First Ever Exoplanets Discovered 30 Years Ago May Be 'Extraordinarily' Rare, Astronomers Reveal

Astronomers discovered the first ever exoplanets 30 years ago around a rapidly rotating star, called a pulsar. These exoplanets are extremely rare, astronomers have revealed.

An artist's concept of the pulsar planet system discovered by Aleksander Wolsczczan in 1992.

Astronomers discovered the first ever exoplanets 30 years ago around a rapidly rotating star, called a pulsar. These exoplanets are extremely rare, astronomers from the University of Manchester have revealed.

The new work was presented July 12 at the National Astronomy Meeting (NAM 22) by Iuliana Nitu, a researcher at the University of Manchester. 

Astronomers are currently not aware of the processes that cause planets to form, and survive, around pulsars. The Jodrell Bank Observatory followed a survey of 800 pulsars over the last 50 years. The survey has revealed that the first detected exoplanet system may be extraordinarily uncommon. This is because less than 0.5 per cent of all known pulsars could host Earth-mass planets. 

What Are Pulsars?

Pulsars are a type of neutron star morning during powerful explosions at the end of a typical star's life. They are the densest stars in the universe, and are exceptionally stable, rapidly rotating, and have incredibly strong magnetic fields. These stars emit beams of bright radio emission from their magnetic poles that appear to pulse as the star rotates. 

According to a statement released by the Royal Astronomical Society, Iuliana Nitu said that pulsars produce signals which sweep the Earth every time they rotate, similar to a cosmic lighthouse. The signals produced by pulsars can be picked up by radio telescopes and turned into a lot of amazing science.

Which Pulsar Do The First Ever Exoplanets Discovered Orbit?

The first ever exoplanets were discovered orbiting a pulsar called PSR B1257+12, in 1992, by Aleksander Wolsczczan. Astronomers now know that the planetary system hosts at least three planets similar in mass to the rocky planets in our solar system. 

Since 1992, a handful of pulsars have been found to host planets. According to the Royal Astronomical Society, the extremely violent conditions surrounding the births and lives of pulsars make 'normal' planet formation unlikely, and many of these detected planets are exotic objects. For instance, there are some planets made mostly of diamonds. These planets are likely those known in our solar system.

Formation Of Pulsar-Planet Systems Different From Traditional Star-Planet Systems

Astronomers at the University of Manchester performed the largest search for planets orbiting pulsars to date, looking for signals that indicate the presence of planetary companions with masses up to 100 times that of the Earth, and orbital time periods between 20 days and 17 years. The astronomers detected 10 potential candidates. The most promising candidate is the system PSR J2007+3120. 

According to the Royal Astronomical Society, the planet has the possibility of hosting at least two planets, with masses a few times bigger than the Earth, and orbital periods between 1.9 and 3.6 years. 

The results present information on the shape of the orbits of these planets. In contrast to the near-circular orbits found in the solar system, the planets would orbit their stars on highly elliptical paths, indicating that the formation process for pulsar-planet systems is vastly different from traditional star-planet systems.