the life cycles of stars
DESCRIPTION
The Life Cycles of Stars. Dr. Jim Lochner, NASA/GSFC. Twinkle, Twinkle, Little Star . How I Wonder What You Are .... Stars have D i f f e r e n t c o l o r s Which indicate different temperatures The hotter a star is, the faster it burns its life away. Stellar Nursery. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/1.jpg)
The Life Cycles of StarsDr. Jim Lochner, NASA/GSFC
![Page 2: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/2.jpg)
Twinkle, Twinkle, Little Star ...
![Page 3: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/3.jpg)
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.
![Page 4: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/4.jpg)
Stellar Nursery
Space is filled with the stuff to make stars.
![Page 5: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/5.jpg)
Stars start from clouds
Clouds provide the gas and dust from which stars form.
But not this kind of dust
Rather: Irregular Grains Of Carbon or Silicon
![Page 6: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/6.jpg)
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.
F
Gm1m2
r2
![Page 7: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/7.jpg)
Nuclear Fusion !
At 15 million degrees Celsius in the center of the star, fusion ignites !
4 (1H) --> 4He + 2 e+ + 2 neutrinos + energyWhere does the energy come from ?Mass of four 1H > Mass of one 4He
E = mc2
![Page 8: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/8.jpg)
How much Energy
4 (1H) --> 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 !
![Page 9: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/9.jpg)
A Balancing Act
Energy released from nuclear fusion counter-acts inward force of gravity.
These two forces determine the stages of a star’s life.
![Page 10: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/10.jpg)
New Stars are not quiet !
Expulsion of gas from a young binary star system
![Page 11: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/11.jpg)
All Types of Stars
Recall - Stars have Different colors which indicate different temperatures
![Page 12: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/12.jpg)
All Types of Stars
Annie J Cannon(1863-1941)
![Page 13: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/13.jpg)
Reprise: the Life Cycle
Sun-like Stars Massive Stars
![Page 14: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/14.jpg)
A Red Giant You Know
![Page 15: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/15.jpg)
The Beginning of the End: Red Giants
After Hydrogen is exhausted in core ...Energy released from nuclear fusion counter-acts inward force of gravity.• Eventually the Core collapses,
· Kinetic energy of collapse converted into heat.
· This heat expands the outer layers.• Meanwhile, as the core collapses it
increases in temperature and pressure.
![Page 16: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/16.jpg)
More Fusion !
At 100 million degrees Celsius, Helium fuses:
3 (4He) --> 12C + energy(Be produced at an intermediate step)
(Only 7.3 MeV produced)
Energy sustains the expanded outer layers of the Red Giant
![Page 17: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/17.jpg)
The end for solar type stars
After Helium is exhausted, outer layers of star expelled and Star becomes a planetary nebulae.
![Page 18: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/18.jpg)
White dwarfs
At the 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.
![Page 19: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/19.jpg)
Fate of high mass stars
After Helium is exhausted the core collapses again until it becomes hot enough to fuse Carbon into Magnesium or Oxygen.
· 12C + 12C --> 24Mg OR 12C + 4H --> 16O
Through a combination of processes, successively heavier elements are formed and burned.
![Page 20: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/20.jpg)
Periodic Table
16O + 16O 32S + energy4He + 16O 20Ne + energy
Light Elements Heavy Elements
4 (1H) 4He + energy 3(4He) 12C + energy 12C + 12C 24Mg + energy4He + 12C 16O + energy28Si + 7(4He) 56Ni + energy 56FeC-N-O Cycle
![Page 21: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/21.jpg)
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.
![Page 22: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/22.jpg)
Supernova !
![Page 23: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/23.jpg)
Supernova Remnants: SN1987A
a b
c d
a) Optical - Feb 2000• Illuminating material
ejected from the star thousands of years before the Super-Nova
b) Radio - Sep 1999c) X-ray - Oct 1999d) X-ray - Jan 2000• The shock wave from
the SN heating the gas
![Page 24: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/24.jpg)
Supernova Remnants: Cas A
Optical X-ray
![Page 25: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/25.jpg)
Elements from Supernovae
All X-ray Energies Silicon
Calcium Iron
![Page 26: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/26.jpg)
What’s Left After the Supernova
Neutron Star (If mass of core < 5 x Solar)• Under collapse, protons and electrons
combine to form neutrons.• 10 Km across
Black Hole (If mass of core > 5 x Solar)• Not even compacted neutrons can
support weight of very massive stars.
![Page 27: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/27.jpg)
A whole new life: X-ray binaries
In close binary systems, material flows from normal star toNeutron Star or Black Hole. X-rays emitted from disk of gas around Neutron Star/Black Hole.
![Page 28: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/28.jpg)
Black Holes - Up Close and Personal
Jet(not always present)
Accretion Disk Event Horizon
Singularity(deep in center)
![Page 29: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/29.jpg)
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.
![Page 30: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/30.jpg)
Which Brings us Back to ...
![Page 31: The Life Cycles of Stars](https://reader035.vdocument.in/reader035/viewer/2022070422/568165a1550346895dd87faf/html5/thumbnails/31.jpg)
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