What happens when a neutron star collides with a black hole?

Till now you might have thought that this adverse space consists of only planets, stars, other celestial bodies and last but not the least black holes. But this gigantic space has got more surprises in store for you. There’s another crazy thing hidden in this unique space.

It is called Neutron star. These are the stellar objects which can have a mass about 1.5 times that of the Sun but condensed into an area of some kilometres.

Now you might be curious that black holes are also kind of the same thing. But no there is a lot of difference between a neutron star and a black hole. Keep calm and curb your curiosity and we will answer all your questions such as what is a neutron star? How are neutron stars formed? How are they different from black holes? What happens when a neutron star collides with a black hole? All your questions would be answered through this article.

What is a Neutron Star?

A neutron star is a celestial object having a huge mass in a small area. They originate from the explosive death of larger stars, which is known as Supernova. After the explosion, the cores of these huge stars get condensed into an ultra-dense object having a mass nearly of Sun with an area of a city.

How are Neutron stars formed?

According to NASA, normal ordinary stars maintain their shapes due to the heavy gravity of their huge masses. This gravity pulls the gases towards the centre of the star. But this is balanced by the energy from nuclear fusion occurring in the cores which is in the outwards direction.

When these stars are at their end, they burn through the fuel available to them and the internal reactions stop. This makes the stars collapse inward, after which they blast out in an explosive explosion.

Even after this, the cores continue to collapse, generating high pressures. This causes protons and electrons to squeeze into neutrons and neutrinos. This results in the formation of a star that contains 90% neutrons. Neutrons can’t be squeezed any further and thus a neutron star cannot be broken down more.

Features of a neutron star

Neutron star was first theorized during the 1930s when the neutron was discovered. But in 1967, a student in England noticed strange pulses in her radio telescope. She thought that they might be signals from an alien civilisation, but the patterns were rather radiations emitted by spinning neutron stars.

Neutron stars are extremely strange in nature. A small piece of neutron star could be weighing easily around a billion tonnes. Theoretically, if you could stand on the surface of a neutron star, the force of gravity that you would experience would be 2 billion times stronger than the Earth’s gravity.

The gravity is so strong that it can bend radiation from the star. This is called gravitational lensing which allows astronomers to see the backside of the star.

A neutron star gets a great amount of energy from its supernova. This energy enables the neutron star to rotate around its axis anywhere between 0.1 times per second to 700 times per second.

A regular neutron star has a magnetic field about billions or trillion times as that of Earth. Larger neutron stars may have much more than these common ones. This creates a unique object called a magnetar.

According to NASA, magnetar is so much powerful that in just one-tenth of a second, it can release energy more than the Sun has emitted in the last 100,000 years. The most massive neutron star was detected recently in 2019. It was about 2.14 times the mass of our sun compressed into a region around 20km.

What happens when two neutron star collide?

Whenever two neutron stars come close to each other, they start orbiting each other. Both of them spiral each other inwards with time due to the gravitational radiations. As they come closer and closer, they merge together and this merger leads to the formation of either a new heavier neutron star or a black hole.

The result of this collision depends on the mass of the remnant, whether it exceeds a certain limit or not. The collision creates an object having magnetic field nearly trillion times that of Earth, within a time limit of just a few milliseconds.

Scientists believe that this event is responsible for the creation of short gamma ray bursts. In August 2017, the first collision of two neutron stars was detected in both light and gravitational waves.

Effects of neutron star colliding with a black hole

Although such a deadly incident hasn’t been witnessed, the collision of a black hole and a neutron star could release huge amounts of energy. But a new study finds out that the collision might not generate any detectable light.

So far, scientists have seen mergers of black holes with other black holes and mergers of neutron stars with other neutron stars. The next thing to be seen is the merger of a black hole with a neutron star.

But recently, astronomers have seen a black hole engulfing a neutron star. Coincidentally, the same incident was witnessed again nearly 10 days later. In both cases, a neutron star orbits a black hole. They finally crash together and then the neutron star is gone in a gobble.

Scientists studied the last orbits of the neutron star before it was swallowed. The black hole was nearly nine times the mass of the Sun while the neutron star, small in size, still was twice the mass of the Sun. It took less than a minute and generated energy around all the visible light in the universe.

The energy released from the collision was detected on Earth by detectors which spotted the gravitational waves and cosmic ripples. The waves came from a distance of nearly one billion light-years. This was the first time when researchers saw the collision of a neutron star and a black hole.

According to scientists, there may be many such pairings of neutron stars and black holes. But no such pairing is yet found in our Milky Way galaxy.


Neutron stars and black holes are such mysterious objects of space. They are constantly under study and scientists and researchers have a keen eye on their recent activities. Estimates say that there may be more than a hundred million neutron stars in our galaxy. Most of them will be quite difficult to detect and won’t be seen ever.

However, recently we got a small answer to what happens when a neutron star collides with a black hole when a neutron star and a black hole collided in which the black hole engulfed its counterpart.

Thank you for staying with us till here in the article on “What happens when neutron star collides with a black hole?” If you are excited about living somewhere else apart from Earth, then go ahead and read our article “What are the chances of life on other planets in our solar system?” If you want us to write on a certain topic or have any recommendations for us, do write them in the comments section.

Frequently Asked Questions

Q- How long is the life of a neutron star?

Ans – theoretically, a neutron star would stay in the universe exactly the same forever. A neutron star doesn’t evolve, it just cools down and would never die.

Q- What would happen if something falls on a neutron star?

Ans – any matter which will fall on a neutron star would be accelerated to enormous speeds because of its gravity. The force would destroy the object completely.

Q- Name the densest thing in the universe.

Ans – the densest thing in this universe is the neutron star because it is a huge mass object compressed into a region of few kilometres.

Q- What are some examples of Neutron stars?

Ans – RX J1856.5−3754 is one of the closest neutron stars to the Earth. It is nearly 400 light-years away from our Earth. Another one is PSR J0108−1431 which is 424 light-years away.

Q- What is a Kilonova?

Ans – Kilonova is an astronomical term given to the event of collision in a compact binary system. This typically involves two neutron stars or a neutron star and a black hole.

Q- Which chemical elements are produced during a Kilonova?

Ans – During a Kilonova, r-process elements such as strontium, gold, silver and europium are produced.

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