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UFO? Why are the pulse variations of binary pulsars so shocking?
In the distant universe, pulsars seem to have attracted the attention of countless astronomers with their uniqueness. Pulsars are rapidly rotating neutron stars that emit electromagnetic waves in regular pulses. In a binary pulsar system, one of the pulsars has a companion star, usually a white dwarf or another neutron star. The study of these binary pulsars not only provides us with the opportunity to observe extreme gravity in the universe, but also is an important source of data for verifying Einstein's general theory of relativity.
In these systems, the time intervals between pulses vary due to the gravitational influence of the companion star, allowing scientists to track the objects' motion.
History of binary pulsars
In 1974, astronomers Joseph Houghton Taylor and Russell Halls discovered PSR B1913+16, the "Halls-Taylor binary pulsar," at the Arecibo Observatory. For this he was awarded the 1993 Nobel Prize in Physics. When Halls observed the newly discovered pulsar, he noticed that the frequency of the pulses showed regular changes. The reason for this change is that the pulsar is orbiting the companion star at a high speed, thus causing the Doppler effect.
As a pulsar moves toward Earth, the pulses become more frequent; conversely, as it moves away, the pulses received decrease.
This discovery not only helped scientists realize that pulsars and their companion stars have similar masses, but also led to the first accurate measurement of the mass of a neutron star. By measuring changes in the timing of the pulses, scientists used relativistic timing effects to discover the mass of the pulsar. Over time, the orbital energy of this pulsar system is converted into gravitational waves, causing them to gradually move closer together.
Binary pulsars of intermediate mass
An intermediate-mass binary pulsar (IMBP) is a relatively long-period pulsar-white dwarf system. Pulsars in such systems typically have high masses and relatively long rotation periods, ranging between 10 and 200 milliseconds. Taking PSR J2222−0137 as an example, the mass of this pulsar's companion is at least 1.3 times the mass of the Sun, making it a medium-mass binary pulsar.
The discovery of PSR J2222−0137 further expands our knowledge of pulsar systems, particularly with regard to the properties and masses of companion stars.
The impact of binary pulsars
In a binary pulsar system, X-ray light is generated when the companion star expands and transfers its outer layers to the pulsar, setting off a chain of interactions. The light from these X-ray emissions sometimes shows a pulsed pattern, a phenomenon known as the X-ray binary phase. Due to the flow of matter, an accretion disk is often formed, and the pulsar releases a "wind" that affects the magnetic field and pulse signal emission of the companion star.
These interactions not only demonstrate the pull of pulsars, but also reveal how closely interacting objects in the universe influence each other.
As scientists study binary pulsars more deeply, they are beginning to understand how these mysterious cosmic phenomena challenge our understanding of the fundamental laws of physics. Not only that, the observation of binary pulsars may bring us deeper new insights into gravitational waves and the evolution of the universe in the future. In this vast universe, are there any deeper secrets in the behavior of these pulsars waiting for us to explore?
