Which of these stars has the shortest life expectancy? 

What happens to a cloud’s thermal pressure if its temperature falls while its density rises? 

Which of these stars has the hottest core? 

Why are the very first stars thought to have been much more massive than the Sun? 

What would stars be like if carbon had the smallest mass per nuclear particle? 

Who was largely responsible for the spectral classification system, and the classification of the stars in the HD catalogue? 

Define the luminosity of a star. The luminosity is: 

Which of these stars does not have fusion occurring in its core? 

Which stellar clusters usually have more stars? 

When

a user fills out circles with a pencil to answer for example, an exam, it will

be read by a _____ scanner.