchpad/1364/Stars.html