Option D.2

Question 1

Hertzsprung-Russel diagram

Answer 1

A logarithmic plot of a star’s luminosity versus its temperature

Question 2

How is the temperature on the horizontal axis of a HR diagram ordered?

Answer 2

Temperature decreases from left to right

Question 3

Main sequence

Answer 3

A long strip from the upper left to the lower right of an HR-diagram, representing long-term stable stars

Question 4

Red giant

Answer 4

Very cool but very bright stars due to their large surface area providing extra radiative power

Question 5

Stellar cluster

Answer 5

A group of stars that are physically close together in the Milky Way galaxy, having condensed from the same nebula and are gravitationally bound together

Question 6

Spectroscopic parallax

Answer 6

Finding the distance to a star using temperature and apparent brightness

Question 7

What measurements are needed find the mass of a binary star system?

Answer 7

The distance between the stars and the period of their orbital motion

Question 8

How do Cepheids work?

Answer 8

Doubly ionized helium traps the energy in the core, causing the temperature to rise so that the star expands. The outer layers cool down as they gain gravitational potential energy and the helium becomes singly ionized, causing the star to collapse