H-R Diagram Trivia Quiz

Answer: Hertzsprung- Russell Diagram

It is named after its two designers Ejnar Hertzsprung and Henry Norris Russell.

Answer: spectral class and absolute magnitude

The H-R Diagram plots spectral class (aka temperature) and absolute magnitude (aka luminosity).

Answer: Oh Be A Fine Guy/Girl Kiss Me

The spectral classes in order of decreasing temperature are: O, B, A, F, G, K, and M. One uncommon variation of this mnemonic is "Oh Be A Fine Guy/Girl Kiss My Lips Tenderly". It was made to include L and T, which are given to stars that are so small they do not generate enough heat to begin nuclear fusion.

Answer: main sequence

A star spends most of its life in the main sequence burning hydrogen fuel. Once the star has stopped burning hydrogen, it leaves the main sequence, evolves, and dies.

Answer: distance

Distance can be found by both main-sequence fitting for stellar clusters, and by spectroscopic parallax for individual main-sequence stars.

Answer: Diagonal lines (top left to bottom right)

The solar diameters of stars are plotted on diagonal lines that cross the diagram. Our Sun (at one solar mass) is on the most central diagonal line.

Answer: True

They are very small (that is why they are at the bottom), but also very bright (B or A spectral type).

Answer: False

Supergiants are rare, giants are more common and found on the RGB (Red Giant Branch).

Answer: red dwarfs

Most H-R Diagrams exclude red dwarfs, although they exist. When they are included in the H-R Diagram they are found in the bottom-right corner.

Answer: True

The Sun is now a part of the main sequence. In a few billion years the Sun will move up in the H-R Diagram, becoming a red giant, and eventually, a white dwarf.