Stars; Adolescence to Old Age

The point on the HR Diagram when a star....

*stops contracting

*settles onto the main sequence

* begins to fuse hydrogen in its core.

• protostar

• red giant

• zero-age main sequence

• yellow dwarf main sequence

Nuclear fusion changes hydrogen to heavier elements. This change in composition also changes the star's ........ (Choose ALL that apply)

• temperature

• size

• luminosity

• velocity

What causes a star to move away from the zero-age main sequence band on the HR Diagram?

• increase in mass, decrease in density

• decrease in radius, increase in density

• decrease in luminosity, increase in temperature

• increase in luminosity, decrease in temperature

How many years a star remains in the main-sequence band depends on its _________.

• mass

• composition

• surface temperature

• velocity

A massive, O type star runs out of fusable material ______ than a low-mass, M type star.

• at the same rate

• slower

• faster

Which type of star has a longer "life"?

• O

• G

• M

• A

When hydrogen runs out in the core, the core is composed of _______

• carbon

• iron

• helium

• sulfur

What happens when hydrogen fusion ends in the helium core? Choose two.

• outwards pressure decreases

• outward pressure increases

• inward force of gravity increases

• inward force of gravity decreases

What happens to the non-fusing helium core as gravity compresses it?

• the hydrogen shell also contracts

• temperature decreases

• temperature increases

• luminosity decreases

What happens when the helium core reaches 100 million degrees?

• fusion of helium into carbon

• fusion of helium into iron

• the star "dies"

• the star explodes