By Stacy Palen

Astronomers set a new record for the densest known white dwarf.

Below are some questions to ask your students about this article.

1). How is a white dwarf typically formed?

Answer: A star less than about 8 times the mass of the Sun loses its outer layers, leaving behind a dense carbon core. (Note: This is NOT in the article, but they should know it from class.)

2). How might a system of two white dwarfs form?

Answer: If a binary star system consists of two stars less than 8 times the mass of the Sun, and both stars evolve, the system will become a binary white dwarf system.

3). The lead author states, “Smaller white dwarfs are more massive.” Is this how normal matter (like cows and people) behaves? What is the name for matter that behaves this way?

Answer: No; degenerate matter.

4). How massive is the combined star?

Answer: 1.35 times the mass of the Sun.

5). Why did this pair of white dwarfs not become a supernova when they merged?

Answer: Because this combined mass is under the Chandrasekhar limit.

6). What comes next for this white dwarf?

Answer: It may become a neutron star, as it is dense enough for charge destruction to take place.

7). How often does a merger like this happen?

Answer: We don’t know, but they are probably common, if there is one nearby.

8). This white dwarf has an extreme magnetic field. How did it develop such a strong magnetic field?

Answer: Nobody knows!