STELLAR BIRTH

By Preston B & Kara P(picture of Protostar)

Interstellar Cloud

• An accumulation of gas, plasma and dust in our and other galaxies

• Also known as denser-than-average region of the interstellar medium

• Initial star formation occurs in these clouds• The creation of stars replenish the cloud with

matter and energy through planetary nebulae, stellar winds, and supernovae

• This helps determine the rate at which a galaxy depletes its gaseous content, and therefore its

lifespan of active star formation

Collapsing Cloud Fragment

• The cloud might contain thousands of times the Sun's mass

• The mass is dominate in the form of cold atomic and molecular gas, with some dust

• The collapsing cloud will break up into tens, hundreds, or thousands of fragments

Fragmentation Ceases

• Several tens of thousands of years after the Interstellar Cloud fragment began to collapse, it becomes opaque at the center, and the central temperature rises significantly

• Cloud has now shrunk to region the size of our Solar System

Protostar

• A protostar is an object that forms by the contraction of the gas of a giant molecular cloud in the interstellar medium. The protostellar phase is an early stage in the process of star formation. For a solar-mass star it lasts about 100,000 years.

Protostar Evolution

• As the core of the cloud begins pulling itself together, its internal temperature and density rise until the protostar within reaches incandescence with a faint red glow. There is increased density in a molecular cloud and then forms a T Tauri star, which then develops into a main sequence star.

Newborn Stars

• New stars are born out of vast clouds of cold gas and dust. As the collective gravity of the gas pulls inward, the whole cloud starts to spin. As the star grows in the middle, it spins faster and faster, and a disk of planet-forming material forms around it. Powerful jets fire off from the top and bottom of the star to relieve its accumulating pressure.

Main Sequence Stars

• After a star has formed, it generates energy at the hot, dense core region through the nuclear fusion of hydrogen atoms into helium. The main sequence is the stage where a star spends most of its existence. Relative to other stages in a star's life, it is extremely long.