Stellar BirthStellar Birth

Nikki BNikki B

Karly BKarly B

Interstellar CloudInterstellar Cloud

An accumulation of An accumulation of dust, gas and plasma dust, gas and plasma that is a denser-than-that is a denser-than-average region of the average region of the interstellar mediuminterstellar medium

Collapsing Cloud FragmentCollapsing Cloud Fragment

The density of the cloud formed begins to The density of the cloud formed begins to decrease.decrease.

Photons absorbed by the thin material of Photons absorbed by the thin material of the fragment are radiated into space, so the fragment are radiated into space, so no temperature increase occurs.no temperature increase occurs.

The fragments continue to contract until The fragments continue to contract until they become so dense that radiation can they become so dense that radiation can not escape the core of the star.not escape the core of the star.

Fragmentation CeasesFragmentation Ceases Tens of thousands of Tens of thousands of

years after the second years after the second stage, the fragment stage, the fragment begins to collapsebegins to collapse

The center becomes The center becomes opaque and the central opaque and the central temperature rises temperature rises significantlysignificantly

A protostar appears at the A protostar appears at the center and the cloud center and the cloud shrinks to the size of our shrinks to the size of our solar systemsolar system

ProtostarProtostar A protostar is the center A protostar is the center

of the disc formed in the of the disc formed in the center of the interstellar center of the interstellar gas cloud.gas cloud.

Hotter than the gas it Hotter than the gas it condensed, but cooler condensed, but cooler than a star.than a star.

Further collapse occurs Further collapse occurs when the protostar when the protostar reaches seven million reaches seven million Kelvin and nuclear Kelvin and nuclear reactions begin in the reactions begin in the core.core.

Protostar EvolutionProtostar Evolution As the protostar moves As the protostar moves

beyond stage 4, it becomes a beyond stage 4, it becomes a T Tauri star, moving toward T Tauri star, moving toward the main sequencethe main sequence this path from stage 4 to 6 is this path from stage 4 to 6 is

known as the known as the Hayashi trackHayashi track Characterized by violent Characterized by violent

surface activity and strong surface activity and strong protostellar windsprotostellar winds

Central temperature is still Central temperature is still not hot enough for not hot enough for thermonuclear fusion thermonuclear fusion repulsion of two positively repulsion of two positively

charged protons (Hydrogen charged protons (Hydrogen nuclei) cannot be overcomenuclei) cannot be overcome

Newborn StarNewborn Star

After 100,000 years of After 100,000 years of formation, a newborn star formation, a newborn star is created.is created.

The temperature of the The temperature of the newborn star begins to newborn star begins to increase, causing the increase, causing the fusion of hydrogen to fusion of hydrogen to create heliumcreate helium

The remaining dust and The remaining dust and gas surrounding the star gas surrounding the star disperses. disperses.

Main SequenceMain Sequence

The star contracts The star contracts and comes into and comes into hydrostatic hydrostatic equilibriumequilibrium

Works Cited

• http://physics.uoregon.edu/~jimbrau/astr122/Notes/Chapter19.html

• http://en.wikipedia.org/wiki/Interstellar_cloud

• http://physics.fortlewis.edu/Astronomy/astronomy

• http://www.nmm.ac.uk/server/show