Ann Aquino's Quiz

Annie Aquino

Chapter 12

12 April 2013

How do stars form?

-Stars are born in cold, dense clouds of gas whose pressure cannot resist gravitational

contraction.

-Molecular fragment heats up and spins faster than gravity and contracts. It begins rotating

rapidly and are surrounded by spinning disks of gas.

How massive are newborn stars?

-The masses of newborn stars depend on the processes that govern clumping and

fragmentation in star forming clouds.

What are the life stages of low mass stars?

-Stars spend about 90% of it life as a main sequence star.

-After exhausting its core hydrogen, the Sun will expand to become a red giant, powered

by rapid hydrogen fusion in a shell surrounding the core.

-The suns core to continue to shrink and hydrogen fusion will continue to intensify as the

sun grows into a red giant.

How do low mass stars die?

-When it dies, the sun will eject its outer layers into space as a planetary nebula leaving it

exposed core behind on white dwarf.

What are the life stages of a high mass star?

-A high mass star lives a shot life, rapidly, fusing its core hydrogen into helium via the

CNO cycle

How do high mass stars make the elements necessary for life?

-helium fusion makes carbon in low ass stars

-high core temperatures allow helium to use with heavier elements

-advanced nuclear burning proceeds in a series of nested shells

How does a high mass star die?

-when gravity overcomes degeneracy pressure in the iron core the core collapses into a

ball of neutrons and the star explodes in a supernova

-the supernova scatters the elements produced by the star into space and leaves behind

either a neutron star or a black hole

How does a stars mass determine its life story?

-more massive stars are brighter and become a supernova and smaller stars share a

similar life stage to our sun

How are the lives of stars with close companions different?

-stars in close binary systems can exchange mass with each other alternating their life