Presentation on theme: "Twinkle, Twinkle, Little Star.... How I Wonder What You Are... Stars have Different colors –Which indicate different temperatures Red stars- cooler White/blue."— Presentation transcript:
Twinkle, Twinkle, Little Star...
How I Wonder What You Are... Stars have Different colors –Which indicate different temperatures Red stars- cooler White/blue stars- hotter The hotter a star is, the faster it burns its life away.
Stellar Nursery Space is filled with the stuff to make stars.
New Stars are not quiet ! Expulsion of gas from a young binary star system
Fusion –Inside a star, the density and temperature increase toward the center, where energy is generated by nuclear fusion. –Fusion reactions involving elements other than hydrogen can produce heavier elements, but few heavier than iron. –The energy produced according to the equation E = mc 2 stabilizes a star by producing the pressure needed to counteract gravity.
A Balancing Act Energy released from nuclear fusion counter-acts inward force of gravity. E = MC 2 Throughout its life, these two forces determine the stages of a stars life. Hydrostatic equilibrium
Star Life Cycle What happens during a stars life cycle depends on its mass. Higher mass stars live shorter lives! –It takes about 10 billion years for a star with the mass of the Sun to convert all of the hydrogen in its core into helium. –When the hydrogen in its core is gone, a star has a helium center and outer layers made of hydrogen-dominated gas.
The Beginning of the End: Red Giants –Some hydrogen continues to react in a thin layer at the outer edge of the helium core. This forces the outer layers of the star to expand and cool and the star becomes a red giant. –As the star cools it begins to contract and heat again, eventually starting fusion all over. –When the helium in the core is all used up, the star is left with a core made of carbon.
The end for solar type stars Planetary Nebulae After Helium exhausted, outer layers of star expelled
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 After Helium exhausted, core collapses again until it becomes hot enough to fuse Carbon into Magnesium or Oxygen. – 12 C + 12 C --> 24 Mg OR 12 C + 4 H --> 16 O Through a combination of processes, successively heavier elements are formed and burned.
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 Remnants: SN1987A ab cd 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
Elements from Supernovae All X-ray Energies Silicon Calcium Iron
Whats 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.
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.
Reprise: the Life Cycle Sun-like Stars Massive Stars