1.3 Stellar Evolution

Stars can take different evolutionary paths due to their initial:

• Brightness

• Mass

• Temperature

• Color

When a red giant's outer atmosphere drifts away, it becomes:

• Expanding nebula

• Planetary nebula

• White dwarf cloud

• Planetary cloud

Stars like the Sun probably do not form iron cores during their evolution because

• All the iron is ejected when they become planetary nebulas.

• Their cores never get hot enough.

• Their strong magnetic fields keep their iron in their atmospheres.

• The iron converted in heavier elements through proton capture

There are evidences that at the center of galaxies live:

• Super massive black hole

• Stellar black hole

• Cosmic black hole

• Compact star

At the late stage of a low mass star evolution the outer layers escape into space, leaving behind a:

• White dwarf

• Neutron star

• Red giant

• Supernova

Our Sun, along with most of the stars in our neighborhood, probably formed …

• … about 10 million years ago.

• … a few million years ago.

• … hundreds of millions of years ago.

• … billions of years ago.

• … at the beginning of the universe.

What is the force that keeps a main sequence star

from blowing apart?

• radiation pressure

• electron degeneration pressure

• the strong force

• magnetism

• gravitation

What is characteristic of a main sequence star?

• It has a mass less than the Sun's.

• It has rapid rotation and a strong stellar wind.

• Nuclear fusion in the core varies due to the amount of gravitational contraction that

  occurs and which heavy elements are produced.

• The star is in a state of equilibrium between gravitational contraction and radiation

  pressure.

• All of these answers are correct.

The single most important determinant of the temperature, density, radius, luminosity, and pace of evolution of a protostar is its

• chemical composition.

• mass.

• magnetic field.

• molecular composition.

• spin.

What is A?

Red giant

Nebula

Where fusion begins

Black dwarf

Main sequence star

White dwarf

Planetary nebula