Among the various celestial bodies that exist in the universe, some celestial bodies are too special in their formation and characteristics. Among these celestial bodies we find the pulsar. Many people do not know what is a pulsar nor what relevance it has. As a general and simple definition, a pulsar is an extremely dense and highly magnetized neutron star that emits electromagnetic radiation in regular pulses as it rotates on its axis.
In this article we are going to tell you what a pulsar is, how it is formed, its characteristics and its importance.
What is a pulsar
A pulsar is a type of highly compact and energetic astronomical object known as a neutron star. Neutron stars are extremely dense remnants that result from the explosion of a supernova into massive stars. A particular pulsar is observable when its axis of rotation points toward Earth and it periodically emits radiation.
The most distinctive feature of a pulsar is its ability to emit regular pulses of electromagnetic radiation, ranging from radio waves to gamma rays. These pulses are caused by the rapid rotation of the neutron star and its intense magnetic fields. As the pulsar spins, its radiation emissions are detected at regular intervals, creating a signal that appears to "pulse" in the sky.
A pulsar's rotation can be incredibly fast, with periods ranging from fractions of a second to several seconds. This rapid rotation also results in extremely intense magnetic fields, billions of times stronger than Earth's magnetic fields. These intense magnetic fields can influence the emission of radiation and the formation of winds of highly energetic particles around the pulsar.
How they are formed
Pulsars form when a massive star (at least three times the mass of the Sun) exhausts its nuclear fuel and explodes as a supernova. During the explosion, the core of the star collapsed under the force of gravity and was compressed into a sphere several kilometers in diameter. As a result, the star becomes extremely dense, about the mass of the Sun, but compressed until it becomes an object the size of a city.
Due to the conservation of angular momentum, the neutron star begins to spin rapidly (in some cases hundreds of times per second). If a star has a strong magnetic field, the magnetic energy stored in the field is converted into electromagnetic radiation, which is emitted in the form of pulses of light as the star rotates.
Pulsars have several notable features. We can say in the first part that they emit radiation of very short wavelengths, such as X-rays and gamma rays, and the radio region of the electromagnetic spectrum. Second, the pulses are extremely regular and precise, with a periodicity that can be measured with great precision. Finally, pulsars have very strong magnetic fields, possibly millions of times stronger than Earth's magnetic field.
Discovery
According to the scientific magazine National Geographic, pulsars were discovered in the late 1960s, in 1967, by a graduate student named Jocelyn Bell and her advisor, Antony Hewish, at the Mullard Shield Radio Astronomy Observatory near Cambridge. The truth of the matter was that they encountered a radio signal source that repeated every night during business hours. They came from the same place in the sky and thought they were making contact with aliens for the first time.
Arguably, pulsars, in addition to being very interesting and unique objects, are also dense, highly magnetized neutron stars that emit radiation in regular pulses as they spin. They are the result of massive stars collapsing into supernovae and are useful for studying fundamental physics such as general relativity and dense matter physics.
Importance of a pulsar
As we have already seen, in addition to providing valuable information about extreme physics in the universe, pulsars play a crucial role in several fields of astronomical research. Some of the areas where pulsars are important include:
- General relativity: Pulsars can be used to study the effects of Einstein's general relativity, such as the curvature of spacetime around massive objects. Precise measurements of the arrival times of pulses as they pass through the gravitational field of another star or massive object allow us to verify the predictions of general relativity.
- Extreme Matter: Pulsars are natural laboratories for exploring matter under extreme conditions. The incredible density and intense pressure in a neutron star provide information about matter in states that we cannot recreate in terrestrial laboratories. This includes the internal structure of neutron stars and the properties of ultra-dense matter.
- Space navigation: Pulsars are used in high-precision space navigation. Pulsar pulse signals can be detected from distant space probes and are used as cosmic "beacons" to accurately calculate the craft's location in space.
- Cosmology: Pulsars are also useful in cosmology. They can be used to study the interstellar medium and to map the distribution of matter in our galaxy. This can provide information about the structure and evolution of the Milky Way.
- Gravitational wave detection: Some pulsars, called millisecond pulsars, have exceptionally high pulsar stability. These can be used as precise cosmic clocks in experiments to detect gravitational waves, helping to confirm the existence of these waves and to study astrophysical phenomena such as black hole mergers.
- Stellar evolution: Studying pulsars and their relationship with supernova explosions provides us with valuable information about the evolution and life cycle of massive stars. This in turn helps us better understand how different species of stars in the universe form and evolve.
As you can see, pulsars are important to astronomers because they provide valuable information about the extreme properties of matter, strong magnetic field interactions, and the dynamics of neutron stars. I hope that with this information you can learn more about what a pulsar is and its characteristics.