Stellar Life Cycles

Most stars develop from very massive nebulae called...

• giant molecular clouds
• protostars
• red giants
• planetary nebulae

When a young, developing star becomes massive enough and dense enough, the process of _______ begins.

• H --> He fusion
• He --> C fusion
• He --> C --> O fusion
• fission

When stars are fusing hydrogen into helium, and are neither expanding nor contracting, they are said to be...

• dying
• in hydrostatic equilibrium
• white dwarfs
• red hypergiants

When a large enough mass of instellar gas compresses, it begins to rotate.  At this point, a __________ has formed.

• giant molecular cloud
• protostar
• red giant
• planetary nebulae

Which type of star has the longest life span?

• A star of 10 solar masses
• A star of 1 solar mass
• A star of 0.1 solar masses
• A star of 50 solar masses

The smallest main sequence stars are called...

• red dwarfs
• white dwarfs
• green dwarfs
• red giants

This life stage of massive stars is responsible for the generation of elements with atomic numbers greater than 26 (the atomic number of Fe; iron)

• white dwarf
• main sequence
• neutron star
• supernova

The smallest, densest stars in the universe are called...

• protostars
• white dwarfs
• neutron stars
• main sequence stars

For sun-sized stars, once the helium is used up, there will be a ___________ , eventually forming a _____________ and a _______________ .

• helium flash; planetary nebula; white dwarf
• helium flash; supernova; black hole
• supernova; neutron star; incredible gravitational pull
• supernova; white dwarf; planetary nebula

Stars in the main sequence neither explode nor collapse in on themselves.  What two forces hold the star in balance during this part of its life span.

• gravitational pressure pushes in; thermal pressure pushes out
• gravitational pressure pushes out; thermal pressure pushes in
• cosmic pressure pushes in; thermal pressure pushes out
• cosmic pressure pushes out; thermal pressure pushes in