PULSAR?

Advantages of Neutron Stars

One key advantage that neutron stars have over black holes is that their surface is visible to us, enabling much to be be learned about their atmospheres and interior structure. 

In 2009, researchers found evidence for a carbon atmosphere on the neutron star in the Cassiopeia A supernova remnant, using NASA's Chandra X-ray Observatory

Figure. The remarkable properties of the carbon atmosphere on the neutron star in the Cassiopeia A supernova remnant.

• It is only about four inches thick and has a density similar to diamond and a pressure more than ten times that found at the center of the Earth .
• As with the Earth's atmosphere, the extent of an atmosphere on a neutron star is proportional to the atmospheric temperature and inversely proportional to the surface gravity. 
• The temperature is estimated to be almost two million degrees, much hotter than the Earth's atmosphere. 
• The surface gravity on Cassiopeia A is 100 billion times stronger than on Earth, resulting in an incredibly thin atmosphere

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.

Formation of Neutron Stars

Figure. The cycle life of stars

• Neutron stars are created when a star a few times the mass of our Sun runs out fuel. The outward pressure generated by fusion reduces rapidly, allowing gravity to pull the star in on itself and trigger a supernova, where the outer layers of a star’s atmosphere get blown into space. 
• The remaining matter continues to collapse under gravity, forcing electrons and protons to be squashed together and become neutrons, and then squashing all the neutrons together. The neutron star will have less mass than its parent star (usually about 1.5 times the mass of the Sun), but this mass will be confined by gravity to a region of just 20 kilometres (12 miles) across!, leading to an incredibly, incredibly dense object
• A neutron star is a very small, super-dense star that is composed mostly of tightly packed neutrons. A rapidly spinning neutron star is known as a pulsar.

Figure. Neutron star formation

Figure. Size neutron stars compared to earth and white dwarf

What is Neutron Stars?

The collapse of a massive star in a supernova explosion is an epic event. In less than a second a neutron star (or in some cases a black hole) is formed and the implosion is reversed, releasing prodigious amounts of light that can outshine billions of Suns. That is a spectacular way to be born.

Figure. 3D illustration of a neutron stars

Neutron stars are the remnants of giant stars that died in a fiery explosion known as a supernova. After such an outburst, the cores of these former stars compact into an ultradense object with the mass of the sun packed into a ball the size of a city.