Advanced RFTS - 1

What is the difference between HI and HII regions?

• HI regions contain ionized hydrogen atoms and HII regions contain un-ionized hydrogen atoms

• HI regions contain neutral, un-ionized hydrogen atoms and HII regions contain ionized hydrogen atoms

• HI and HII regions both contain neutral hydrogen atoms

• HI and HII regions both contain charged, hydrogen ions

Place the evolutionary stages of a star in the correct order.

• Main sequence - red giant branch - horizontal branch - asymptotic giant branch

• Main sequence - horizontal branch - red giant branch - asymptotic giant branch

• Red giant branch - main sequence - horizontal branch - asymptotic giant branch

• Asymptotic giant branch - main sequence - red giant branch - horizontal branch

A star cluster is a useful natural “laboratory” for studying stellar evolution because the stars in a cluster all:

• Have similar age and similar distance

• Have about the same mass

• Have similar spectral type

• Are in binary systems

White Dwarfs are comparable in size to what?

• Earth

• Mars

• Red Dwarfs

• Pluto

Which of the following is the dominant source of energy for star formation from a nebula/gas cloud?

• Heat from cosmic microwaves

• Nuclear fission

• Gravitational potential energy

• Nuclear fusion

What molecules are typically abundant on ice giant planets?

• CO2, H2O, N2

• H2O, CH4 and NH3

• Ne, H2O, NH3

• He, H2, H2O

Very luminous stars with low temperatures:

• Have small diameters compared with that of the Sun.

• 1. Have diameters comparable with that of the Sun.

• 1. Have large diameters compared with that of the Sun.

• 1. Could have variable diameter depending on spectral class

If two stars have the same surface area but one has 3 times the temperature of the other, how many times more energy is radiated by the more luminous star?

• 3

• 9

• 12

• 27

The Stefan-Boltzmann relation allows us to draw lines on the Hertzsprung-Russell diagram that are constant:

• Mass

• Radius

• Age

• Density

Stars within a stellar population have similar:

• Chemical composition and age

• Mass and temperature

• Fusion processes in their cores.

• Luminosities and temperatures