Stellar Evolution. Chapters 12 and 13. Topics. Humble beginnings cloud core pre-main-sequence star Fusion main sequence star brown dwarf Life on the main sequence Retirement low mass stars (<10 solar masses) high mass stars (>10 solar masses). H-R Diagram. Mass related to luminosity.
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Chapters 12 and 13
A shock wave likely produced by a nearby nova or supernova disturbs the cloud.
The cloud is no longer in equilibrium.
Local regions of higher density.
Some of the dust and gas get close enough to each other that the gravitational force is significant enough that they collide and begin to clump.
dense cores form
these cores are protostars
Internal temperature and pressure increases
loss of gravitational energy results in a gain of kinetic energy and thermal energy
temperature and pressure at the core increases
rate of collapse slows down
continues to contract although at a slower rate
pre-main-sequence star“Pickles and Lamaze”
as the star contracts, the temperature and pressure at the core increase
high temperature allows fusion to take place
most common type of fusion at this stage is the proton-proton chain; six hydrogen atoms yield one helium and two hydrogen atoms
mass is transformed into energy (E=mc2)
temperature and pressure increase in the core
the outward pressure balances the inward gravitational force
star is in hydrostatic equilibrium
main-sequence star“The water breaks!A star is born!”