Stellar Birth Nikki B Karly B

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

Collapsing Cloud Fragment The density of the cloud formed begins to decrease. The density of the cloud formed begins to decrease. Photons absorbed by the thin material of the fragment are radiated into space, so no temperature increase occurs. Photons absorbed by the thin material of the fragment are radiated into space, so no temperature increase occurs. The fragments continue to contract until they become so dense that radiation can not escape the core of the star. The fragments continue to contract until they become so dense that radiation can not escape the core of the star.

Fragmentation Ceases Tens of thousands of years after the second stage, the fragment begins to collapse Tens of thousands of years after the second stage, the fragment begins to collapse The center becomes opaque and the central temperature rises significantly The center becomes opaque and the central temperature rises significantly A protostar appears at the center and the cloud shrinks to the size of our solar system A protostar appears at the center and the cloud shrinks to the size of our solar system

Protostar A protostar is the center of the disc formed in the center of the interstellar gas cloud. A protostar is the center of the disc formed in the center of the interstellar gas cloud. Hotter than the gas it condensed, but cooler than a star. Hotter than the gas it condensed, but cooler than a star. Further collapse occurs when the protostar reaches seven million Kelvin and nuclear reactions begin in the core. Further collapse occurs when the protostar reaches seven million Kelvin and nuclear reactions begin in the core.

Protostar Evolution As the protostar moves beyond stage 4, it becomes a T Tauri star, moving toward the main sequence As the protostar moves beyond stage 4, it becomes a T Tauri star, moving toward the main sequence this path from stage 4 to 6 is known as the Hayashi track this path from stage 4 to 6 is known as the Hayashi track Characterized by violent surface activity and strong protostellar winds Characterized by violent surface activity and strong protostellar winds Central temperature is still not hot enough for thermonuclear fusion Central temperature is still not hot enough for thermonuclear fusion repulsion of two positively charged protons (Hydrogen nuclei) cannot be overcome repulsion of two positively charged protons (Hydrogen nuclei) cannot be overcome

Newborn Star After 100,000 years of formation, a newborn star is created. After 100,000 years of formation, a newborn star is created. The temperature of the newborn star begins to increase, causing the fusion of hydrogen to create helium The temperature of the newborn star begins to increase, causing the fusion of hydrogen to create helium The remaining dust and gas surrounding the star disperses. The remaining dust and gas surrounding the star disperses.

Main Sequence The star contracts and comes into hydrostatic equilibrium The star contracts and comes into hydrostatic equilibrium

Works Cited 2/Notes/Chapter19.htmlhttp://physics.uoregon.edu/~jimbrau/astr12 2/Notes/Chapter19.html udhttp://en.wikipedia.org/wiki/Interstellar_clo ud onomy