Birth of a star
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Birth of a Star. Jenn R and Kim B. Interstellar Cloud. an accumulation of gas, plasma and dust in our and other galaxies They are very high in density. Collapsing Cloud Fragment. Cores of the molecular interstellar clouds become gravitationally unstable, fragment, and begin to collapse

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Birth of a Star

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Birth of a star

Birth of a Star

Jenn R

and

Kim B


Interstellar cloud

Interstellar Cloud

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

  • They are very high in density


Collapsing cloud fragment

Collapsing Cloud Fragment

  • Cores of the molecular interstellar clouds become gravitationally unstable, fragment, and begin to collapse

    • Shockwaves from supernovae or other energetic astronomical processes trigger star formation in nearby nebulae


Fragmentation ceases

Fragmentation Ceases

  • When the density and temperature is high enough, deuterium fusion ignition occurs

    • Outward pressure of the resultant radiation slows the collapse

  • The accretion of material happens partially through a circumstellar disc


  • Protostar

    Protostar

    • The material the cloud is made of continues to “rain” on the protostar which is an object that forms by contraction out of the gas of a giant molecular cloud

      • In this stage bipolar flows are produces probably in effect of the angular momentum of the falling material


    Protostar evolution

    Protostar Evolution

    • Hydrogen begins to fuse in the core of the star and the rest of the enveloping material is cleared away

    • The protostar follows a Hayashi track which is the path in the HR Diagram after protostellar cloud has reached approximate hydrostatic equillibrium

    • Once Hayashi limit is reached the contraction stops

      • Stars with less than .5 solar mass then join the main sequence


    Newborn star

    Newborn Star

    • Once the weight of the stars matter is balanced by radiation pressure it evolves to a stable state

    • New stars come in a variety of sizes and colors

      • They range from hot and blue to cool and red. The brightness and color depend on surface temperature, which depends on mass

        • Mass ranges from .085 to 20 solar masses


    Main sequence

    Main Sequence

    • A new star will fall at a certain point on the main sequence of the HR Diagram

      • Cool red dwarfs burn slowly and remain on main sequence for billions of years

      • Hot supergiants leave the main sequence after only a few million years

  • After a star burns most of the hydrogen in its core it moves off the main sequence

  • The amount of energy generated at the dense core region when hydrogen fuses into helium determines where it is on the main sequence


  • Works cited

    Works Cited

    • www.wikipedia.org

    • http://www.harvard.edu/COMPLETE/learn/star_and_planet_formation.html


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