The numbers
- How big it is
- 19mi(30 km)As big as a city
- How much it weighs
- From 1.5 to 3 times the Sun
- What it is made of
- Almost only neutronsDegenerate matter
- Where it comes from
- The collapse of a big starMore than ten times the Sun
To get an idea
A single teaspoon of that matter, brought to the Earth, would weigh as much as a mountain.
Below a certain mass a white dwarf is left; above it gravity keeps going and a black hole is born.
Fun facts
These are not in the book: there was no room on paper.
It is born from the collapse of the heart of a star more than ten times as massive as the Sun.
Its final mass is between one and a half and three times that of the Sun.
The heaviest one observed so far reaches a little more than twice the mass of the Sun.
Below a certain mass threshold a white dwarf forms instead, which is much less extreme.
Above that threshold gravity does not stop, and the collapse goes on until it makes a black hole.
Test yourself
The first question is the one printed under the QR code, with the answer the book did not give. The other four only exist here.
Question 1 of 5★ is the one from your book
How big is a neutron star?
Question 2 of 5
How much matter does it hold?
Question 3 of 5
What is it made of?
Question 4 of 5
Where does it come from?
Question 5 of 5
What happens if the mass is even bigger?
Riddles
I am as wide as a city, and yet inside me there is more stuff than inside the star that warms you. A teaspoon of me, at your place, would weigh as much as a mountain. What am I?
Inside me the atoms did not hold up: they were crushed into one another until almost only one kind of piece was left, the one with no charge. What am I?
I am born from the heart of a huge star that has just exploded. If I were a little lighter I would end up as something less extreme; if I were heavier I would vanish completely. What am I?
Try it yourself
Take a marble and imagine squeezing the whole mass of a mountain inside it: that is the density we are talking about.
Spin on an office chair with your arms wide and then pull them to your chest: you suddenly speed up. A collapsing star's heart does the same.
The words
- degenerate matter
- Matter squeezed so hard that it behaves in a completely new way.
Sources: Wikidata (Q34490), Wikipedia (Stella di neutroni).