Q 01/05

A white dwarf packs a mass comparable to the Sun's into a volume roughly the size of what?

A) Earth

B) The Moon

C) Jupiter

D) A city

Answer · why

A) Earth

That gives an average density of about a tonne per cubic centimetre.

Q 02/05

What is the source of a white dwarf's light?

A) Gravitational collapse

B) Residual heat, not fusion

C) Ongoing hydrogen fusion

D) Helium burning in a shell

Answer · why

B) Residual heat, not fusion

Once formed, its material no longer undergoes fusion, so it slowly cools and reddens.

Q 03/05

How far away is Sirius B, the nearest known white dwarf?

A) 11.9 ly

B) 25 ly

C) 8.6 ly

D) 4.2 ly

Answer · why

C) 8.6 ly

It is the smaller partner of the brightest star in the night sky.

Q 04/05

In which year was 40 Eridani B recognised as the first white dwarf?

A) 1862

B) 1922

C) 1931

D) 1910

Answer · why

D) 1910

Russell, Pickering and Fleming found the dim star had a puzzling white A-type spectrum.

Q 05/05

Who coined the name 'white dwarf' in 1922?

A) Willem Jacob Luyten

B) Arthur Eddington

C) Henry Norris Russell

D) Ejnar Hertzsprung

Answer · why

A) Willem Jacob Luyten

Eddington then popularised the term.