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These pulses are not just flashes of light, but rather coded messages that hold keys to understanding the universe and its evolution. So, what are these mysterious pulses? How do they contribute to our understanding of the vast universe? What are the mysterious signals they send, and what cosmic forces drive them?
What are the pulses of stars?
Pulsars are neutron stars that spin very rapidly, emitting beams of electromagnetic radiation, radio waves, X-rays, and gamma rays. These beams are seen as regular pulses of light, which is why they are called pulsars.
Pulsars are formed when a massive star collapses at the end of its life, leaving behind an extremely dense, compact core. This core, a neutron star, retains most of the original star's spin momentum, causing it to spin at incredible speeds, hundreds or even thousands of times per second.
Stellar pulsations are the extremely dense remnants of massive stars that exploded as supernovae, so it is believed that the very strong magnetic field of the neutron star is responsible for generating these beams of radiation..
Detecting stellar pulses
The discovery of stellar pulsations is a revolutionary event in astronomy. It was not the product of a single moment, but rather the result of the development of technology and scientific research. It went through several different stages, including:
Stage 1: Theoretical predictions (late 1940s and 1950s)
Before the actual discovery, there were theoretical predictions about the possibility of the existence of extremely dense astronomical objects that rotate very quickly and emit periodic radiation, but these predictions were not precise enough to determine the nature of these objects..
Stage 2: Accidental Discovery (1967)
In 1967, Jocelyn Bell Burnell, a graduate student at Cambridge University, was working under Anthony Hewish to build a large radio telescope to study cosmic radio flashes.
While analyzing the data, they noticed a strange radio signal that repeated regularly every 1.33 seconds. Initially, the team thought the signal might be from an Earth-based source, such as a secret military transmission, or an extraterrestrial source.
Stage Three: Confirmation and Analysis (1968 and later)
After ruling out all terrestrial possibilities, the team concluded that the signal came from an astronomical source. They called these sources: Stellar pulsations), after discovering more pulsations, scientists realized that they were caused by neutron stars rotating at high speed, emitting beams of radio radiation..
The importance of star pulses
Stellar pulsations are very important in astronomy for several reasons, including::
Testing physical theories: Stellar pulsations are unique natural laboratories for testing physical theories under extremely harsh conditions, such as extreme gravity and strong magnetic properties. Studying them helps us better understand gravity, matter at high densities, and strong magnetic fields. .
Measuring cosmic distances: Some types of stellar pulsations, such as millisecond pulsations, have consistent properties that enable astronomers to use them as “standard candles” to measure cosmic distances with high accuracy. .
Studying the evolution of stars: Stellar pulsations are the remains of massive stars, and studying them helps us understand the stages of stellar evolution, especially in their final stages. They show us how the lives of massive stars end, and how these dense objects are formed. .
Detecting gravitational waves: Stellar pulsations are used to detect gravitational waves, which are ripples in the fabric of spacetime predicted by Einstein's theory of general relativity. Studying subtle changes in the signals of stellar pulsations helps detect these waves. .
Strong Understanding magnetic fields: Stellar pulsations are characterized by extremely strong magnetic fields, and studying them helps understand the generation and evolution of these fields in the universe..
Therefore, stellar pulsations are valuable tools for better understanding the universe, by providing valuable information about fundamental physics, stellar evolution, measuring cosmic distances, and revealing rare physical phenomena.
Properties of stellar pulsations
Pulsating stars (pulsars) are characterized by a set of distinctive properties, the most important of which are :
High periodicity: The most distinctive feature of stellar pulsations is that they emit radio signals and other electromagnetic waves, sometimes in a very precise and periodic manner, ie at a very regular frequency. This periodicity results from the star rotating at a very high speed .
High rotation speed: Pulsars rotate at an enormous speed, hundreds or thousands of revolutions per second. This rapid rotation is what causes the periodic signals to be emitted. .
Strong magnetic field: Stellar pulsations are characterized by extremely strong magnetic fields, millions of times stronger than the Earth's magnetic field. This magnetic field plays a fundamental role in the mechanism of producing periodic radiation. .
High mass and density: Pulsating stars are made of high-density material, where the material is tightly compressed, resulting in a high mass in a small volume.
Composition: They are mostly made of neutrons, so they are sometimes called neutron stars, reflecting the intense pressure of matter that forces electrons and protons to fuse and form neutrons. .
Type of radiation: Stellar pulsations are usually detected through their radio emissions, but some also emit in other bands of the electromagnetic spectrum, such as X-rays and gamma rays..
Small Sizes: Despite their high mass, pulsars are extremely small, with diameters ranging from 10 to 20 kilometers. These combined characteristics make pulsars unique and interesting phenomena in astronomy.
The difference between the pulses of stars and ordinary stars
There is a big difference between the pulsations of stars and ordinary stars, which is:
Composition and physical properties: Ordinary stars are massive celestial bodies composed primarily of hydrogen and helium, producing energy through nuclear fusion in their cores.
As for pulsating stars, they are extremely dense neutron stars, the remnants of a supernova explosion of a massive star. Neutron stars are very small, with a diameter of only about 20 km.
The pulsating stars have a mass much greater than that of the Sun. Their density is so enormous that a teaspoon of neutron star material would weigh millions of tons on Earth. .
Rotational Speed: Pulsating stars rotate at tremendous speeds, reaching hundreds of revolutions per second. This high speed results from the conservation of angular momentum during the collapse of the original star into a neutron star. Regular stars also rotate, but at much slower speeds..
Radiation: Stellar pulsations emit very powerful radiation, especially radio waves, in the form of regular, recurring pulses, as a result of the neutron star's enormous magnetic field and high rotational speed. Normal stars, on the other hand, emit thermal radiation continuously, to varying degrees depending on their mass and temperature..
Activity: Pulsating stars exhibit strong dynamic activity, such as powerful emissions of charged particles and electromagnetic waves, but normal stars, although some may show some activity, are generally more stable. .
Pulsating stars are unique and extreme celestial bodies, completely different from ordinary stars in their composition, density, rotational speed, type of radiation, and extent of activity..
The importance of studying stellar pulsations
Studying stellar pulsations greatly helps in understanding the evolution of other stars, since stellar pulsations are the remains of massive stars that collapsed in on themselves after running out of their nuclear fuel. Studying their properties, such as their rotational speed, mass, and magnetic field, gives us valuable information about:
The final stages of the lives of massive stars: Stellar pulsations show us what happens to massive stars at the end of their lives, and how they collapse into extremely compact objects..
Physical processes in stars: Studying stellar pulsations helps us understand the complex physical processes that occur inside stars, such as nuclear reactions and magnetic processes. This information is applicable to understanding other stars, even those that have not yet reached the final stages of their lives..
Galaxy Evolution: The distribution of pulsations of stars in galaxies tells us about the history of star formation in those galaxies, and how they evolved over time..
Physical conditions in extreme environments: Stellar pulsations represent extremely harsh environments, and studying them helps us understand the behavior of matter under conditions of very high pressure and density. This knowledge is applicable to understanding other stars that experience similar conditions, albeit to a lesser extent..
In short, stellar pulsations, despite being stellar remnants, provide valuable examples of physical processes and stellar evolution, helping us understand the life cycle of stars more deeply and comprehensively.
These celestial bodies raise more questions than they answer, inspiring us to search for answers that will unravel the mystery surrounding these amazing cosmic rhythms. The journey of discovery is far from over, as the chambers of the universe still hold many surprises behind the lights of these pulsating stars. Will their full secrets ever be revealed? The question remains suspended in the realm of infinite possibilities.