Rare Exoplanets Orbiting Pulsars Searched in the Largest Survey Conducted by Researchers

A survey of rapidly rotating neutron stars, known as pulsars, has revealed that the first exoplanet discovery was an extremely rare find. The first time that exoplanets were discovered was thirty years ago in the year 1992. The exoplanet system was found to be orbiting a pulsar called PSR B1257+12. Later, it was learned that the system has at least three planets having mass similar to that of planets in our solar system. In addition, more pulsars were found to be hosting such planets.

But, considering the violent conditions around a pulsar, it should not be common for such planets to form and survive around them. Pulsars are the densest stars in the universe that are born during supernova explosions at the end of a star's life. They emit beams of bright radio emissions from their magnetic poles which appear to be pulsating to us due to their rotation.

In the latest research, astronomers from the University of Manchester have conducted the largest search for pulsar orbiting exoplanets. The survey included more than 800 pulsars which were analysed over the last 50 years.

“Pulsars produce signals which sweep the Earth every time they rotate, similarly to a cosmic lighthouse. These signals can then be picked up by radio telescopes and turned into a lot of amazing science,” said Iuliana Nițu, a PhD student at the University of Manchester, who will present the paper at the National Astronomy Meeting (NAM 2022) on July 12.

The researchers have tried to detect signals indicating the presence of planetary companions that had around 100 times more mass than Earth with orbital time periods between 20 days and 17 years. The astronomer managed to make 10 potential detections where a system called PSR J2007+3120 was expected to host planets. They were a few times bigger than Earth in terms of mass and had an orbital period of 1.9 and nearly 3.6 years.

The result of the research has shown that these exoplanets would revolve around their stars in a highly elliptical orbit. According to Nitu, the process of formation and survival of planets around pulsars is still yet to be unravelled. “Finding out how common these are, and what they look like is a crucial step towards this,” she added.