life cycles v2 1

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The Life Cycles of Stars: 

The Life Cycles of Stars Dr. Jim Lochner, NASA/GSFC

Twinkle, Twinkle, Little Star ...: 

Twinkle, Twinkle, Little Star ...

How I Wonder What You Are ... : 

How I Wonder What You Are ... Stars have Different colors Which indicate different temperatures The hotter a star is, the faster it burns its life away.

Stellar Nursery: 

Stellar Nursery Space is filled with the stuff to make stars.

Stars start from clouds: 

Stars start from clouds Clouds provide the gas and dust from which stars form. Rather: Irregular Grains Of Carbon or Silicon

Collapse to Protostar: 

Collapse to Protostar Stars begin with slow accumulation of gas and dust. Gravitational attraction of Clumps attracts more material. Contraction causes Temperature and Pressure to slowly increase.

Nuclear Fusion !: 

Nuclear Fusion ! At 15 million degrees Celsius in the center of the star, fusion ignites ! 4 (1H) --andgt; 4He + 2 e+ + 2 neutrinos + energy Where does the energy come from ? Mass of four 1H andgt; Mass of one 4He E = mc2

How much Energy: 

How much Energy 4 (1H) --andgt; 4He + 2 e+ + 2 neutrinos + energy Energy released = 25 MeV = 4 x 10 -12 Joules = 1 x 10 -15 Calories But the sun does this 1038 times a second ! Sun has 1056 H atoms to burn !

A Balancing Act: 

A Balancing Act Energy released from nuclear fusion counter-acts inward force of gravity. Throughout its life, these two forces determine the stages of a star’s life.

New Stars are not quiet !: 

New Stars are not quiet ! Expulsion of gas from a young binary star system

All Types of Stars: 

All Types of Stars Recall - Stars have Different colors which indicate different temperatures

All Types of Stars: 

All Types of Stars Out Beyond Andromeda, Fiery Gases Kindle Many Red New Stars Oh! Be a Fine Girl - Kiss Me ! Oh! Be a Fine Girl - Kiss Me Right Now Sweetheart !

Reprise: the Life Cycle: 

Reprise: the Life Cycle Sun-like Stars Massive Stars

A Red Giant You Know: 

A Red Giant You Know

The Beginning of the End: Red Giants: 

The Beginning of the End: Red Giants After Hydrogen is exhausted in core ... Energy released from nuclear fusion counter-acts inward force of gravity. Core collapses, Kinetic energy of collapse converted into heat. This heat expands the outer layers. Meanwhile, as core collapses, Increasing Temperature and Pressure ...

More Fusion !: 

More Fusion ! At 100 million degrees Celsius, Helium fuses: 3 (4He) --andgt; 12C + energy (Be produced at an intermediate step) (Only 7.3 MeV produced) Energy sustains the expanded outer layers of the Red Giant

The end for solar type stars: 

The end for solar type stars Planetary Nebulae After Helium exhausted, outer layers of star expelled

White dwarfs: 

White dwarfs At center of Planetary Nebula lies a White Dwarf. Size of the Earth with Mass of the Sun 'A ton per teaspoon' Inward force of gravity balanced by repulsive force of electrons.

Fate of high mass stars: 

Fate of high mass stars After Helium exhausted, core collapses again until it becomes hot enough to fuse Carbon into Magnesium or Oxygen. 12C + 12C --andgt; 24Mg OR 12C + 4H --andgt; 16O Through a combination of processes, successively heavier elements are formed and burned.

Periodic Table: 

Periodic Table

The End of the Line for Massive Stars: 

The End of the Line for Massive Stars Massive stars burn a succession of elements. Iron is the most stable element and cannot be fused further. Instead of releasing energy, it uses energy.

Supernova !: 

Supernova !

Supernova Remnants: SN1987A: 

Supernova Remnants: SN1987A a b c d a) Optical - Feb 2000 Illuminating material ejected from the star thousands of years before the SN b) Radio - Sep 1999 c) X-ray - Oct 1999 d) X-ray - Jan 2000 The shock wave from the SN heating the gas

Supernova Remnants: Cas A: 

Supernova Remnants: Cas A Optical X-ray

Elements from Supernovae: 

Elements from Supernovae All X-ray Energies Silicon Calcium Iron

What’s Left After the Supernova: 

What’s Left After the Supernova Neutron Star (If mass of core andlt; 5 x Solar) Under collapse, protons and electrons combine to form neutrons. 10 Km across Black Hole (If mass of core andgt; 5 x Solar) Not even compacted neutrons can support weight of very massive stars.

A whole new life: X-ray binaries: 

A whole new life: X-ray binaries In close binary systems, material flows from normal star to Neutron Star or Black Hole. X-rays emitted from disk of gas around Neutron Star/Black Hole.

Black Holes - Up Close and Personal: 

Black Holes - Up Close and Personal

SN interaction with ISM: 

SN interaction with ISM Supernovae compress gas and dust which lie between the stars. This gas is also enriched by the expelled material. This compression starts the collapse of gas and dust to form new stars.

Which Brings us Back to ...: 

Which Brings us Back to ...

Materials for Life Cycles of Stars: 

Materials for Life Cycles of Stars This presentation, and other materials on the Life Cycles of Stars, are available on the Imagine the Universe! web site at: http://imagine.gsfc.nasa.gov/docs/teachers/lifecycles/stars.html

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