Characteristics of Neutron Stars

(Image: © NASA/Dana Berry)

• A single teaspoon of neutron-star material would weigh a billion tons

• An ordinary neutron star's magnetic field might be trillions of times stronger than Earth's.

• Neutron stars are the smallest and densest stars

• Neutron stars have a radius on the order of 10 kilometres (6.2 mi) and a mass of about 1.4 solar masses

• Neutron stars are composed almost entirely of neutrons (subatomic particles with no net electrical charge and with slightly larger mass than protons); the electrons and protons present in normal matter combine to produce neutrons at the conditions in a neutron star.

• Neutron stars are partially supported against further collapse by neutron degeneracy pressure, a phenomenon described by the Pauli exclusion principle, just as white dwarfs are supported against collapse by electron degeneracy pressure.

• Neutron stars that can be observed are very hot and typically have a surface temperature of around 600000 K.

• They are so dense that a normal-sized matchbox containing neutron-star material would have a weight of approximately 3 billion tonnes, the same weight as a 0.5 cubic kilometre chunk of the Earth (a cube with edges of about 800 metres) from Earth's surface.

• Their magnetic fields are between 10⁸ and 10¹⁵ (100 million to 1 quadrillion) times stronger than Earth's magnetic field

• The gravitational field at the neutron star's surface is about 2×10¹¹ (200 billion) times that of Earth's gravitational field.

• There are thought to be around 100 million neutron stars in the Milky Way.

• Neutron stars in binary systems can undergo accretion which typically makes the system bright in X-rays.