Astronomers believe that the first-ever exoplanets discovered about 30 years ago around a rapidly rotating star called a pulsar could be incredibly rare. The Jodrell Bank Observatory surveyed 800 pulsars over the last 50 years and revealed that the first exoplanet system might be uncommon since less than 0.5% of all known pulsars could host Earth-mass planets.
Iuliana Nițu, a Ph.D. student at the University of Manchester, and the team of astronomers are set to present their findings on July 12 at the National Astronomy Meeting (NAM 2022).
First-Ever Exoplanets Discovered 30 Years Ago Might Be Extraordinarily Rare
What Are Pulsars?
Pulsars were first discovered in 1967 and had always looked like a flickering star from Earth with its on and off light that seemed to blink with a regular rhythm. However, according to Space.com, pulsars do not flicker or pulse and are not actual stars.
They are spherical and compact objects, a type of neutron star that is about the same size as a large city but contains more mass than the sun. Scientists study pulsars to learn the extreme states of matter, search for planets outside the Solar System, and measure cosmic distances. They also help scientists find gravitational waves that could point to energetic cosmic events.
Pulsars are born from powerful explosions of stars and are exceptionally stable with a strong magnetic field. They emit beams of bright radio emission from their magnetic poles, making them appear to pulse as they rotate.
According to Nitu, pulsars produce signals that sweep the Earth every time they rotate, just like a cosmic lighthouse. Radio telescopes pick up these signals that scientists study.
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Pulsar System Holding Planets Are Incredibly Rare
Scientists first discovered exoplanets in 1992, wherein they found some planets orbiting the pulsar called PSR B1257+12. The pulsar system holds three exoplanets that are similar in mass to the rocky planets in the Solar System.
Since then, astronomers have found a few pulsars that also host planets. But since extremely violent conditions surround their birth, the formation of a typical planet is improbable. Most of the planets they detected orbiting a pulsar are also made up of exotic objects, such as planets made up of diamonds, that are unusual in the Solar System, EurekAlert! reported.
The team of astronomers from Manchester University performed the largest search of pulsar systems to date and looked for signals that indicate the presence of exoplanets that have a mass of up to 100 times of Earth and an orbital period of 20 days and 17 years.
They were able to detect 10 possible pulsar systems, but the most promising of them all is the PSR J2007+3120. The team noted that it is possibly hosting at least two planets and has a mass a few times bigger than Earth. It also has an orbital period of 1.9 and approximately 3.6 years.
The results yield information about the shape of the orbit of the exoplanets in pulsar systems, which is different from the orbits found in the Solar System. Planets orbiting a pulsar follow a highly elliptical orbit, indicating that it has a different formation process than a traditional star system.
Three decades have passed since the first discovery of exoplanets, but scientists are yet to understand how these planets can form and survive in such extreme conditions. The findings could be a crucial step towards understanding them.
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